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Barrett M, Miranda C, Veloso IT, Flint C, Perl CD, Martinez A, Fischer B, Tomberlin JK. Grinding as a slaughter method for farmed black soldier fly ( Hermetia illucens) larvae: Empirical recommendations to achieve instantaneous killing. Anim Welf 2024; 33:e16. [PMID: 38510427 PMCID: PMC10951668 DOI: 10.1017/awf.2024.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/02/2024] [Accepted: 01/12/2024] [Indexed: 03/22/2024]
Abstract
At least 200 billion black soldier fly (Hermetia illucens) larvae (BSFL) are reared each year as food and feed, and the insect farming industry is projected to grow rapidly. Despite interest by consumers, producers, and legislators, no empirical evidence exists to guide producers in practicing humane - or instantaneous - slaughter for these novel mini-livestock. BSFL may be slaughtered via freezing, boiling, grinding, or other methods; however standard operating procedures (SOPs) and equipment design may affect the likelihood of instantaneous death using these methods. We tested how larval body size and particle size plate hole diameter affect the likelihood of instantaneous death for black soldier fly larvae that are slaughtered using a standard meat grinder. Larval body size did not affect the likelihood of instantaneous death for larvae that are 106-175 mg in mass. However, particle size plate hole diameter had a significant effect on the likelihood of instantaneous death, with only 54% of larvae experiencing an instant death when using the largest particle size plate (12-mm hole diameter) compared to 84% using the smallest particle size plate (2.55 mm). However, a higher percentage of instantaneous death (up to 99%) could be achieved by reducing the proportion of larvae that become stuck in the machine. We conclude by outlining specific recommendations to support producers in achieving a 99% instantaneous death rate through specific SOPs to be used with similarly designed machines. We also develop a protocol for producers that wish to test their own grinding SOPs.
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Affiliation(s)
- Meghan Barrett
- Department of Biology, Indiana University Indianapolis, Indianapolis, IN, USA
- Department of Biology, California State University Dominguez Hills, Carson, CA, USA
| | - Chelsea Miranda
- Department of Biology, Howard Payne University, Brownwood, TX, USA
| | - I Theresse Veloso
- Department of Biology, California State University Dominguez Hills, Carson, CA, USA
| | - Casey Flint
- Department of Entomology, Texas A & M University, College Station, TX, USA
| | - Craig D Perl
- Insect Welfare Research Society, Indianapolis, IN, USA
| | - Austin Martinez
- Department of Biology, California State University Dominguez Hills, Carson, CA, USA
| | - Bob Fischer
- Department of Philosophy, Texas State University, San Marcos, TX, USA
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2
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Bretzlaff T, Kerr JT, Darveau CA. High temperature sensitivity of bumblebee castes and the colony-level costs of thermoregulation in Bombus impatiens. J Therm Biol 2023; 117:103710. [PMID: 37716225 DOI: 10.1016/j.jtherbio.2023.103710] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 09/02/2023] [Accepted: 09/03/2023] [Indexed: 09/18/2023]
Abstract
Physiological thermal limits often reflect species distribution, but the role that ambient temperature (Ta) plays in limiting species within their thermal environment remains unclear. Climate change-linked declines in bumblebees, an important pollinator group, leave questions regarding which aspect of their physiology is hindered under high Ta. As a eusocial species, bumblebees utilize their ability to thermoregulate as a superorganism to maintain nest temperature (Tn) within a narrow thermal window to buffer developing larvae from developmental defects. Thermoregulatory behaviours, such as thermogenesis to warm up and fanning to cool down the nest, are energetically expensive and it is uncertain how successful large colonies are at maintaining Tn within its optimal range. Using a common bumblebee species, Bombus impatiens, our study first established the critical thermal limits (CTmax) of workers, queens, drones and larvae to determine which caste is most thermally sensitive to heat. We found that larvae had significantly lower heat tolerance than adults, highlighting the importance of colonial thermoregulation. We then measured the energy expenditure of large colonies under acute thermal stress (5-40 °C) using flow-through respirometry while simultaneously quantifying Tn. Colonies that experienced Ta at or below optimal Tn (≤30 °C) were successful at thermoregulation. At 35 °C and above, however, Tn increased despite high energetic costs to the colony. Together our results demonstrate that high Ta poses a risk to colonies that fail to buffer thermally sensitive larvae from changes in Tn.
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Affiliation(s)
- Tiffany Bretzlaff
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
| | - Jeremy T Kerr
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
| | - Charles-A Darveau
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
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3
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Putero FA, Mensch J, Schilman PE. Effect of brief exposures of anesthesia on thermotolerance and metabolic rate of the spotted-wing fly, Drosophila suzukii: Differences between sexes? JOURNAL OF INSECT PHYSIOLOGY 2023; 149:104549. [PMID: 37495184 DOI: 10.1016/j.jinsphys.2023.104549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 07/28/2023]
Abstract
The spotted-wing fly, Drosophila suzukii, is a world-wide pest insect for which there is increasing interest in its physiological traits including metabolism and thermotolerance. Most studies focus only on survival to different time exposures to extreme temperatures, mainly in female flies. In addition, it has not been tested yet how anesthesia affects these measurements. We analyzed the effects of anesthesia by brief exposures to cold, anoxia by CO2 or N2 on three standard thermotolerance assays, as well as the aerobic metabolic rate in both sexes. For heat tolerance we measured CTmax by thermolimit respirometry, and CTmin and chill-coma recovery time for cold tolerance. Aerobic metabolism was calculated by CO2 production of individual flies in real time by open flow respirometry. Results showed that females have a significantly higher V̇CO2 for inactive (at 25 °C) and maximum metabolic rate than males. This difference is mainly explained by body mass and disappears after mass correction. Males had a more sensitive MR to temperature than females showed by a significantly higher Q10 (2.19 vs. 1.98, for males and females, respectively). We observed a significantly lower CTmin (X2 = 4.27, P = 0.03) in females (3.68 ± 0.38 °C) than males (4.56 ± 0.39 °C), although we did not find significant effects of anesthesia. In contrast, anesthesia significantly modifies CTmax for both sexes (F3,62 = 7.86, P < 0.001) with a decrease of the CTmax in cold-anesthetized flies. Finally, we found a significantly higher CTmax in females (37.87 ± 0.07 °C) than males (37.36 ± 0.09 °C). We conclude that cold anesthesia seems to have detrimental effects on heat tolerance, and females have broader thermotolerance range than males, which could help them to establish in invaded temperate regions with more variable environmental temperatures.
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Affiliation(s)
- Florencia A Putero
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Laboratorio de Ecofisiología de Insectos, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Buenos Aires, Argentina
| | - Julian Mensch
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ecología, Genética y Evolución, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina.
| | - Pablo E Schilman
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Laboratorio de Ecofisiología de Insectos, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Buenos Aires, Argentina.
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4
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Prileson EG, Clark J, Diamond SE, Lenard A, Medina-Báez OA, Yilmaz AR, Martin RA. Keep your cool: Overwintering physiology in response to urbanization in the acorn ant, Temnothorax curvispinosus. J Therm Biol 2023; 114:103591. [PMID: 37276746 DOI: 10.1016/j.jtherbio.2023.103591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 06/07/2023]
Abstract
Winter presents a challenge for survival, yet temperate ectotherms have remarkable physiological adaptations to cope with low-temperature conditions. Under recent climate change, rather than strictly relaxing pressure on overwintering survival, warmer winters can instead disrupt these low-temperature trait-environment associations, with negative consequences for populations. While there is increasing evidence of physiological adaptation to contemporary warming during the growing season, the effects of winter warming on physiological traits are less clear. To address this knowledge gap, we performed a common garden experiment using relatively warm-adapted versus cold-adapted populations of the acorn ant, Temnothorax curvispinosus, sampled across an urban heat island gradient, to explore the effects of winter conditions on plasticity and evolution of physiological traits. We found no evidence of evolutionary divergence in chill coma recovery nor in metabolic rate at either of two test temperatures (4 and 10 °C). Although we found the expected plastic response of increased metabolic rate under the 10 °C acute test temperature as compared with the 4 °C test temperature, this plastic response, (i.e., the acute thermal sensitivity of metabolic rate), was not different across populations. Surprisingly, we found that winter-acclimated urban ant populations exhibited higher heat tolerance compared with rural ant populations, and that the magnitude of divergence was comparable to that observed among growing-season acclimated ants. Finally, we found no evidence of differences between populations with respect to changes in colony size from the beginning to the end of the overwintering experiment. Together, these findings indicate that despite the evolution of higher heat tolerance that is often accompanied by losses in low-temperature tolerance, urban acorn ants have retained several components of low-temperature physiological performance when assessed under ecologically relevant overwintering conditions. Our study suggests the importance of measuring physiological traits under seasonally-relevant conditions to understand the causes and consequences of evolutionary responses to contemporary warming.
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Affiliation(s)
- Eric G Prileson
- Case Western Reserve University, Department of Biology, USA.
| | - Jordan Clark
- Case Western Reserve University, Department of Biology, USA
| | | | - Angie Lenard
- Case Western Reserve University, Department of Biology, USA
| | | | - Aaron R Yilmaz
- USDA Agricultural Research Service, Horticultural Insects Research Laboratory, USA
| | - Ryan A Martin
- Case Western Reserve University, Department of Biology, USA
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5
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Habitat-dependent variation in consistent behavioural traits does not affect the efficiency of resource acquisition in a thermophilic ant. Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-022-03274-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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6
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Kearney MR, Jasper ME, White VL, Aitkenhead IJ, Blacket MJ, Kong JD, Chown SL, Hoffmann AA. Parthenogenesis without costs in a grasshopper with hybrid origins. Science 2022; 376:1110-1114. [PMID: 35653484 DOI: 10.1126/science.abm1072] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The rarity of parthenogenetic species is typically attributed to the reduced genetic variability that accompanies the absence of sex, yet natural parthenogens can be surprisingly successful. Ecological success is often proposed to derive from hybridization through enhanced genetic diversity from repetitive origins or enhanced phenotypic breadth from heterosis. Here, we tested and rejected both hypotheses in a classic parthenogen, the diploid grasshopper Warramaba virgo. Genetic data revealed a single hybrid mating origin at least 0.25 million years ago, and comparative analyses of 14 physiological and life history traits showed no evidence for altered fitness relative to its sexual progenitors. Our findings imply that the rarity of parthenogenesis is due to constraints on origin rather than to rapid extinction.
