Effects of deformed wing virus infection on honey bee vision and color preferences

The decline of managed colonies of honey bees in the United States has garnered the attention of the scientific and agricultural communities. Although multiple factors contribute to colony losses, it is widely agreed upon that infection with viruses is the most damaging. The majority of viral infections, including deformed wing virus (DWV), occur at relatively low titers, and are presumed to be of little consequence. Our recent work has demonstrated colonies with covert viral infections suffer from weakness and altered foraging decisions, thus challenging the notion ‘covert’ infections are truly asymptomatic. Altered foraging decisions are multifactorial, yet vision is believed to be the most relevant to bee behavior outside of the hive, leading us to speculate that DWV infection of bee eyes may affect visual system function to alter behavior. Indeed, quantitative RT-PCR verified asymptomatic honey bees exhibit high viral expression in the eyes and thus, this study aimed test the influence of DWV infection to the transcription of key visual genes, as well as visually guided behaviors. We developed a behavioral assay to measure individual bee attraction to spectrally pure colors, and data show shifts in behavior after inoculation with DWV; infection significantly reduced the blue visitation time by 2.5-fold and increased the green visitation time by 8-fold when compared to sham injected bees. These data indicate that ‘covert’ DWV infections may indeed alter bee vision and visually guided behavior, such as foraging and homing, that are likely to effect colony health.