GENETIC AND ENVIRONMENTAL-INFLUENCES ON THE DURATION OF PREIMAGINAL WORKER DEVELOPMENT IN EASTERN (APIS-CERANA) AND WESTERN (APIS-MELLIFERA) HONEY-BEES IN RELATION TO VARROATOSIS

The parasitic mite Varroa jacobsoni could recently switch from its ori ginal host, the Asian honey been Apis cerana, to the western hive bee Apis mellifera. With the exception of the Africanized bee in Brazil, c olonies of western honey bees suffer much by this parasitation. The le vel of incidence depends on the efficacy of reproduction of the mite. One factor of importance is the duration of the postcapping period of worker brood development of the host, because reproduction of V. jacob soni can only occur in capped brood cells. Data on this parameter are lacking from tropical honey bees and European colonies kept under trop ical environmental conditions. In the present study the contribution o f genetic and environmental influences on preimaginal worker developme nt was investigated under both tropical and temperate climate conditio ns in the original host, A, cerana, as well as in the new host, A. mel lifera, of which European, African and Africanized colonies were used. The data are discussed in relation to tolerance against varroatosis. With respect to the situation in Brazil, the well established non-susc eptibility of the Africanized honey bees towards an infestation by V. jacobsoni evidently is not affected by the short duration of the postc apping phase in worker brood.