Sealing up and non-removal of diseased and Varroa jacobsoni infested drone brood cells is part of the hygienic behaviour in Apis cerana
The occurrence of drone brood cells with a closed pore in the conical cocoon cap of Apis cerana was investigated in the Philippines and in Nepal. Closed pores in A. cerana drone cell caps result from nurse bees that fill in wax material from outside until the pore is plugged, as SEM pictures and a preliminary experiment revealed. All these closed cells contained dead brood that had been killed either by European foulbrood or by Thai sacbrood virus. In Nepal, some dead drone pupae were found infested with Varroa jacobsoni that also had a sealed pore in the cocoon cap. The results of this study demonstrate that sealing up and non-removal of diseased and V. jacobsoni infested drone brood cells can be considered as part of the hygienic behaviour of A. cerana honey bees.