One thousand three hundred and eighty-eight valid species of Pipunculidae have been described and over 2,500 species likely exist (De Meyer, 1996; De Meyer and Skevington, 2000; Skevington unpublished database, 2005). Most big-headed flies that have been studied are endoparasitoids of leafhoppers and planthoppers, including Cicadellidae, Cercopidae, Delphacidae, Membracidae, Issidae, Cixiidae and Flatidae. The only exceptions to this rule occur in the genus Nephrocerus, flies that were recently discovered to attack Crane Flies (Tipulidae) (Skevington, 2005). The potential value of Pipunculidae for biological control has stimulated some work on the bionomics of this family. For example, recent research into the control of the potato leafhopper, Empoasca fabae (Harris), a major pest of alfalfa in mid-western and eastern United States and Canada, involved exploration within Europe for natural enemies to be introduced into the United States (Jervis, 1992) and included rearing of Chalarus for release (Skevington & Marshall, 1997). Current research in Texas is focusing on the discovery of pipunculid parasitoids in the pest leafhopper, Homalodisca coagulata Say (Glassy-winged Sharpshooter). Despite the economic importance of the group, few data on host relationships exist and some genera have no known hosts (for example Allomethus, Basileunculus, Elmohardyia, and Protonephrocerus).
Some of the recent Pipunculidae systematists: Top row left to right: Martin Dempewolf, Jeff Skevington, Mihaly Foldvari. Bottom row left to right: Michael Ackland, Marc De Meyer, Jose Rafael, Forbes Benton. International Congress of Dipterology, Oxford, 1998.
Adults are frequently seen hovering among vegetation; their flight is similar to that of Syrphidae. Adults utilize all terrestrial habitats; however, diversity and numbers are greatest in forest openings and along forest edges. Adult flies feed on honeydew and can occasionally be found in large, mixed feeding groups on Sternorrhyncha secretions (Skevington & Marshall, 1998). Many pipunculids employ the landmark mating system known as hilltopping (Skevington, 2000, 2001). Hilltop collecting is an excellent way to sample much of the pipunculid diversity in an area and often provides large numbers of specimens. Other effective methods frequently employed to capture pipunculids include sweeping, Malaise trapping, and less successfully, using yellow pan traps. Occasionally, mating pairs are discovered hovering in copula or temporarily settled on vegetation. Pronounced sexual dimorphism in pipunculids makes association of the sexes difficult so these occasional discoveries are very useful.
Females of most pipunculid species deposit their eggs in early instar nymphs or adults of their hosts. After visually locating a host, some species remove the host from the food plant and oviposit one egg inside each host whilst in flight (Huq, 1982; May, 1979; Williams, 1919), whereas others leave the host in situ (Benton, 1975). Larvae develop to maturity within the nymph or adult hosts. When mature, the larva leaves the host through a break in one of the dorsal intersegmental membranes of the abdomen in order to pupate in the soil, in the litter, at the base of plants or rarely, attached to leaves (Ferrar, 1987; Perkins, 1905). More detailed information on immature stages together with information on rearing techniques can be found in Benton (1975), Coe (1966), Ferrar (1987), Freytag (1988), Huq (1984), Jervis (1980), Morakote & Yano (1987) and Perkins (1906). Pipunculid-host associations are best known for the European fauna (Waloff & Jervis, 1987), followed by Nearctic Region (Skevington & Marshall, 1997) and the Australian region (Skevington, 2001). However, most species have no biological data available.
Most pipunculid species attack more than one species of host, but show a preference for a particular set of host species. Only two species have been reared from more than one subfamily of host (Skevington, 2001). Superparasitism and multiple parasitism are rare and survival of more than one pipunculid in these cases is exceptional (Jervis, 1980; Morakote & Yano, 1988; Waloff & Jervis, 1987).
