Molekulare Grundlagen der Genom-Interaktion zwischen der Honigbiene Apis mellifera und Nosema

We use the honeybee, Apis mellifera, and its Microsporidian parasite, Nosema as a model system to study co-evolution in social insect species. In the previous funding period we could map a single QTL on chromosome 14 which reduced the spore load in the gut in a strain honeybees which had been selected for Nosema resistance in Denmark. The QTL was independently confirmed by a selective sweep in the identical chromosome region  comprising only four open reading frames. Two of these genes are prime candidates for resistance mechanisms against Nosema infections. One gene is part of the RNAi machinery and the other interferes with the innate insect immune system. In the forthcoming period we want to study how the parasite genome negotiates with this host defence gene. We will screen for patterns of selection in the pathogen genome in two different Nosema species using artificial evolution experiments using both the animal and a cell culture system. Nosema will be selected for high and low virulence in the resistant, the susceptible honeybee strain and the cell culture system. Using drones produced by a hybrid queen which is heterozygote for the susceptibility and the resistance allele, we will screen for interactions at the host/pathogen transcriptome level and also assess the importance of phenotypic plasticity for pathogen virulence for host-parasite co-evolution after artificial selection for high and low virulence.