Immunity to Entomogenous Nematodes
Most insects avoid or escape nematode parasitism by their normal habits or behavior or by the structure of their cuticle or conditions inside their digestive tracts. Recently, a study showed how this type of immunity can develop in an insect population that was originally completely susceptible to a specific parasite. There are other unusual types of insect response that occur only rarely against nematode parasites. These include intracellular melanization and responses of certain tissues other than blood cells, such as intestinal epithelium and fat body cells. From the standpoint of biological control, it is important to test host populations against the parasite before actual applications are made in order to determine if any host immunity is present. On the other hand, the specificity of entomogenous nematodes can be an advantage itself, since beneficial insects in the same habitat as the target host will not be parasitized.