Predicting effects of warming on insect pollinators using the metabolic
theory of ecology
Abstract
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.