Changes in innate immune response and detoxification in Melipona quadrifasciata (Apinae: Meliponini) on oral exposure to azadirachtin and spinosad

Abstract

Exposure to agrochemicals and pathogens has been indicated as critical factors of declining pollinator populations, including species of native tropical bees. In the present study, we investigated the sublethal effects of acute oral exposure to azadirachtin and spinosad bioinsecticides on the expression of immunity-related genes and the number of hemocytes in uninfected and Escherichia coli–infected workers of the stingless bee Melipona quadrifasciata. Expression of the immune-related gene vitellogenin decreased and the number of circulating hemocytes increased in bioinsecticide-exposed uninfected bees and in unexposed E. coli–infected bees as compared with unexposed uninfected bees. Our results show that though bioinsecticides are considered safe, contamination by sublethal doses of azadirachtin and spinosad can interfere with the immune system of bees.