Survival and infectivity of Heterorhabditis indica Poinar in different formulations against pests of bitter gourd

Abstract

Epilachna beetle (Henosepilachna septima Dieke) and melon fruit fly (Zeugodacus cucurbitae Coquillett) are serious pests of bitter gourd in Kerala. Studies were conducted to evaluate pathogenicity of Entomopathogenic nematodes (EPNs) against H. septima and Z. cucurbitae under laboratory conditions. NBAIR isolates of EPNs viz. Heterorhabditis indica Poinar and Steinernema carpocapsae Weiser were tested for their pathogenicity against 3rd instar larvae of H. septima. Among EPN species, H. indica @100 IJs recorded highest percentage mortality (100.00) followed by S. carpocapsae (90.00) at 48 hours after treatment (HAT). Three different formulations viz. sponge, talc and alginate gel of effective EPN strain was prepared and stored for 11 weeks. Infective juveniles stored in alginate gel formulation showed more than 50.00 per cent survival upto eight weeks after storage and recorded 72.22 per cent mortality of H. septima larvae at 72 HAT. Results of laboratory experiment on the effect of EPN formulation on adult emergence of fruit fly revealed that both alginate gel and talc based formulations of H. indica is equally effective to chemical. The study highlighted the efficacy of H. indica formulations as soil application for the management of Z. cucurbitae.