Infertility of Varroa jacobsoni females after invasion into Apis mellifera worker brood as a tolerance factor against varroatosisP. Rosenkranz and W. Engels
Department of Developmental Biology, Zoological Institute, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
Abstract - The fertility of Varroa jacobsoni females was studied in worker brood invaded by a single mite. Africanized and European colonies of Apis mellifera were used as sources to sample capped brood cells in a tropical area of Brazil and, in addition, Carnolian colonies were sampled in Germany. In the Africanized bees over 40% of the female mites in worker brood were infertile, whereas in European bees only 10-20% infertile Varroa females were found. These differences do not depend on broodnest or ambient temperatures. If a female mite was fertile, then the fecundity, measured as the mean number of eggs produced, was the same, irrespective of the host honey bee race. The low Varroa fertility in worker brood of the Africanized bees resembles the situation known from the original host species, Apis cerana. Since host-dependent infertility evidently has a strong influence on the population dynamics of this parasite, it should be properly considered in future selection and breeding efforts in order to produce European bee strains tolerant against varroatosis.
Key words: Varroa jacobsoni / infertility / tolerance against varroatosis / Apis mellifera / Africanized bee