OBSERVATIONS ON THE INITIATION AND STIMULATION OF OVIPOSITION OF THE VARROA MITE

Female Varroa mites were collected from adult bees and were classified as swollen or not swollen. After introduction of these mites into recently sealed worker brood cells the average number of offspring of reproducing swollen mites was similar to that of naturally invaded mites, but the non-swollen mites produced a significantly lower number of offspring. This suggests that the oviposition of adult mites is stimulated by a preceding stay on adult bees. When (non-swollen) mites collected from brood cells were kept for 35 days in Eppendorf test tubes containing a larva or a pupa, their reproduction was similar to that of swollen mites. Contact of young mites, collected from brood cells, with adult bees was not essential for the initiation of oviposition. However, the number of offspring of reproducing mites, even after a third or fourth introduction into brood cells, was as a rule lower than that of mites that had been in contact with adult bees. The period of artificial introduction into sealed brood cells proved to be essential for subsequent reproduction. When introduced 48-52 h or 72-76 h after cell sealing, the mites did not produce eggs. When introduced 0-4 h after cell sealing a high percentage of the mites reproduced. Contact of the mites with a spinning larva seems necessary for initiation of oviposition.