Synergistic effects between Nosema sp. and insecticide imidacloprid on honeybees africanized Apis mellifera

Abstract

The decline of Apis mellifera colonies has become a concern worldwide and this phenomenon, known as colony colapse disorder (CCD), has been attributed to infection of the colonies by Nosema ceranae and to action of the insecticides. Nosema apis and N. ceranae are microsporidian parasite mainly found in the midgut of infected bees. It was demonstrated that the interaction between N. apis, N. ceranae and imidacloprid increased the mortality rates of the honeybees and weakened the colonies. The insecticide imidacloprid acts agonistically on nicotinic acetylcholine receptors of insects and in sublethal doses, this compound impairs learning performance and memory formation, result of morphophysiological changes caused by this insecticide. This work aims to evaluate the synergistic effects between N. ceranae and imidacloprid on mushroom bodies of the nervous system, target structure of this insecticide, and midgut, reservoir of the microsporidian spores and region involved with the metabolization of the insecticides when these are ingested. So, worker honeybees of africanized A. mellifera will be exposed to the microsporidian N. ceranae and/or will be treated orally with imidacloprid. After that, the bees will be dissected and the tissues will be analyzed with light microscopy and confocal microscopy.