What is the difference between biological control nematodes and insect-parasitic nematodes?
There are nematodes that are insect parasites, but the nematodes that are sold commercially are not parasites. True parasites feed from their host. However, biological control nematodes feed on the bacteria, and the bacteria are the true parasites. There are species of nematodes that are true insect parasites. Some examples are mermithid nematodes that parasitize grasshoppers (Figure 4), cockroaches, and mosquitoes. You might see these when you squash a cockroach in your home. These nematodes can play a part in natural suppression of pest insects. But, because they only feed on their insect hosts, they must be raised in live insects. This is not a very efficient means of production. Biological control nematodes can be raised in vats and fed with bacteria, so they are much easier to produce. Figure 4. These nematodes (Agamermis sp.), from the body of a grasshopper, are true insect-parasitic nematodes.
