Pollen foraging mediates exposure to dichotomous stressor syndromes in honey bees

Recent declines in the health of honey bee colonies pose an imminent threat to global food security. Foraging by honey bee workers likely represents the primary route of exposure to a plethora of toxins and pathogens known to affect bee health, but it remains unclear how foraging preferences impact colony-level stressor exposure. Resolving this knowledge gap is crucial for enhancing the health of honey bees and the agricultural systems that rely on them for pollination. To address this, we carried out a continental-scale experiment to first characterize bee foraging preferences in relation to major North American crops, then explored how these preferences influence patterns of stressor exposure. We used a metagenomic approach to quantify honey bee dietary breadth and found that bees display distinct foraging preferences that vary substantially relative to crop type and proximity. We also discovered that dietary diversity is positively associated with greater pathogen exposure, and negatively associated with agrochemical exposure. Our results indicate that foraging behaviour in agro-ecosystems mediates exposure to dichotomous stressor syndromes, characterized by either greater exposure to agrochemicals or pathogens. These findings highlight the importance of understanding how crop pollination influences bee health and suggest that honey bee health interventions need to account for the substantively different stressor syndromes found near and away from crop monocultures.