Studies on the behavioral responses ofApis melliferato the pathogenNosema ceranaeand the parasiteVarroa destructor, and on the predatory waspVespula germanicain apiary

Declining honey bee health has been a major concern worldwide and the responses of bees to biotic factors has not been fully understood yet. This thesis is divided into three parts: the first two chapters concern the use of propolis, as an extract or as a raw propolis, in adult bees experimentally treated with the microsporidiumNosema ceranae(first chapter) and the parasitic miteVarroa destructor(second chapter); and the third chapter relates to the impact of the predatory waspVespula germanicaon bee hives. The aim of this three-year study was to investigate the behavioral responses ofApis melliferato the parasite and the pathogen in laboratory, and observe the behavior of the wasp in an experimental apiary. Our results showed that the lifespan of bees artificially infected withN. ceranaeor parasitized byV. destructorincreased when bees were treated with propolis compared to untreated bees. In particular, laboratory experiments evidenced that raw propolis had a narcoleptic effect onV. destructormites, by contact, and propolis extract caused a decrease in spore load ofN. ceranae. In the study on the feeding strategies ofV. germanicain apiary, our results showed the major role of the wasp as a scavenger, because we found that its diet is based mostly on bee carrions. In order to improve the protection measures of honey bees, it would be important to conduct further studies focusing on impact and control of biotic stress factors of this species.