Submitted to: Journal of Apicultural Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/14/2006
Publication Date: 11/1/2006
Citation: Villegas, A.J., Villa, J.D. 2006. Uncapping of sealed worker brood by european bees as responses to infestation by varroa destructor and to activity by galleria mellonella. Journal of Apicultural Research 45(4):203-206 Interpretive Summary: Varroa mites were introduced into the United States in the mid 1980s and unless they are controlled with chemicals, they will kill beekeepers' colonies. Genetic improvement of honey bees is viewed as the safest permanent solution to the problem. We investigated the responses of adult bees to mites infesting developing bees in their colonies. Adult bees are able to discover a proportion of the mite-infested young bees, uncover the cell and remove the immature bee and developing mites. They are much more selective towards cells with activity of wax moth larvae, a parasite that has coexisted with honey bee colonies for a much longer time. It therefore seems possible to improve the specificity of honey bee colonies towards mite parasites with further selection and breeding. This genetic trait could potentially be combined with others already in development to produce bee colonies that eliminate the need for any chemical treatment of bee colonies.
Technical Abstract: We investigated the uncapping of sealed brood cells by honey bees as possible responses to infestation with V. destructor and G. mellonella. In a group of 15 colonies, we counted the number of uncapped brood cells that should have been sealed, and estimated the total sealed brood area. At the same time, the infestation by V. destructor and evidence of wax moth activity were measured in uncapped cells (U), in sealed cells neighboring those uncapped cells (N), and in sealed cells along randomly selected linear transects (R). The relative amount of uncapped cells (uncapped cells/total sealed cells) increased with infestation (linear regression R2 = 0.64, b = 0.16), but was mostly influenced by the high rate of uncapping in a colony with a very high infestation with varroa mites (54% of R). Varroa mite infestation of U (30 %) significantly exceeded that of N (14 %) and also that of R (12 %), but infestations of N and R were similar. The infestation of U cells compared with their adjacent cells (U-N) increased as the infestation of R increased (linear regression R2= 0.61, b=0.97), suggesting that discrimination of infested cells increases with overall colony infestation. Frequencies of wax moth activity (presence of larvae, frass, tunneling and webbing) was highest in U cells (33 % ), lower in N cells (21 %) and extremely low in R cells (4 %) but there were no linear relationships between U, N and R. We followed the uncapping, removing and recapping of individual brood cells every 24 h in two combs from two colonies with the highest and lowest levels of mites (and the opposite for wax moth activity). More than half of the uncapped or partly removed cells were found in a different condition after 24 hours.