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Holt JR, Cavichiolli de Oliveira N, Medina RF, Malacrinò A, Lindsey ARI. Insect-microbe interactions and their influence on organisms and ecosystems. Ecol Evol 2024; 14:e11699. [PMID: 39041011 PMCID: PMC11260886 DOI: 10.1002/ece3.11699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 06/14/2024] [Accepted: 06/21/2024] [Indexed: 07/24/2024] Open
Abstract
Microorganisms are important associates of insect and arthropod species. Insect-associated microbes, including bacteria, fungi, and viruses, can drastically impact host physiology, ecology, and fitness, while many microbes still have no known role. Over the past decade, we have increased our knowledge of the taxonomic composition and functional roles of insect-associated microbiomes and viromes. There has been a more recent shift toward examining the complexity of microbial communities, including how they vary in response to different factors (e.g., host genome, microbial strain, environment, and time), and the consequences of this variation for the host and the wider ecological community. We provide an overview of insect-microbe interactions, the variety of associated microbial functions, and the evolutionary ecology of these relationships. We explore the influence of the environment and the interactive effects of insects and their microbiomes across trophic levels. Additionally, we discuss the potential for subsequent synergistic and reciprocal impacts on the associated microbiomes, ecological interactions, and communities. Lastly, we discuss some potential avenues for the future of insect-microbe interactions that include the modification of existing microbial symbionts as well as the construction of synthetic microbial communities.
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Affiliation(s)
| | | | - Raul F. Medina
- Department of EntomologyTexas A&M University, Minnie Bell Heep CenterCollege StationTexasUSA
| | - Antonino Malacrinò
- Department of AgricultureUniversità Degli Studi Mediterranea di Reggio CalabriaReggio CalabriaItaly
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Rutschmann A, Perry C, Le Galliard JF, Dupoué A, Lourdais O, Guillon M, Brusch G, Cote J, Richard M, Clobert J, Miles DB. Ecological responses of squamate reptiles to nocturnal warming. Biol Rev Camb Philos Soc 2024; 99:598-621. [PMID: 38062628 DOI: 10.1111/brv.13037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 03/06/2024]
Abstract
Nocturnal temperatures are increasing at a pace exceeding diurnal temperatures in most parts of the world. The role of warmer nocturnal temperatures in animal ecology has received scant attention and most studies focus on diurnal or daily descriptors of thermal environments' temporal trends. Yet, available evidence from plant and insect studies suggests that organisms can exhibit contrasting physiological responses to diurnal and nocturnal warming. Limiting studies to diurnal trends can thus result in incomplete and misleading interpretations of the ability of species to cope with global warming. Although they are expected to be impacted by warmer nocturnal temperatures, insufficient data are available regarding the night-time ecology of vertebrate ectotherms. Here, we illustrate the complex effects of nocturnal warming on squamate reptiles, a keystone group of vertebrate ectotherms. Our review includes discussion of diurnal and nocturnal ectotherms, but we mainly focus on diurnal species for which nocturnal warming affects a period dedicated to physiological recovery, and thus may perturb activity patterns and energy balance. We first summarise the physical consequences of nocturnal warming on habitats used by squamate reptiles. Second, we describe how such changes can alter the energy balance of diurnal species. We illustrate this with empirical data from the asp viper (Vipera aspis) and common wall lizard (Podarcis muralis), two diurnal species found throughout western Europe. Third, we make use of a mechanistic approach based on an energy-balance model to draw general conclusions about the effects of nocturnal temperatures. Fourth, we examine how warmer nights may affect squamates over their lifetime, with potential consequences on individual fitness and population dynamics. We review quantitative evidence for such lifetime effects using recent data derived from a range of studies on the European common lizard (Zootoca vivipara). Finally, we consider the broader eco-evolutionary ramifications of nocturnal warming and highlight several research questions that require future attention. Our work emphasises the importance of considering the joint influence of diurnal and nocturnal warming on the responses of vertebrate ectotherms to climate warming.
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Affiliation(s)
- Alexis Rutschmann
- Station d'Ecologie Théorique et Expérimentale de Moulis, CNRS UAR2029, 02 route du CNRS, Moulis, 09200, France
| | - Constant Perry
- Station d'Ecologie Théorique et Expérimentale de Moulis, CNRS UAR2029, 02 route du CNRS, Moulis, 09200, France
| | - Jean-François Le Galliard
- Sorbonne Université, CNRS, UMR 7618, IRD, INRAE, Institut d'écologie et des sciences de l'environnement (iEES Paris), Tours 44-45, 4 Place Jussieu, Paris, 75005, France
- Département de Biologie, Ecole Normale Supérieure, PSL Research University, CNRS, UMS 3194, Centre de Recherche en écologie expérimentale et Prédictive (CEREEP-Ecotron IleDeFrance), 78 rue du château, Saint-Pierre-Lès-Nemours, 77140, France
| | - Andréaz Dupoué
- Ifremer, Univ Brest, CNRS, IRD, UMR 6539, LEMAR, 1625 Rte de Sainte-Anne, Plouzané, 29280, France
| | - Olivier Lourdais
- Centre d'Etudes Biologiques de Chizé, CNRS UMR 7372-Université de La Rochelle, 405 Route de Prissé la Charrière, Villiers-en-Bois, 79630, France
- School of Life Sciences, Arizona State University, Life Sciences Center Building, 427E Tyler Mall, Tempe, AZ, 85281, USA
| | - Michaël Guillon
- Centre d'Etudes Biologiques de Chizé, CNRS UMR 7372-Université de La Rochelle, 405 Route de Prissé la Charrière, Villiers-en-Bois, 79630, France
- Cistude Nature, Chemin du Moulinat-33185, Le Haillan, France
| | - George Brusch
- Department of Biological Sciences, California State University San Marcos, 333 S. Twin Oaks Valley Rd., San Marcos, CA, 92096, USA
| | - Julien Cote
- Laboratoire Evolution et Diversité Biologique (EDB), UMR5174, Université Toulouse 3 Paul Sabatier, CNRS, IRD, 118 Rte de Narbonne, Toulouse, 31077, France
| | - Murielle Richard
- Station d'Ecologie Théorique et Expérimentale de Moulis, CNRS UAR2029, 02 route du CNRS, Moulis, 09200, France
| | - Jean Clobert
- Station d'Ecologie Théorique et Expérimentale de Moulis, CNRS UAR2029, 02 route du CNRS, Moulis, 09200, France
| | - Donald B Miles
- Department of Biological Sciences, 131 Life Science Building, Ohio University, Athens, OH, 45701, USA
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Tougeron K, Iltis C, Rampnoux E, Goerlinger A, Dhondt L, Hance T. Still standing: The heat protection delivered by a facultative symbiont to its aphid host is resilient to repeated thermal stress. CURRENT RESEARCH IN INSECT SCIENCE 2023; 3:100061. [PMID: 37304568 PMCID: PMC10250925 DOI: 10.1016/j.cris.2023.100061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 04/05/2023] [Accepted: 05/29/2023] [Indexed: 06/13/2023]
Abstract
Insects have evolved diverse strategies to resist extreme high temperatures (EHT). The adaptive value of such strategies has to be evaluated when organisms experience multiple EHT events during their lifetime, as predicted in a changing climate. This is particularly the case for associations with facultative microbial partners involved in insect heat tolerance, the resilience of which to repeated heat stress has never been studied. We compared two artificial lines of the pea aphid (Acyrthosiphon pisum) differing by the absence or presence of the heat-protective facultative bacterium Serratia symbiotica. We exposed insect nymphs to a varying number of EHT events (between 0 and 3), and recorded fitness parameters. Except survival traits, fitness estimates were affected by the interaction between aphid infection status (absence/presence of S. symbiotica) and thermal treatment (number of heat shocks applied). Costs of bacterial infection were detected in the absence of thermal stress: symbiont-hosting aphids incurred longer development, decreased fecundity and body size. However, symbiotic infection turned neutral, and even beneficial for some traits (development and body size), as the number of heat shocks increased, and compared to the aposymbiotic strain. Conversely, symbiotic infection mediated aphid response to heat shock(s): fitness decreased only in the uninfected group. These findings suggest that (i) the facultative symbiont may alternatively act as a pathogen, commensal or mutualist depending on thermal environment, and (ii) the heat protection it delivered to its host persists under frequent EHT. We discuss eco-evolutionary implications and the role of potentially confounding factors (stage-specific effects, genetic polymorphism displayed by the obligate symbiont).
