Entomopathogenic nematode performance in three honey bee pests: small hive beetle, greater and lesser wax moths

Western honey bee (Apis mellifera) faces substantial threats from pests such as small hive beetle (SHB; Aethina tumida), greater wax moth (GWM; Galleria mellonella) and lesser wax moth (LWM; Achroia grisella). Entomopathogenic nematodes (EPNs) could serve as promising biocontrol agents to manage these pests; however, their efficacy can vary with target pest species with different body mass and life cycles, EPN species and isolates, and concentrations applied. Although numerous EPN studies have been performed on GWM and some on SHB, very few have been conducted on LWM, and none have directly compared EPN performance across these three pests. Here, we evaluated and compared the virulence, penetration rates and reproductive potential of 15 Australian isolates of five EPN species against body mass-standardised larvae of SHB, GWM and LWM. We found that SHB consistently experienced the lowest and slowest mortality across all EPNs, while GWM consistently experienced the highest and fastest mortality. Notably, Heterorhabditis indica Hi.HRN2 and Hi.HIE2 were among the most virulent isolates in SHB and GWM, whereas Heterorhabditis bacteriophora Hb.EG was the most virulent EPN isolate in LWM. Additionally, EPN isolates exhibited on average 5 × lower penetration rates and 1.5 × lower reproductive success in SHB compared to GWM and LWM. Our study found significant variation in EPN efficacy across the three honey bee pests and provides the basis for the selection of effective isolates and concentrations for targeted biological control of honey bee pests, though the evaluation of EPN safety for honey bee will also be essential.