Culture of Steinernema glaseri on three solid media and their virulence against Galleria mellonella larvae

Steinernema glaseri is a potential biocontrol agent against white grubs of the Phyllophaga spp. complex; however, its suitability for in vitro multiplication has been scarcely investigated. In this study, the effects of the surface culture of NJ-43 strain with its symbiotic bacteria Xenorhabdus poinarii on egg-yolk agar (P2), chicken-liver agar and nutrient meat-peptone (MP) agar on infective juvenile (IJ) productivity and their virulence against Galleria mellonella larvae were investigated. The bacteria on the surface of the agar were first incubated in darkness at 30 °C for 54-102 h, and then 100 surface-sterilised IJs were added. After two harvests, the accumulated productivity was higher on chicken-liver agar (536 × 103 IJs/m2 day) and P2 agar (534 × 103 IJs/m2 day) than on nutrient MP agar (58 × 103 IJs/m2 day). The mean virulence of the in vitro produced IJs was 46-60% and showed no statistically significant difference among the three culture media. In conclusion, the maximum multiplication factor of S. glaseri NJ-43 on solid media was 385, and its original virulence was retained.