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

Abstract

The devastating effects of Varroa destructor on European honeybee colonies (Apis mellifera L.) have been well documented. Not only do these mites cause physical damage to parasitised individuals when they feed on them, they also transmit viruses and other pathogens, weaken colonies and can ultimately cause their death.Nevertheless, not all honeybee colonies are doomed once Varroa mites become established. Some populations, such as the savannah honeybee, A. m. scutellata, have become tolerant after the introduction of the parasite and are able to withstand the presence of these mites without the need for acaricides. In this study, we measured daily Varroa mite fall, Varroa infestation rates of adult honeybees and worker brood and total Varroa population size in acaricide treated and untreated honeybee colonies. In addition, honeybee colony development was compared in order to measure the cost incurred by Varroa mites to their hosts. Daily Varroa mite fall decreased over the experimental period with different dynamics in treated and untreated colonies. Varroa infestation rates in treated adult honeybees and brood were lower than in untreated colonies, but not significantly so. Thus indicating a minimal benefit of treatment thereby suggesting that A. m. scutellata have the ability to maintain mite populations at low levels. We obtained baseline data on Varroa population dynamics in a tolerant honeybee over the winter period. Varroa mites appeared to have a low impact on this honeybee population, given that colony development was similar in the treated and untreated colonies.

Hygienic and grooming behaviors in African and European honeybees—New damage categories in Varroa destructor

“…The percentage of Varroa mite infestation rates in adult honeybees was determined by taking the number of Varroa mite collected divided by 100 adult worker honeybee and then multiplied by 100 [21,22]. …”

“…m . scutellata against the mite was found to be associated with reduced population growth, low viral prevalence, short post-capping stage, low fertility, fecundity and reproductive success of Varroa mite foundresses [19,22–24]. Interestingly, the East African population of A .…”

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

“…In A. m. capensis, the short post-capping stage (Moritz, 1985), grooming behaviour (Moritz and Mautz, 1990) and the removal of mites through hygienic behaviour are likely explanations for colony survival (Allsopp, 2006). In A. m. scutellata colonies, survival has been attributed to reduced Varroa population growth (Strauss et al 2015) and the low prevalence of viruses (Strauss et al 2013).…”

Effects of genotype, environment, and their interactions on honey bee health in Europe

“…In addition, data are lacking on potential variability of DWV virulence factors and how these may be related to honey bee genotypes. For instance, in South Africa where colonies were never treated against mites since their arrival in 1997, Varroa is not considered a significant factor for losses [49,50]. Yet, in a recent comprehensive study of pathogen prevalence in honey bee colonies in South Africa, of all DWV varieties only VDV-1 was found [51].…”