Parasites and parasitoids
Slugs are parasitised by several organisms, including acari and a wide variety of nematodes. The slug mite, Riccardoella limacum, is known to parasitise several dozen species of mollusks, including many slugs, such as Agriolimax agrestis, Arianta arbustrum, Arion ater, Arion hortensis, Limax maximus, Milax budapestensis, Milax gagates, and Milax sowerbyi. R. limacum can often be seen swarming about their host's body, and live in its respiratory cavity.
Several species of nematodes are known to parasitise slugs. The nematode worms Agfa flexilis and Angiostoma limacis respectively live in the salivary glands and rectum of Limax maximus. Species of widely known medical importance pertaining to the genus Angiostrongylus are also parasites of slugs. Both Angiostrongylus costaricensis and Angiostrongylus cantonensis, a meningitis-causing nematode, have larval stages that can only live in mollusks, including slugs, such as Limax maximus.
Insects such as dipterans are known parasitoids of mollusks. To complete their development, many dipterans use slugs as hosts during their ontogeny. Some species of blow-flies (Calliphoridae) in the genus Melinda are known parasitoids of Arionidae, Limacidae and Philomycidae. Flies in the family Phoridae, specially those in the genus Megaselia, are parasitoids of Agriolimacidae, including many species of Deroceras. House flies in the family Muscidae, mainly those in the genus Sarcophaga, are facultative parasitoids of Arionidae.
Dotty Bowen wrote:According to slughelp in UK, Spanish slugs aren't bothered by nematodes because the slugs don't really burrow underground.
I have found the only way to begin to control them is by hand, by the bucketful almost nightly.
I put them in soapy water. They die in moments.
Suggest starting early in the season.
Nemaslug doesn't work on this species, because nematodes live in the soil.