Reproduction of Varroa destructor in South African honey bees: does cell space influence Varroa male survivorship?

Abstract

-The ability of Varroa destructor to reproduce in the African honey bee Apis mellifera scutellata was studied. In addition, the effects of space within the brood cell and short brood developmental time on mite reproduction, was investigated using A. m. scutellata cells parasitised by a A. m. capensis worker pseudo-clone. In A. m. scutellata worker cells Varroa produced 0.9 fertilised females per mother mite which is the same as found in susceptible European honey bees, but greater than the 0.4 produced in cells containing the pseudo-clone. Low mite reproductive success in cells containing pseudo-clone was mainly as a result of increased mite mortality. This was caused by male protonymphs and some mothers becoming trapped in the upper part of the cell due to the pseudo-clone being 8% larger than their host and not due to their short developmental time. Therefore, mite populations in South African A. m. scutellata and A. m. capensis honey bees are expected to increase to levels observed in Europe and USA.Varroa destructor / reproduction / cell size / mite mortality / Apis mellifera scutellata

Impact of Varroa destructor on honeybee (Apis mellifera scutellata) colony development in South Africa

“…Even though most of the evidence obtained so far points towards Varroa mite tolerance in both sub-species of South Africa, Martin and Kryger (2002) found that Varroa mite reproductive rates were similar in A. m. scutellata and European honeybees, thereby suggesting that Varroa mites should have the same negative effect in A. m. scutellata as in European honeybees. Also, Martin and Kryger (2002) showed that Varroa mites were reproductively more successful in A. m. scutellata drone and worker cells compared to Africanised workers cells and that a higher percentage of fertile female mites were produced in A. m. scutellata compared to Africanised honeybees. Consequently, more studies are needed to give us a better idea of the reproductive potential of Varroa mites in both honeybee sub-species of South Africa and on the tolerance mechanisms that these honeybees developed against the parasite.…”

“…However, fertility rates can change over time, as was found in Brazilian honeybees where mite fertility was low before the late 1990's but increased after this period (Corrêa-Marques et al 2003;Garrido et al 2003;Carneiro et al 2007). Even though most of the evidence obtained so far points towards Varroa mite tolerance in both sub-species of South Africa, Martin and Kryger (2002) found that Varroa mite reproductive rates were similar in A. m. scutellata and European honeybees, thereby suggesting that Varroa mites should have the same negative effect in A. m. scutellata as in European honeybees. Also, Martin and Kryger (2002) showed that Varroa mites were reproductively more successful in A. m. scutellata drone and worker cells compared to Africanised workers cells and that a higher percentage of fertile female mites were produced in A. m. scutellata compared to Africanised honeybees.…”

“…Cape honeybees, however, showed no direct aggression towards Varroa mites, nor did they exhibit grooming behaviour (Allsopp 2006). He concluded that the shorter postcapping stage (between 9.6-12 days in Cape honeybees, 10-12 days in A. m. scutellata, 11.5-11.6 in Africanised honeybees compared to 11.6-12 in European honeybees (Moritz and Hänel 1984;Moritz 1985;Vandame et al 1999;Tribe and Allsopp 2001;Martin and Kryger 2002;Allsopp 2006;Calderón et al 2010) and the ability of these honeybees to eliminate reproductive Varroa mites from brood (hygienic behaviour) contributed to tolerance. No studies on the mechanisms of Varroa mite tolerance have been done on A. m. scutellata honeybees in South Africa.…”

“…Varroa mites were introduced into the Western Cape region during 1997, and they spread to most parts of the country within a few years and infested both endemic sub-species, A. m. scutellata and A. m. capensis (Martin and Kryger 2002;Allsopp 2006). During the first few years of invasion by Varroa mites, typical symptoms of Varroa mite presence in honeybee colonies were observed and Varroa mite population sizes were estimated at approximately 10 000-50 000 per colony (Allsopp 2006).…”

Resistance rather than tolerance explains survival of savannah honeybees (Apis mellifera scutellata) to infestation by the parasitic mite Varroa destructor

“…**Fecundity calculated in cells containing 3 or more offspring, to allow for a better comparison with Martin and Kryger (2002). ***Values as re-calculated by Martin and Kryger (2002). ****Only fertile foundresses were included in the fecundity assessment.…”