Comparative Virulence of Entomopathogenic Nematodes to the Small Hive Beetle (Aethina tumida Murray, Coleoptera: Nitidulidae)

The small hive beetle (SHB), Aethina tumida Murray (Coleoptera: Nitidulidae), has become a ubiquitous, invasive, and highly destructive pest of western honeybee (Apis mellifera Linnaeus) hives worldwide. Beekeepers often attempt to control this beetle chemically. Still, ineffective registered control options and rampant off-label chemical use in the beekeeping industry have driven research toward alternative pest management strategies. Entomopathogenic nematodes (EPNs) of the families Heterorhabditidae and Steinernematidae have been established as potential biocontrol agents against soil-dwelling insect pests. However, studies are needed to determine the most appropriate EPN species to control SHB. In this study, an LD₅₀ of ~700 infective juveniles (IJs) of EPN per SHB larva was determined through dose-response experiments. This application rate was used to compare the virulence of the following seven species of EPNs against SHB larvae: Heterorhabditis bacteriophora (VS), H. floridensis (K22), H. georgiana (Kesha), H. indica (HOM1), Steinernema carpocapsae (All), S. rarum (17C+E), and S. riobrave (355). Steinernema carpocapsae (All) and H. floridensis (K22) were found to cause 100% larval mortality of SHB at 14 days post-inoculation. Assays for the persistence of virulence of H. floridensis (K22) and S. carpocapsae in the soil over several weeks from a single application found that both species maintained efficacy, causing 96% mortality of SHB larvae by week 6 post-inoculation. We recommend that S. carpocapsae (All) and H. floridensis (K22) due to their superior virulence for the control of small hive beetles.