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Affiliation(s)
- Michael R Kearney
- School of BioSciences, The University of Melbourne, Victoria 3010, Australia
| | - Moshe E Jasper
- Bio21 Institute, School of BioSciences, The University of Melbourne, Victoria 3010, Australia
| | - Vanessa L White
- School of BioSciences, The University of Melbourne, Victoria 3010, Australia
| | - Ian J Aitkenhead
- School of Biological Sciences, Monash University, Victoria 3800, Australia
| | - Mark J Blacket
- School of BioSciences, The University of Melbourne, Victoria 3010, Australia
| | - Jacinta D Kong
- School of BioSciences, The University of Melbourne, Victoria 3010, Australia
| | - Steven L Chown
- School of Biological Sciences, Monash University, Victoria 3800, Australia
| | - Ary A Hoffmann
- Bio21 Institute, School of BioSciences, The University of Melbourne, Victoria 3010, Australia
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7
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Nascimento G, Câmara T, Arnan X. Critical thermal limits in ants and their implications under climate change. Biol Rev Camb Philos Soc 2022; 97:1287-1305. [PMID: 35174946 DOI: 10.1111/brv.12843] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/28/2022]
Abstract
Critical thermal limits (CTLs) constrain the performance of organisms, shaping their abundance, current distributions, and future distributions. Consequently, CTLs may also determine the quality of ecosystem services as well as organismal and ecosystem vulnerability to climate change. As some of the most ubiquitous animals in terrestrial ecosystems, ants are important members of ecological communities. In recent years, an increasing body of research has explored ant physiological thermal limits. However, these CTL data tend to centre on a few species and biogeographical regions. To encourage an expansion of perspectives, we herein review the factors that determine ant CTLs and examine their effects on present and future species distributions and ecosystem processes. Special emphasis is placed on the implications of CTLs for safeguarding ant diversity and ant-mediated ecosystem services in the future. First, we compile, quantify, and categorise studies on ant CTLs based on study taxon, biogeographical region, methodology, and study question. Second, we use this comprehensive database to analyse the abiotic and biotic factors shaping ant CTLs. Our results highlight how CTLs may affect future distribution patterns and ecological performance in ants. Additionally, we identify the greatest remaining gaps in knowledge and create a research roadmap to promote rapid advances in this field of study.
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Affiliation(s)
- Geraldo Nascimento
- Universidade de Pernambuco - Campus Garanhuns, Rua Capitão Pedro Rodrigues, 105 - São José, Garanhuns, 55294-902, Brazil.,Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, Universidade de Pernambuco - Campus Petrolina, BR 203, KM 2 - Vila Eduardo, Petrolina, 56328-900, Brazil
| | - Talita Câmara
- Universidade de Pernambuco - Campus Garanhuns, Rua Capitão Pedro Rodrigues, 105 - São José, Garanhuns, 55294-902, Brazil.,Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, Universidade de Pernambuco - Campus Petrolina, BR 203, KM 2 - Vila Eduardo, Petrolina, 56328-900, Brazil
| | - Xavier Arnan
- Universidade de Pernambuco - Campus Garanhuns, Rua Capitão Pedro Rodrigues, 105 - São José, Garanhuns, 55294-902, Brazil.,Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, Universidade de Pernambuco - Campus Petrolina, BR 203, KM 2 - Vila Eduardo, Petrolina, 56328-900, Brazil.,CREAF, Campus de Bellaterra (UAB) Edifici C, Cerdanyola del Vallès, 08193, Spain
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8
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Why Do Insects Close Their Spiracles? A Meta-Analytic Evaluation of the Adaptive Hypothesis of Discontinuous Gas Exchange in Insects. INSECTS 2022; 13:insects13020117. [PMID: 35206691 PMCID: PMC8878836 DOI: 10.3390/insects13020117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/15/2022] [Accepted: 01/20/2022] [Indexed: 02/04/2023]
Abstract
Simple Summary Insects breathe with the aid of thin capillary tubes that open out to the exterior of their body as spiracles. These spiracles are often modulated in a rhythmic gas pattern known as the discontinuous gas exchange cycle. During this cycle, spiracles are either firmly shut to allow no gaseous exchange or slightly open/fully open to allow for gaseous exchange. Two explanations are put forward to rationalize this process, namely, the rhythmic pattern is to (1) reduce water loss or (2) facilitate gaseous exchange in environments with high carbon dioxide and low oxygen. Interestingly, certain insects (such as some desert insects) do not use this rhythmic pattern where it would have been most beneficial and logical. Such an observation has led to the questioning of the explanations of the discontinuous gas exchange cycle. Consequently, we attempt to resolve this controversy by conducting a meta-analysis by synthesizing apposite data from across all insects where a discontinuous gas exchange cycle has been reported. A meta-analysis allows for a shift from viewing data through the lens of a single species to an order view. Thus, our goal is to use this holistic view of data to examine the explanations of the discontinuous gas exchange cycle across multiple groups of insects. Abstract The earliest description of the discontinuous gas exchange cycle (DGC) in lepidopterous insects supported the hypothesis that the DGC serves to reduce water loss (hygric hypothesis) and facilitate gaseous exchange in hyperoxia/hypoxia (chthonic hypothesis). With technological advances, other insect orders were investigated, and both hypotheses were questioned. Thus, we conducted a meta-analysis to evaluate the merit of both hypotheses. This included 46 insect species in 24 families across nine orders. We also quantified the percent change in metabolic rates per °C change of temperature during the DGC. The DGC reduced water loss (−3.27 ± 0.88; estimate ± 95% confidence limits [95% CI]; p < 0.0001) in insects. However, the DGC does not favor gaseous exchange in hyperoxia (0.21 ± 0.25 [estimate ± 95% CI]; p = 0.12) nor hypoxia, but did favor gaseous exchange in normoxia (0.27 ± 0.26 [estimate ± 95% CI]; p = 0.04). After accounting for variation associated with order, family, and species, a phylogenetic model reflected that metabolic rate exhibited a significant, non-zero increase of 8.13% (± 3.48 95% CI; p < 0.0001) per °C increase in temperature. These data represent the first meta-analytic attempt to resolve the controversies surrounding the merit of adaptive hypotheses in insects.
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9
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Castillo-Pérez EU, Suárez-Tovar CM, González-Tokman D, Schondube JE, Córdoba-Aguilar A. Insect thermal limits in warm and perturbed habitats: Dragonflies and damselflies as study cases. J Therm Biol 2022; 103:103164. [PMID: 35027186 DOI: 10.1016/j.jtherbio.2021.103164] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 11/29/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022]
Abstract
Disturbance (e.g. loss of plant cover) increases ambient temperature which can be lethal for ectotherm insects especially in hot places. We compared the thorax temperatures of 26 odonate species as a function of body size, habitat quality ("conserved" and cooler vs "perturbed" and warmer) and suborder (Anisoptera vs Zygoptera), as well as critical thermal maximum (CTmax) and as a function of habitat quality in Argia pulla (Zygoptera) and Orthemis ferruginea (Anisoptera). We expected thorax temperatures to differ between suborders based on their differences in body size and habitat quality status, and that populations in perturbed sites would have higher critical thermal maxima compared to those in conserved sites. This study was done in a tropical region with high ambient temperatures. Anisopterans had a higher body temperature than zygopterans, with no difference between habitats. Thoracic and air temperature were positively related, yet body temperatures were higher than the ambient temperature. A. pulla had higher CTmax in the perturbed sites, while O. ferruginea showed the opposite trend. Microenvironmental changes increase the ambient temperature, perhaps filtering insect species. The apparent resilience of odonates to disturbance should be examined more closely (using more species), especially in small species like the zygopterans which appear to be more strongly affected by ambient temperature.
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Affiliation(s)
- E Ulises Castillo-Pérez
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Av. Ciudad Universitaria 3000, Coyoacán, 04510, México City, Mexico; Instituto de Ecología, Universidad Nacional Autónoma de México, Apdo. Postal 70-275, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510, México City, Mexico
| | - Catalina M Suárez-Tovar
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Av. Ciudad Universitaria 3000, Coyoacán, 04510, México City, Mexico; Instituto de Ecología, Universidad Nacional Autónoma de México, Apdo. Postal 70-275, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510, México City, Mexico
| | - Daniel González-Tokman
- CONACyT, Red de Ecoetología, Instituto de Ecología A.C, Carretera Antigua a Coatepec 351, El Haya, 91073, Xalapa, Veracruz, Mexico
| | - Jorge E Schondube
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Mexico
| | - Alex Córdoba-Aguilar
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apdo. Postal 70-275, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510, México City, Mexico.
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10
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Deluen M, Blanchet S, Aubret F, Trochet A, Gangloff EJ, Guillaume O, Le Chevalier H, Calvez O, Carle C, Genty L, Arrondeau G, Cazale L, Kouyoumdjian L, Ribéron A, Bertrand R. Impacts of temperature on O 2 consumption of the Pyrenean brook newt (Calotriton asper) from populations along an elevational gradient. J Therm Biol 2022; 103:103166. [PMID: 35027206 DOI: 10.1016/j.jtherbio.2021.103166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 12/11/2021] [Accepted: 12/16/2021] [Indexed: 11/28/2022]
Abstract
Global warming impacts biodiversity worldwide, leading to species' adaptation, migration, or extinction. The population's persistence depends on the maintenance of essential activities, which is notably driven by phenotypic adaptation to local environments. Metabolic rate - that increases with temperature in ectotherms - is a key physiological proxy for the energy available to fuel individuals' activities. Cold-adapted ectotherms can exhibit a higher resting metabolism than warm-adapted ones to maintain functionality at higher elevations or latitudes, known as the metabolic cold-adaptation hypothesis. How climate change will affect metabolism in species inhabiting contrasting climates (cold or warm) is still a debate. Therefore, it is of high interest to assess the pace of metabolic responses to global warming among populations adapted to highly different baseline climatic conditions. Here, we conducted a physiological experiment in the endemic Pyrenean brook newt (Calotriton asper). We measured a proxy of standard metabolic rate (SMR) along a temperature gradient in individuals sampled among 6 populations located from 550 to 2189 m a.s.l. We demonstrated that SMR increased with temperature, but significantly diverged depending on populations' origins. The baseline and the slope of the relationship between SMR and temperature were both higher for high-elevation populations than for low-elevation populations. We discussed the stronger metabolic response observed in high-elevation populations suggesting a drop of performance in essential life activities for these individuals under current climate change. With the increase of metabolism as the climate warms, the metabolic-cold adaptation strategy selected in the past could compromise the sustainability of cold-adapted populations if short-term evolutionary responses do not allow to offset this evolutionary legacy.
