Nurse Honey Bee Behavior and Sensorial-Related Genes are Altered by Deformed Wing Virus Variant A

Insect behavior is coordinated mainly by smell, through the diverse odor-binding proteins (OBP) that allow them to identify and recognize their environment. Sensory information collected through smell is then analyzed and interpreted in the brain, allowing for correct insect functioning. The behavior of honey bees (Apis mellifera L.) can be affected by different pathogens, such as deformed wing virus (DWV). In particular, DWV variant A (DWV-A) is capable of altering olfactory sensitivity, reducing the gene expression of different OBPs, including those associated with nursing behavior. DWV is also capable of replicating itself in the sensory lobes of the brain, further compromising the processing of sensory information. This study evaluated the behavioral response of nurse honey bees exposed to a pheromone compound and the alterations in the gene expression of pre- and post-synaptic neuronal genes neuroxins-1 and neurogilin-1 in the bee heads and OBP proteins in antennae of nurse bees inoculated with DWV-A. The behavioral response of nurse bees exposed to the larval pheromone compounds benzyl alcohol was analyzed using a Y-tube olfactometer. The viral load, gene expression of OBP5 and OBP11 in antennae and the neuroxins-1 and neurogilin-1 in the bee heads were analyzed by qPCR. High viral loads significantly reduced the ability of 10- and 15-day-old nurse honey bees to choose the correct pheromone compound. Also, the gene expression of OBP5, OBP11, neuroxin-1 and neurogilin-1 in nurse honey bees decreased when they were highly infected with DWV-A. These results suggest that a DWV-A infection can disturb information processing and cause nurse honey bees to reduce their activity inside the hive, altering internal cohesion.