Some have been encapsulated in pellets made from calcium arginate to aid in their dispersal in the field and to provide a food source until a nematode is encountered. HIrsutella rhossiliensis is one example of a fungus with conidia which adhere to nematodes which may accidentally contact them. Fungal hyphae then penetrate the cuticle, utilize the internal contents for food, and the cuticle for protection. When the food source has been utilized, adhesive conidia grow out of the cuticle to await passage of another host. Zoosporic fungi have swimming spores which can seek out nematodes, attach to the cuticle, and develop hyphae which feed on nematodes.
Some fungi parasitize vermiform adult or larval nematodes, while others parasitize eggs, or cysts.
Egg parasites include fungi from a variety of taxonomic groups. The actinomycete Pasteuria penetrans is the primary bacterial parasite which has been studied and was first described by Thorne in 1940 as a protozoan. A number of different strains have been isolated and tested. In spite of extensive work, this bacteria still cannot be reared on artificial media and this has greatly hindered commercial development. Spores of this bacteria adhere to the cuticle of a nematode and a penetration tube develops which penetrates the nematode.