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A note on the occurrence of Varroa destructor in Singida, Tanzania
During our beekeeping experience in Tanzania in January 2018 we found several colonies which were infested with Varroa destructor in the Singida region, Ikungi district. Yet, no devastating picture or visual detection of symptoms, like spotty brood nest, deformed wings, deformed workers etc. could be found in both strong and weak colonies and infestation rates per hive were low. The first scientific report of Varroa mites in Tanzania only dates to 2014 (Mumbi et al., 2014). This suggests, that the parasite is spreading rather fast.
A similar picture has been reported in other African countries, as reflected in the review by (Pirk et al., 2016). One of the latest studies sampled colonies from Ghana (Llorens-Picher et al., 2017). Out of 49 colonies, 89% were infested with Varroa destructor, whereas the first report of Varroa in Ghana dates back only 8 years (Fazier et al., 2010). High infestation rates are now thought to be either reflecting the local subspecies of Apis mellifera adansonii being more tolerant or an invasion wave of V. destructor taking place right now.
Not all honeybees stick to the likable picture that is drawn of them: In South Africa, cape honeybees (A. mellifera capensis) can make a pseudoclone of themselves the next queen of a colony. They are, from a genetic point of view, a real threat to their own queen. They will pass their own genome on to the next generation instead of providing support for the whole colony. Scientists have called these individuals “reproductive cheats“. In this essay I will use this example to show how changes in the mode of reproduction of organisms are linked to social parasitism within species and that several reproductive strategies can emerge and exist in parallel. This depends on the life circumstances of the individual.