Once the right nematodes are identified, they can be suspended in a gelatinous matrix, or dried in powder, then mixed in water and sprayed, broadcast or irrigated onto crops.
Large numbers of infectious juveniles are released to inundate and kill the pest insects quickly. Depending on climate conditions, this method works best on greenhouse ornamentals and vegetables, citrus, cranberry, turfgrass and other crops, rather than on high-acreage crops like cotton and soybeans.
"The beauty of this is that in the last 20 years nematodes have been formulated and commercialized," Stock says. "They are more expensive than a chemical product, but so far they have been demonstrated not to harm humans, livestock, beneficial insects or the environment. Nematodes usually have to be underground; their targets are soil insects."
The formulations keep improving as newer isolates of nematodes are found, and there is a lot of commercial interest in matching nematodes to pests, Stock says.
"Yet these nematodes are so powerful and pathogenic not in and of themselves, but because they live in symbiosis with bacteria," Stock concludes. "Both the bacteria and the nematode need each other to survive, making them not only good as biological agents, but also as model systems for understanding basic questions in biology." Given the number of nematodes that exist in the world, the possibilities for discovery are immense.
"The whole nematode phylum is estimated to have 500,000 to a million species. About 25,000 species have been identified so far," Stock says.