Pipunculids are exclusively parasitic in Auchenorrhyncha, attacking the nymphal and/or the adult stages. (Hardy 1987)
Rather small typically dark-bodies flies, 3.4-4.0 mm long, characterized by globose to semiglobose compound eyes covering almost entire head. Wing typically long and slender. (Hardy 1987)
Because of their small size, black coloration, and the paucity of external characters, pipunculids are difficult to identify. It is particularly important to have male and female specimens from the same sample in order to associate the sexes. For secure identification it is necessary to dissect the male terminalia. To accomplish this, remove the abdomen and heat in 85% lactic acid for roughly 30 minutes. Remove the macerated abdomen and place it directly into clean glycerin. Dissection involves separating syntergosternite 8 from the remainder of the abdomen. Store the abdomen and dissected terminalia in glycerin in plastic microvials on the same pin as the source specimen. Surstyli shape, presence or absence of a membranous area on syntergosternite 8, phallic guide shape, phallus shape and ramification, sperm pump shape and sclerotization, ejaculatory apodeme shape, hypandrium shape and modifications of the sternites are often informative. In female specimens the ovipositor shape is often useful but few other diagnostic characters are available. Description of new species on the basis of females often complicates the taxonomy of the family and should be avoided unless new character systems are discovered for females.
In order to secure the ground color and pruinescence of pipunculids, specimens should ultimately be dried and pinned. Pinning fresh material killed with cyanide or ethyl acetate is the easiest and a number of techniques can be used. The best method for obtaining views of the insect's genitalia involves double mounting. Pinning through the right mesopleuron with a minuten, then pinning to pith is more expensive and time consuming than pointing, but produces excellent specimens that are less likely to require dissection than other pinning techniques. Note that the heads of pipunculids fall off very easily. Some collectors remove the head and pin it separately on the tip of the minuten. Material collected into alcohol is preferably dried with a critical point drier and then pointed or glued directly to the side of a pin. Chemical drying using HMDS (hexamethyldisilazane) or ethyl acetate is also acceptable. Although some researchers prefer to study pipunculids preserved in 70% alcohol, specimens preserved in this way discolor over time and become brittle and difficult to dissect.
A key to the genera of Pipunculidae is available in Skevington and Yeates (2001).
Evolution and Systematics
Discussion of Phylogenetic Relationships
The first phylogeny of the family was proposed by Aczél (1948). Although not a quantitative analysis, this phylogeny has remained remarkably robust through time. Recent phylogenetic hypotheses proposed by Rafael and De Meyer (1992) and Skevington and Yeates (2000, 2001) support many of the lineages proposed by Aczél.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:4492
Specimens with Barcodes:3831
Species With Barcodes:842
Pipunculidae is a family of flies (Diptera) commonly termed big-headed flies, a reference to the large (holoptic) eyes, which cover nearly the entire head. The family is found worldwide and more than 1300 species have been described.
The larvae of Pipunculidae develop as parasitoids almost exclusively in Auchenorrhyncha, the exception being the genus Nephrocerus, whose hosts are adult Tipulidae (crane flies). The larvae develop rapidly within the crane flies before pupating in the soil. In all pipunculids there are only two larval stages. Some species are used as biological control agents in rice fields.
- Tribe Cephalopsini
- Tribe Microcephalopsini
- Tribe Eudorylini
- Tribe Tomosvaryellini
- Tribe incertae sedis
- Genus Pipunculus
- Koenig, D.P. & C.W. Young. (January 2007). "First observation of parasitic relations between bigheaded flies of the genus Nephrocerus (Diptera: Pipunculidae) and crane flies of the genus Tipula (Diptera: Tupulidae: Tipulinae), with larval and puparial descriptions of Nephrocerus atrapilus Skevington.". Proceedings of the Entomological Society of Washington (Washington DC: Allen Press/The Entomological Society of Washington) 109 (1): 52–65. ISSN 0013-8797.
- Pipunculidae at the Tree of life
- Kehlmaier, C; Dierick, M; Skevington, JH (2014). "Micro-CT studies of amber inclusions reveal internal genitalic features of big-headed flies, enabling a systematic placement of Metanephrocerus Aczel, 1948 (Insecta: Diptera: Pipunculidae)". Arthropod Systematics & Phylogeny 72 (1): 23–36.
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