Effect of temperatures on infectivity of Entomopathogenic Nematodes

The infectivity of eight native isolates of EPNs, Heterorhabditis sp. (IISR-EPN 01), Steinernema sp. (IISR-EPN 02), S. ramanai (IISR-EPN 03), S. carpocapsae (IISR-EPN 06), Oscheius spp. (IISR-EPN 04, 05 & 08) and O. gingeri (IISR-EPN 07) were tested against lepidopteran insect pest, Galleria mellonella larva and multiplication into host at different temperatures viz., 20, 25, 30 and 35°C. The temperature significantly affected the pathogenicity and multiplication ability of all tested EPNs. Among the test temperature, maximum mortality of larvae was found at 30°C followed by 25°C, whereas the least mortality of insects was recorded at 20 and 35°C. Maximum number of infective juveniles of EPNs were multiplied at 30°C, followed by 25°C, whereas, minimum multiplication was recorded at 35°C. However, no multiplication of EPNs was recorded at 20°C. Therefore, the optimal temperature for infection and multiplication of EPNs was 30°C.