ABSTRACT
The family contains the single genus Heterorhabditis with H. bacteriophora as the type species. This chapter deals with the biology and taxonomy of representatives of these two families. The ability of two nematode populations to mate and produce fertile F1 progeny determines a true biological species and has been used to identify new species of Steinernematidae. In Heterorhabditis, each infective juvenile develops into a hermaphroditic female and never an amphimictic female or male. Males can be separated from other Steinernema species by the absence of a terminal tail mucron, bluntly rounded spicule tips, and the strongly curved spicules. Obligate entomopathogenic nematodes capable of infecting a wide variety of insects. Hermaphroditic and amphimictic populations found only inside infected insect cadavers in nature. Infection by both Steinernema and Heterorhabditis is initiated by a third-stage juvenile which is morphologically and physiologically adapted to remain in the environment for a prolonged period while waiting for an insect host.
