Biology, immature stages, and systematics of snail-killing flies of the genus Colobaea (Diptera: Sciomyzidae), with overviews of aspects of the tribe Sciomyzini.

All reared larvae of flies of the genus Colobaea Zetterstedt, 1837 (Diptera: Sciomyzidae), which comprises 15 valid species, kill and consume freshwater nonoperculate pulmonate snails. New data are presented on the geographic distribution, biology, morphology of immature stages, and classification of Colobaea. Life cycle information is provided from field data and laboratory rearings for four of the 11 Palearctic species-C. bifasciella (Fallén), C. deemingi Knutson Bratt n.sp., C. pectoralis (Zetterstedt), and C. punctata (Lundbeck)-and for one of the three Nearctic species, C. americana Steyskal. Colobaea bifasciella is shown to be one of the most highly specialized parasitoid Sciomyzini, laying eggs on shells of Galba truncatula (O.F. Müller) and Stagnicola palustris (O.F. Müller) in temporary, intermittent, or vernal semiterrestrial situations. Each larva feeds in only one host snail, which is not killed until shortly before the larva completes development. Puparia are strongly modified to fit tightly within the shell of the host. The other reared species are shown to be less specialized than C. bifasciella, with eggs being laid upon vegetation, the larvae behaving as parasitoids-predators-saprophages of exposed aquatic snails, and the puparia of all four species being adapted to a lesser degree than C. bifasciella to fitting within the shell of the host snail. In nature, C. americana attacks Gyraulus parvus (Say) and Physa Draparnaud sp.; C. pectoralis attacks Anisus vortex (L.) and Bathyomphalus contortus (L.); and C. punctata attacks Gyraulus albus O.F. Müller, Lymnaea "peregra," Planorbarius corneus (L.), and Planorbis planorbis (L.). In the laboratory, these species also attacked and consumed other freshwater nonoperculate snails; C. deemingi was reared on Gyraulus intermixtus (Mousson) and Radix gedrosiana (Say), and an adult fly of the Palearctic C. distincta (Meigen) emerged from a puparium found in the shell of Anisus spirorbis (L.) collected in nature. Described and figured are eggs, larvae of all three instars, and puparia of the five laboratory-reared species. To provide perspective on features of Colobaea, diagnostic features are summarized of the immature stages of the Sciomyzini and the suprageneric categories of Sciomyzidae. The biogeography of the tribe Sciomyzini is presented, along with details of known geographical distribution. The classification and phylogenetic position of Colobaea are discussed. Included are a checklist of all known taxa of Colobaea, maps of geographic distribution, and a key to adults of the 15 valid species.

Comprehensive taxonomic, faunistic, biological, and geographic inventory and analysis of the Sciomyzidae (Diptera: Acalyptratae) of the Delmarva region and nearby states in eastern North America.

Genera and species of Sciomyzidae known from the Delmarva region (Delaware, the District of Columbia, Maryland, Virginia, and West Virginia) and nearby states are reviewed taxonomically, faunistically, biologically, and geographically. Although restricted to the taxa in that area, this work amounts to a revision of the sciomyzid fauna of that portion of the Nearctic region. Treated are 91 species in 19 genera, i.e. 46% of the 199 species and all but four of the 23 genera of Sciomyzidae known from the Nearctic Region. Included are 67 species in 16 genera from Delmarva and 24 other species in 10 genera from nearby states. Euthycera flavescens (Loew) is resurrected; Renocera cressoni Mathis and Knutson sp. nov. is described from eastern North America; R. amanda Cresson is given new status as a junior synonym of R. longipes (Loew); and Chaetomacera brevis Cresson, R. cyathiformis Melander, R. pacifica Curran, and R. bergi Steyskal are given new status as junior synonyms of R. striata (Meigen). Newly diagnosed are taxonomic categories ranging from family to species level, including the first diagnoses of abdomens of females of many species, where known. Provided for each genus and species are annotated taxonomic/nomenclatorial catalogs of all North American references to all species, with generic combinations noted, with previously unrecorded synonymies as well as North American literature references, illustrations, and information on natural history and morphology of immature stages. Results of cross-mating studies of Dictya are reported and discussed. Provided are label data from examined specimens, lists of Canadian provinces and U.S. states from which reviewed species have been recorded, and detailed maps of geographical distribution of species in Delmarva, with references to previously published maps.

The Snail-killing Flies (Diptera: Sciomyzidae) of West Africa.

A review of the West African "snail-killing flies" or "marsh flies" (Sciomyzidae) shows that the fauna is not as dominated by the generally aquatic, predaceous genus Sepedon as was previously considered. Twenty species in seven genera, including three new species, Colobaea occidentalis, Pteromicra zariae and Sepedonella castanea are recorded. The Holarctic-Oriental genera Colobaea and Pteromicra are documented from Africa south of the Sahara for the first time. Biogeographical analyses based on the discovery of "Palaearctic" genera of Diptera south of the Sahara, faunal connections, and dispersal routes are presented. A key for identification and illustrations of diagnostic characters for some species are included.

Key aspects of the biology of snail-killing Sciomyzidae flies.

The biology of snail-killing flies (Diptera: Sciomyzidae) has been studied intensively over the past half-century, especially over the past decade. Today, sciomyzids are biologically the best-known group of higher Diptera. The overarching research objectives are evaluation of sciomyzids as biocontrols of disease-carrying or agriculturally important snails and slugs and as a paradigm group for the study of the evolution of diverse feeding and associated behaviors in flies. We present reviews and analyses of some key features of particular scientific and societal interest, including behavioral and phenological groups; laboratory experimental studies on behavior and development; population biology, bioindicators, ecosystem service provision, and conservation; phylogenetics, molecular studies, and evolutionary biology; and biocontrol.