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Affiliation(s)
- Kévin Tougeron
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
- Institut de Recherche en Biosciences, Université de Mons, Av. du Champ de Mars 6, 7000 Mons, Belgium
| | - Corentin Iltis
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Eliott Rampnoux
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Alexandre Goerlinger
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Linda Dhondt
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
| | - Thierry Hance
- Earth and Life Institute, Ecology and Biodiversity, Université catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-Neuve, Belgium
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Majeed MZ, Sayed S, Bo Z, Raza A, Ma CS. Bacterial Symbionts Confer Thermal Tolerance to Cereal Aphids Rhopalosiphum padi and Sitobion avenae. INSECTS 2022; 13:insects13030231. [PMID: 35323529 PMCID: PMC8949882 DOI: 10.3390/insects13030231] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/10/2022] [Accepted: 02/23/2022] [Indexed: 02/04/2023]
Abstract
Simple Summary This study assesses the putative association between the chronic and acute thermal tolerance of cereal aphids Rhopalosiphum padi (L.) and Sitobion avenae (F.) and the abundance of their bacterial symbionts. Thermal tolerance indices were determined for 5-day-old apterous aphid individuals and were associated with the aphid-specific and total bacterial symbionts’ gene abundance (copy numbers). The results show a significantly higher bacterial symbionts’ gene abundance in temperature-tolerant aphid individuals than the susceptible ones for both aphid species. Moreover, the gene abundance of total (16S rRNA) bacteria and most of the aphid-specific bacterial symbionts for both cereal aphid species were significantly and positively associated with their critical thermal maxima values. Overall, the findings of the study suggest the potential role of the bacterial symbionts of aphids in conferring thermal tolerance to their hosts. Abstract High-temperature events are evidenced to exert significant influence on the population performance and thermal biology of insects, such as aphids. However, it is not yet clear whether the bacterial symbionts of insects mediate the thermal tolerance traits of their hosts. This study is intended to assess the putative association among the chronic and acute thermal tolerance of two cereal aphid species, Rhopalosiphum padi (L.) and Sitobion avenae (F.), and the abundance of their bacterial symbionts. The clones of aphids were collected randomly from different fields of wheat crops and were maintained under laboratory conditions. Basal and acclimated CTmax and chronic thermal tolerance indices were measured for 5-day-old apterous aphid individuals and the abundance (gene copy numbers) of aphid-specific and total (16S rRNA) bacterial symbionts were determined using real-time RT-qPCR. The results reveal that R. padi individuals were more temperature tolerant under chronic exposure to 31 °C and also exhibited about 1.0 °C higher acclimated and basal CTmax values than those of S. avenae. Moreover, a significantly higher bacterial symbionts’ gene abundance was recorded in temperature-tolerant aphid individuals than the susceptible ones for both aphid species. Although total bacterial (16S rRNA) abundance per aphid was higher in S. avenae than R. padi, the gene abundance of aphid-specific bacterial symbionts was nearly alike for both of the aphid species. Nevertheless, basal and acclimated CTmax values were positively and significantly associated with the gene abundance of total symbiont density, Buchnera aphidicola, Serratia symbiotica, Hamilton defensa, Regiella insecticola and Spiroplasma spp. for R. padi, and with the total symbiont density, total bacteria (16S rRNA) and with all aphid-specific bacterial symbionts (except Spiroplasma spp.) for S. avenae. The overall study results corroborate the potential role of the bacterial symbionts of aphids in conferring thermal tolerance to their hosts.
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Affiliation(s)
- Muhammad Zeeshan Majeed
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Climate Change Biology Research Group, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
- Department of Entomology, College of Agriculture, University of Sargodha, Sargodha 40100, Pakistan
- Correspondence: (M.Z.M.); (C.-S.M.)
| | - Samy Sayed
- Department of Science and Technology, University College-Ranyah, Taif University, B.O. Box 11099, Taif 21944, Saudi Arabia;
| | - Zhang Bo
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Climate Change Biology Research Group, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
| | - Ahmed Raza
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Cereal Fungal Diseases Research Group, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
- Department of Plant Pathology, Sub-Campus Depalpur, University of Agriculture, Okara 56300, Pakistan
| | - Chun-Sen Ma
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Climate Change Biology Research Group, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
- Correspondence: (M.Z.M.); (C.-S.M.)
