Immune-related gene expression of Apis mellifera larvae in response to cold stress and Abscisic Acid (ABA) dietary supplementation

Abstract

The effects of parasites, pathogens and agrochemical exposure combined with the cold temperatures of winter in temperate-climate regions contribute to the immunosuppression of honey bees. Recently, we demonstrated that abscisic acid (ABA) dietary supplementation increased the tolerance of Apis mellifera brood to low temperatures. Here, we study the relationship between cold exposure, dietary ABA supplementation, and the expression of genes involved in the immune response of in-vitro-reared bee larvae. We found that cold exposure induced the expression of several immune-associated genes in honey bee larvae, supporting that the immune system is active during the cold stress response in A. mellifera. At the same time, the ingestion of ABA alone increased the expression levels of the Toll pathway receptor toll18W and nitric oxide synthase (nos) genes, which were induced also by low temperatures, reinforcing the connection between honey bees’ response to cold stress and ABA.