Social Immunity in honeybee: behavioral, chemical and microbiological aspects

Social insects have evolved collective immune defense strategies to combat predators, parasites and pathogens, which constantly threaten the survival of the hive. Some of these defense systems are preventative and are intended to restrict the transmission of diseases within the nest, whereas others are activated in case of need, when pathogens and/or pests have already penetrated into the hive. The first subject of this thesis focuses on the predator–prey relationship between Apis mellifera ligustica and Vespula germanica by evaluating the effectiveness of attack and defense behaviors, as well as the actual damage and disturbance caused to the colonies under attack. Another topic of this thesis is the resin collection dynamics in Varroa destructor infested honeybee colonies. Comparative experiments involving hives with different mite infestation levels were conducted to assess propolis amount and quality within the hive. Finally, we investigated the variations in the immune-related gene expression levels and in the relative abundance of representative bacterial phylotypes of the core honeybee microbiota, in colonies infested by DWV carrying-Varroa mites in comparison with honeybees from non-infested colonies. In conclusion, our results are important for future development of more environmentally friendly management practices to improve bees survival.