Colony impact of pesticide‐induced sublethal effects on honeybee workers: A simulation study using BEEHAVE

Abstract

Research on neonicotinoids and honeybees have changed focus from direct mortality to sublethal effects. In the present study, a published honeybee model, BEEHAVE, is used to compare induced colony level impact of pesticides including direct mortality, poor brood care, disorientation, and increased handling time in oilseed rape and sunflower crops. Actual effects on individual bees will depend on exposure concentrations, but in the present study large effects were enforced. In oilseed rape, poor brood care had the largest colony impact, because it created a bottleneck for spring build-up of the workforce, and colony impact for all effect types peaked 1 mo after exposure ceased. In sunflower, the later exposure changed the response so colony impact peaked during exposure, and the bottleneck was honey store build-up. In all scenarios, good forage mitigated effects substantially. It is concluded that field studies should continue at least 1 mo after exposure to ensure detection of ecologically relevant sublethal effects. The results indicated that even if a sublethal effect is difficult to detect in the field, subsequent ecologically relevant colony level impacts would be clear if studies are continued for 1 mo after exposure. Guidance for regulatory studies recommends extended observation periods, and published field studies already use extended observation periods, so it is concluded that current methods are adequate for detecting ecologically relevant sublethal effects. Although published laboratory and semifield studies conducted under controlled exposure conditions suggest that sublethal effects may occur, published field studies with neonicotinoid seed treatments, naturally foraging bees, and extended observation periods do not report colony-level effects, suggesting that in these studies no ecologically relevant sublethal effects occurred. Environ Toxicol Chem 2017;36:831-840. © 2016 SETAC.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

“…Their model study suggests that monitoring of field experiments must continue for at least 1 month to identify sublethal effects. In another publication the authors criticize the Khoury bee population model used by EFSA to set exposure values for colony losses related to pesticides as too conservative (Thorbek et al 2017b). …”

Honey bee colony‐level exposure and effects in realistic landscapes: An application of BEEHAVE simulating clothianidin residues in corn pollen

“…Nonetheless, it is unclear how the sublethal endpoints of abnormal behavior or movement relate to behaviors important for colony success such as brood care and foraging. Thorbek et al () assessed the sensitivity of BEEHAVE to increased foraging times and decreased brood care as behaviors that could be implicated in sublethal effects. Dose–response relationships for behavioral processes linked to colony performance would need to be available for the inclusion in realistic exposure‐effects evaluations with a honey bee colony model.…”

BeeNestABM: An open-source agent-based model of spatiotemporal distribution of bumblebees in nests

“…Agent-based modeling allows for building understanding of the colony scale impacts of multiple interacting factors that affect numerous individuals in close proximity and how those change upon pesticide exposure. The scientific significance is that the model solved in the software focuses on the effects of pesticides that occur in bumblebees over short time scales (hours to days) inside a single nest, which includes a much smaller spatial region with finer resolution than that considered in the state-of-the-art (Thorbek, Campbell, and Thompson 2017). These temporal and spatial scales are appropriate for modeling the effects of neonicotinoid pesticides that account for colony size and interactions between exposed and unexposed individuals.…”