Efficacy of indigenous Steinernema abbasi and Heterorhabditis indica isolates as potential biocontrol agent against Holotrichia consanguinea Blanch. (Coleoptera: Scarabaeidae)

Abstract

Holotrichia consanguinea is a serious pest of peanut and sugarcane that attacks other commercial crops in India. The efficacy of two species of entomopathogenic nematodes (EPN), Steinernema abbasi and Heterorhabditis indica, against H. consanguinea was tested under laboratory and field conditions. In a laboratory assay, H. indica caused significantly greater mortality (25-100%) than S. abbasi (20-80%) against second instars and H. indica caused 17.5-82.5% mortality in third instar grub larvae, while S. abbasi caused (10-60%) mortality. These results revealed that second instar grubs were more susceptible than third instar grubs and efficacy of EPN against H. consanguinea varies with nematode species. The penetration and multiplication rate for H. indica was significantly higher than those of S. abbasi. Infective juveniles (IJ) of both nematode species and a commonly used insecticide (phorate) were tested against this insect in a field experiment. Field trail data showed that the percentage reduction in H. consanguinea grub population was significantly higher using H. indica at a dose of 2.5 × 109 IJ ha−1 than S. abbasi and phorate application. Phorate application was more efficient in reducing the grub population than both nematode species at the lower application rate (1.25 × 109 IJ ha−1). Overall, these experiments suggest that H. indica may be a promising biocontrol agent against H. consanguinea.