Steinernema riobravis: This novel and highly pathogenic species, isolated to date only from the Rio Grande Valley of Texas, possesses several novel features. Its effective host range runs across multiple insect orders. This versatility is likely due in part to its ability to exploit aspects of both ambusher and cruiser means of finding hosts. Trials have demonstrated its effectiveness against corn earworm and mole crickets.
In Florida, 60,000 acres of citrus are treated annually for control of citrus root weevil with impressive results. This is a high temperature nematode, effective at killing insects at soil temperatures above 35°C. Persistence is excellent even under semi-arid conditions, a feature no doubt enhanced by the uniquely high lipid levels found in infective juveniles. Its small size provides high yields whether using in vivo (up to 375,000 infective juveniles per wax moth larvae) or in vitro methods. Only formulation improvements that impart increased stability are needed for this parasite to achieve its full potential.
It must also be noted that S. riobravis is currently being marketed for suppression of plant parasitic nematodes infesting turfgrass. There is substantial correlative data suggesting that some entomopathogenic nematodes can suppress plant species. Some skepticism may be healthy until this puzzling assertion can be fully confirmed by rigorously designed, multiple field experiments.
