A volatilized pyrethroid insecticide from a mosquito repelling device does not impact honey bee foraging and recruitment.

Because nontarget, beneficials, like insect pollinators, may be exposed unintentionally to insecticides, it is important to evaluate the impact of chemical controls on the behaviors performed by insect pollinators in field trials. Here we examine the impact of a portable mosquito repeller, which emits prallethrin, a pyrethroid insecticide, on honey bee foraging and recruitment using a blinded, randomized, paired, parallel group trial. We found no significant effect of the volatilized insecticide on foraging frequency (our primary outcome), waggle dance propensity, waggle dance frequency, and feeder persistency (our secondary outcomes), even though an additional deposition study confirmed that the treatment device was performing appropriately. These results may be useful to consumers that are interested in repelling mosquitos, but also concerned about potential consequences to beneficial insects, such as honey bees.

Dance-communicated distances support nectar foraging as a supply-driven system.

Much like human consumers, honeybees adjust their behaviours based on resources' supply and demand. For both, interactions occur in fluctuating conditions. Honeybees weigh the cost of flight against the benefit of nectar and pollen, which are nutritionally distinct resources that serve different purposes: bees collect nectar continuously to build large honey stores for overwintering, but they collect pollen intermittently to build modest stores for brood production periods. Therefore, nectar foraging can be considered a supply-driven process, whereas pollen foraging is demand-driven. Here we compared the foraging distances, communicated by waggle dances and serving as a proxy for cost, for nectar and pollen in three ecologically distinct landscapes in Virginia. We found that honeybees foraged for nectar at distances 14% further than for pollen across all three sites (n = 6224 dances, p < 0.001). Specific temporal dynamics reveal that monthly nectar foraging occurs at greater distances compared with pollen foraging 85% of the time. Our results strongly suggest that honeybee foraging cost dynamics are consistent with nectar supply-driven and pollen demand-driven processes.

Honey Bees (Hymenoptera: Apidae) Decrease Foraging But Not Recruitment After Neonicotinoid Exposure.

Honey bees (Linnaeus, Hymenoptera: Apidae) are widely used as commercial pollinators and commonly forage in agricultural and urban landscapes containing neonicotinoid-treated plants. Previous research has demonstrated that honey bees display adverse behavioral and cognitive effects after treatment with sublethal doses of neonicotinoids. In laboratory studies, honey bees simultaneously increase their proportional intake of neonicotinoid-treated solutions and decrease their total solution consumption to some concentrations of certain neonicotinoids. These findings suggest that neonicotinoids might elicit a suboptimal response in honey bees, in which they forage preferentially on foods containing pesticides, effectively increasing their exposure, while also decreasing their total food intake; however, behavioral responses in semifield and field conditions are less understood. Here we conducted a feeder experiment with freely flying bees to determine the effects of a sublethal, field-realistic concentration of imidacloprid (IMD) on the foraging and recruitment behaviors of honey bees visiting either a control feeder containing a sucrose solution or a treatment feeder containing the same sucrose solution with IMD. We report that IMD-treated honey bees foraged less frequently (-28%) and persistently (-66%) than control foragers. Recruitment behaviors (dance frequency and dance propensity) also decreased with IMD, but nonsignificantly. Our results suggest that neonicotinoids inhibit honey bee foraging, which could potentially decrease food intake and adversely affect colony health.