First tabulation and analysis of natural enemies of snail-killing flies (Diptera: Sciomyzidae), their position in the fly/mollusc ecosystem, and implications for use of sciomyzids in biological control

In this first tabulation and analysis of natural enemies of Sciomyzidae (snailkilling flies), 218 records are presented for 97 species and morphospecies in 44 genera of parasitoids, predators and pathogens. These represent 27 families in 7 orders attacking 64 of the 548 valid sciomyzid species in 23 of the 60 genera, in all major biogeographical regions, mainly North America and Western Europe. Our objectives are (1) to cast the data on natural enemies of a group of flies, with analysis, into a broad biological perspective; and (2) to provide specific data for selection of biocontrol agents. Parasitoid Hymenoptera are the primary natural enemies, 67 species and morphospecies in 25 genera of egg, larva/pupal and pupal parasitoids having been reared in nature from 24 sciomyzid species in 8 genera. Notably, all of our records of larval/pupal and pupal parasitoids are of rearings from isolated puparia, unlike many of the records of parasitoids of Tephritidae, reared from mass cultures of fruit, in which several species of Tephritidae (and other Diptera) were feeding. Herein we take a broad view of the complex of natural enemies, relating them to the extensive knowledge on the biology of the family, and analyse them in relation to the classification, phylogeny, distribution, habitats, and phenological and behavioural groups of Sciomyzidae. Parasitoid genera in the hymenopterous families Braconidae, Chalcididae, Diapriidae, Ichneumonidae, Pteromalidae and Trichogrammatidae are characterised briefly in regard to geographical distribution, host range, habitats, phenology and other aspects. Background information on Sciomyzidae and keys to the families and genera of parasitoid Hymenoptera attacking Sciomyzidae are included to encourage collection of and research on parasitoid natural enemies. Natural enemies are evaluated as to their impact on the use of Sciomyzidae as biological control agents of disease-carrying freshwater snails and pestiferous terrestrial snails and slugs in fieldcrop and greenhouses.