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Carpenter M, Peng L, Smith AH, Joffe J, O’Connor M, Oliver KM, Russell JA. Frequent Drivers, Occasional Passengers: Signals of Symbiont-Driven Seasonal Adaptation and Hitchhiking in the Pea Aphid, Acyrthosiphon pisum. INSECTS 2021; 12:805. [PMID: 34564245 PMCID: PMC8466206 DOI: 10.3390/insects12090805] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 12/25/2022]
Abstract
Insects harbor a variety of maternally inherited bacterial symbionts. As such, variation in symbiont presence/absence, in the combinations of harbored symbionts, and in the genotypes of harbored symbiont species provide heritable genetic variation of potential use in the insects' adaptive repertoires. Understanding the natural importance of symbionts is challenging but studying their dynamics over time can help to elucidate the potential for such symbiont-driven insect adaptation. Toward this end, we studied the seasonal dynamics of six maternally transferred bacterial symbiont species in the multivoltine pea aphid (Acyrthosiphon pisum). Our sampling focused on six alfalfa fields in southeastern Pennsylvania, and spanned 14 timepoints within the 2012 growing season, in addition to two overwintering periods. To test and generate hypotheses on the natural relevance of these non-essential symbionts, we examined whether symbiont dynamics correlated with any of ten measured environmental variables from the 2012 growing season, including some of known importance in the lab. We found that five symbionts changed prevalence across one or both overwintering periods, and that the same five species underwent such frequency shifts across the 2012 growing season. Intriguingly, the frequencies of these dynamic symbionts showed robust correlations with a subset of our measured environmental variables. Several of these trends supported the natural relevance of lab-discovered symbiont roles, including anti-pathogen defense. For a seventh symbiont-Hamiltonella defensa-studied previously across the same study periods, we tested whether a reported correlation between prevalence and temperature stemmed not from thermally varying host-level fitness effects, but from selection on co-infecting symbionts or on aphid-encoded alleles associated with this bacterium. In general, such "hitchhiking" effects were not evident during times with strongly correlated Hamiltonella and temperature shifts. However, we did identify at least one time period in which Hamiltonella spread was likely driven by selection on a co-infecting symbiont-Rickettsiella viridis. Recognizing the broader potential for such hitchhiking, we explored selection on co-infecting symbionts as a possible driver behind the dynamics of the remaining six species. Out of twelve examined instances of symbiont dynamics unfolding across 2-week periods or overwintering spans, we found eight in which the focal symbiont underwent parallel frequency shifts under single infection and one or more co-infection contexts. This supported the idea that phenotypic variation created by the presence/absence of individual symbionts is a direct target for selection, and that symbiont effects can be robust under co-habitation with other symbionts. Contrastingly, in two cases, we found that selection may target phenotypes emerging from symbiont co-infections, with specific species combinations driving overall trends for the focal dynamic symbionts, without correlated change under single infection. Finally, in three cases-including the one described above for Hamiltonella-our data suggested that incidental co-infection with a (dis)favored symbiont could lead to large frequency shifts for "passenger" symbionts, conferring no apparent cost or benefit. Such hitchhiking has rarely been studied in heritable symbiont systems. We propose that it is more common than appreciated, given the widespread nature of maternally inherited bacteria, and the frequency of multi-species symbiotic communities across insects.
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Affiliation(s)
- Melissa Carpenter
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
| | - Linyao Peng
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Andrew H. Smith
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Jonah Joffe
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
| | - Michael O’Connor
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
| | - Kerry M. Oliver
- Department of Entomology, University of Georgia, 120 Cedar St., Athens, GA 30602, USA;
| | - Jacob A. Russell
- Department of Biodiversity, Earth, and Environmental Science, Drexel University, 3250 Chestnut St., Philadelphia, PA 19104, USA; (M.C.); (A.H.S.); (M.O.)
- Department of Biology, Drexel University, 3245 Chestnut St., Philadelphia, PA 19104, USA; (L.P.); (J.J.)
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Engl T, Schmidt THP, Kanyile SN, Klebsch D. Metabolic Cost of a Nutritional Symbiont Manifests in Delayed Reproduction in a Grain Pest Beetle. INSECTS 2020; 11:insects11100717. [PMID: 33092035 PMCID: PMC7589553 DOI: 10.3390/insects11100717] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/15/2020] [Accepted: 10/17/2020] [Indexed: 01/24/2023]
Abstract
Simple Summary Animals engage in various symbioses. However, these interactions are not always beneficial for the host; they can also incur costs under certain circumstances. The bacterial symbiont supports, on the one hand, the cuticle formation of the sawtoothed grain beetle Oryzaephilus surinamensis, which is extremely beneficial under dry conditions as a thicker and more melanized cuticle prevents desiccation of the insect. On the other hand, under higher humidity, the benefit is strongly reduced. In this study, we investigated whether harboring a symbiont can also be a disadvantage. Therefore, we first measured the number of symbionts throughout the beetles’ life and found a strong increase during the end of metamorphosis, just before beetles reach adulthood. Afterwards, males lose the symbionts again, whereas females retain a stable number. A comparison of beetles with and without symbionts revealed no differences in many life history traits. Larval development took the same time and there was also no difference in adult mortality or lifespan or the number of offspring of females. However, females with symbionts started to reproduce significantly later by one to two weeks, meaning they have a disadvantage in comparison to females without symbionts. Thus, harboring a symbiont is beneficial or costly in a context-dependent manner. Abstract Animals engage in a plethora of mutualistic interactions with microorganisms that can confer various benefits to their host but can also incur context-dependent costs. The sawtoothed grain beetle Oryzaephilus surinamensis harbors nutritional, intracellular Bacteroidetes bacteria that supplement precursors for the cuticle synthesis and thereby enhance desiccation resistance of its host. Experimental elimination of the symbiont impairs cuticle formation and reduces fitness under desiccation stress but does not disrupt the host’s life cycle. For this study, we first demonstrated that symbiont populations showed the strongest growth at the end of metamorphosis and then declined continuously in males, but not in females. The symbiont loss neither impacted the development time until adulthood nor adult mortality or lifespan. Furthermore, lifetime reproduction was not influenced by the symbiont presence. However, symbiotic females started to reproduce almost two weeks later than aposymbiotic ones. Thus, symbiont presence incurs a metabolic and context-dependent fitness cost to females, probably due to a nutrient allocation trade-off between symbiont growth and sexual maturation. The O. surinamensis symbiosis thereby represents an experimentally amenable system to study eco-evolutionary dynamics under variable selection pressures.
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Affiliation(s)
- Tobias Engl
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55128 Mainz, Germany; (T.H.P.S.); (S.N.K.); (D.K.)
- Research Group Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, 07745 Jena, Germany
- Correspondence:
| | - Thorsten H. P. Schmidt
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55128 Mainz, Germany; (T.H.P.S.); (S.N.K.); (D.K.)
| | - Sthandiwe Nomthandazo Kanyile
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55128 Mainz, Germany; (T.H.P.S.); (S.N.K.); (D.K.)
| | - Dagmar Klebsch
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, 55128 Mainz, Germany; (T.H.P.S.); (S.N.K.); (D.K.)
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Lemoine MM, Engl T, Kaltenpoth M. Microbial symbionts expanding or constraining abiotic niche space in insects. CURRENT OPINION IN INSECT SCIENCE 2020; 39:14-20. [PMID: 32086000 DOI: 10.1016/j.cois.2020.01.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/07/2020] [Accepted: 01/13/2020] [Indexed: 05/06/2023]
Abstract
In addition to their well-studied contributions to their host's nutrition, digestion, and defense, microbial symbionts of insects are increasingly found to affect their host's response toward abiotic stressors. In particular, symbiotic microbes can reduce or enhance tolerance to temperature extremes, improve desiccation resistance by aiding cuticle biosynthesis and sclerotization, and detoxify heavy metals. As such, individual symbionts or microbial communities can expand or constrain the abiotic niche space of their host and determine its adaptability to fluctuating environments. In light of the increasing impact of humans on climate and environment, a better understanding of host-microbe interactions is necessary to predict how different insect species will respond to changes in abiotic conditions.