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Affiliation(s)
- Marine Deluen
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France.
| | - Simon Blanchet
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Fabien Aubret
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Audrey Trochet
- Société Herpétologique de France, Muséum National d'Histoire Naturelle, CP41, 57 rue Cuvier, 75005, Paris
| | - Eric J Gangloff
- Department of Zoology, Ohio Wesleyan University, Delaware, Ohio
| | - Olivier Guillaume
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Hugo Le Chevalier
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Olivier Calvez
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Clémentine Carle
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Léa Genty
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Gaëtan Arrondeau
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Lucas Cazale
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Laura Kouyoumdjian
- Station d'Ecologie Théorique et Expérimentale, CNRS, UPR2001, 09200 Moulis, France
| | - Alexandre Ribéron
- Laboratoire Évolution et Diversité Biologique, UMR5174, Université de Toulouse III Paul Sabatier, CNRS, IRD, Toulouse, France
| | - Romain Bertrand
- Laboratoire Évolution et Diversité Biologique, UMR5174, Université de Toulouse III Paul Sabatier, CNRS, IRD, Toulouse, France
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11
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Bawa SA, Gregg PC, Del Soccoro AP, Miller C, Andrew NR. Estimating the differences in critical thermal maximum and metabolic rate of Helicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) across life stages. PeerJ 2021; 9:e12479. [PMID: 34820201 PMCID: PMC8605760 DOI: 10.7717/peerj.12479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/21/2021] [Indexed: 11/22/2022] Open
Abstract
Temperature is a crucial driver of insect activity and physiological processes throughout their life-history, and heat stress may impact life stages (larvae, pupae and adult) in different ways. Using thermolimit respirometry, we assessed the critical thermal maxima (CTmax-temperature at which an organism loses neuromuscular control), CO2 emission rate (V́CO2) and Q10 (a measure of V́CO2 temperature sensitivity) of three different life stages of Helicoverpa punctigera (Wallengren) by increasing their temperature exposure from 25 °C to 55 °C at a rate of 0.25 °C min−1. We found that the CTmax of larvae (49.1 °C ± 0.3 °C) was higher than pupae (47.4 °C ± 0.2 °C) and adults (46.9 °C ± 0.2 °C). The mean mass-specific CO2 emission rate (ml V́CO2 h−1) of larvae (0.26 ± 0.03 ml V́CO2 h−1) was also higher than adults (0.24 ± 0.04 ml V́CO2 h−1) and pupae (0.06 ± 0.02 ml V́CO2 h−1). The Q10: 25–35 °C for adults (2.01 ± 0.22) was significantly higher compared to larvae (1.40 ± 0.06) and Q10: 35–45 °C for adults (3.42 ± 0.24) was significantly higher compared to larvae (1.95 ± 0.08) and pupae (1.42 ± 0.98) respectively. We have established the upper thermal tolerance of H. punctigera, which will lead to a better understanding of the thermal physiology of this species both in its native range, and as a pest species in agricultural systems.
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Affiliation(s)
- Samuel A Bawa
- Zoology, Insect Ecology Laboratory, University of New England, Armidale, NSW, Australia.,Asuansi Agric. Station, Cape Coast, Central Region, Ghana
| | - Peter C Gregg
- Agronomy and Soil Science, University of New England, Armidale, NSW, Australia
| | - Alice P Del Soccoro
- Agronomy and Soil Science, University of New England, Armidale, NSW, Australia
| | - Cara Miller
- Science and Technology, University of New England, Armidale, NSW, Australia
| | - Nigel R Andrew
- Zoology, Insect Ecology Laboratory, University of New England, Armidale, NSW, Australia
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12
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Laursen SF, Hansen LS, Bahrndorff S, Nielsen HM, Noer NK, Renault D, Sahana G, Sørensen JG, Kristensen TN. Contrasting Manual and Automated Assessment of Thermal Stress Responses and Larval Body Size in Black Soldier Flies and Houseflies. INSECTS 2021; 12:380. [PMID: 33922364 PMCID: PMC8146041 DOI: 10.3390/insects12050380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 11/16/2022]
Abstract
Within ecophysiological and genetic studies on insects, morphological and physiological traits are commonly assessed and phenotypes are typically obtained from manual measurements on numerous individuals. Manual observations are, however, time consuming, can introduce observer bias and are prone to human error. Here, we contrast results obtained from manual assessment of larval size and thermal tolerance traits in black soldier flies (Hermetia illucens) and houseflies (Musca domestica) that have been acclimated under three different temperature regimes with those obtained automatically using an image analysis software (Noldus EthoVision XT). We found that (i) larval size estimates of both species, obtained by manual weighing or by using the software, were highly correlated, (ii) measures of heat and cold tolerance using manual and automated approaches provided qualitatively similar results, and (iii) by using the software we obtained quantifiable information on stress responses and acclimation effects of potentially higher ecological relevance than the endpoint traits that are typically assessed when manual assessments are used. Based on these findings, we argue that automated assessment of insect stress responses and largescale phenotyping of morphological traits such as size will provide new opportunities within many disciplines where accurate and largescale phenotyping of insects is required.
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Affiliation(s)
- Stine Frey Laursen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (S.B.); (N.K.N.); (T.N.K.)
| | - Laura Skrubbeltrang Hansen
- Center for Quantitative Genetics and Genomics, Faculty of Technical Sciences, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark; (L.S.H.); (H.M.N.); (G.S.)
| | - Simon Bahrndorff
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (S.B.); (N.K.N.); (T.N.K.)
| | - Hanne Marie Nielsen
- Center for Quantitative Genetics and Genomics, Faculty of Technical Sciences, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark; (L.S.H.); (H.M.N.); (G.S.)
| | - Natasja Krog Noer
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (S.B.); (N.K.N.); (T.N.K.)
| | - David Renault
- University of Rennes, CNRS, ECOBIO (Ecosystémes, Biodiversité, Evolution)-UMR, 6553 Rennes, France;
- Institut Universitaire de France, 1 Rue Descartes, CEDEX 05, 75231 Paris, France
| | - Goutam Sahana
- Center for Quantitative Genetics and Genomics, Faculty of Technical Sciences, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark; (L.S.H.); (H.M.N.); (G.S.)
| | - Jesper Givskov Sørensen
- Section for Genetics, Ecology and Evolution, Department of Biology, Aarhus University, Ny Munkegade 116, 8000 Aarhus C, Denmark;
| | - Torsten Nygaard Kristensen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark; (S.B.); (N.K.N.); (T.N.K.)
- Department of Agroecology, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark
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13
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Martin RA, Chick LD, Garvin ML, Diamond SE. In a nutshell, a reciprocal transplant experiment reveals local adaptation and fitness trade-offs in response to urban evolution in an acorn-dwelling ant. Evolution 2021; 75:876-887. [PMID: 33586171 PMCID: PMC8247984 DOI: 10.1111/evo.14191] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 02/07/2021] [Indexed: 01/02/2023]
Abstract
Urban-driven evolution is widely evident, but whether these changes confer fitness benefits and thus represent adaptive urban evolution is less clear. We performed a multiyear field reciprocal transplant experiment of acorn-dwelling ants across urban and rural environments. Fitness responses were consistent with local adaptation: we found a survival advantage of the "home" and "local" treatments compared to "away" and "foreign" treatments. Seasonal bias in survival was consistent with evolutionary patterns of gains and losses in thermal tolerance traits across the urbanization gradient. Rural ants in the urban environment were more vulnerable in the summer, putatively due to low heat tolerance, and urban ants in the rural environment were more vulnerable in winter, putatively due to an evolved loss of cold tolerance. The results for fitness via fecundity were also generally consistent with local adaptation, if somewhat more complex. Urban-origin ants produced more alates in their home versus away environment, and rural-origin ants had a local advantage in the rural environment. Overall, the magnitude of local adaptation was lower for urban ants in the novel urban environment compared with rural ants adapted to the ancestral rural environment, adding further evidence that species might not keep pace with anthropogenic change.
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Affiliation(s)
- Ryan A. Martin
- Department of BiologyCase Western Reserve UniversityClevelandOhio44106
| | - Lacy D. Chick
- Department of BiologyCase Western Reserve UniversityClevelandOhio44106
- Hawken SchoolGates MillsOhio44040
| | - Matthew L. Garvin
- Department of BiologyCase Western Reserve UniversityClevelandOhio44106
- Department of BiologyCentral Michigan UniversityMount PleasantMichigan48859
| | - Sarah E. Diamond
- Department of BiologyCase Western Reserve UniversityClevelandOhio44106
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14
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Bohn J, Halabian R, Schrader L, Shabardina V, Steffen R, Suzuki Y, Ernst UR, Gadau J, Makałowski W. Genome assembly and annotation of the California harvester ant Pogonomyrmex californicus. G3 (BETHESDA, MD.) 2021; 11:jkaa019. [PMID: 33561225 PMCID: PMC8022709 DOI: 10.1093/g3journal/jkaa019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 11/18/2020] [Indexed: 11/12/2022]
Abstract
The harvester ant genus Pogonomyrmex is endemic to arid and semiarid habitats and deserts of North and South America. The California harvester ant Pogonomyrmex californicus is the most widely distributed Pogonomyrmex species in North America. Pogonomyrmex californicus colonies are usually monogynous, i.e. a colony has one queen. However, in a few populations in California, primary polygyny evolved, i.e. several queens cooperate in colony founding after their mating flights and continue to coexist in mature colonies. Here, we present a genome assembly and annotation of P. californicus. The size of the assembly is 241 Mb, which is in agreement with the previously estimated genome size. We were able to annotate 17,889 genes in total, including 15,688 protein-coding ones with BUSCO (Benchmarking Universal Single-Copy Orthologs) completeness at a 95% level. The presented P. californicus genome assembly will pave the way for investigations of the genomic underpinnings of social polymorphism in the number of queens, regulation of aggression, and the evolution of adaptations to dry habitats.
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Affiliation(s)
- Jonas Bohn
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany
| | - Reza Halabian
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany
| | - Lukas Schrader
- Faculty of Biology, Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Victoria Shabardina
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany
| | - Raphael Steffen
- Faculty of Biology, Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
| | - Ulrich R Ernst
- Faculty of Biology, Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Jürgen Gadau
- Faculty of Biology, Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Wojciech Makałowski
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany
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15
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Smith A, Turnbull KF, Moulton JH, Sinclair BJ. Metabolic cost of freeze-thaw and source of CO 2 production in the freeze-tolerant cricket Gryllus veletis. J Exp Biol 2021; 224:jeb234419. [PMID: 33144372 DOI: 10.1242/jeb.234419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/28/2020] [Indexed: 12/28/2022]
Abstract
Freeze-tolerant insects can survive the conversion of a substantial portion of their body water to ice. While the process of freezing induces active responses from some organisms, these responses appear absent from freeze-tolerant insects. Recovery from freezing likely requires energy expenditure to repair tissues and re-establish homeostasis, which should be evident as elevations in metabolic rate after thaw. We measured carbon dioxide (CO2) production in the spring field cricket (Gryllus veletis) as a proxy for metabolic rate during cooling, freezing and thawing and compared the metabolic costs associated with recovery from freezing and chilling. We hypothesized that freezing does not induce active responses, but that recovery from freeze-thaw is metabolically costly. We observed a burst of CO2 release at the onset of freezing in all crickets that froze, including those killed by either cyanide or an insecticide (thiacloprid), implying that the source of this CO2 was neither aerobic metabolism nor a coordinated nervous system response. These results suggest that freezing does not induce active responses from G. veletis, but may liberate buffered CO2 from hemolymph. There was a transient 'overshoot' in CO2 release during the first hour of recovery, and elevated metabolic rate at 24, 48 and 72 h, in crickets that had been frozen compared with crickets that had been chilled (but not frozen). Thus, recovery from freeze-thaw and the repair of freeze-induced damage appears metabolically costly in G. veletis, and this cost persists for several days after thawing.
