Investigação

Início / Investigação / Provas e Teses / The tolerance of four commercial strains of honey bee (Apis mellifera L.) to infestation by Varroa Jacobsoni Oud. in mediterranean conditions

The tolerance of four commercial strains of honey bee (Apis mellifera L.) to infestation by Varroa Jacobsoni Oud. in mediterranean conditions

Ano
1998
Instituição
University of Wales (School of BioSciences)
País
Reino Unido
Total de páginas
311
Abstract

Varroa (Varroa jacobsoni Oud.), a common parasite of A. mellifera L., has had great economic impact on beekeeping with this honey bee species throughout most of the temperate world, Portugal included. The aims and results of the experiments reported in this thesis were as follows: (I) To compare the impact of Varroa upon honey bee colony population dynamics of four strains of honey bees (A. m. carnica, A. m. caucasica, A. m. iberica and A. m. ligustica) in the Alentejo region (southern Portugal). For this purpose, 42 honey bee colonies were either maintained free of Varroa or artificially infested with Varroa to allow for the study of open brood, capped worker and drone brood, adult honey bee population, pollen and honey. A. m. iberica appeared to be the least tolerant strain to Varroa, where the heaviest colony losses were recorded. Most regional beekeepers are expected to experience high A. m. iberica colony Varroa-related mortality and, in surviving colonies, to incur on annual average honey losses of 64 %. (II) Another major aim pursued in this thesis was to simultaneously assess Varroa population dynamics in honey bee colonies of all studied strains in the Alentejo. In this field, the apparent Varroa infestation rates of capped worker and drone brood and adult honey bees, the total Varroa population and its distribution within host colonies and the environmental Varroa reinfestation pressure were studied. A much faster Varroa population growth occurs in the Alentejo (compared to what has been reported for temperate climates), with most colonies hosting Varroa populations critical to their survival within one year after becoming infested. Over winter, A. m. iberica colonies hosted considerably more (68%) of their total Varroa populations within capped worker brood than any of the other studied strains (26 to 45 %), this appears to have been related to the very high overwinter Varroa-infested colony mortality observed in the former strain. A single relatively high (19 V. jacobsoni per day) absolute peak of environmental Varroa reinfestation pressure occurred in all studied strains during early winter, apparently associated with robbing of Varroa-infested weakened neighbour honey bee colonies. (III) Finally, the length of worker and drone brood postcapping periods, the level of hygienic behaviour, the worker larvae attractiveness to Varroa, the degree of Varroa non-reproduction on worker brood, the fertility level and offspring family structure of Varroa reproducing on capped worker brood and the efficiency of grooming behaviour directed towards phoretic Varroa were also investigated, as these variables had previously been reported associated with between-strain differences in degrees of honey bee colony tolerance to Varroa. It appears that the lower tolerance of A. m. iberica to Varroa in the Alentejo may have been linked to (i) their longer brood postcapping periods, (ii) the higher initial level (but identical final level) of hygienic behaviour that they may have displayed towards Varroa-infested capped worker brood cells, (iii) the apparently higher attractiveness to Varroa of their worker larvae, (iv) the scarcer occurrence, on worker brood, of reproducing Varroa producing exclusively female offspring and, possibly, (v) also a slightly higher Varroa reproductive rate on worker brood

Palavras Chave

Varroa; Abelhas; Dinâmica populacional; Tolerância; Clima Mediterrânico

Keywords

Varroa; Honey bees; Population dynamics; Tolerance; Mediterraneam climate

Tipo de tese
Doutoramento
Situação
Aprovada
Área de Trabalho
Referência

Murilhas, A (1998). The tolerance of four commercial strains of honey bee (Apis mellifera L.) to infestation by Varroa Jacobsoni Oud. in mediterranean conditions. University of Wales (Reino Unido ): 311 pp.