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Affiliation(s)
- Marion M Lemoine
- Department of Evolutionary Ecology, Institute for Organismic and Molecular Evolution (iomE), Johannes Gutenberg University, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Tobias Engl
- Department of Evolutionary Ecology, Institute for Organismic and Molecular Evolution (iomE), Johannes Gutenberg University, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute for Organismic and Molecular Evolution (iomE), Johannes Gutenberg University, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany.
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Heyworth ER, Smee MR, Ferrari J. Aphid Facultative Symbionts Aid Recovery of Their Obligate Symbiont and Their Host After Heat Stress. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00056] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Obligate bacterial endosymbionts limit thermal tolerance of insect host species. Proc Natl Acad Sci U S A 2019; 116:24712-24718. [PMID: 31740601 DOI: 10.1073/pnas.1915307116] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The thermal tolerance of an organism limits its ecological and geographic ranges and is potentially affected by dependence on temperature-sensitive symbiotic partners. Aphid species vary widely in heat sensitivity, but almost all aphids are dependent on the nutrient-provisioning intracellular bacterium Buchnera, which has evolved with aphids for 100 million years and which has a reduced genome potentially limiting heat tolerance. We addressed whether heat sensitivity of Buchnera underlies variation in thermal tolerance among 5 aphid species. We measured how heat exposure of juvenile aphids affects later survival, maturation time, and fecundity. At one extreme, heat exposure of Aphis gossypii enhanced fecundity and had no effect on the Buchnera titer. In contrast, heat suppressed Buchnera populations in Aphis fabae, which suffered elevated mortality, delayed development and reduced fecundity. Likewise, in Acyrthosiphon kondoi and Acyrthosiphon pisum, heat caused rapid declines in Buchnera numbers, as well as reduced survivorship, development rate, and fecundity. Fecundity following heat exposure is severely decreased by a Buchnera mutation that suppresses the transcriptional response of a gene encoding a small heat shock protein. Similarly, absence of this Buchnera heat shock gene may explain the heat sensitivity of Ap. fabae Fluorescent in situ hybridization revealed heat-induced deformation and shrinkage of bacteriocytes in heat-sensitive species but not in heat-tolerant species. Sensitive and tolerant species also differed in numbers and transcriptional responses of heat shock genes. These results show that shifts in Buchnera heat sensitivity contribute to host variation in heat tolerance.
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Renoz F, Pons I, Hance T. Evolutionary responses of mutualistic insect-bacterial symbioses in a world of fluctuating temperatures. CURRENT OPINION IN INSECT SCIENCE 2019; 35:20-26. [PMID: 31302355 DOI: 10.1016/j.cois.2019.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/29/2019] [Accepted: 06/20/2019] [Indexed: 06/10/2023]
Abstract
Climate change is altering the abundance and distribution of millions of insect species around the world and is a major contributor to the decline of numerous species. Many insect species may be indirectly affected through their nutritional dependence on mutualistic bacteria. Indeed, these bacterial partners generally have a highly reduced and static genome, resulting from millions of years of coevolution and isolation in insect cells, and have limited adaptive capacity. The dependence of insects on bacterial partners with narrow environmental tolerance also restricts their ability to adapt, potentially increasing the risk of their extinction, particularly in a world characterized by increasing and fluctuating temperatures. In this review, we examine how climate change can affect the evolutionary trajectories of bacterial mutualism in insects by considering the possible alternatives that may compensate for the dependence on bacterial partners that have become 'Achilles' heels'. We also discuss the beneficial and compensatory effects, as well as the antagonistic effects associated with so-called facultative symbionts in the context of an increased incidence of transient extreme temperatures.
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Affiliation(s)
- François Renoz
- Université catholique de Louvain, Earth and Life Institute, Biodiversity Research Center, Croix de Sud 4-5, bte L7.07.04, 1348 Louvain-la-Neuve, Belgium.
| | - Inès Pons
- Université catholique de Louvain, Earth and Life Institute, Biodiversity Research Center, Croix de Sud 4-5, bte L7.07.04, 1348 Louvain-la-Neuve, Belgium
| | - Thierry Hance
- Université catholique de Louvain, Earth and Life Institute, Biodiversity Research Center, Croix de Sud 4-5, bte L7.07.04, 1348 Louvain-la-Neuve, Belgium
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11
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Feng H, Park JS, Zhai RG, Wilson ACC. microRNA-92a regulates the expression of aphid bacteriocyte-specific secreted protein 1. BMC Res Notes 2019; 12:638. [PMID: 31564246 PMCID: PMC6767646 DOI: 10.1186/s13104-019-4665-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/18/2019] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVE Aphids harbor a nutritional obligate endosymbiont in specialized cells called bacteriocytes, which aggregate to form an organ known as the bacteriome. Aphid bacteriomes display distinct gene expression profiles that facilitate the symbiotic relationship. Currently, the mechanisms that regulate these patterns of gene expression are unknown. Recently using computational pipelines, we identified miRNAs that are conserved in expression in the bacteriomes of two aphid species and proposed that they function as important regulators of bacteriocyte gene expression. Here using a dual luciferase assay in mouse NIH/3T3 cell culture, we aimed to experimentally validate the computationally predicted interaction between Myzus persicae miR-92a and the predicted target region of M. persicae bacteriocyte-specific secreted protein 1 (SP1) mRNA. RESULTS In the dual luciferase assay, miR-92a interacted with the SP1 target region resulting in a significant downregulation of the luciferase signal. Our results demonstrate that miR-92a interacts with SP1 to alter expression in a heterologous expression system, thereby supporting our earlier assertion that miRNAs are regulators of the aphid/Buchnera symbiotic interaction.
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Affiliation(s)
- Honglin Feng
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA. .,Boyce Thompson Institute, Ithaca, NY, 14853, USA.
| | - Joun S Park
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA
| | - R Grace Zhai
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, 33136, USA
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12
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Horváthová T, Babik W, Kozłowski J, Bauchinger U. Vanishing benefits - The loss of actinobacterial symbionts at elevated temperatures. J Therm Biol 2019; 82:222-228. [PMID: 31128651 DOI: 10.1016/j.jtherbio.2019.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 04/15/2019] [Accepted: 04/20/2019] [Indexed: 12/11/2022]
Abstract
Only a few insect species are known to engage in symbiotic associations with antibiotic-producing Actinobacteria and profit from this kind of protection against pathogens. However, it still remains elusive how widespread the symbiotic interactions with Actinobacteria in other organisms are and how these partnerships benefit the hosts in terms of the growth and survival. We characterized a drastic temperature-induced change in the occurrence of Actinobacteria in the gut of the terrestrial isopod Porcellio scaber reared under two different temperature (15 °C and 22 °C) and oxygen conditions (10% and 22% O2) using 16S rRNA gene sequencing. We show that the relative abundance of actinobacterial gut symbionts correlates with increased host growth at lower temperature. Actinobacterial symbionts were almost completely absent at 22 °C under both high and low oxygen conditions. In addition, we identified members of nearly half of the known actinobacterial families in the isopod microbiome, and most of these include members that are known to produce antibiotics. Our study suggests that hosting diverse actinobacterial symbionts may provide conditions favorable for host growth. These findings show how a temperature-driven decline in microbiome diversity may cause a loss of beneficial functions with negative effects on ectotherms.
