Incorporating a nectar-based pesticide module into BeeHave, an agent-based model of honey-bee population dynamics

Honey bees are important pollinators for many agricultural food crops, and the response of honey bee colonies to pesticides must be included in pesticide risk assessments. However, honey bee colony dynamics are driven by complex interactions of ecological, physiological, and chemical factors. Such complexity lends itself to a modeling approach to characterize colony responses to pesticides. The NetLogo-based model BeeHave is a detailed model of honey bee colony dynamics. One recently released version of this model (BeeHave_BeeMap_PEEM) considers pesticide exposure via the pollen ingestion pathway. However, nectar ingestion is also a critical exposure pathway, and an exposure module via nectar is needed for this model. We adapted BeeHave to include a nectar-based pesticide exposure module. Exposure is proportional to consumption of nectar and honey based on the energetic needs (kJ) of bee cohorts, and dose depends on the pesticide concentrations of nectar and honey. We assessed the model using a sensitivity analysis and by parameterizing the model to mimic a field-based colony feeding trial. The resulting modeled counts of honey bee adults and eggs followed the expected dose-based response of the parameterizing study, and were generally of the same magnitude. The addition of this module to BeeHave will allow for a comparison of predicted pesticide impacts via the nectar pathway with other honey bee colony models. Furthermore, by building on a prior pesticide exposure module, this version of BeeHave will also allow for the simultaneous estimation of pesticide impacts from two different exposure pathways.