A study was carried out during May 1993. in southern England, on eight chemically untreated Apis mellifera L. colonies heavily inl~sted with Varroa jacobsoni ( 15-40% of worke, sealed brood). The position and time of capping of 3,228 worker sealed br~n)d were recorded. At two hour intervals, starting from when each cell was capped, groups of worker cells were uncapped and their contents recorded. It was found that each ~: jacobsoni female could deposit five or sometimes six larvae in a worker cell, of which four (1 male and 3 females) may reach maturity before the bee emerged from its cell. However. mortality of the oft~pring resulted in only 1.45 female offspring reaching maturity. for each normally reproducing mother mite, before the bee emerged. The mean development time of the firsl three female offspring was 134 hours (_+ =3 h. n=3), shorter than that of lhe male ( 154 hours). The first larva was deposited approximately 60 hours alter the cell was capped, and developed into a male, Subsequent larvae were deposited at intervals varying from 26-32 hours, and all developed into females.
INTRODUC~ON
Varlva.jacobsoni Oud. is a parasite mesostigmatid mite which lives exclusively on honeybees (Apis spp.). The mites reproduce only in the sealed brood of the honey bee and feed on the developing bee. Fertilised females survive broodless periods (e.g. during winter) on the adult bees. The development of the mite is restricted mainly to drone (male) brood in Apis cerana E, the mite's natural host. This is believed to be due to various behavioural and physiological traits (Rosenkranz et al., 1993). However, in A. meIlifera L., the mite reproduces successfully in both worker and drone sealed brood. Worker brood is always more numerous than drone brood in a colony, and unlike drone brood, is present throughout the entire breeding season. These facts, coupled with the lack of any of the behavioural and