Studying the sublethal effects of agrochemical pesticides on nontarget honeybees 
(Apis mellifera) is important for agricultural development. Carbendazim is a 
widely used broad-spectrum fungicide that inhibits mitotic microtubule formation 
and cell division. However, the impact of carbendazim on bee health and 
development has not been fully elucidated. Here, using proteomics approaches, we 
assessed in vitro the changes in the expression of functional proteins in the 
head of newly emerged adults following treatment with field concentration of 
carbendazim during the larval stage. Treatment with carbendazim severely altered 
266 protein expression patterns in the heads of adults and 218 of them showed 
downregulation after carbendazim exposure. Notably, major royal jelly proteins, 
a crucial multifunctional protein family with irreplaceable function in 
sustaining the development of colonies, were significantly suppressed in 
carbendazim-treated bees. This result was verified in both head and 
hypopharyngeal gland of nurse bees. Moreover, visual and olfactory loss, immune 
functions, muscular activity, social behavior, neural and brain development, 
protein synthesis and modification, and metabolism-related proteins were likely 
inhibited by carbendazim treatment. Together, these results suggest that 
carbendazim is an environmental risk factor that likely weakens bee colonies, 
partially due to reduced expression of major royal jelly proteins, which may be 
potential causes of colony collapse disorder.