Pathogenicity and Effectiveness of Entomopathogen Nematode Heterorhabditis sp. on Potato Tuber Moth Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae).

Abstract

Potato tuber moth, Phthorimaea operculella Zell. (Lepidoptera: Gelechiidae) is one of the important potato pest due to the potential loss can reach 100% if not well controlled. One of potential biological agents to control this pest is Entomopathogen Nematode Heterorhabditis. The effectiveness of Heterorhabditis has been studied to control several crop pests. Infective juveniles (IJ’s) of nematodes are able to find and penetrate the insects that live in the soil as well as in the plant tissues. The objective of this research is to study the pathogenicity of the Heterorhabditis sp. against P. operculella in the laboratory with direct and indirect (in the potato tuber) treatment. The experiments were conducted using completely randomized design with 6 treatments and 4 replications. The treatments were based on the density level of nematodes Heterorhabditis sp. (100, 200, 300, 400, and 500 IJ/ml) and the control. The result showed that P. operculella infected by Heterorhabditis sp. has symptoms by reducing the movement and feeding activity. The body of dead insects become soft and the color change to dark brown. For the direct treatment, Heterorhabditis sp. can kill P. operculella within 12 hours after application (HAA). At density level 100 IJ/ml, it can control P. operculella until 85% within 24 HAA. In contrast, the mortality rates of P. operculella in the indirect treatment (in the tubers) was 35% at doses of 1000 IJ/tubers.