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Affiliation(s)
- Adam Smith
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Kurtis F Turnbull
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
| | - Julian H Moulton
- Department of Organismal Biology and Ecology, Colorado College, Colorado Springs, CO 80903, USA
| | - Brent J Sinclair
- Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7
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16
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Yilmaz AR, Diamond SE, Martin RA. Evidence for the evolution of thermal tolerance, but not desiccation tolerance, in response to hotter, drier city conditions in a cosmopolitan, terrestrial isopod. Evol Appl 2021; 14:12-23. [PMID: 33519953 PMCID: PMC7819561 DOI: 10.1111/eva.13052] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 06/09/2020] [Accepted: 06/15/2020] [Indexed: 11/29/2022] Open
Abstract
Cities are often hotter and drier compared with nearby undeveloped areas, but how organisms respond to these multifarious stressors associated with urban heat islands is largely unknown. Terrestrial isopods are especially susceptible to temperature and aridity stress as they have retained highly permeable gills from their aquatic ancestors. We performed a two temperature common garden experiment with urban and rural populations of the terrestrial isopod, Oniscus asellus, to uncover evidence for plastic and evolutionary responses to urban heat islands. We focused on physiological tolerance traits including tolerance of heat, cold, and desiccation. We also examined body size responses to urban heat islands, as size can modulate physiological tolerances. We found that different mechanisms underlie responses to urban heat islands. While evidence suggests urban isopods may have evolved higher heat tolerance, urban and rural isopods had statistically indistinguishable cold and desiccation tolerances. In both populations, plasticity to warmer rearing temperature diminished cold tolerance. Although field-collected urban and rural isopods were the same size, rearing temperature positively affected body size. Finally, larger size improved desiccation tolerance, which itself was influenced by rearing temperature. Our study demonstrates how multifarious changes associated with urban heat islands will not necessarily contribute to contemporary evolution in each of the corresponding physiological traits.
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Affiliation(s)
- Aaron R. Yilmaz
- Department of BiologyCase Western Reserve UniversityClevelandOhioUSA
| | - Sarah E. Diamond
- Department of BiologyCase Western Reserve UniversityClevelandOhioUSA
| | - Ryan A. Martin
- Department of BiologyCase Western Reserve UniversityClevelandOhioUSA
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17
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Perez R, Aron S. Adaptations to thermal stress in social insects: recent advances and future directions. Biol Rev Camb Philos Soc 2020; 95:1535-1553. [PMID: 33021060 DOI: 10.1111/brv.12628] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 01/20/2023]
Abstract
Thermal stress is a major driver of population declines and extinctions. Shifts in thermal regimes create new environmental conditions, leading to trait adaptation, population migration, and/or species extinction. Extensive research has examined thermal adaptations in terrestrial arthropods. However, little is known about social insects, despite their major role in ecosystems. It is only within the last few years that the adaptations of social insects to thermal stress have received attention. Herein, we discuss what is currently known about thermal tolerance and thermal adaptation in social insects - namely ants, termites, social bees, and social wasps. We describe the behavioural, morphological, physiological, and molecular adaptations that social insects have evolved to cope with thermal stress. We examine individual and collective responses to both temporary and persistent changes in thermal conditions and explore the extent to which individuals can exploit genetic variability to acclimatise. Finally, we consider the costs and benefits of sociality in the face of thermal stress, and we propose some future research directions that should advance our knowledge of individual and collective thermal adaptations in social insects.
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Affiliation(s)
- Rémy Perez
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, Brussels, Belgium
| | - Serge Aron
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, Brussels, Belgium
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18
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Betz A, Andrew NR. Influence of Non-lethal Doses of Natural Insecticides Spinetoram and Azadirachtin on Helicoverpa punctigera (Native Budworm, Lepidoptera: Noctuidae) Under Laboratory Conditions. Front Physiol 2020; 11:1089. [PMID: 32982799 PMCID: PMC7485216 DOI: 10.3389/fphys.2020.01089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 08/06/2020] [Indexed: 11/13/2022] Open
Abstract
Helicoverpa punctigera (native budworm) is an important pest species in crops across Australia. From the third instar onward, this species causes severe damage to crop plants: therefore, caterpillars need to be managed at an early stage of their development. In our experiment, we raised H. punctigera on an artificial diet, which included different concentrations of the natural insecticides Spinetoram and Azadirachtin. The survival of the larvae, growth and body mass gain was recorded over 17 days. Only caterpillars raised on lowest toxin concentrations survived and molted successfully to the fifth instar, but had slower growth and body mass gain compared to the insecticide-free control group. Caterpillars fed on higher toxin concentrations never molted to the next instar or died in the first few days. To test how the toxins influence physiological conditions including metabolic rate and water loss, surviving fifth instar larvae were exposed to thermolimit respirometry: starting at 25°C following a constant increasing temperature ramping rate of 0.25°C–1, until reaching the critical thermal maxima (CTmax). Caterpillars raised on a non-lethal dose of insecticides had higher metabolic rates and lost more water compared to the control group. Insects that have seem to consume more energy per mg tissue and have a higher water loss at high temperatures. Non-lethal concentrations of insecticides on pest insects physiology may reduce their impact on crops and may enable more targetted insecticide application.
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Affiliation(s)
- Anja Betz
- Insect Ecology Lab, Zoology, University of New England, Armidale, NSW, Australia.,Institut für Insektenbiotechnologie, Justus-Liebig-Universität Giessen, Giessen, Germany
| | - Nigel R Andrew
- Insect Ecology Lab, Zoology, University of New England, Armidale, NSW, Australia
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19
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Tattersall GJ, Danner RM, Chaves JA, Levesque DL. Activity analysis of thermal imaging videos using a difference imaging approach. J Therm Biol 2020; 91:102611. [PMID: 32716861 DOI: 10.1016/j.jtherbio.2020.102611] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/16/2020] [Accepted: 04/26/2020] [Indexed: 01/02/2023]
Abstract
Infrared thermal imaging is a passive imaging technique that captures the emitted radiation from an object to estimate surface temperature, often for inference of heat transfer. Infrared thermal imaging offers the potential to detect movement without the challenges of glare, shadows, or changes in lighting associated with visual digital imaging or active infrared imaging. In this paper, we employ a frame subtraction algorithm for extracting the pixel-by-pixel relative change in signal from a fixed focus video file, tailored for use with thermal imaging videos. By summing the absolute differences across an entire video, we are able to assign quantitative activity assessments to thermal imaging data for comparison with simultaneous recordings of metabolic rates. We tested the accuracy and limits of this approach by analyzing movement of a metronome and provide an example application of the approach to a study of Darwin's finches. In principle, this "Difference Imaging Thermography" (DIT) would allow for activity data to be standardized to energetic measurements and could be applied to any radiometric imaging system.
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Affiliation(s)
- Glenn J Tattersall
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S3A1, Canada.
| | - Raymond M Danner
- Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Rd, Wilmington, NC, 28403, USA
| | - Jaime A Chaves
- Colegio de Ciencias Biológicas y Ambientales, Campus Cumbayá, Universidad San Francisco de Quito, Diego de Robles y Av. Interoceánica, Cumbayá, Quito, Ecuador; Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA, 94132, USA
| | - Danielle L Levesque
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia; School of Biology and Ecology, University of Maine, Orono, ME, USA
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20
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Chen C, Condon CH, Boardman L, Meagher RL, Jeffers LA, Beam A, Bailey WD, Hahn DA. Critical PO 2 as a diagnostic biomarker for the effects of low-oxygen modified and controlled atmospheres on phytosanitary irradiation treatments in the cabbage looper Trichoplusia ni (Hübner). PEST MANAGEMENT SCIENCE 2020; 76:2333-2341. [PMID: 32003078 DOI: 10.1002/ps.5768] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/24/2020] [Accepted: 01/30/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Phytosanitary irradiation is a sustainable alternative to chemical fumigants for disinfesting fresh commodities from insect pests. However, irradiating insects in modified atmospheres with very low oxygen (<1 kPa O2 ) has repeatedly been shown to increase radioprotective response. Thus, there is a concern that modified atmosphere packaging could reduce the efficacy of phytosanitary irradiation. One hurdle slowing the widespread application of phytosanitary irradiation is a lack of knowledge about how moderate levels of hypoxia relevant to the modified atmosphere packaging of most fresh commodities (3-10 kPa O2 ) may affect phytosanitary irradiation treatments. Therefore, we hypothesize that critical PO2 (Pcrit ), the level of oxygen at which an insect's metabolism becomes impaired, can be used as a diagnostic biomarker to predict the induction of a radioprotective response. RESULTS Using the cabbage looper Trichoplusia ni (Hübner), we show that there is a substantial increase in radiation resistance when larvae are irradiated in atmospheres more hypoxic than their Pcrit (3.3 kPa O2 ). These data are consistent with our hypothesis that Pcrit could be used as a diagnostic biomarker for what levels of hypoxia may induce radioprotective effects that could impact phytosanitary irradiation treatments. CONCLUSION We propose that the relationship between Pcrit and radioprotective effects could allow us to build a framework for predicting the effects of low-oxygen atmospheres on the efficacy of phytosanitary irradiation. However, more widespread studies across pest species are still needed to test the generality of this idea.
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Affiliation(s)
- Chao Chen
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Catriona H Condon
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Leigh Boardman
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Robert L Meagher
- USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, USA
| | - Laura A Jeffers
- USDA-APHIS-PPQ Center for Plant Health Science and Technology, Raleigh, NC, USA
| | - Andrea Beam
- USDA-APHIS-PPQ Center for Plant Health Science and Technology, Miami, FL, USA
| | - Woodward D Bailey
- USDA-APHIS-PPQ Center for Plant Health Science and Technology, Miami, FL, USA
| | - Daniel A Hahn
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
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21
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Johnson DJ, Stahlschmidt ZR. City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community. Ecol Evol 2020; 10:4944-4955. [PMID: 32551072 PMCID: PMC7297767 DOI: 10.1002/ece3.6247] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 11/25/2022] Open
Abstract
Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. We used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (CT max) in urban ants-specifically, that (a) body size, (b) hydration status, and (c) chosen microenvironments influence CT max. We further tested a fourth hypothesis that native species are particularly physiologically vulnerable in urban environments. We manipulated water access and determined CT max for 11 species common to cities in California's Central Valley that exhibit nearly 300-fold variation in body size. There was a moderate phylogenetic signal influencing CT max, and inter (but not intra) specific variation in body size influenced CT max where larger species had higher CT max. The sensitivity of ants' CT max to water availability exhibited species-specific thresholds where short-term water limitation (8 hr) reduced CT max and body water content in some species while longer-term water limitation (32 hr) was required to reduce these traits in other species. However, CT max was not related to the temperatures chosen by ants during activity. Further, we found support for our fourth hypothesis because CT max and estimates of thermal safety margin in native species were more sensitive to water availability relative to non-native species. In sum, we provide evidence of links between heat tolerance and water availability, which will become critically important in an increasingly warm, dry, and urbanized world that others have shown may be selecting for smaller (not larger) body size.
