No effect of abscisic and p-coumaric acids as food supplements and stimulants of the immunological system of Africanized hybrids of Apis mellifera

Abstract

Bee colonies determined as Apis mellifera scutellata haplotype A1 were administered with a food supplement of sugar syrup mixed with p-coumaric acid (CUM), to test its supposed antioxidant effects; abscisic acid (ABA), to test whether it promotes innate immunity in bees, the combination of both (ABACUM), and syrup as a control. During three months, the number of cells with brood, honey and pollen reserves, as well as the concentration of hemocytes in worker bees were counted. Besides, Varroa destructor and Nosema ceranae were monitored. At the concentrations used, ABA and CUM had no effect on oviposition; however, there was a significant increase in the number of cells with brood or with honey and pollen reserves between the beginning and the end of the study. Regarding the monitoring of V. destructor, there were no significant differences between treatments; this mite did not cause obvious damage, seemingly because the experimental (Africanized) bees are considered tolerant to its infestation. There were no significant differences between treatments in infection by N. ceranae; however, there was a significant decrease in intensity, prevalence, and abundance of spores between the beginning and the end of the study, which was associated with the fact that the bees collected nectar and this resulted in the development of colonies. The number of hemocytes did not show a significant difference between treatments, but there was a significant increase between the first and the last evaluation. Neither ABA, CUM or ABACUM produced the predicted effects on the experimental bees.