The two nematode families Steinernematidae and Heterorhabditidae , contain the insect parasitic nematode species. The most commonly used beneficial nematodes are Steinernema carpocapsae , S. feltiae, S. glaseri, Heterorhabditisheliothidis and H bacteriophora . Nematodes that are endoparasites of insects attack a wide variety of agricultural pests. The life cycle of beneficial nematodes consists of eggs, four larval stages and the adults. They search out susceptible hosts, primarily insect larvae, by detecting excretory products, carbon dioxide and temperature changes.
Juvenile nematodes enter the insect host.
Heterorhabditid nematodes can also pierce through the insect' s body wall. The juvenile form of the nematode carries Xenorhabdus sp. Once the bacteria are introduced into the insect host, death of the host usually occurs in 24 to 48 hours. As the bacteria enzymatically breaks down the internal structure of the insect, the Steinernematids develop into adult males and females which mate within the insect's body cavity. Heterorhabditids produce young through hermaphroditic females.