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Affiliation(s)
- Dustin J. Johnson
- Department of Biological SciencesUniversity of the PacificStocktonCalifornia
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22
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Preston DB, Johnson SG. Generalist grasshoppers from thermally variable sites do not have higher thermal tolerance than grasshoppers from thermally stable sites - A study of five populations. J Therm Biol 2020; 88:102527. [PMID: 32126002 DOI: 10.1016/j.jtherbio.2020.102527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 01/20/2020] [Accepted: 01/20/2020] [Indexed: 11/24/2022]
Abstract
Thermal tolerance allows many organisms, including insects, to withstand stressful temperatures. Thermal generalists are expected to have higher thermal tolerance than specialists, but the environmental conditions leading to the evolution of a thermal generalist life history are not fully understood. Thermal variability has been put forth as an evolutionary driver of high thermal tolerance, but rarely has this been empirically tested. We used a generalist agricultural pest grasshopper, Melanoplus differentialis, to test upper and lower thermal limits of populations that experienced different levels of thermal variability. We quantified thermal heterogeneity at five sites in a longitudinal transect in the Midwestern U.S. by examining, over a 101-year period, 1) variance in daily thermal maxima and minima; and 2) daily range. Also, as a measure of a biologically relevant thermal extreme, we depicted days per month at each site that reached a stressfully high temperature for M. differentialis. We collected individuals from these sites and tested their upper and lower thermal limits. We found that most of our metrics of thermal heterogeneity differed among sites, while all sites experienced an average of at least two stressfully high temperature events per month. We found that heavier males from these sites were able to withstand both warmer and colder temperatures than smaller males, while heavier females had no thermal advantage over lighter females. However, site of origin had no effect on thermal tolerance. Our findings indicate three things: 1) there is no clear correlation between thermal variability and thermal tolerance in the populations we studied; 2) weight affects thermal tolerance range among sites for M. differentialis males, and 3) thermal extremes may be more important than thermal variability in determining CTMax in this species.
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Affiliation(s)
- Devin B Preston
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, USA.
| | - Steven G Johnson
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, USA.
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23
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The Respiratory Metabolism of Polistes biglumis, a Paper Wasp from Mountainous Regions. INSECTS 2020; 11:insects11030165. [PMID: 32143398 PMCID: PMC7142496 DOI: 10.3390/insects11030165] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/27/2020] [Accepted: 02/29/2020] [Indexed: 12/03/2022]
Abstract
European Polistine wasps inhabit mainly temperate and warm climate regions. However, the paper wasp Polistes biglumis represents an exception; it resides in mountainous areas, e.g., in the Alps and in the Apennines. In these habitats, the wasps are exposed to a broad temperature range during their lifetime. We investigated whether they developed adaptations in their metabolism to their special climate conditions by measuring their CO2 production. The standard or resting metabolic rate and the metabolism of active wasps was measured in the temperature range which they are exposed to in their habitat in summer. The standard metabolic rate increased in a typical exponential progression with ambient temperature, like in other wasps. The active metabolism also increased with temperature, but not in a simple exponential course. Some exceptionally high values were presumed to originate from endothermy. The simultaneous measurement of body temperature and metabolic rate revealed a strong correlation between these two parameters. The comparison of the standard metabolic rate of Polistes biglumis with that of Polistes dominula revealed a significantly lower metabolism of the alpine wasps. This energy saving metabolic strategy could be an adaptation to the harsh climate conditions, which restricts foraging flights and energy recruitment.
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24
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Nagarajan-Radha V, Aitkenhead I, Clancy DJ, Chown SL, Dowling DK. Sex-specific effects of mitochondrial haplotype on metabolic rate in Drosophila melanogaster support predictions of the Mother's Curse hypothesis. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190178. [PMID: 31787038 DOI: 10.1098/rstb.2019.0178] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Evolutionary theory proposes that maternal inheritance of mitochondria will facilitate the accumulation of mitochondrial DNA (mtDNA) mutations that are harmful to males but benign or beneficial to females. Furthermore, mtDNA haplotypes sampled from across a given species distribution are expected to differ in the number and identity of these 'male-harming' mutations they accumulate. Consequently, it is predicted that the genetic variation which delineates distinct mtDNA haplotypes of a given species should confer larger phenotypic effects on males than females (reflecting mtDNA mutations that are male-harming, but female-benign), or sexually antagonistic effects (reflecting mutations that are male-harming, but female-benefitting). These predictions have received support from recent work examining mitochondrial haplotypic effects on adult life-history traits in Drosophila melanogaster. Here, we explore whether similar signatures of male-bias or sexual antagonism extend to a key physiological trait-metabolic rate. We measured the effects of mitochondrial haplotypes on the amount of carbon dioxide produced by individual flies, controlling for mass and activity, across 13 strains of D. melanogaster that differed only in their mtDNA haplotype. The effects of mtDNA haplotype on metabolic rate were larger in males than females. Furthermore, we observed a negative intersexual correlation across the haplotypes for metabolic rate. Finally, we uncovered a male-specific negative correlation, across haplotypes, between metabolic rate and longevity. These results are consistent with the hypothesis that maternal mitochondrial inheritance has led to the accumulation of a sex-specific genetic load within the mitochondrial genome, which affects metabolic rate and that may have consequences for the evolution of sex differences in life history. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
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Affiliation(s)
| | - Ian Aitkenhead
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - David J Clancy
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
| | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
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Huey RB, Kingsolver JG. Climate Warming, Resource Availability, and the Metabolic Meltdown of Ectotherms. Am Nat 2019; 194:E140-E150. [DOI: 10.1086/705679] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Javal M, Thomas S, Lehmann P, Barton MG, Conlong DE, Du Plessis A, Terblanche JS. The Effect of Oxygen Limitation on a Xylophagous Insect's Heat Tolerance Is Influenced by Life-Stage Through Variation in Aerobic Scope and Respiratory Anatomy. Front Physiol 2019; 10:1426. [PMID: 31824337 PMCID: PMC6879455 DOI: 10.3389/fphys.2019.01426] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/04/2019] [Indexed: 12/21/2022] Open
Abstract
Temperature has a profound impact on insect fitness and performance via metabolic, enzymatic or chemical reaction rate effects. However, oxygen availability can interact with these thermal responses in complex and often poorly understood ways, especially in hypoxia-adapted species. Here we test the hypothesis that thermal limits are reduced under low oxygen availability - such as might happen when key life-stages reside within plants - but also extend this test to attempt to explain that the magnitude of the effect of hypoxia depends on variation in key respiration-related parameters such as aerobic scope and respiratory morphology. Using two life-stages of a xylophagous cerambycid beetle, Cacosceles (Zelogenes) newmannii we assessed oxygen-limitation effects on metabolic performance and thermal limits. We complement these physiological assessments with high-resolution 3D (micro-computed tomography scan) morphometry in both life-stages. Results showed that although larvae and adults have similar critical thermal maxima (CTmax) under normoxia, hypoxia reduces metabolic rate in adults to a greater extent than it does in larvae, thus reducing aerobic scope in the former far more markedly. In separate experiments, we also show that adults defend a tracheal oxygen (critical) setpoint more consistently than do larvae, indicated by switching between discontinuous gas exchange cycles (DGC) and continuous respiratory patterns under experimentally manipulated oxygen levels. These effects can be explained by the fact that the volume of respiratory anatomy is positively correlated with body mass in adults but is apparently size-invariant in larvae. Thus, the two life-stages of C. newmannii display key differences in respiratory structure and function that can explain the magnitude of the effect of hypoxia on upper thermal limits.
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Affiliation(s)
- Marion Javal
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
| | - Saskia Thomas
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
| | - Philipp Lehmann
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Madeleine G. Barton
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
| | - Desmond E. Conlong
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
- South African Sugarcane Research Institute, Mount Edgecombe, South Africa
| | - Anton Du Plessis
- CT Scanner Facility, Central Analytical Facilities, Stellenbosch University, Stellenbosch, South Africa
- Physics Department, Stellenbosch University, Stellenbosch, South Africa
| | - John S. Terblanche
- Department of Conservation Ecology & Entomology, Faculty of AgriSciences, Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa
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Verdú JR, Cortez V, Oliva D, Giménez-Gómez V. Thermoregulatory syndromes of two sympatric dung beetles with low energy costs. JOURNAL OF INSECT PHYSIOLOGY 2019; 118:103945. [PMID: 31520597 DOI: 10.1016/j.jinsphys.2019.103945] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/21/2019] [Accepted: 09/11/2019] [Indexed: 06/10/2023]
Abstract
In heterotherm insects, endothermy implies a high energy cost due to the generation and regulation of body temperature during different activities such as flight, food location, fighting and even walking. We studied the thermoregulation process and the cost of the thermoregulation strategies in two sympatric dung beetles, Sulcophanaeus batesi and S. imperator under heat and cold stress conditions. We used a set of physiological variables to exemplify the capacity of thermolimit respirometry combined with infrared thermography to derive relevant variables capable of describing different thermoregulation syndromes. Habitat use and thermal niche differed notably between S. batesi and S. imperator, reflecting their contrasted thermal requirements. In S. imperator, thermal specialization for high temperatures was observed, being active mainly during the warmer period of the day. On the other hand, thermal adaptation in S. batesi allows its preference for cold exhibiting a morning activity periods, avoiding higher temperatures. The thermophilic strategy used by Sulcophanaeus imperator minimized the energy expenditure produced during the cooling of the body by respiration without thereby endangering higher thermal limits. In this case, S. batesi, the species with a preference for the coldest environments, presented the lowest thermal limits, although the energy cost needed to stay active during cooling was significantly lower than that in S. imperator. Sulcophanaeus imperator and S. batesi showed evident 'economizing' strategies associated with hot and cold environmental conditions, respectively. In contrast, if both species experience a deviation from their thermal optimum, a decrement in their performance could be produced.
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Affiliation(s)
- José R Verdú
- I.U.I. CIBIO, Universidad de Alicante, Alicante E-03690, Spain.
| | - Vieyle Cortez
- I.U.I. CIBIO, Universidad de Alicante, Alicante E-03690, Spain
| | - Daniela Oliva
- Centro de Investigación e Innovación Tecnológica (CENIIT), Universidad Nacional de La Rioja, Av. Luis M. De La Fuente s/n, Ciudad de La Rioja 5300, Argentina
| | - Victoria Giménez-Gómez
- Instituto de Biología Subtropical, Universidad Nacional de Misiones-CONICET, Puerto Iguazú, Argentina
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Belliard SA, De la Vega GJ, Schilman PE. Thermal Tolerance Plasticity in Chagas Disease Vectors Rhodnius prolixus (Hemiptera: Reduviidae) and Triatoma infestans. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:997-1003. [PMID: 30849174 DOI: 10.1093/jme/tjz022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Indexed: 06/09/2023]
Abstract
Temperature is recognized as the most influential abiotic factor on the distribution and dispersion of most insect species including Rhodnius prolixus (Stål, 1859) and Triatoma infestans (Klug, 1834), the two most important Chagas disease vectors. Although, these species thermotolerance range is well known their plasticity has never been addressed in these or any other triatomines. Herein, we investigate the effects of acclimation on thermotolerance range and resistance to stressful low temperatures by assessing thermal critical limits and 'chill-coma recovery time' (CCRT), respectively. We found positive effects of acclimation on thermotolerance range, especially on the thermal critical minimum of both species. In contrast, CCRT did not respond to acclimation in either. Our results reveal the plasticity of these Triatomines thermal tolerance in response to a wide range of acclimation temperatures. This presumably represents a physiological adaptation to daily or seasonal temperature variation with concomitant improvement in dispersion potential.
