Association between insecticide residues in vineyards and Vitellogenin expression as an indicator of physiological stress in Apis mellifera

The occurrence of colony collapse in honey bees is widely documented worldwide, attributed to various factors such as exposure to agricultural pesticides, habitat destruction, and the prevalence of numerous diseases. Agricultural pesticides are among these causes. The Piedmont region and the Asti province are recognized for extensive cultivation of grapes and significant beekeeping production, making them ideal locations to examine the potential effects of pesticide application in vineyards on honey bee physiological stress. Vitellogenin (VG), a precursor protein of yolk in honey bees, is often used as a marker of physiological stress, having a key role in immune defense, protection from oxidative stress, and promoting longevity. The current study investigates the correlation between pesticide use in viticulture and the levels of VG expression (VG mRNA levels) in honey bee colonies. This study aims to clarify the relationship between pesticide exposure in viticulture and the respective vitellogenin expression levels in honey bee populations. We used RT-PCR to measure the VG mRNA levels, as well as chromatography coupled with tandem mass spectrometry for pesticide residue analysis in honey bee samples obtained from three apiaries at different distances from vineyards that were treated with pesticides, thus assessing their potential relationship. The analysis of pesticide residues indicated that insecticides were the predominant agrochemicals detected in honey bee samples, especially in apiaries situated near treated vineyards. The expression of Vitellogenin was found to be significantly modulated between the sampling periods and sites, showing a clear association with the levels of insecticide residues detected in the apiaries. These findings improve understanding of the impact of pesticide exposure associated with viticulture on the physiological dynamics of honey bee colonies.