Honey bee larval toxicity study designs: Applicability of the current study protocols and endpoints as a predictor of pesticide hazard for pollinators.

The assessment of pesticide risks to bees in North America currently relies in part on Tier 1 honey bee laboratory toxicity studies to support the registration and registration review processes for crop protection chemicals. For immature stages, the studies follow two standardized test designs recommended by the Organization for Economic Cooperation (OECD), evaluating acute (seven-day single-dose, TG OECD 237) and chronic (22-day repeated-dose, GD OECD 239) toxicity in bee larvae. In this article, we aim to evaluate the current approach for generating and interpreting honey bee larval toxicity data, enhancing pesticide risk assessment for pollinators.

Probabilistic co-occurrence assessment for suites of listed species.

Section 7 of the Endangered Species Act requires the US Environmental Protection Agency (US EPA) to consult with the Services (US Fish and Wildlife Service and National Marine Fisheries Service) over potential pesticide impacts on federally listed species. Consultation is complicated by the large number of pesticide products and listed species, as well as by lack of consensus on best practices for conducting co-occurrence analyses. Previous work demonstrates that probabilistic estimates of species' ranges and pesticide use patterns improve these analyses.

Assessment of the Vulnerability to Pesticide Exposures Across Bee Species.

In many countries, the western honey bee is used as surrogate in pesticide risk assessments for bees. However, uncertainty remains in the estimation of pesticide risk to non-Apis bees because their potential routes of exposure to pesticides, life histories, and ecologies differ from those of honey bees. We applied the vulnerability concept in pesticide risk assessment to 10 bee species including the honey bee, 2 bumble bee species, and 7 solitary bee species with different nesting strategies.

A Probabilistic Co-Occurrence Approach for Estimating Likelihood of Spatial Overlap Between Listed Species Distribution and Pesticide Use Patterns.

Characterizing potential spatial overlap between federally threatened and endangered ("listed") species distributions and registered pesticide use patterns is important for accurate risk assessment of threatened and endangered species. Because accurate range information for such rare species is often limited and agricultural pesticide use patterns are dynamic, simple spatial co-occurrence methods may overestimate or underestimate overlap and result in decisions that benefit neither listed species nor the regulatory process. Here, we demonstrate a new method of co-occurrence analysis that employs probability theory to estimate spatial distribution of rare species populations and areas of pesticide use to determine the likelihood of potential exposure.

Thiamethoxam: Long-term effects following honey bee colony-level exposure and implications for risk assessment.

Neonicotinoid insecticides have been used in a wide range of crops through seed treatment, soil and foliar applications and a large database exists on both their lethal and sub-lethal effects on honey bees under controlled laboratory conditions. However, colony-level studies on the effects of neonicotinoids in field studies are limited, primarily due to their complexity and the resources required. This paper reports the combined results of two large-scale colony-feeding studies, each with 6 weeks of continuous dosing of 12 colonies per treatment (24 control) to 12.

Thiamethoxam honey bee colony feeding study: Linking effects at the level of the individual to those at the colony level.

Neonicotinoid insecticides have been used globally on a wide range of crops through seed treatment as well as soil and foliar applications and have been increasingly studied in relation to the potential risk to bees because of their detection in pollen and nectar of bee-attractive crops. The present article reports the results of laboratory studies (10-d adult and 22-d larval toxicity studies assessing the chronic toxicity of thiamethoxam to adult honey bees and larvae, respectively) and a colony feeding study, with 6 wk of exposure in an area with limited alternative forage, to provide a prewintering colony-level endpoint. The endpoints following exposure of individuals in the laboratory (10-d adult chronic no-observed-effect concentration [NOEC] for mortality 117 μg thiamethoxam/kg sucrose solution, 141 μg thiamethoxam/L sucrose solution; 22-d larval chronic NOEC 102 μg thiamethoxam/kg diet) are compared with those generated at the colony level, which incorporates sublethal effects (no-observed-adverse-effect concentration [NOAEC] 50 μg thiamethoxam/L sucrose solution, 43 μg thiamethoxam/kg sucrose solution).