Efficacy of entomopathogenic Steinernema and Heterorhabditis nematodes against Holotrichia oblita

Abstract

The white grub Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae) causes serious damage in peanut fields in China. The development of an environmentally friendly control method for this pest is urgently needed. The efficacy of entomopathogenic nematodes against this pest in the laboratory and peanut fields was evaluated in this study. Both Steinernema longicaudum Shen and Wang and Heterorhabditis bacteriophora Poinar (Rhabditida: Steinernematidae and Heterorhabditidae) had promising control efficacy against H. oblita larvae in the laboratory. S. longicaudum X-7 and H. bacteriophora H06 at 1.0 × 104 and 5.0 × 103 IJs per plant caused a similar percentage reduction of the grub larvae and percentage of the injured legumes to chlorpyrifos. The peanut yields from the nematode-treated plots at 5.0 × 103 IJs per plant were at least 55 and 15 % higher than those from the water control and the chlorpyrifos-treated plots. No significant differences were found in the percentage reductions of the grub larvae at different larval stage applications. The peanut yields in plots treated by S. longicaudum X-7 and H. bacteriophora H06 were also not significantly different. The cost-benefit analysis showed that S. longicaudum X-7 and H. bacteriophora H06 are promising agents for H. oblita larvae control in peanut fields. Our findings indicate that entomopathogenic nematodes have good potential for safe management of H. oblita in peanut production.