Biology of entomopathogenic nematodes Heterorhabditis sp. and Steinernema spp

Abstract

Nematodes associated with insects are referred to as entomophagous nematodes. Entomopathogenic nematodes are highly potential biocontrol agents for several lepidopteran and coleopteran insect pests. These nematodes are mutually symbiotic with the bacteria Xenorhabdus and Photorhabdus spp. and the bacteria are responsible for the death of the host. The biology of three species of Steinernema viz., Heterorhabditis was studied under laboratory conditions at a temperature of 28±2oC. The infective juveniles caused mortality of Corcyra cephalonica in about 48 hours. Hermaphrodites were observed 72 hrs after infection. Females and males of amphimictic generation were observed 120 hrs after infection in Heterorhabditis and 48 hours after infection in Steinernema spp. Exit of infective juveniles from cadavers of C. cephalonica was observed after 192 hrs in Heterorhabditis. In Steinernema glaseri and thermophilum the exit of infective juveniles was observed 120 hrs after infection while in S. tami the exit of infective juveniles was observed 96 hrs after infection. The study revealed that H. indica completed two generations (First generation - hermaphrodite and Second generation - Amphimictic) in one insect. But all the three species of Sterinernema completed only one generation (Amphimictic) in the insect host. © JBiopest.