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Affiliation(s)
- Terézia Horváthová
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland; Institute of Soil Biology, Biology Centre, Czech Academy of Sciences, Na Sádkách 7, České Budějovice, Czech Republic.
| | - Wiesław Babik
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Jan Kozłowski
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
| | - Ulf Bauchinger
- Institute of Environmental Sciences, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland
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13
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Mech AM, Harper SJ, Havill NP, von Dohlen CD, Burke GR. Ecological factors influencing the beneficial endosymbionts of the hemlock woolly adelgid (Hemiptera: Adelgidae). INSECT SCIENCE 2019; 26:97-107. [PMID: 28791805 DOI: 10.1111/1744-7917.12514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 05/16/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Bacterial endosymbionts of sap-sucking insects provide their host with a number of beneficial qualities, including the supply of nutrition, defense against parasitoids, and protection from heat stress. Damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host. We evaluated observational and experimental factors regarding the nonnative hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera: Adelgidae) to help understand the roles of its three recently identified symbionts, including under heat stress conditions. The prevalence of A. tsugae's facultative symbiont (Serratia symbiotica) was examined at different spatial scales to determine how variable infection rates are for this symbiont. There was no significant difference found in infection rates between adelgids on a tree, within a plot, or within a state. However, significantly more adelgids in Georgia (95%) had S. symbiotica compared to those in New York (68%). Microsatellite genotyping of the adelgids found that this difference was most likely not the result of a second introduction of A. tsugae into eastern North America. Comparison of S. symbiotica proportions between first and fourth instars showed that symbiont absence did not affect the ability of A. tsugae to survive aestivation. Evaluations of symbiont densities within each adelgid found that when S. symbiotica was absent, the density of obligate symbionts was significantly higher. Exposure to heat stress (32.5 °C) was not consistently correlated with changes in symbiont densities over a 4-d period. Overall, we have shown that symbiont prevalence and densities vary within the broad population of A. tsugae in eastern North America, with potentially significant effects upon the ecology of this important pest.
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Affiliation(s)
- Angela M Mech
- Department of Entomology, University of Georgia, Athens, Georgia, USA
- School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, USA
| | - Sherilyn J Harper
- Department of Entomology, University of Georgia, Athens, Georgia, USA
| | - Nathan P Havill
- USDA Forest Service, Northern Research Station, Hamden, Connecticut, USA
| | | | - Gaelen R Burke
- Department of Entomology, University of Georgia, Athens, Georgia, USA
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14
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Zhu L, Wang L, Ma CS. Sporadic short temperature events cannot be neglected in predicting impacts of climate change on small insects. JOURNAL OF INSECT PHYSIOLOGY 2019; 112:48-56. [PMID: 30529236 DOI: 10.1016/j.jinsphys.2018.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/04/2018] [Accepted: 12/04/2018] [Indexed: 06/09/2023]
Abstract
Climate warming is characterized by increase in extreme heat events (EHEs). EHEs and mild temperature periods alternate with each other and form complex climate scenarios. Among these scenarios, low-frequency and short-duration extreme heat events during long mild periods (sporadic short EHEs) and low-frequency and short-duration mild periods during long extreme heat events (sporadic short mild periods) commonly occur in nature. The biological effects of these two types of temperature events have not been thoroughly elucidated to date. To clarify the biological effects of these temperature events on organisms, we selected the English grain aphid, a globally important cereal pest, as our model system. We exposed aphids to simulated 24-h diurnal fluctuating temperatures, inserted these events during the wheat growing season and then investigated development, adult longevity, fecundity, survival, and demographic parameters. We found that sporadic short mild periods during a long EHE could improve their life history traits. Increasing the duration of mild periods from 1 day to 2 days did not significantly change their demographic performance. Sporadic short EHEs during a long mild period did not significantly affect vital rates, while increasing the duration of EHEs from 1 day to 2 days worsened the aphids' performance. We found that short mild episodes in the hot season may benefit small insects to buffer long duration heatwaves. We discussed how sporadic short mild periods during a long EHE supplied aphids a chance to recover from heat stress. Thus, we suggest that sporadic temperature events should be considered in population prediction of small insects under climate change and should be integrated into pest management.
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Affiliation(s)
- Liang Zhu
- Climate Change Biology Research Group, State Key Laboratory for Biology of Plant Diseases and Insect Pests, Inst. of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2 Yuanmingyuan West Road, Haidian District, CN-100193 Beijing, PR China; Institute of Plant and Environmental Protection, Beijing Academy of Agriculture and Forestry Sciences, No. 9 Shuguanghuayuan Middle Road, Haidian District, CN-100097 Beijing, PR China
| | - Lin Wang
- Climate Change Biology Research Group, State Key Laboratory for Biology of Plant Diseases and Insect Pests, Inst. of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2 Yuanmingyuan West Road, Haidian District, CN-100193 Beijing, PR China
| | - Chun-Sen Ma
- Climate Change Biology Research Group, State Key Laboratory for Biology of Plant Diseases and Insect Pests, Inst. of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2 Yuanmingyuan West Road, Haidian District, CN-100193 Beijing, PR China.
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15
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Hoffmann AA. Rapid adaptation of invertebrate pests to climatic stress? CURRENT OPINION IN INSECT SCIENCE 2017; 21:7-13. [PMID: 28822492 DOI: 10.1016/j.cois.2017.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 04/16/2017] [Accepted: 04/19/2017] [Indexed: 06/07/2023]
Abstract
There is surprisingly little information on adaptive responses of pests and disease vectors to climatic stresses even though the short generation times and large population sizes associated with pests make rapid adaptation likely. Most evidence of adaptive differentiation has been obtained from geographic comparisons and these can directly or indirectly indicate rates of adaptation where historical data on invasions are available. There is very little information on adaptive shifts in pests detected through molecular comparisons even though the genomes of many pests are now available and can help to identify markers underlying adaptation. While the limited evidence available points to frequent rapid adaptation that can affect pest and disease vector control, constraints to adaptation are also evident and a predictive framework around the likelihood and limits of rapid adaptation is required.
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Affiliation(s)
- Ary A Hoffmann
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia.
