Comparison of the responses of some New Zealand and Australian honey bees (Apis mellifera L) to Nosema apis Z

To determine whether the introduction of Carniolan stock may alter the impact of Nosema apis on New Zealand bees, the responses of Italian (Apis mellifera ligustica) and dark (Apis mellifera mellifera) New Zealand bees and Carniolan (Apis mellifera carnica) bees from Australia to dosing with N apis spores were compared. Newly emerged adult bees were individually dosed with 2 x 10(5) N apis spores, caged together in groups of 50, and incubated at 33 degrees C. The longevity of each bee and number of N apis spores carried by each bee at the time of death were recorded. All bees dosed with N apis spores had significantly reduced longevity compared with the undosed control bees. Furthermore, there were no significant differences among the 3 stocks of bees in the degree of this reduction in longevity. However, dark and Carniolan bees survived better in cages than Italian bees, whether dosed or not. There were significant differences among the 3 stocks in the mean numbers of spores carried by each dosed bee at the time of death, with Italian bees carrying the highest spore loads, Carniolan bees the lowest, and dark bees carrying an intermediate number of spores. Thus, Carniolan bees from Australia may support a slower rate of N apis proliferation and thus have lighter infections than New Zealand dark or Italian bees receiving similar doses of spores.