Cold and CO₂ narcosis have long-lasting and dissimilar effects on Bombus terrestris

Abstract

Carbon dioxide and cold narcosis have been found to have various effects on insect behaviour and physiology, ranging from changes in fecundity and memory to alterations in aggression and foraging. In spite of these potentially confounding effects, narcosis is repeatedly used to handle insects prior to experimental studies. To begin disentangling the unintended effects of narcosis from the effects of experimental manipulation, a better understanding is needed of how different types of narcosis affect insect behaviour, as well as the time frames of these effects. Here, we compare the effects of CO2 and cold narcosis relative to control animals regarding activity, foraging, brood care, aggression, and productivity of worker bumblebees, Bombus terrestris. We show that even a single narcosis event with either cold or CO2 affects these behaviours often in dissimilar ways, and these effects are maintained for at least 4 days following narcosis.