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16
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Hunter MS, Asiimwe P, Himler AG, Kelly SE. Host nuclear genotype influences phenotype of a conditional mutualist symbiont. J Evol Biol 2016; 30:141-149. [DOI: 10.1111/jeb.12993] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/15/2016] [Accepted: 10/13/2016] [Indexed: 11/29/2022]
Affiliation(s)
- M. S. Hunter
- Department of Entomology University of Arizona Tucson AZ USA
| | - P. Asiimwe
- Department of Entomology University of Arizona Tucson AZ USA
| | - A. G. Himler
- Department of Entomology University of Arizona Tucson AZ USA
| | - S. E. Kelly
- Department of Entomology University of Arizona Tucson AZ USA
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17
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Mondo SJ, Salvioli A, Bonfante P, Morton JB, Pawlowska TE. Nondegenerative Evolution in Ancient Heritable Bacterial Endosymbionts of Fungi. Mol Biol Evol 2016; 33:2216-31. [DOI: 10.1093/molbev/msw086] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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18
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Host Plant Determines the Population Size of an Obligate Symbiont (Buchnera aphidicola) in Aphids. Appl Environ Microbiol 2016; 82:2336-2346. [PMID: 26850304 DOI: 10.1128/aem.04131-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 02/02/2016] [Indexed: 12/24/2022] Open
Abstract
Buchnera aphidicolais an obligate endosymbiont that provides aphids with several essential nutrients. Though much is known about aphid-Buchnera interactions, the effect of the host plant on Buchnera population size remains unclear. Here we used quantitative PCR (qPCR) techniques to explore the effects of the host plant on Buchnera densities in the cotton-melon aphid, Aphis gossypii Buchneratiters were significantly higher in populations that had been reared on cucumber for over 10 years than in populations maintained on cotton for a similar length of time. Aphids collected in the wild from hibiscus and zucchini harbored more Buchnera symbionts than those collected from cucumber and cotton. The effect of aphid genotype on the population size of Buchnera depended on the host plant upon which they fed. When aphids from populations maintained on cucumber or cotton were transferred to novel host plants, host survival and Buchnera population size fluctuated markedly for the first two generations before becoming relatively stable in the third and later generations. Host plant extracts from cucumber, pumpkin, zucchini, and cowpea added to artificial diets led to a significant increase in Buchnera titers in the aphids from the population reared on cotton, while plant extracts from cotton and zucchini led to a decrease in Buchnera titers in the aphids reared on cucumber. Gossypol, a secondary metabolite from cotton, suppressed Buchnera populations in populations from both cotton and cucumber, while cucurbitacin from cucurbit plants led to higher densities. Together, the results suggest that host plants influence Buchnera population processes and that this may provide phenotypic plasticity in host plant use for clonal aphids.
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19
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Cass BN, Himler AG, Bondy EC, Bergen JE, Fung SK, Kelly SE, Hunter MS. Conditional fitness benefits of the Rickettsia bacterial symbiont in an insect pest. Oecologia 2015; 180:169-79. [PMID: 26376661 DOI: 10.1007/s00442-015-3436-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 08/25/2015] [Indexed: 11/25/2022]
Abstract
Inherited bacterial symbionts are common in arthropods and can have strong effects on the biology of their hosts. These effects are often mediated by host ecology. The Rickettsia symbiont can provide strong fitness benefits to its insect host, Bemisia tabaci, under laboratory and field conditions. However, the frequency of the symbiont is heterogeneous among field collection sites across the USA, suggesting that the benefits of the symbiont are contingent on additional factors. In two whitefly genetic lines collected from the same location, we tested the effect of Rickettsia on whitefly survival after heat shock, on whitefly competitiveness at different temperatures, and on whitefly competitiveness at different starting frequencies of Rickettsia. Rickettsia did not provide protection against heat shock nor affect the competitiveness of whiteflies at different temperatures or starting frequencies. However, there was a strong interaction between Rickettsia infection and whitefly genetic line. Performance measures indicated that Rickettsia was associated with significant female bias in both whitefly genetic lines, but in the second whitefly genetic line it conferred no significant fitness benefits nor conferred any competitive advantage to its host over uninfected whiteflies in population cages. These results help to explain other reports of variation in the phenotype of the symbiosis. Furthermore, they demonstrate the complex nature of these close symbiotic associations and the need to consider these interactions in the context of host population structure.
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Affiliation(s)
- Bodil N Cass
- Graduate Interdisciplinary Program in Entomology and Insect Science, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
| | - Anna G Himler
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
- Department of Biology, The College of Idaho, 2112 Cleveland Blvd., Box 44, Caldwell, ID, 83605, USA
| | - Elizabeth C Bondy
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
| | - Jacquelyn E Bergen
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
| | - Sierra K Fung
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
| | - Suzanne E Kelly
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA
| | - Martha S Hunter
- Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
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20
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Heritable symbiosis: The advantages and perils of an evolutionary rabbit hole. Proc Natl Acad Sci U S A 2015; 112:10169-76. [PMID: 25713367 DOI: 10.1073/pnas.1421388112] [Citation(s) in RCA: 282] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Many eukaryotes have obligate associations with microorganisms that are transmitted directly between generations. A model for heritable symbiosis is the association of aphids, a clade of sap-feeding insects, and Buchnera aphidicola, a gammaproteobacterium that colonized an aphid ancestor 150 million years ago and persists in almost all 5,000 aphid species. Symbiont acquisition enables evolutionary and ecological expansion; aphids are one of many insect groups that would not exist without heritable symbiosis. Receiving less attention are potential negative ramifications of symbiotic alliances. In the short run, symbionts impose metabolic costs. Over evolutionary time, hosts evolve dependence beyond the original benefits of the symbiosis. Symbiotic partners enter into an evolutionary spiral that leads to irreversible codependence and associated risks. Host adaptations to symbiosis (e.g., immune-system modification) may impose vulnerabilities. Symbiont genomes also continuously accumulate deleterious mutations, limiting their beneficial contributions and environmental tolerance. Finally, the fitness interests of obligate heritable symbionts are distinct from those of their hosts, leading to selfish tendencies. Thus, genes underlying the host-symbiont interface are predicted to follow a coevolutionary arms race, as observed for genes governing host-pathogen interactions. On the macroevolutionary scale, the rapid evolution of interacting symbiont and host genes is predicted to accelerate host speciation rates by generating genetic incompatibilities. However, degeneration of symbiont genomes may ultimately limit the ecological range of host species, potentially increasing extinction risk. Recent results for the aphid-Buchnera symbiosis and related systems illustrate that, whereas heritable symbiosis can expand ecological range and spur diversification, it also presents potential perils.
