Deformed wing virus–induced changes in honey bee reception and preference for pollen scents

Abstract

Honey bees (Apis mellifera L.) play a crucial role in pollination, and their olfactory system is essential for food collection and source selection. This study evaluates how the deformed wing virus (DWV), particularly its variant A, affects the olfactory sensitivity and behavioral responses of bees (10 to 20 days old) to volatile compounds from different pollen sources. We collected and analyzed the volatile fractions of three types of pollen (polyfloral and two monofloral) using dynamic HeadSpace and gas chromatography–mass spectrometry (GC–MS). The chemical analysis revealed differences in volatile compound profiles among the pollen types, including the presence of benzaldehyde, lilac alcohol, and 1–4 cineole, which are known to impact honey bee olfaction. Behavioral assays using a Y-olfactometer showed that while non-inoculated bees (N-DWV) responded to the aromas of all pollens in higher proportions, DWV-inoculated bees (I-DWV) exhibited significant reductions in behavioral responses. Specifically, I-DWV bees showed lower response rates, and a higher proportion of non-responding individuals compared to N-DWV bees. Notably, I-DWV bees were more attracted to the aroma of Eucryphia cordifolia when exposed simultaneously to the aroma of Rubus ulmifolius. This preference may be related to specific volatiles emitted by E. cordifolia that signal higher nutritional or medicinal value. Future analyses focused on the antiviral activity of this pollen could help clarify whether such attraction is associated with adaptive mechanisms against viral infection. Additionally, electrophysiological recordings indicated that DWV-A infection decreases olfactory sensitivity, particularly in response to complex odors. This decline in olfactory function and behavioral preferences could compromise foraging efficiency and overall colony health. These findings highlight the impact of DWV-A on honey bee sensory and behavioral processes, raising concerns about broader implications for colony survival and pollination services.