In-hive Pesticide Exposome: Assessing risks to migratory honey bees from in-hive pesticide contamination in the Eastern United States

Abstract

This study measured part of the in-hive pesticide exposome by analyzing residues from live in-hive bees, stored pollen, and wax in migratory colonies over time and compared exposure to colony health. We summarized the pesticide burden using three different additive methods: (1) the hazard quotient (HQ), an estimate of pesticide exposure risk, (2) the total number of pesticide residues, and (3) the number of relevant residues. Despite being simplistic, these models attempt to summarize potential risk from multiple contaminations in real-world contexts. Colonies performing pollination services were subject to increased pesticide exposure compared to honey-production and holding yards. We found clear links between an increase in the total number of products in wax and colony mortality. In particular, we found that fungicides with particular modes of action increased disproportionally in wax within colonies that died. The occurrence of queen events, a significant risk factor for colony health and productivity, was positively associated with all three proxies of pesticide exposure. While our exposome summation models do not fully capture the complexities of pesticide exposure, they nonetheless help elucidate their risks to colony health. Implementing and improving such models can help identify potential pesticide risks, permitting preventative actions to improve pollinator health.

High pesticide risk to honey bees despite low focal crop pollen collection during pollination of a mass blooming crop

“…Cyfluthrin alone accounted for 48% and 25% of total contact and oral pesticide risk in the study, respectively (Table 1). Considering that >150 additional insecticide, fungicide and herbicide compounds have been found in beebread1435, but weren’t screened for in our study, our data may in fact overestimate the proportion of pesticide risk that comes from during-bloom sprays.…”

Acute toxicity of five pesticides to Apis mellifera larvae reared in vitro

“…Honey bees often are simultaneously exposed to natural toxins from plants and microorganisms, pesticides and environmental contaminants, as well as apicultural drugs applied by beekeepers . Some studies list pesticide exposure as a possible contributor to high yearly loss rates in managed bee populations …”

Candidate stress biomarkers for queen failure diagnostics

“…Since queens are fed a strict diet of worker glandular secretions (i.e, they do not consume potentially contaminated flower products) [13][14][15], they are normally buffered from direct oral xenobiotic exposure [16,17]. However, pesticides (including miticides, fungicides, herbicides, and insecticides) accumulate in wax [18,19] and thus can pose a contact exposure hazard to queens. A cumulative hazard quotient (HQ)…”