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21
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Xie J, Winter C, Winter L, Mateos M. Rapid spread of the defensive endosymbiont Spiroplasma in Drosophila hydei under high parasitoid wasp pressure. FEMS Microbiol Ecol 2014; 91:1-11. [DOI: 10.1093/femsec/fiu017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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22
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Repetitive sequence variations in the promoter region of the adhesin-encoding gene sabA of Helicobacter pylori affect transcription. J Bacteriol 2014; 196:3421-9. [PMID: 25022855 DOI: 10.1128/jb.01956-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The pathogenesis of diseases elicited by the gastric pathogen Helicobacter pylori is partially determined by the effectiveness of adaptation to the variably acidic environment of the host stomach. Adaptation includes appropriate adherence to the gastric epithelium via outer membrane protein adhesins such as SabA. The expression of sabA is subject to regulation via phase variation in the promoter and coding regions as well as repression by the two-component system ArsRS. In this study, we investigated the role of a homopolymeric thymine [poly(T)] tract -50 to -33 relative to the sabA transcriptional start site in H. pylori strain J99. We quantified sabA expression in H. pylori J99 by quantitative reverse transcription-PCR (RT-PCR), demonstrating significant changes in sabA expression associated with experimental manipulations of poly(T) tract length. Mimicking the length increase of this tract by adding adenines instead of thymines had similar effects, while the addition of other nucleotides failed to affect sabA expression in the same manner. We hypothesize that modification of the poly(T) tract changes DNA topology, affecting regulatory protein interaction(s) or RNA polymerase binding efficiency. Additionally, we characterized the interaction between the sabA promoter region and ArsR, a response regulator affecting sabA expression. Using recombinant ArsR in electrophoretic mobility shift assays (EMSA), we localized binding to a sequence with partial dyad symmetry -20 and +38 relative to the sabA +1 site. The control of sabA expression by both ArsRS and phase variation at two distinct repeat regions suggests the control of sabA expression is both complex and vital to H. pylori infection.
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23
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Pinheiro P, Bereman MS, Burd J, Pals M, Armstrong S, Howe KJ, Thannhauser TW, MacCoss MJ, Gray SM, Cilia M. Evidence of the biochemical basis of host virulence in the greenbug aphid, Schizaphis graminum (Homoptera: Aphididae). J Proteome Res 2014; 13:2094-108. [PMID: 24588548 DOI: 10.1021/pr4012415] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biotypes of aphids and many other insect pests are defined based on the phenotypic response of host plants to the insect pest without considering their intrinsic characteristics and genotypes. Plant breeders have spent considerable effort developing aphid-resistant, small-grain varieties to limit insecticide control of the greenbug, Schizaphis graminum. However, new S. graminum biotypes frequently emerge that break resistance. Mechanisms of virulence on the aphid side of the plant-insect interaction are not well understood. S. graminum biotype H is highly virulent on most small grain varieties. This characteristic makes biotype H ideal for comparative proteomics to investigate the basis of biotype virulence in aphids. In this study, we used comparative proteomics to identify protein expression differences associated with virulence. Aphid proteins involved in the tricarboxylic acid cycle, immune system, cell division, and antiapoptosis pathways were found to be up-regulated in biotype H relative to other biotypes. Proteins from the bacterial endosymbiont of aphids were also differentially expressed in biotype H. Guided by the proteome results, we tested whether biotype H had a fitness advantage compared with other S. graminum biotypes and found that biotype H had a higher reproductive fitness as compared with two other biotypes on a range of different wheat germplasms. Finally, we tested whether aphid genetics can be used to further dissect the genetic mechanisms of biotype virulence in aphids. The genetic data showed that sexual reproduction is a source of biotypic variation observed in S. graminum.
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Affiliation(s)
- Patricia Pinheiro
- Department of Entomology, Cornell University , 2130 Comstock Hall, Ithaca, New York 14853 United States
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24
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Zhao F, Zhang W, Hoffmann AA, Ma CS. Night warming on hot days produces novel impacts on development, survival and reproduction in a small arthropod. J Anim Ecol 2014; 83:769-78. [PMID: 24372332 DOI: 10.1111/1365-2656.12196] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 12/14/2013] [Indexed: 12/15/2022]
Affiliation(s)
- Fei Zhao
- Climate Change Biology Research Group; State Key Laboratory for Biology of Plant Diseases and Insect Pests; Institute of Plant Protection; Chinese Academy of Agricultural Sciences; Yuan-Ming-Yuan West Road No.2 Beijing 100193 China
- Laboratory for Integrated Pest Management of Insect; Institute of Plant Protection; Shanxi Academy of Agricultural Sciences; Wu-Cheng South Road No.59 Taiyuan 030031 China
| | - Wei Zhang
- Climate Change Biology Research Group; State Key Laboratory for Biology of Plant Diseases and Insect Pests; Institute of Plant Protection; Chinese Academy of Agricultural Sciences; Yuan-Ming-Yuan West Road No.2 Beijing 100193 China
| | - Ary A. Hoffmann
- Pest and Disease Vector Group; Departments of Zoology and Genetics; Bio21 Institute; The University of Melbourne; Flemington Road 30 Melbourne Vic. 3052 Australia
| | - Chun-Sen Ma
- Climate Change Biology Research Group; State Key Laboratory for Biology of Plant Diseases and Insect Pests; Institute of Plant Protection; Chinese Academy of Agricultural Sciences; Yuan-Ming-Yuan West Road No.2 Beijing 100193 China
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25
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Fan Y, Wernegreen JJ. Can't take the heat: high temperature depletes bacterial endosymbionts of ants. MICROBIAL ECOLOGY 2013; 66:727-33. [PMID: 23872930 PMCID: PMC3905736 DOI: 10.1007/s00248-013-0264-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 07/01/2013] [Indexed: 05/22/2023]
Abstract
Members of the ant tribe Camponotini have coevolved with Blochmannia, an obligate intracellular bacterial mutualist. This endosymbiont lives within host bacteriocyte cells that line the ant midgut, undergoes maternal transmission from host queens to offspring, and contributes to host nutrition via nitrogen recycling and nutrient biosynthesis. While elevated temperature has been shown to disrupt obligate bacterial mutualists of some insects, its impact on the ant-Blochmannia partnership is less clear. Here, we test the effect of heat on the density of Blochmannia in two related Camponotus species in the lab. Transcriptionally active Blochmannia were quantified using RT-qPCR as the ratio of Blochmannia 16S rRNA to ant host elongation factor 1-α transcripts. Our results showed that 4 weeks of heat treatment depleted active Blochmannia by >99 % in minor workers and unmated queens. However, complete elimination of Blochmannia transcripts rarely occurred, even after 16 weeks of heat treatment. Possible mechanisms of observed thermal sensitivity may include extreme AT-richness and related features of Blochmannia genomes, as well as host stress responses. Broadly, the observed depletion of an essential microbial mutualist in heat-treated ants is analogous to the loss of zooanthellae during coral bleaching. While the ecological relevance of Blochmannia's thermal sensitivity is uncertain, our results argue that symbiont dynamics should be part of models predicting how ants and other animals will respond and adapt to a warming climate.
