Temperature dependence of metabolic rate in tropical and temperate aquatic insects: Support for the Climate Variability Hypothesis in mayflies but not stoneflies

Abstract

A fundamental gap in climate change vulnerability research is an understanding of the relative thermal sensitivity of ectotherms. Aquatic insects are vital to stream ecosystem function and biodiversity but insufficiently studied with respect to their thermal physiology. With global temperatures rising at an unprecedented rate, it is imperative that we know how aquatic insects respond to increasing temperature and whether these responses vary among taxa, latitudes, and elevations. We evaluated the thermal sensitivity of standard metabolic rate in stream‐dwelling baetid mayflies and perlid stoneflies across a ~2,000 m elevation gradient in the temperate Rocky Mountains in Colorado, USA, and the tropical Andes in Napo, Ecuador. We used temperature‐controlled water baths and microrespirometry to estimate changes in oxygen consumption. Tropical mayflies generally exhibited greater thermal sensitivity in metabolism compared to temperate mayflies; tropical mayfly metabolic rates increased more rapidly with temperature and the insects more frequently exhibited behavioral signs of thermal stress. By contrast, temperate and tropical stoneflies did not clearly differ. Varied responses to temperature among baetid mayflies and perlid stoneflies may reflect differences in evolutionary history or ecological roles as herbivores and predators, respectively. Our results show that there is physiological variation across elevations and species and that low‐elevation tropical mayflies may be especially imperiled by climate warming. Given such variation among species, broad generalizations about the vulnerability of tropical ectotherms should be made more cautiously.

A hierarchical approach to understanding physiological associations with climate

“…Additionally, shelter availability Schwarzkopf & Alford, 1996), and organismal aspects such as body size and behaviour affect the water balance of ectotherms (Farallo et al, 2020;Gouveia et al, 2019;Pirtle et al, 2019), which is known to evolve in response to aridity (Cox & Cox, 2015). Finally, metabolic rates of ectotherms are not only related to air temperature, but also to microclimatic temperatures and food availability (Angilletta, 2001;Dupoué et al, 2017;Shah et al, 2021). Thus, a global analysis investigating these interactions of organisms with their environment at improved resolutions could lead to new, testable hypotheses for physiological variation.…”

A Systematic Review of the Effects of Temperature on Anopheles Mosquito Development and Survival: Implications for Malaria Control in a Future Warmer Climate

“…In addition, thermal stress could affect the survival of immature mosquitoes [ 56 ]. The immature stages are sensitive to temperature because they usually live in small, isolated pools and cannot easily escape unfavorable environments [ 59 ]. To overcome the thermal stress experienced, mosquitoes may have to increase their metabolic rates, resulting in higher energy expenditure [ 60 ].…”

Estimating the differences in critical thermal maximum and metabolic rate of Helicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) across life stages

“…Energy is the crucial currency of life-history traits of animals including insects ( Terblanche & Chown, 2007 ; Desforges et al, 2019 ). Metabolism combines organism’s energy supply and fitness-related activities ( Shah et al, 2021 ). Measurement of metabolic rate is one way of measuring the energy cost related with different life-functions like growth, development, movement among others ( Shah et al, 2021 ).…”

“…Metabolism combines organism’s energy supply and fitness-related activities ( Shah et al, 2021 ). Measurement of metabolic rate is one way of measuring the energy cost related with different life-functions like growth, development, movement among others ( Shah et al, 2021 ). In insects, metabolic rates can influence not only fitness in individuals but also geographic distributions and abundances ( Shah et al, 2021 ).…”

“…Measurement of metabolic rate is one way of measuring the energy cost related with different life-functions like growth, development, movement among others ( Shah et al, 2021 ). In insects, metabolic rates can influence not only fitness in individuals but also geographic distributions and abundances ( Shah et al, 2021 ). Therefore, estimating the metabolic rates of organisms will assist in identifying the cost of living and performance in a particular environment ( Terblanche et al, 2005 ; Terblanche & Chown, 2007 ), and can help predict geographic variations in response to global warming ( Shah et al, 2021 ).…”