René Devenish

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For decades, the broad application of the Metabolic Theory of Ecology (MTE) to predict ecological patterns and processes has been a major source of contention among ecologists. Nevertheless, the MTE could potentially explain and predict the responses of functionally important organisms, such as pollinating insects, to a warming climate. Here, we tested whether the main predictions of the MTE hold for four species of globally distributed pollinating insects: Eristalis tenax, Lucilia sericata, Apis mellifera, and Bombus terrestris. We used a closed respirometry system to measure insect CO2 production rates across a continuous range of temperatures (15- 35°C). We tested four major hypotheses derived from the MTE: 1) metabolism will scale with body mass following a ¾ power-law relationship, 2) metabolism positively scales exponentially with temperature according to Arrhenius’ Law, 3) the slopes (i.e., activation energy) of the temperature-metabolism relationship falls within the range of -0.60 and -0.70 eV, and 4) hypotheses 1-3 hold, both within and among species. Our findings suggest that the MTE, as it stands, is only partially applicable across different species of insect pollinators, such that MTE-derived predictions of temperature responses can be made. Nevertheless, the scaling relationships presented in this study provide species-specific metabolic scaling coefficients that are crucial for developing predictive models of pollinator species responses to climate change.