Pathogenicity of Entomopathogenic Nematode on Sugarcane White Grub Lepidiota stigma (Coleoptera: Scarabaeidae)

Abstract
Sugarcane (Saccharum officinarum) is one of high-value commodities in Indonesia for producing sugar. Sugarcane production recently reduced due to insect pests attacked, mainly white grub Lepidiota stigma (Coleoptera: Scarabaeidae). Utilization of entomopathogenic nematodes (EPN) is one of the alternative control methods for sugarcane white grub. The aim of the presentstudy was to select the higher pathogenicity of EPN isolates for controlling the sugarcane insect pest. The study was conducted in Insect Pathology Laboratory of Indonesia Sweeteners and Fiber Crops Research Institute. Nine isolates of EPN, e.g. DKS-1, AGH-1, DKH-1, DKH-5, NH-1, NH-2, PH-1, PH-2, and PH-4 and one untreated control were tested for their pathogenicity against sugarcane white grub, L. stigma. Each treatment was arranged in Completely Randomized Design with three replications. Every treatment consisted of 30 individuals of the third instar of white grub which treated by 2 × 104 infective juvenile or IJ of EPNisolates. Parameter observed was the mortality of sugarcane white grub, L. stigma. The result showed that all of EPN isolates tested were promising pathogenic against the white grub with about 10 to 80% of the average percentage of mortality. However, DKS-1 and PH-1 showed more pathogenic against L. stigma with about 80–90% and 70–80% of white grub mortality,respectively. The highest enhancement of white grub mortality occurred at 72 hours after treatment and it was showed by DKS-1 and PH-1 isolates which increased the percentage of white grub mortality about 57.1 and 50%, respectively. Obtaining the promising isolates of NPS with different host seeking strategies will potentially increase the effectivity of control against whitegrub with the result to increase the yield of sugarcane.