Social Buffering of Pesticides in Bumblebees: Agent-Based Modeling of the Effects of Colony Size and Neonicotinoid Exposure on Behavior Within Nests

Abstract

Neonicotinoids are a globally prevalent class of pesticides that can negatively affect bees and the pollination services they provide. While there is evidence suggesting that colony size may play an important role in mitigating neonicotinoid exposure in bees, mechanisms underlying these effects are not well understood. Here, a recently developed agent-based computational model is used to investigate how the effects of sub-lethal neonicotinoid exposure on intranest behavior of bumblebees (Bombus impatiens) are modulated by colony size. Simulations from the model, parameterized using empirical data on bumblebee workers exposed to imidacloprid (a common neonicotinoid pesticide), suggest that colony size has significant effects on neonicotinoid-sensitivity within bumblebee nests. Specifically, differences are reduced between treated and untreated workers in larger colonies for several key aspects of behavior within nests. Our results suggest that changes in both number of workers and nest architecture may contribute to making larger colonies less sensitive to pesticide exposure.

Movement, Encounter Rate, and Collective Behavior in Ant Colonies

“…It is because the encounter rate depends on density that task allocation changes with colony size ( Gordon 1989 , Karsai and Wenzel 1998 , Kang and Theraulaz 2016 , Schmickl and Karsai 2018 , Crall et al 2019 ). As a colony grows, and numbers of workers increase, so does the probability of encounter.…”

Urban colonies are more resistant to a trace metal than their forest counterparts in the ant Temnothorax nylanderi

“…Eusociality could enhance robustness against environmental changes. For example, eusocial species of bees are less negatively impacted by neocotinoids than solitary species (47), and models suggest that, within species, larger colonies resist better to pesticides (48). In ants, social life enhances resistance to parasites and starvation (49,50).…”

Combined nutritional stress and a new systemic pesticide (flupyradifurone, Sivanto®) reduce bee survival, food consumption, flight success, and thermoregulation

“…Neonicotinoids act upon the central nervous system of insects as agonists of the nicotinic acetylcholine receptors (nAChRs) and can cause lethal and sublethal effects in bees (Crall et al, 2019(Crall et al, , 2018Pisa et al, 2017;Tosi et al, 2017aTosi et al, , 2016Tosi and Nieh, 2017). Bee flight ability (duration, distance, average velocity, and maximum velocity of flights) is altered by chronic or acute exposure (Tosi et al, 2017a).…”