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Affiliation(s)
- Silvina A Belliard
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada. CONICET-UBA, Buenos Aires, Argentina
| | - Gerardo J De la Vega
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada. CONICET-UBA, Buenos Aires, Argentina
| | - Pablo E Schilman
- Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada. CONICET-UBA, Buenos Aires, Argentina
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Shik JZ, Arnan X, Oms CS, Cerdá X, Boulay R. Evidence for locally adaptive metabolic rates among ant populations along an elevational gradient. J Anim Ecol 2019; 88:1240-1249. [DOI: 10.1111/1365-2656.13007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 03/22/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Jonathan Zvi Shik
- Section for Ecology and Evolution, Department of Biology University of Copenhagen Copenhagen Denmark
| | | | | | - Xim Cerdá
- Estación Biológica Doñana (CSIC) Sevilla Spain
| | - Raphaël Boulay
- Institute of Insect Biology Tours University Tours France
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30
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Holley JM, Andrew NR. Experimental warming alters the relative survival and emigration of two dung beetle species from an Australian dung pat community. AUSTRAL ECOL 2019. [DOI: 10.1111/aec.12750] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jean M. Holley
- Insect Ecology Lab; Zoology; The University of New England; Armidale New South Wales 2351 Australia
| | - Nigel R. Andrew
- Insect Ecology Lab; Zoology; The University of New England; Armidale New South Wales 2351 Australia
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Andrew NR, Miller C, Hall G, Hemmings Z, Oliver I. Aridity and land use negatively influence a dominant species' upper critical thermal limits. PeerJ 2019; 6:e6252. [PMID: 30656070 PMCID: PMC6334740 DOI: 10.7717/peerj.6252] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 12/10/2018] [Indexed: 11/25/2022] Open
Abstract
Understanding the physiological tolerances of ectotherms, such as thermal limits, is important in predicting biotic responses to climate change. However, it is even more important to examine these impacts alongside those from other landscape changes: such as the reduction of native vegetation cover, landscape fragmentation and changes in land use intensity (LUI). Here, we integrate the observed thermal limits of the dominant and ubiquitous meat ant Iridomyrmex purpureus across climate (aridity), land cover and land use gradients spanning 270 km in length and 840 m in altitude across northern New South Wales, Australia. Meat ants were chosen for study as they are ecosystem engineers and changes in their populations may result in a cascade of changes in the populations of other species. When we assessed critical thermal maximum temperatures (CTmax) of meat ants in relation to the environmental gradients we found little influence of climate (aridity) but that CTmax decreased as LUI increased. We found no overall correlation between CTmax and CTmin. We did however find that tolerance to warming was lower for ants sampled from more arid locations. Our findings suggest that as LUI and aridification increase, the physiological resilience of I. purpureus will decline. A reduction in physiological resilience may lead to a reduction in the ecosystem service provision that these populations provide throughout their distribution.
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Affiliation(s)
- Nigel R. Andrew
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Cara Miller
- School of Science and Technology, University of New England, Armidale, NSW, Australia
| | - Graham Hall
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Zac Hemmings
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Ian Oliver
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
- Office of Environment and Heritage, Armidale, NSW, Australia
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Rolandi C, Lighton JRB, de la Vega GJ, Schilman PE, Mensch J. Genetic variation for tolerance to high temperatures in a population of Drosophila melanogaster. Ecol Evol 2018; 8:10374-10383. [PMID: 30464811 PMCID: PMC6238130 DOI: 10.1002/ece3.4409] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 07/01/2018] [Accepted: 07/02/2018] [Indexed: 12/26/2022] Open
Abstract
The range of thermal tolerance is one of the main factors influencing the geographic distribution of species. Climate change projections predict increases in average and extreme temperatures over the coming decades; hence, the ability of living beings to resist these changes will depend on physiological and adaptive responses. On an evolutionary scale, changes will occur as the result of selective pressures on individual heritable differences. In this work, we studied the genetic basis of tolerance to high temperatures in the fly Drosophila melanogaster and whether this species presents sufficient genetic variability to allow expansion of its upper thermo-tolerance limit. To do so, we used adult flies derived from a natural population belonging to the Drosophila Genetic Reference Panel, for which genomic sequencing data are available. We characterized the phenotypic variation of the upper thermal limit in 34 lines by measuring knockdown temperature (i.e., critical thermal maximum [CTmax]) by exposing flies to a ramp of increasing temperature (0.25°C/min). Fourteen percent of the variation in CTmax is explained by the genetic variation across lines, without a significant sexual dimorphism. Through a genomewide association study, 12 single nucleotide polymorphisms associated with the CTmax were identified. In most of these SNPs, the less frequent allele increased the upper thermal limit suggesting that this population harbors raw genetic variation capable of expanding its heat tolerance. This potential upper thermal tolerance increase has implications under the global warming scenario. Past climatic records show a very low incidence of days above CTmax (10 days over 25 years); however, future climate scenarios predict 243 days with extreme high temperature above CTmax from 2045 to 2070. Thus, in the context of the future climate warming, rising temperatures might drive the evolution of heat tolerance in this population by increasing the frequency of the alleles associated with higher CTmax.
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Affiliation(s)
- Carmen Rolandi
- IBBEA‐CONICET‐UBA. DBBEAFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | | | - Gerardo J. de la Vega
- Grupo de Ecología de Poblaciones de Insectos (GEPI)INTA EEA BarilocheBarilocheArgentina
| | - Pablo E. Schilman
- IBBEA‐CONICET‐UBA. DBBEAFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
| | - Julián Mensch
- IEGEBA‐CONICET‐UBADEGEFacultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresBuenos AiresArgentina
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Burton T, Zeis B, Einum S. Automated measurement of upper thermal limits in small aquatic animals. J Exp Biol 2018; 221:jeb182386. [PMID: 30012577 PMCID: PMC6140313 DOI: 10.1242/jeb.182386] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/11/2018] [Indexed: 11/20/2022]
Abstract
We present a method for automating the measurement of upper thermal limits in small aquatic organisms. Upper thermal limits are frequently defined by the cessation of movement at high temperature, with measurement being performed by manual observation. Consequently, estimates of upper thermal limits may be subject to error and bias, both within and among observers. Our method utilises video-based tracking software to record the movement of individuals when exposed to high, lethal temperatures. We develop an algorithm in the R computing language that can objectively identify the loss of locomotory function from tracking data. Using independent experimental data, we validate our approach by demonstrating the expected response in upper thermal limits to acclimation temperature.
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Affiliation(s)
- Tim Burton
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
| | - Bettina Zeis
- Institut für Zoophysiologie, Westfälische Wilhelms-Universität, Hindenburgplatz 55, D-48143 Münster, Germany
| | - Sigurd Einum
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
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Garcia-Robledo C, Charlotten-Silva M, Cruz C, Kuprewicz EK. Low quality diet and challenging temperatures affect vital rates, but not thermal tolerance in a tropical insect expanding its diet to an exotic plant. J Therm Biol 2018; 77:7-13. [PMID: 30196902 DOI: 10.1016/j.jtherbio.2018.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/09/2018] [Accepted: 07/22/2018] [Indexed: 10/28/2022]
Abstract
Determining responses of organisms to changing temperatures is a research priority, as global warming threatens populations and ecosystems worldwide. Upper thermal limits are frequently measured as the critical thermal maximum (CTmax), a quick bioassay where organisms are exposed to increasing temperatures until individuals are not able to perform basic motor activities such as walking or flying. A more informative approach to understand organism responses to global warming is to evaluate how vital rates, such as growth or survival, change with temperatures. The main objectives of this study are: (1) to determine if factors affecting insect vital rates such as diet quality, developmental temperatures or acclimation also affect CTmax and (2) to determine if vital rates of different life stages (i.e., insect larvae or adults) display different responses to temperature changes. If different life stages have particular thermal requirements, this may indicate different susceptibility to global warming. This study focuses on Cephaloleia belti (Coleoptera: Chrysomelidae), a tropical insect currently expanding its diet to an exotic host plant. We determined how high and low-quality diets (i.e., native vs novel host), as well as exposure temperatures affect CTmax of adult beetles. We also estimated larval and adult survival when feeding on high and low quality host plants, when exposed to temperatures typical of the elevational distribution of this species, or when exposed to projected temperatures in 100 years. We did not detect an effect of diet quality or acclimation on CTmax. However, larvae and adults had different thermal requirements. CTmax is not affected by previous diet or acclimation as an adult. We propose that to understand processes involved in the adaptation and persistence of ectotherm populations in a warming world, studies must explore responses beyond CTmax, and focus on the response of vital rates to changing temperatures.
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Affiliation(s)
- Carlos Garcia-Robledo
- Department of Ecology & Evolutionary Biology, University of Connecticut, 75 North Eagleville Rd., Unit 3043, Storrs, CT 06269, USA.
| | - Mariela Charlotten-Silva
- Department of Biology, University of Puerto Rico at Ponce, PO Box 7183, Ponce, PR 00732, USA; Research Experience for Undergraduates NSF LSAMP-OTS. Organization for Tropical Studies (OTS), Duke University, Box 90633, Durham, NC 27708, USA
| | - Christopher Cruz
- SUNY College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, NY 13210, USA; Research Experience for Undergraduates NSF LSAMP-OTS. Organization for Tropical Studies (OTS), Duke University, Box 90633, Durham, NC 27708, USA
| | - Erin K Kuprewicz
- Department of Ecology & Evolutionary Biology, University of Connecticut, 75 North Eagleville Rd., Unit 3043, Storrs, CT 06269, USA
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Agosta SJ, Joshi KA, Kester KM. Upper thermal limits differ among and within component species in a tritrophic host-parasitoid-hyperparasitoid system. PLoS One 2018; 13:e0198803. [PMID: 29894508 PMCID: PMC5997305 DOI: 10.1371/journal.pone.0198803] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/27/2018] [Indexed: 12/02/2022] Open
Abstract
Understanding how climate change affects host-parasite systems and predicting the consequences for ecosystems, economies, and human health has emerged as an important task for science and society. Some basic insight into this complex problem can be gained by comparing the thermal physiology of interacting host and parasite species. In this study, we compared upper thermal tolerance among three component species in a natural host-parasitoid-hyperparasitoid system from Virginia, USA. To assess the ecological relevance of our results, we also examined a record of maximum daily air temperatures collected near the study site in the last 124 years. We found that the caterpillar host Manduca sexta had a critical thermal maximum (CTmax) about 4°C higher than the parasitic wasp, Cotesia congregata, and the hyperparasitic wasp, Conura sp., had a CTmax about 6°C higher than its host, C. congregata. We also found significant differences in CTmax among instars and between parasitized and non-parasitized M. sexta. The highest maximum daily air temperature recorded near the study in the last 124 years was 42°C, which equals the average CTmax of one species (C. congregata) but is several degrees lower than the average CTmax of the other two species (M. sexta, Conura sp.) in this study. Our results combined with other studies suggest that significant differences in thermal performance within and among interacting host and parasite species are common in nature and that climate change may be largely disruptive to these systems with responses that are highly variable and complex.
