The susceptibility of small hive beetle (Aethina tumida Murray) pupae to Aspergillus niger (van Tieghem) and A-flavus (Link:Grey)

The small hive beetle, (Aethina tumida Murray, Coleoptera: Nitidulidae, SHB) endemic to sub-Saharan Africa, causes considerable damage to European honey bee (Apis mellifera) colonies in North America, parts of Europe and Australia, ultimately destroying infected colonies. Although chemical control has proven to be very effective, a cheaper, more environmentally friendly and sustainable approach is desirable. The pathogenic effect of two fungal species, namely Aspergillus niger van Tieghem (Eurotiaceae) and A. flavus Link:Grey (Eurotiaceae) were tested against SHB. The fungal isolates were tested alone and in combination with diatomaceous earth (an abrasive substance). Small hive beetle pupae mortality did not significantly differ in the A. niger, diatomaceous earth and diatomaceous earth + A. niger treatments when compared to the controls. Aspergillus flavus caused a 38% mortality of SHB pupae which differed significantly to the 3% of the control. The combined treatment of diatomaceous earth + A. flavus increased SHB pupae mortality to 46%, although this did not differ significantly from the A. flavus treatment alone. Aspergillus flavus is a generalist pathogen that infects many insects and some plants and animals and therefore cannot be considered as a potential mycoinsecticide for SHB control. Small hive beetle post-feeding larvae exposed to diatomaceous earth were examined using a scanning electron microscope. Lacerations were observed on SHB cuticles between all abdominal and most thoracic segments, as well as on the mid and hind legs.