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Affiliation(s)
- Yongliang Fan
- Institute for Genome Sciences and Policy, Duke University, Durham, NC, USA
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26
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Oliver KM, Smith AH, Russell JA. Defensive symbiosis in the real world - advancing ecological studies of heritable, protective bacteria in aphids and beyond. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12133] [Citation(s) in RCA: 255] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Kerry M. Oliver
- Department of Entomology; University of Georgia; Athens GA 30602 USA
| | - Andrew H. Smith
- Department of Biology; Drexel University; Philadelphia PA 19104 USA
| | - Jacob A. Russell
- Department of Biology; Drexel University; Philadelphia PA 19104 USA
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27
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Wernegreen JJ. Mutualism meltdown in insects: bacteria constrain thermal adaptation. Curr Opin Microbiol 2012; 15:255-62. [PMID: 22381679 DOI: 10.1016/j.mib.2012.02.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 01/30/2012] [Accepted: 02/08/2012] [Indexed: 11/29/2022]
Abstract
Predicting whether and how organisms will successfully cope with climate change presents critical questions for biologists and environmental scientists. Models require knowing how organisms interact with their abiotic environment, as well understanding biotic interactions that include a network of symbioses in which all species are embedded. Bacterial symbionts of insects offer valuable models to examine how microbes can facilitate and constrain adaptation to a changing environment. While some symbionts confer plasticity that accelerates adaptation, long-term bacterial mutualists of insects are characterized by tight lifestyle constraints, genome deterioration, and vulnerability to thermal stress. These essential bacterial partners are eliminated at high temperatures, analogous to the loss of zooanthellae during coral bleaching. Recent field-based studies suggest that thermal sensitivity of bacterial mutualists constrains insect responses. In this sense, highly dependent mutualisms may be the Achilles' heel of thermal responses in insects.
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Affiliation(s)
- Jennifer J Wernegreen
- Nicholas School of the Environment, Duke University, Durham, NC 27708, United States.
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Influence of host phylogeographic patterns and incomplete lineage sorting on within-species genetic variability in Wigglesworthia species, obligate symbionts of tsetse flies. Appl Environ Microbiol 2011; 77:8400-8. [PMID: 21948847 DOI: 10.1128/aem.05688-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vertical transmission of obligate symbionts generates a predictable evolutionary history of symbionts that reflects that of their hosts. In insects, evolutionary associations between symbionts and their hosts have been investigated primarily among species, leaving population-level processes largely unknown. In this study, we investigated the tsetse (Diptera: Glossinidae) bacterial symbiont, Wigglesworthia glossinidia, to determine whether observed codiversification of symbiont and tsetse host species extends to a single host species (Glossina fuscipes fuscipes) in Uganda. To explore symbiont genetic variation in G. f. fuscipes populations, we screened two variable loci (lon and lepA) from the Wigglesworthia glossinidia bacterium in the host species Glossina fuscipes fuscipes (W. g. fuscipes) and examined phylogeographic and demographic characteristics in multiple host populations. Symbiont genetic variation was apparent within and among populations. We identified two distinct symbiont lineages, in northern and southern Uganda. Incongruence length difference (ILD) tests indicated that the two lineages corresponded exactly to northern and southern G. f. fuscipes mitochondrial DNA (mtDNA) haplogroups (P = 1.0). Analysis of molecular variance (AMOVA) confirmed that most variation was partitioned between the northern and southern lineages defined by host mtDNA (85.44%). However, ILD tests rejected finer-scale congruence within the northern and southern populations (P = 0.009). This incongruence was potentially due to incomplete lineage sorting that resulted in novel combinations of symbiont genetic variants and host background. Identifying these novel combinations may have public health significance, since tsetse is the sole vector of sleeping sickness and Wigglesworthia is known to influence host vector competence. Thus, understanding the adaptive value of these host-symbiont combinations may afford opportunities to develop vector control methods.
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29
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Burke GR, Moran NA. Responses of the pea aphid transcriptome to infection by facultative symbionts. INSECT MOLECULAR BIOLOGY 2011; 20:357-365. [PMID: 21382108 DOI: 10.1111/j.1365-2583.2011.01070.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Serratia symbiotica is a facultative symbiont of pea aphids (Acyrthosiphon pisum) that provides tolerance to heat stress. Although the phenotypic effects of facultative symbionts upon hosts have been studied in some detail, little is known about the molecular and genomic basis of these interactions. Previous studies show a large impact of S. symbiotica upon the aphid metabolome. Whole-genome transcriptional profiling and next-generation sequencing demonstrated expression of 94% of RefSeq genes from the pea aphid genome, providing the largest dataset to date on aphid gene expression. However, only 28 genes showed changes in expression with S. symbiotica infection, and these changes were of small magnitude. No expression differences in genes involved in innate immunity in other insects were observed. Therefore, the large metabolic impact of S. symbiotica is most likely a result of metabolism of the symbiont itself, or of post-transcriptional modification of host gene expression. Although S. symbiotica has a major influence on its host's metabolome and resistance to heat, it induces little change in gene expression in its host.
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Affiliation(s)
- G R Burke
- Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, AZ, USA.
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MacDonald SJ, Thomas GH, Douglas AE. Genetic and metabolic determinants of nutritional phenotype in an insect-bacterial symbiosis. Mol Ecol 2011; 20:2073-84. [PMID: 21392141 DOI: 10.1111/j.1365-294x.2011.05031.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The pervasive influence of resident microorganisms on the phenotype of their hosts is exemplified by the intracellular bacterium Buchnera aphidicola, which provides its aphid partner with essential amino acids (EAAs). We investigated variation in the dietary requirement for EAAs among four pea aphid (Acyrthosiphon pisum) clones. Buchnera-derived nitrogen contributed to the synthesis of all EAAs for which aphid clones required a dietary supply, and to none of the EAAs for which all four clones had no dietary requirement, suggesting that low total dietary nitrogen may select for reduced synthesis of certain EAAs in some aphid clones. The sequenced Buchnera genomes showed that the EAA nutritional phenotype (i.e. the profile of dietary EAAs required by the aphid) cannot be attributed to sequence variation of Buchnera genes coding EAA biosynthetic enzymes. Metabolic modelling by flux balance analysis demonstrated that EAA output from Buchnera can be determined precisely by the flux of host metabolic precursors to Buchnera. Specifically, the four EAA nutritional phenotypes could be reproduced by metabolic models with unique profiles of host inputs, dominated by variation in supply of aspartate, homocysteine and glutamate. This suggests that the nutritional phenotype of the symbiosis is determined principally by host metabolism and transporter genes that regulate nutrient supply to Buchnera. Intraspecific variation in the nutritional phenotype of symbioses is expected to mediate partitioning of plant resources among aphid genotypes, potentially promoting the genetic subdivision of aphid populations. In this way, microbial symbioses may play an important role in the evolutionary diversification of phytophagous insects.
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Affiliation(s)
- S J MacDonald
- Department of Biology, University of York, York YO10 5DD, UK
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