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Affiliation(s)
- Salvatore J. Agosta
- Center for Environmental Studies, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Kanchan A. Joshi
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Karen M. Kester
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
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Oyen KJ, Dillon ME. Critical thermal limits of bumblebees ( Bombus impatiens) are marked by stereotypical behaviors and are unchanged by acclimation, age or feeding status. ACTA ACUST UNITED AC 2018. [PMID: 29530975 DOI: 10.1242/jeb.165589] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Critical thermal limits often determine species distributions for diverse ectotherms and have become a useful tool for understanding past and predicting future range shifts in response to changing climates. Despite recently documented population declines and range shifts of bumblebees (genus Bombus), the few measurements of thermal tolerance available for the group have relied on disparate measurement approaches. We describe a novel stereotypical behavior expressed by bumblebee individuals during entry into chill coma. This behavioral indicator of minimum critical temperature (CTmin) occurred at ambient temperatures of 3-5°C (approximately 7-9°C core temperatures) and was accompanied by a pronounced CO2 pulse, indicative of loss of spiracle function. Maximum critical temperature (CTmax) was indicated by the onset of muscular spasms prior to entering an unresponsive state and occurred at ambient temperatures of approximately 52-55°C (42-44°C core temperatures). Measurements of CTmin and CTmax were largely unaffected by acclimation, age or feeding status, but faster ramping rates significantly increased CTmax and decreased CTmin This high-throughput approach allows rapid measurement of critical thermal limits for large numbers of individuals, facilitating large-scale comparisons among bumblebee populations and species - a key step in determining current and future effects of climate on these critical pollinators.
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Affiliation(s)
- K Jeannet Oyen
- Department of Zoology and Physiology & Program in Ecology, University of Wyoming, Laramie, WY 82071, USA
| | - Michael E Dillon
- Department of Zoology and Physiology & Program in Ecology, University of Wyoming, Laramie, WY 82071, USA
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DE LA Vega GJ, Schilman PE. Ecological and physiological thermal niches to understand distribution of Chagas disease vectors in Latin America. MEDICAL AND VETERINARY ENTOMOLOGY 2018; 32:1-13. [PMID: 28857300 DOI: 10.1111/mve.12262] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/21/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
In order to assess how triatomines (Hemiptera, Reduviidae), Chagas disease vectors, are distributed through Latin America, we analysed the relationship between the ecological niche and the limits of the physiological thermal niche in seven species of triatomines. We combined two methodological approaches: species distribution models, and physiological tolerances. First, we modelled the ecological niche and identified the most important abiotic factor for their distribution. Then, thermal tolerance limits were analysed by measuring maximum and minimum critical temperatures, upper lethal temperature, and 'chill-coma recovery time'. Finally, we used phylogenetic independent contrasts to analyse the link between limiting factors and the thermal tolerance range for the assessment of ecological hypotheses that provide a different outlook for the geo-epidemiology of Chagas disease. In triatomines, thermo-tolerance range increases with increasing latitude mainly due to better cold tolerances, suggesting an effect of thermal selection. In turn, physiological analyses show that species reaching southernmost areas have a higher thermo-tolerance than those with tropical distributions, denoting that thermo-tolerance is limiting the southern distribution. Understanding the latitudinal range along its physiological limits of disease vectors may prove useful to test ecological hypotheses and improve strategies and efficiency of vector control at the local and regional levels.
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Affiliation(s)
- G J DE LA Vega
- Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental/Laboratorio de Ecofisiología de Insectos, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
| | - P E Schilman
- Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental/Laboratorio de Ecofisiología de Insectos, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
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Chronic Nosema ceranae infection inflicts comprehensive and persistent immunosuppression and accelerated lipid loss in host Apis mellifera honey bees. Int J Parasitol 2018; 48:433-444. [PMID: 29452081 DOI: 10.1016/j.ijpara.2017.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 01/05/2023]
Abstract
Nosema ceranae is an intracellular microsporidian parasite of the Asian honey bee Apis cerana and the European honey bee Apis mellifera. Until relatively recently, A. mellifera honey bees were naïve to N. ceranae infection. Symptoms of nosemosis, or Nosema disease, in the infected hosts include immunosuppression, damage to gut epithelium, nutrient and energetic stress, precocious foraging and reduced longevity of infected bees. Links remain unclear between immunosuppression, the symptoms of nutrient and energetic stress, and precocious foraging behavior of hosts. To clarify physiological connections, we inoculated newly emerged A. mellifera adult workers with N. ceranae spores, and over 21 days post inoculation (21 days pi), gauged infection intensity and quantified expression of genes representing two innate immune pathways, Toll and Imd. Additionally, we measured each host's whole-body protein, lipids, carbohydrates and quantified respirometric and activity levels. Results show sustained suppression of genes of both humorally regulated immune response pathways after 6 days pi. At 7 days pi, elevated protein levels of infected bees may reflect synthesis of antimicrobial peptides from an initial immune response, but the lack of protein gain compared with uninfected bees at 14 days pi may represent low de novo protein synthesis. Carbohydrate data do not indicate that hosts experience severe metabolic stress related to this nutrient. At 14 days pi infected honey bees show high respirometric and activity levels, and corresponding lipid loss, suggesting lipids may be used as fuel for increased metabolic demands resulting from infection. Accelerated lipid loss during nurse honey bee behavioral development can have cascading effects on downstream physiology that may lead to precocious foraging, which is a major factor driving colony collapse.
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Hamblin AL, Youngsteadt E, López-Uribe MM, Frank SD. Physiological thermal limits predict differential responses of bees to urban heat-island effects. Biol Lett 2017. [PMID: 28637837 DOI: 10.1098/rsbl.2017.0125] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Changes in community composition are an important, but hard to predict, effect of climate change. Here, we use a wild-bee study system to test the ability of critical thermal maxima (CTmax, a measure of heat tolerance) to predict community responses to urban heat-island effects in Raleigh, NC, USA. Among 15 focal species, CTmax ranged from 44.6 to 51.3°C, and was strongly predictive of population responses to urban warming across 18 study sites (r2 = 0.44). Species with low CTmax declined the most. After phylogenetic correction, solitary species and cavity-nesting species (bumblebees) had the lowest CTmax, suggesting that these groups may be most sensitive to climate change. Community responses to urban and global warming will likely retain strong physiological signal, even after decades of warming during which time lags and interspecific interactions could modulate direct effects of temperature.
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Affiliation(s)
- April L Hamblin
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC 27695, USA
| | - Elsa Youngsteadt
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC 27695, USA
| | - Margarita M López-Uribe
- Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, University Park, PA 16802, USA
| | - Steven D Frank
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC 27695, USA
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40
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Javal M, Roques A, Roux G, Laparie M. Respiration-based monitoring of metabolic rate following cold-exposure in two invasive Anoplophora species depending on acclimation regime. Comp Biochem Physiol A Mol Integr Physiol 2017; 216:20-27. [PMID: 29129757 DOI: 10.1016/j.cbpa.2017.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 10/27/2017] [Accepted: 10/29/2017] [Indexed: 02/03/2023]
Abstract
The Asian and Citrus longhorned beetles, Anoplophora glabripennis (ALB) and A. chinensis (CLB) respectively, are two closely related invasive species with overlapping native ranges. Although both species have rather similar biological characteristics, they differ in their invasion patterns. ALB shows numerous, but local, outbreaks in urban areas of North-East America, Western and Central Europe, whereas CLB has colonized a large part of Northern Italy. Temperature is pivotal in setting distribution limits of ectotherms. Low temperature may be limiting for larvae since they are the main overwintering stage for both species. To investigate whether differential cold tolerance may contribute to setting the respective limits of the range invaded by each species, we monitored larval metabolic rate before and after exposure to a one-week ecologically relevant moderate cold stress (-2/+2°C, 14/10h). We tested two distinctive fluctuating regimes before the cold exposure to check whether larval acclimation significantly altered their cold tolerance. Survival was high in all conditions for both species. Visual examination showed temporary locomotor inactivity during the stress but respiration rates were not altered after the stress suggesting that larvae could rapidly resume their initial metabolic activity. The respiration rate was globally higher in ALB than in CLB. Together, these results tend to indicate that both species have similar tolerance to the moderate cold stress tested, but also that ALB may be better at maintaining metabolic activity at cold than CLB. These observed differences could affect phenology in both species and in turn their establishment potential.
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Affiliation(s)
- M Javal
- INRA, UR0633, Zoologie Forestière, 45075 Orléans, France.
| | - A Roques
- INRA, UR0633, Zoologie Forestière, 45075 Orléans, France
| | - G Roux
- INRA, UR0633, Zoologie Forestière, 45075 Orléans, France; Université d'Orléans, 45075 Orléans, France
| | - M Laparie
- INRA, UR0633, Zoologie Forestière, 45075 Orléans, France; Norwegian Institute for Nature Research (NINA), Arctic Ecology Department, Fram Centre, 9296 Tromsø, Norway
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41
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Heinrich EC, Gray EM, Ossher A, Meigher S, Grun F, Bradley TJ. Aerobic function in mitochondria persists beyond death by heat stress in insects. J Therm Biol 2017; 69:267-274. [PMID: 29037393 DOI: 10.1016/j.jtherbio.2017.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 08/07/2017] [Accepted: 08/17/2017] [Indexed: 11/25/2022]
Abstract
The critical thermal maximum (CTmax) of insects can be determined using flow-through thermolimit respirometry. It has been demonstrated that respiratory patterns cease and insects do not recover once the CTmax temperature has been reached. However, if high temperatures are maintained following the CTmax, researchers have observed a curious phenomenon whereby the insect body releases a large burst of carbon dioxide at a rate and magnitude that often exceed that of the live insect. This carbon dioxide release has been termed the post-mortal peak (PMP). We demonstrate here that the PMP is observed only at high temperatures, is oxygen-dependent, is prevented by cyanide exposure, and is associated with concomitant consumption of oxygen. We conclude that the PMP derives from highly active, aerobic metabolism in the mitochondria. The insect tracheal system contains air-filled tubes that reach deep into the tissues and allow mitochondria access to oxygen even upon organismal death. This unique condition permits the investigation of mitochondrial function during thermal failure in a manner that cannot be achieved using vertebrate organisms or in vitro preparations.
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Affiliation(s)
- Erica C Heinrich
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA.
| | - Emilie M Gray
- Department of Organismal Biology & Ecology, Colorado College, 14 East Cache La Poudre St., Colorado Springs, CO 80903, USA
| | - Ashley Ossher
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Stephen Meigher
- Department of Organismal Biology & Ecology, Colorado College, 14 East Cache La Poudre St., Colorado Springs, CO 80903, USA
| | - Felix Grun
- Center for Complex Biological Systems, University of California, Irvine, 2620 Biological Sciences III, Irvine, CA 92697-2280, USA
| | - Timothy J Bradley
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
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42
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Monaco CJ, McQuaid CD, Marshall DJ. Decoupling of behavioural and physiological thermal performance curves in ectothermic animals: a critical adaptive trait. Oecologia 2017; 185:583-593. [DOI: 10.1007/s00442-017-3974-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 09/27/2017] [Indexed: 10/18/2022]
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43
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Robertson RM, Spong KE, Srithiphaphirom P. Chill coma in the locust, Locusta migratoria, is initiated by spreading depolarization in the central nervous system. Sci Rep 2017; 7:10297. [PMID: 28860653 PMCID: PMC5579280 DOI: 10.1038/s41598-017-10586-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/10/2017] [Indexed: 11/12/2022] Open
Abstract
The ability of chill-sensitive insects to function at low temperatures limits their geographic ranges. They have species-specific temperatures below which movements become uncoordinated prior to entering a reversible state of neuromuscular paralysis. In spite of decades of research, which in recent years has focused on muscle function, the role of neural mechanisms in determining chill coma is unknown. Spreading depolarization (SD) is a phenomenon that causes a shutdown of neural function in the integrating centres of the central nervous system. We investigated the role of SD in the process of entering chill coma in the locust, Locusta migratoria. We used thermolimit respirometry and electromyography in whole animals and extracellular and intracellular recording techniques in semi-intact preparations to characterize neural events during chilling. We show that chill-induced SD in the central nervous system is the mechanism underlying the critical thermal minimum for coordinated movement in locusts. This finding will be important for understanding how insects adapt and acclimate to changing environmental temperatures.
