NEMATODES AS BIOLOGICAL-CONTROL AGENTS .2.

Of the nine families that have adverse effects on their insect hosts, four––the Mermithidae, the Allantonematidae, the Steinernematidae, and the Heterorhabditidae––have shown potential in insect control programs. The Mermithidae are obligate parasites of arthropods, mostly insects. They have not become established as biological control agents, because the results of field trials have been inconclusive and economical methods for large scale production do not exist. Within the Allantonematidae, one species, Deladenus siricidicola, has been used successfully for insect control. Deladenus is a facultative parasite of the woodwasp, Sirex noctilio. The use of the members of the Steinernematidae and Heterorhabditidae for insect control is currently receiving unprecedented attention in both academia and industry. These nematodes are symbiotically associated with the bacteria of the genus Xenorhabdus, which play an essential role in pathogenesis and nematode development. Most species can be routinely mass produced and have been successfully used for the control of several insects. This chapter provides a review of the biology, efficacy, and commercial prospects of steinernematids and heterorhabditids. © 1992, Academic Press Limited