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Contreras HL, Goyret J, Pierce CT, Raguso RA, Davidowitz G. Eat, Drink, Live: Foraging behavior of a nectarivore when relative humidity varies but nectar resources do not. J Insect Physiol 2022; 143:104450. [PMID: 36265566 DOI: 10.1016/j.jinsphys.2022.104450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/06/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
To meet energetic and osmotic demands, animals make dynamic foraging decisions about food quality and quantity. In the wild, foraging animals may be forced to consume a less preferred or sub-optimal food source for long periods of time. Few choice feeding assays in laboratory settings approximate such contingencies. In this study the foraging behaviors of the hawkmoth Manduca sexta were measured when adult moths were placed within different relative humidity (RH) environments (20%, 40%, 60% and 80% RH) and provided with only one of the following experimental nectars: 0% (water), 12% or 24 % w/V sucrose solutions. Overall, ambient humidity influenced survivorship and foraging behaviors. Moth survivorship increased at higher ambient humidity regardless of experimental nectar. Moths that had access to experimental nectar imbibed large volumes of fluid regardless of what nectar was offered when placed at the lowest humidity (20% RH). However, when placed at the highest humidity (80% RH), moths imbibed higher volumes of fluid when given access to experimental nectar with sucrose in comparison with water. RH also influenced daily foraging behaviors: peak nectar consumption occurred earlier at lower RH levels. Consistent with previous studies in which moths could choose among nectar solutions, total energy intake was not affected by ambient RH under no-choice conditions. However, the proportion of time spent foraging and total energy consumption were significantly reduced across all RH levels in no-choice assays, when compared with previous studies of choice assays under the same conditions. Our results show that even when M. sexta moths are presented with limited options, they can alter their foraging behavior in response to environmental changes, enabling them to meet osmotic and/or energetic demands.
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Affiliation(s)
- Heidy L Contreras
- Department of Biology, California State University San Bernardino, San Bernardino, CA, USA; Department of Entomology, University of Arizona, Tucson, AZ, USA.
| | - Joaquin Goyret
- Department of Biology, University of Tennessee, Martin, TN, USA
| | - Clayton T Pierce
- Department of Entomology, University of Arizona, Tucson, AZ, USA; Family Medicine Residency, Banner University Medical Center, Phoenix, AZ, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Goggy Davidowitz
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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Vrtar A, Toogood C, Keen B, Beeman M, Contreras HL. The Effect of Ambient Humidity on the Metabolic Rate and Respiratory Patterns of the Hissing Cockroach, Gromphadorhina portentosa (Blattodea: Blaberidae). Environ Entomol 2018; 47:477-483. [PMID: 29462264 DOI: 10.1093/ee/nvx208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We examined the effects of humidity on the metabolic rates and respiratory patterns of Gromphadorhina portentosa (Schaum) (Blattodea: Blaberidae) to determine whether insects transition from continuous, cyclical, and discontinuous (DGC) respiration in response to water conservation. Eight male G. portentosa were placed under five different humidity treatments (0, 23, 40, 60, 80% RH). Using flow through respirometry we: (i) determined the effect of humidity on metabolic rate; (ii) observed if changes in metabolic rate were correlated with changes in closed/flutter (CF) or the open (O) phase of DGC; and (iii) determined whether increased spiracular closure was correlated with an increase in water retention. Although G. portentosa had similar rates of CO2 release when placed under 0, 40, 60, and 80% RH, cockroaches placed at 23% RH had a significantly higher metabolic rate. There was no effect of humidity on the duration of the CF phase of the DGC. However, the O phase of DGC was significantly longer when G. portentosa was placed at humidity levels above 23% RH. Interestingly, we saw that the average rate of mass lost to the environment did not change when cockroaches were placed at humidity levels ranging from 0 to 80% RH. This suggests that modulation of the spiracles allows G. portentosa to regulate the amount of water lost to the environment.
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Affiliation(s)
- Andrew Vrtar
- Department of Biology, University of La Verne, CA, USA
| | | | - Blake Keen
- Department of Biology, University of La Verne, CA, USA
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Contreras HL, Heinrich EC, Bradley TJ. Hypotheses regarding the discontinuous gas exchange cycle (DGC) of insects. Curr Opin Insect Sci 2014; 4:48-53. [PMID: 28043408 DOI: 10.1016/j.cois.2014.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/12/2014] [Accepted: 08/13/2014] [Indexed: 06/06/2023]
Abstract
The evolutionary origin of the insect respiratory pattern referred to as the discontinuous gas exchange cycle (DGC) has been a topic of extensive discussion among insect physiologists for at least 50 years. This pattern has often been thought to reduce respiratory water loss (RWL). However, because this pattern does not consistently conserve water among all taxa, other hypotheses have been proposed to try and explain the significance of the DGC. In this review we briefly describe the different hypotheses postulated to date. We conclude that the DGC is primarily a respiratory pattern deriving from the simultaneous regulation of O2 and CO2. It may nonetheless have additional adaptive functions in insects.
