Entomopathogenic Nematodes as Biological Control of Insects

Of all nematodes studied for biological control of insects, those in the families Steinematidae and Heterorhabditidae have aroused the most interest, and information about them is growing exponentially. These two families mutually associated with gram negative facultative anaerobic bacteria, and the bacterium carried by Steinematidae is usually a species of the genus Xenorhabdus, and that carried by Heterorhabditidae is a species of Photorhabdus. The free living, non-feeding infective juveniles of these nematodes possess attributes of both insect parasitoids or predators and microbial pathogens, like parasitoids/predators, they have chemoreceptor and are motile; like pathogens, they are highly virulent, killing their hosts quickly, and can be cultured easily in vitro, have a high reproductive potential, and have a numerical but no functional response. They have a broad host range, are safe to vertebrates, plants, and other non target organisms, have been exempt from registration in the United States, are easily applied using standard spray equipment, and are compatible with many chemical pesticides. These nematodes, because serve as vectors of Xenorhabdus and Photorhabdus bacteria, termed Entomopathogenic, reinforcing the link between insect nematology and insect pathology. Therefore, these fascinating animals may contribute more to science than their use solely as biological control agents, as they may be useful tools in understanding the evolution of parasitism and symbiosis and the mechanism of insect resistance to infection.

Tewodros Tamiru