Biological control of white grubs (Lepidiota stigma L; Coleoptera; Scarabaeidae) with entomopathogenic nematodes and fungus Metharizium anisopliae (Metsch)

Abstract

Biological Control Agents (BCA) Entomopathogenic nematodes (EPn) Heterorhabditis spp. and fungi Metarhizium anisopliae have been known to control the major pests of sugarcane and cassava, namely the white grub larvae Lepidiota stigma L. This study was conducted to test the effectiveness of biological control agents for controlling three species of pests: L.stigma, Galleria melonella, and Tenebrio molitor. We tracked larval mortality for 24, 48, and 72 hours after the initial inoculation. Similarly, organic fertilizer mixed with the fungus M. anisopliae (in a 25-L pot) was tested on the larvae. The results showed that entomopathogenic nematodes were effective in killing 100% of L.stigma larvae pests, whereas M. anisopliae was only 10% effective. When organic fertilizer was mixed with both biological control agents types (nematode and fungi), mortality of the three larvae species reached 100% at a nematode concentration of 10 IJ-1000 ml. In contrast, M. anisopliae only caused 70% mortality at a concentration of 107 spores-L after 72 hours of inoculation. It was difficult to collect white grub larvae of L. stigma from the field. From May to June, the larvae were present in the ground at a depth of more than one meter in the soil and therefore it was hard to dig them out.