Known pests, diseases and disorders include viruses, fungi, the larvae of flies, mites and nematodes. Carnivorous species maintain populations of small invertebrates such as nematodes, rotifers, and other collembolan species. Other problems include parasitic nematodes (roundworms) and viruses. Mayfly nymphs may serve as hosts for parasites such as nematodes and trematodes. Blood parasites of the family Haemoproteidae and intestinal nematodes of Toxocaridae also affect megabat species. Seedlings are susceptible to fungal infection and predation by banana slugs, bush rabbits, and nematodes. Below ground, nematodes and springtails also consume fungal tissue. Some nematodes and rotifers can also undergo cryptobiosis. This eliminates infestations by narcissus fly and nematodes. Raw salmon flesh may contain "Anisakis" nematodes, marine parasites that cause anisakiasis. Trypanosamatid flagellates, nematodes, and parasitic Hymenoptera all act as endoparasites. Slugs are parasitised by several organisms, including acari and a wide variety of nematodes. "Arthrobotrys oligospora" is the model organism for interactions between fungi and nematodes. It belongs to a group of nematodes called roundworms. Several species of nematodes are known to parasitise slugs.