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Affiliation(s)
- Heidy L Contreras
- Biology Department, University of La Verne, 1950 3rd Street, La Verne, CA 91750, United States.
| | - Erica C Heinrich
- Department of Ecology & Evolutionary Biology, University of California, Irvine, CA 92697-2525, United States
| | - Timothy J Bradley
- Department of Ecology & Evolutionary Biology, University of California, Irvine, CA 92697-2525, United States
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Contreras HL, Bradley TJ. The effect of ambient humidity and metabolic rate on the gas-exchange pattern of the semi-aquatic insectAquarius remigis. J Exp Biol 2011; 214:1086-91. [DOI: 10.1242/jeb.050971] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYWe have examined the effects of temperature on metabolic rate and respiratory pattern in the water strider Aquarius remigis. As temperature was increased from 10 to 30°C, the metabolic rate of the insects increased and the respiratory pattern transitioned from discontinuous, to cyclic, to continuous. The discontinuous gas-exchange cycle (DGC) was observed even in insects standing on water when the respirometry chamber was being perfused with humid (>95% relative humidity) air. Comparisons of insects at 20°C in humid and dry air showed no statistically significant differences in metabolic rate or respiratory pattern (P>0.05). The proportion of time that the spiracles were closed was greater at 10°C than at 20°C (P<0.01), and greater at 20°C than at 30°C (P<0.05). These results are compatible with the hypothesis that the respiratory patterns of insects are determined by the relationship between oxygen supply and oxygen demand. There was no evidence in this insect that humidity had any effect on the respiratory pattern. The results are discussed in the context of the ongoing discussion in the literature of the origin, maintenance and adaptive significance of the DGC in insects.
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Affiliation(s)
- Heidy L. Contreras
- Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, CA 92697-2525, USA
| | - Timothy J. Bradley
- Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, CA 92697-2525, USA
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Contreras HL, Bradley TJ. Transitions in insect respiratory patterns are controlled by changes in metabolic rate. J Insect Physiol 2010; 56:522-528. [PMID: 19523955 DOI: 10.1016/j.jinsphys.2009.05.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 05/20/2009] [Accepted: 05/28/2009] [Indexed: 05/27/2023]
Abstract
We examined the respiratory patterns of Rhodnius prolixus and Gromphadorhina portentosa as metabolic rates varied with temperature to determine whether insects transition from discontinuous (DGC), cyclical and continuous respiration as a response to increasing aerobic demand. Using flow through respirometry we: (1) determined the effects of temperature on metabolic rate; (2) objectively defined periods of spiracular closure; (3) observed whether there was a correlation between metabolic rate and length of spiracular closure. At low temperatures both species exhibit lengthy periods of spiracular closure reflecting a discontinuous respiratory pattern. As metabolic rate increased, periods of spiracular closure decreased and insects displayed a more cyclical pattern of respiration. As metabolic rates increased even further under the highest experimental temperatures, periods of spiracular closure decreased even more and a continuous respiratory pattern was employed by both species. Our results suggest that the three described respiratory patterns in insects are not distinct but are instead a continuum of respiratory responses driven by the metabolic demand experienced by the insect.
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Affiliation(s)
- H L Contreras
- University of California, Irvine, Ecology and Evolutionary Biology Department, 321 Steinhaus Hall, Irvine, CA 92697-2525, United States.
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Bradley TJ, Briscoe AD, Brady SG, Contreras HL, Danforth BN, Dudley R, Grimaldi D, Harrison JF, Kaiser JA, Merlin C, Reppert SM, Vandenbrooks JM, Yanoviak SP. Episodes in insect evolution. Integr Comp Biol 2009; 49:590-606. [PMID: 21665843 DOI: 10.1093/icb/icp043] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This article derives from a society-wide symposium organized by Timothy Bradley and Adriana Briscoe and presented at the 2009 annual meeting of the Society for Integrative and Comparative Biology in Boston, Massachusetts. David Grimaldi provided the opening presentation in which he outlined the major evolutionary events in the formation and subsequent diversification of the insect clade. This presentation was followed by speakers who detailed the evolutionary history of specific physiological and/or behavioral traits that have caused insects to be both ecologically successful and fascinating as subjects for biological study. These include a review of the evolutionary history of the insects, the origins of flight, osmoregulation, the evolution of tracheal systems, the evolution of color vision, circadian clocks, and the evolution of eusociality. These topics, as covered by the speakers, provide an overview of the pattern and timing of evolutionary diversification and specialization in the group of animals we know as insects.
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Affiliation(s)
- Timothy J Bradley
- *Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697-2525, USA;Department of Entomology and Laboratories of Analytical Biology, National Museum of the Smithsonian Institution, Washington, D.C. 20013-7012, USA;Department of Entomology, Cornell University, Ithaca, NY 14853, USA;Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA;Division of Invertebrate Zoology, Museum of Natural History, New York, NY 10024, USA;Section of Organismal, Integrative and Systems Biology, School of Life Sciences, Arizona State University, Tempe AZ 85287-4501, USA;Department of Basic Sciences, Midwestern University, Glendale, AZ 85308, USA;Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA;Department of Biology, University of Arkansas Little Rock, Little Rock, AR 72204, USA
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