Colony and individual life‐history responses to temperature in a social insect pollinator

Abstract

Summary1. Pollinating insects are of major ecological and commercial importance, yet they may be facing ecological disruption from a changing climate. Despite this threat, few studies have investigated the life-history responses of pollinators to experimentally controlled changes in temperature, which should be especially informative for species with complex life histories such as eusocial insects. 2. This study uses the key pollinator Bombus terrestris, a eusocial bumblebee with an annual colony cycle, to determine how temperature affects life-history traits at both individual and colony levels. 3. In two laboratory experiments, we reared B. terrestris colonies at either 20 or 25°C, and measured differences in a set of life-history traits including colony longevity, queen longevity, worker longevity, production of workers, production of sexuals (queen and male production) and growth schedule, as well as effects on thermoregulatory behaviours. 4. Higher rearing temperature had a significant positive effect on colony longevity in one of the two experiments but no significant effects on queen or worker longevity. Higher rearing temperature significantly increased colony size but did not affect the timing of peak colony size. It was also associated with significantly higher queen production but had no effect on the production of workers or males or the timing of male production. Higher temperature colonies exhibited significantly more wing fanning by workers and significantly less wax canopy construction. Hence, an increase in rearing temperature of a few degrees increased colony longevity, colony size and queen production. However, individual longevity was not affected and so may have been buffered by changes in costly thermoregulatory behaviours. 5. We conclude that eusocial insects may show complex phenotypic responses to projected temperature increases under climate change, including effects on productivity and reproduction at the colony level. Such effects should be considered when predicting the impact of climate change on the provision of essential pollination services.

Bumble bee colony dynamics: quantifying the importance of land use and floral resources for colony growth and queen production

“…Therefore, if we could understand and manage other factors that cause some colonies to grow quickly and others to grow slowly under the same resource conditions, it would have a larger effect on colony dynamics than supplementing floral resources. We know that bumble bee colony growth depends on multiple drivers, such as parasites (Shykoff & Schmid-Hempel 1991), temperature (Holland & Bourke 2015) and pesticides (Whitehorn et al 2012). Variation in these factors could cause differences in the observed colony growth rate per flower.…”

Neonicotinoid exposure disrupts bumblebee nest behavior, social networks, and thermoregulation

“…S7 and tables S5 and S6). Imidacloprid-treated colonies were also less likely to construct an insulating wax canopy around the developing brood, an important behavioral adaptation to cold (30) (Fig. 3, E and F, permutation test, p = 0.0005).…”

Responses to a warming world: Integrating life history, immune investment, and pathogen resistance in a model insect species

“…Difficulties in predicting outcomes lie not only in the need to understand the direct impact of temperature on individual components, but to also review the system as a whole, taking into account the dynamic nature of the selective pressures acting on life-history trade-offs across time (Alto & Bettinardi, 2013;Blanford, Thomas, Pugh, & Pell, 2003;Holland & Bourke, 2015;Laughton, Boots, & Siva-Jothy, 2011).…”