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.