Efficacy of entomopathogenic nematodes against white grub, Holotrichia longipennis Today, I read a paper published in Journal of Pest Science by Khatri-Chhetri et al. (2011), who tested the efficacy of two newly isolated entomopathogenic nematode species from Nepal against white grub, Holotrichia longipennis. This white grub is a very serious pest of many crops including black gram, cabbage, chilies, maize, millet, paddy soybean and tomato. Khatri-Chhetri et al. (2011) compared the efficacies of Nepalese strains of entomopathogenic nematodes including Steinernema lamjungense LMT5, S. lamjungense SS4, S. everestense DKP4 with other nematode species including S. abbasi CS1, S. sp. KL1, Heterorhabditis indica CK2 and H. indica CK6) and with an insecticide, chlorpyrifos against second third stages of white grub, Holotrichia longipennis. These researchers reported that when Nepalese entomopathogenic nematodes were applied at the rate of 2.5 billion nematodes per hectare, they were able to reduce over 73% larval populations of white grubs and these results were comparable with efficacy of traditional insecticide, Chlorpyrifos 19 weeks after nematode application. I found that these findings are very exciting because it is always difficult get over 50% mortality of any insect host when entomopathogenic nematodes are applied under field conditions. I think these researchers could have compared 3 and 9 week % corrected mortality data using repeated measure analysis, which would have gave them a better understanding about the nematode efficacy differences between two nematode application time intervals.
Khatri-Chhetri, H.B., Timsina, G.P., Manandhar, H.K. and Moens, M. 2011. Potential of Nepalese entomopathogenic nematodes as biocontrol agents against Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae). Journal of Pest Science 84: 457-469.