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

Authors: WILLIAM, C. - Liverpool John Moores University; KNUTSON, L. - Retired Non ARS Employee; GORDH, G. - Animal And Plant Health Inspection Service (APHIS); MCDONNELL, R. - Oregon State University; Kula, Robert; Gates, Michael; Buffington, Matthew; BROAD, G. - Natural History Museum - London

Submitted to: Journal of Natural History
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2024
Publication Date: 1/30/2025
Citation: William, C.D., Knutson, L., Gordh, G., Mcdonnell, R.J., Kula, R.R., Gates, M.W., Buffington, M.L., Broad, G.R. 2025. 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. Journal of Natural History. 59(5-8):331-396. https://doi.org/10.1080/00222933.2024.2443125.
DOI: https://doi.org/10.1080/00222933.2024.2443125

Interpretive Summary: Snail-killing flies are parasitoids and predators of snails and slugs, notably freshwater species that serve as intermediate hosts for parasites of humans and livestock; they also attack terrestrial hosts that are crop pests. These parasites and agricultural pests cause millions of dollars in damage annually via disease treatment and prevention, as well as losses to crops via control costs and lower yields. This research is the first of its kind to comprehensively report all information about natural enemies of snail-killing flies, including a novel assessment of information to help inform decisions on the use of snail-killing flies for biocontrol. Ninety-seven natural enemy species, mostly parasitoid wasps, were reported from 64 snail-killing fly species. The potential impact of those natural enemies on the efficacy of snail-killing flies for biocontrol was explored. This research is useful to scientists, as well as personnel in public health, livestock production, and pest snail/slug management and regulation.

Technical Abstract: In this first tabulation and analysis of natural enemies of Sciomyzidae (snail-killing 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 541 valid sciomyzid species in 23 of the 63 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 characterized 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 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 field-crop and greenhouse situations. The importance of polyphagous parasitoids of Diptera larvae, especially those feeding in dead snails is first brought out. As the natural enemies of Diptera larvae have seldom been treated in a detailed manner, the new format of our Tables 3 and 4 are proposed as efficient and instructive ways of presenting such data. As a large amount of parasitoid Hymenoptera reared from Sciomyzidae remains to be identified, pending availability of identifiers and revisionary taxonomic studies, we document the existence and location of this material