Sucrose sensitivity of honey bees Is differently affected by dietary protein and a neonicotinoid pesticide
Abstract
Over a decade, declines in honey bee colonies have raised worldwide concerns. Several potentially contributing factors have been investigated, e.g. parasites, diseases, and pesticides. Neonicotinoid pesticides have received much attention due to their intensive use in crop protection, and their adverse effects on many levels of honey bee physiology led the European Union to ban these compounds. Due to their neuronal target, a receptor expressed throughout the insect nervous system, studies have focused mainly on neuroscience and behaviour. Through the Geometric Framework of nutrition, we investigated effects of the neonicotinoid thiamethoxam on survival, food consumption and sucrose sensitivity of honey bees (Apis mellifera). Thiamethoxam did not affect protein and carbohydrate intake, but decreased responses to high concentrations of sucrose. Interestingly, when bees ate fixed unbalanced diets, dietary protein facilitated better sucrose detection. Both thiamethoxam and dietary protein influenced survival. These findings suggest that, in the presence of a pesticide and unbalanced food, honey bee health may be severely challenged. Consequences for foraging efficiency and colony activity, cornerstones of honey bee health, are also discussed. ; S1 Fig. Daily nutrient intake is influenced by the amount of dietary protein, but not by the THX pesticide dose. The panels show the effect of THX doses among different diets. The top panel is the choice experiment, where bees were able to regulate their nutrient intake. The four panels below the line represent the no-choice experiment with the four different fixed diets (indicated at the top-left corner of each panel). For each panel, days are indicated on the x-axis, from day 1 to day 14, while the four THX doses are represented on the y-axis. Nutrient intake (in mg/bee) is colour-scaled. Maximal intake is achieved during the choice experiment, around day 6, independent of THX dose. The patterns of daily consumption of P:C ratios 1:30 and 1:3 diets are similar to those in ...
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