Exposure to pollen-bound pesticide mixtures induces longer-lived but less efficient honey bees

International audience ; Due to the widespread use of pesticides and their persistence in the environment, non-target organisms are chronically exposed tomixtures of toxic residues. Fungicides, herbicides and insecticides are all found at low doses in the diet of pollinators such as honey bees, but due to the lack of data on the toxicological effects of these mixtures, determining their risk is difficult to assess.We therefore developed a study combining the identification of common pollen-bound pesticide mixtures associated with poor colony development and tested their effects on bee behavior and physiology.Weexposed bees to the identified pesticidemixtures during the first days of their adult life, a crucial period for physiological development. Using optic bee counters we recorded the behavior of bees throughout their lives and identified two pesticidemixtures that delay the onset of foraging and slow-down foraging activity. Furthermore, one of thesemixtures hampers pollen foraging. As bee longevity is strongly influenced by the time spent foraging, bees exposed to these pesticide mixtures outlived control bees. Physiological analysis revealed that perturbations of the energeticmetabolism preceded the altered behavior. In conclusion,we found that early-life exposure to lowdoses of pesticidemixtures can have long-termeffects that translate into longer-lived but slower and less efficient bees. These surprising findings contrast with the commonly reported increase in bee mortality upon pesticide exposure, and demonstrate that exposure that may seem harmless (e.g., very low doses, pesticides not intended to kill insects) can have undesirable effects on non-target organisms.