The effect of Israeli acute paralysis infection on honey bee brood care behavior

To protect themselves from communicable diseases, social insects utilize
social immunity—behavioral, phsyiological, and organizational means to
combat disease transmission and severity. Within a honey bee colony,
larvae are visited thousands of times by nurse bees, representing a prime
environment for pathogen transmission. We investigated a potential social
immune response to Israeli acute paralysis virus (IAPV) infection in brood
care, testing the hypotheses that bees will respond with behaviors that
result in reduced brood care, or that infection results in elevated brood
care as a virus-driven mechanism to increase transmission. We tested for
group-level effects by comparing three different social environments in
which 0%, 50%, or 100% of bees were experimentally infected with IAPV. We
investigated individual-level effects by comparing exposed bees to
unexposed bees within the mixed-exposure treatment group. We found no
evidence for a social immune response at the group level; however,
individually, exposed bees interacted with the larva more frequently than
their unexposed nestmates. While this could increase virus transmission
from adults to larvae, it could also represent a hygienic response to
increase grooming when an infection is detected. Together, our findings
underline the complexity of disease dynamics in complex social animal
systems.