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Affiliation(s)
- R Meldrum Robertson
- Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
| | - Kristin E Spong
- Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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44
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Diamond SE, Chick L, Penick CA, Nichols LM, Cahan SH, Dunn RR, Ellison AM, Sanders NJ, Gotelli NJ. Heat tolerance predicts the importance of species interaction effects as the climate changes. Integr Comp Biol 2017; 57:112-120. [DOI: 10.1093/icb/icx008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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45
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Cooley NL, Emlen DJ, Woods HA. Self-heating by large insect larvae? J Therm Biol 2016; 62:76-83. [PMID: 27839554 DOI: 10.1016/j.jtherbio.2016.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 10/08/2016] [Accepted: 10/16/2016] [Indexed: 11/28/2022]
Abstract
Do insect larvae ever self-heat significantly from their own metabolic activity and, if so, under what sets of environmental temperatures and across what ranges of body size? We examine these questions using larvae of the Japanese rhinoceros beetle (Trypoxylus dichotomus), chosen for their large size (>20g), simple body plan, and underground lifestyle. Using CO2 respirometry, we measured larval metabolic rates then converted measured rates of gas exchange into rates of heat production and developed a mathematical model to predict how much steady state body temperatures of underground insects would increase above ambient depending on body size. Collectively, our results suggest that large, extant larvae (20-30g body mass) can self-heat by at most 2°C, and under many common conditions (shallow depths, moister soils) would self-heat by less than 1°C. By extending the model to even larger (hypothetical) body sizes, we show that underground insects with masses >1kg could heat, in warm, dry soils, by 1.5-6°C or more. Additional experiments showed that larval critical thermal maxima (CTmax) were in excess of 43.5°C and that larvae could behaviorally thermoregulate on a thermal gradient bar. Together, these results suggest that large larvae living underground likely regulate their temperatures primarily using behavior; self-heating by metabolism likely contributes little to their heat budgets, at least in most common soil conditions.
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Affiliation(s)
- Nikita L Cooley
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA
| | - Douglas J Emlen
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA
| | - H Arthur Woods
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA.
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46
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Kovac H, Käfer H, Petrocelli I, Stabentheiner A. Comparison of thermal traits of Polistes dominula and Polistes gallicus, two European paper wasps with strongly differing distribution ranges. J Comp Physiol B 2016; 187:277-290. [PMID: 27744515 PMCID: PMC5253161 DOI: 10.1007/s00360-016-1041-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 09/26/2016] [Accepted: 10/06/2016] [Indexed: 11/27/2022]
Abstract
The two paper wasps, Polistes dominula and Polistes gallicus, are related species with strongly differing distribution ranges. We investigated thermal tolerance traits (critical thermal limits and metabolic response to temperature) to gain knowledge about physiological adaptations to their local climate conditions and to get evidence for the reasons of P. dominula’s successful dispersion. Body and ambient temperature measurements at the nests revealed behavioural adaptations to microclimate. The species differed clearly in critical thermal minimum (P. dominula −1.4 °C, P. gallicus −0.4 °C), but not significantly in critical thermal maximum of activity (P. dominula 47.1 °C, P. gallicus 47.6 °C). The metabolic response did not reveal clear adaptations to climate conditions. At low and high temperatures, the metabolic rate of P. dominula was higher, and at intermediate temperatures, we determined higher values in P. gallicus. However, the species exhibited remarkably differing thermoregulatory behaviour at the nest. On average, P. gallicus tolerated a thoracic temperature up to ~41 °C, whereas P. dominula already tried at ~37 °C to keep the thorax below ambient temperature. We suggest this to be an adaptation to the higher mean ambient temperature we measured at the nest during a breeding season. Although we determined for P. dominula a 0.5 °C larger thermal tolerance range, we do not presume this parameter to be solely responsible for the successful distribution of P. dominula. Additional factors, such as the thermal tolerance of the queens could limit the overwintering success of P. gallicus in a harsher climate.
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Affiliation(s)
- Helmut Kovac
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria.
| | - Helmut Käfer
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria
| | - Iacopo Petrocelli
- Dipartimento di Biologia, Università degli Studi di Firenze, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Italy
| | - Anton Stabentheiner
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria.
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47
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Boardman L, Sørensen JG, Koštál V, Šimek P, Terblanche JS. Cold tolerance is unaffected by oxygen availability despite changes in anaerobic metabolism. Sci Rep 2016; 6:32856. [PMID: 27619175 PMCID: PMC5020647 DOI: 10.1038/srep32856] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/10/2016] [Indexed: 12/18/2022] Open
Abstract
Insect cold tolerance depends on their ability to withstand or repair perturbations in cellular homeostasis caused by low temperature stress. Decreased oxygen availability (hypoxia) can interact with low temperature tolerance, often improving insect survival. One mechanism proposed for such responses is that whole-animal cold tolerance is set by a transition to anaerobic metabolism. Here, we provide a test of this hypothesis in an insect model system (Thaumatotibia leucotreta) by experimental manipulation of oxygen availability while measuring metabolic rate, critical thermal minimum (CTmin), supercooling point and changes in 43 metabolites in moth larvae at three key timepoints (before, during and after chill coma). Furthermore, we determined the critical oxygen partial pressure below which metabolic rate was suppressed (c. 4.5 kPa). Results showed that altering oxygen availability did not affect (non-lethal) CTmin nor (lethal) supercooling point. Metabolomic profiling revealed the upregulation of anaerobic metabolites and alterations in concentrations of citric acid cycle intermediates during and after chill coma exposure. Hypoxia exacerbated the anaerobic metabolite responses induced by low temperatures. These results suggest that cold tolerance of T. leucotreta larvae is not set by oxygen limitation, and that anaerobic metabolism in these larvae may contribute to their ability to survive in necrotic fruit.
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Affiliation(s)
- Leigh Boardman
- Department of Conservation Ecology and Entomology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Jesper G Sørensen
- Section for Genetics, Ecology &Evolution, Department of Bioscience, Aarhus University, Ny Munkegade 116, DK-8000 Aarhus C, Denmark
| | - Vladimír Koštál
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Petr Šimek
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - John S Terblanche
- Department of Conservation Ecology and Entomology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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48
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The role of nest surface temperatures and the brain in influencing ant metabolic rates. J Therm Biol 2016; 60:132-9. [DOI: 10.1016/j.jtherbio.2016.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/03/2016] [Accepted: 07/06/2016] [Indexed: 11/18/2022]
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49
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Bentley MT, Hahn DA, Oi FM. The Thermal Breadth of Nylanderia fulva (Hymenoptera: Formicidae) Is Narrower Than That of Solenopsis invicta at Three Thermal Ramping Rates: 1.0, 0.12, and 0.06°C min-1. ENVIRONMENTAL ENTOMOLOGY 2016; 45:1058-1062. [PMID: 27252409 DOI: 10.1093/ee/nvw050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/10/2016] [Indexed: 06/05/2023]
Abstract
Determining the upper (CTmax) and lower (CTmin) critical thermal limits of invasive ants provides insight into how temperature could shape their distribution, seasonality, and daily activity. Understanding the potential distribution of invasive ants is imperative to improving quarantine and management efforts. Nylanderia fulva (Mayr) (tawny crazy ant) and Solenopsis invicta (Buren) (red imported fire ant) are invasive ants that are established throughout the southeastern United States. Recent studies have found that body size and thermal ramping rate can affect the estimation of critical thermal limits. However, the effects of both variables and their interactions on the thermal limits of N. fulva and S. invicta have not previously been described. Thus, we evaluated the impacts of body size and ramping rate on the critical thermal limits of N. fulva and S. invicta Overall, N. fulva had a narrower thermal breadth than S. invicta (Nf CTmin = 7.3°C and Nf CTmax = 41.3°C vs. Si CTmin = 4.1°C and Si CTmax = 45.3°C). For both species, slower ramping rates resulted in lower CTmax values and ants with smaller head capsules had a narrower thermal breadth than ants with larger head capsules. These data improve our understanding of the critical thermal limits of both species and could be useful for developing predictive models that estimate the future spread of these invasive ants in nonnative ranges.
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Affiliation(s)
- M T Bentley
- Department of Entomology and Nematology, University of Florida, P.O. Box 110620, Gainesville, FL 32611 (; ; )
| | - D A Hahn
- Department of Entomology and Nematology, University of Florida, P.O. Box 110620, Gainesville, FL 32611 (; ; )
| | - F M Oi
- Department of Entomology and Nematology, University of Florida, P.O. Box 110620, Gainesville, FL 32611 (; ; )
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50
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King KJ, Sinclair BJ. Water loss in tree weta (Hemideina): adaptation to the montane environment and a test of the melanisation-desiccation resistance hypothesis. ACTA ACUST UNITED AC 2016; 218:1995-2004. [PMID: 26157158 DOI: 10.1242/jeb.118711] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Montane insects are at a higher risk of desiccation than their lowland counterparts and are expected to have evolved reduced water loss. Hemideina spp. (tree weta; Orthoptera: Anostostomatidae) have both lowland (Hemideina femorata, Hemideina crassidens and Hemideina thoracica) and montane (Hemideina maori and Hemideina ricta) species. H. maori has both melanic and yellow morphs. We use these weta to test two hypotheses: that montane insects lose water more slowly than lowland species, and that cuticular water loss rates are lower in darker insects than lighter morphs, because of incorporation of melanin in the cuticle. We used flow-through respirometry to compare water loss rates among Hemideina species and found that montane weta have reduced cuticular water loss by 45%, reduced respiratory water loss by 55% and reduced the molar ratio of V̇H2 O:V̇CO2 by 64% compared with lowland species. Within H. maori, cuticular water loss was reduced by 46% when compared with yellow morphs. Removal of cuticular hydrocarbons significantly increased total water loss in both melanic and yellow morphs, highlighting the role that cuticular hydrocarbons play in limiting water loss; however, the dark morph still lost water more slowly after removal of cuticular hydrocarbons (57% less), supporting the melanisation-desiccation resistance hypothesis.
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Affiliation(s)
- Keith J King
- Department of Zoology, University of Otago, Dunedin 9054, New Zealand
| | - Brent J Sinclair
- Department of Biology, University of Western Ontario, London, Ontario, Canada N6A 5B7
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