Interactions among parasites, pathogens and pesticides in the colony
Understanding the impact of pathogens and pesticides on the individual bee is important but equally important is the understanding of the effect at the next higher biological level, the colony. The colony is much more than just the sum of the individual bees. Workers interact with themselves, the brood, the queen, the colony structure (comb building) in a complex and highly nonlinear fashion which is the very the basis for the functioning of the colony and for the success of social insects in general.
However, this is not only true for the beneficial interactions among the colony members, it is also true for the detrimental effects generated by pathogens and pesticides and there are many examples of how such interactions have been shown to interfere with colony health. So although a pesticide or a pathogen may not immediately kill the foraging worker or the colony, it might kill the colony because the next generation bees produced may suffer in a lethal fashion (i.e. by not being able to produce a new queen). The best example for nonlinear long term effects may be that of the Varroa mite, where an infestation in one year will cause colony death three years later when not treated.
Although the colony is the ultimate level of concern when dealing with colony health, it is at the same time the most challenging system to experimentally test. Colonies are genetically very non-homogenous units due to the multiple mating of the queen and the coexistence of typically over 20 subfamilies in the colony. To overcome this problem the BEE DOC will work with colony splits, headed by sister queens to address specific aspects in the life history of the honeybee in a social context. This ensures that the social units are as genetically homogenous as possible, thereby minimising any differences that might result form genetic variance among the colonies.