Résumé
Global change presents a threat to pollinators, with declining populations trends jeopardising the delivery ofpollination services. In agroecosystems, the reduction of floral resources and exposure to pesticides have beenidentified as stressors of bee pollinators. The present study investigated the interaction between nutritional andagrochemical stresses on sublethal endpoints in the bumblebee Bombus terrestris. We used two pollen dietsdiffering in quality and quantity and exposed micro-colonies to various concentrations of two insecticides(sulfoxaflor and cyantraniliprole), a fungicide (Amistar®; active ingredient azoxystrobin), or an herbicide(glyphosate) in a crossed experiment comprising 29 experimental conditions. Regardless of the pollen regime,there were negative impacts of the insecticides on both brood development and proteome; however, there was no significant impact on brood development following exposure to Amistar® or glyphosate. The proteome wasaffected by all pesticides when the colonies were nutritionally stressed, indicating that pesticides induced amolecular differentiation between groups fed on different diets. Nutritionally stressed colonies were lessdeveloped compared to control colonies, but this effect was not synergistically increased by exposure to sulfoxaflor,Amistar®, or glyphosate. The development of colonies exposed to cyantraniliprole was affected similarly,regardless of the nutritional condition and therefore did not benefit from a quality pollen diet. Overall, ourresults highlight that the effects of agrochemicals on bumblebees can vary depending on diet and can be detectedvia proteome analyses. We therefore urge for conservation action supporting pollinators with suitable anddiverse floral resources alongside improved risk assessment regarding pesticides.