12: Foraging traits impact pollinator health in agriculture

Bee parasites may be transmitted via shared floral use, but the role of agricultural land use and bee trait variation in shaping transmission dynamics is almost entirely unexplored. We study parasitism in $1,309$ wild bees from $15$ different genera in a mass-blooming sunflower crop system interspersed with restored hedgerow and remnant habitat. We use model selection to examine the role of mass-bloom events, non-crop habitat, and bee traits (sociality, diet breadth, and body size) on pollinator-parasite dynamics. We show that wild bee abundance is determined by mass-bloom dynamics. Wild bee abundance in turn amplifies parasitism for wild bees and dilutes parasitism for honey bees. Encouragingly, parasitism is mitigated by non-crop floral diversity provided by hedgerows and weeds. We also find that larger bees host more parasites. By examining how resource pulses, non-crop habitat, and bee traits influence parasitism, we link hedgerows and diversification practices with health outcomes for declining pollinator populations. We demonstrate the importance maintaining habitat for healthy bee communities.