Schätzung von Populationsparametern für die Toleranz der Honigbiene (Apis mellifera carnica) gegenüber Varroa jacobsoni Oudemans

Abstract - Estimation of population parameters for tolerance of the honey bee (Apis mellifera carnica) for Varroa jacobsoni Oudemans
Estimation of population parameters for tolerance of the honey bee (Apis mellifera carnica) for Varroa jacobsoni Oudemans. The steady chemical treatment against V. jacobsoni mites shows some essential problems: residuals of the drugs in the bee products and resistance of the mites to the active agents in the drugs. A method to control varrooosis without chemical treatments must be found. The best way to avoid problems created by chemical treatments is through selection for a higher tolerance to V. jacobsoni by the honey bees. A basic requirement to achieve this aim is the knowledge of population parameters for the tolerance to the mite. Considering that the reproductive biology of the honey bee deviates from that of other livestock species, heritabilities were estimated for tolerance to V. jacobsoni and for honey yield. Data were sampled from a total of 1 638 performance-tested colonies reared from 412 queens in the years 1988-1995. The queens belonged to the Institute of Bee Research in Lunz am See, Austria and private beekeepers of the breeding union, Austrian Carnica Association. Traits recorded were honey yield and tolerance to V. jacobsoni. As a general selection criterion for tolerance, the number of mites were counted on a special bottom board during the annual treatment with Apistan at the end of the testing season. Population parameters were estimated by an adapted half-sib analysis based on queens, using the restricted maximum likelihood (REML) methodology. The average relationship between two randomly chosen females (queens) was estimated as 0.38. The estimated heritability for honey yield was 0.20, which is documented by several other studies. The estimated heritability for tolerance to V. jacobsoni was 0.13 (table II). The phenotypic correlation between honey yield and tolerance to V. jacobsoni indicated a positive tendency (+0.17). The genetic correlation (-0.05) showed a very weak favourable direction, but owing to the standard deviation (0.24) it has to be interpreted very carefully. Further studies are necessary to analyse the genetic correlation between honey yield and varroa tolerance precisely. According to the results, selection response for tolerance to V. jacobsoni can be expected if performance testing and selection is carried out in large breeding populations. © Inra/DIB/AGIB/Elsevier, Paris