Fertility costs of cryptic viral infections in queen honey bees (Apis mellifera)

Many insects are subject to a trade-off between reproduction and immune activity, meaning that infections can have indirect impacts on fecundity, even in the absence of overt symptoms. While eusocial insects have escaped a broader trade-off between reproduction and lifespan, our results suggest that honey bees may be susceptible to reproduction-immunity compromises. We report that natural viral infection is associated with decreased ovary mass and upregulation of heat-shock proteins (HSPs) which are part of the honey bee’s antiviral response. Failed (poor quality) queens sampled from a wide geographic range have higher levels of viral infection, smaller ovaries, and altered ovarian protein composition, with over 20% of proteins differentially expressed. Significantly reduced levels of the yolk-protein precursor vitellogenin in the ovaries indicate a direct decline in fertility. These findings suggest that viral infections occurring naturally in the field are compromising reproductive success, even among social insects.