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DIPTERA, Pipunculidae (Walker 1835) -- <Images> & <Juveniles> Description & Statistics
Pipunculids are primary, solitary endoparasitoids of homopterous
nymphs and adults, especially cicadellids, fulgorids, cercopids and
membracids. Pipunculus is the dominant genus. Perkins (1905e) studied the immature stages of Pipunculus sp. and Keilin & Thompson
(1915a) of Ateleneura spuria Meig. During oviposition, the female fly pounces on the host nymph
while it is feeding or resting on foliage.
It is then carried into the air.
During this time the parasitoid's abdomen is curved beneath the body
and the ovipositor is inserted through the intersegmental membrane of the
abdomen. The egg is thought to lie
free in the body cavity. Clausen
(1940) commented that there is no apparent proof for the assertion of several
authors that oviposition in some species is external and that the young larva
makes its own way into the host body.
Female ovipositors in this family are distinctly of the piercing type. There were only two larval instars of A. spuria recorded by
Keilin & Thompson (1915a), the second having all the characteristics of a
normal 3rd instar cyclorrhaphous larva.
The first instar is 1.0 mm. long and a bit elongate. It bears a vesicle-like organ at the
posterior end of the body. The skin
bears no sensory spines nor setae, and no tracheal system is distinguishable
until late in the stage when the lateral trunks fill with air. The second instar, or mature larva, is
robust and oval in outline, with the caudal vesicle still present although
reduced in size. The anterior
spiracles are elevated, and each has 4-5 openings. The posterior spiracles, each with three openings, are also
elevated and are situated at the lateral margins of a large, black, heavily
sclerotized peristigmatic plate. This
single plate, on which both spiracles are borne, is typical of the
family. In most cases the advanced 1st instar Ateleneura larva lies with its head directed toward the host's
thorax, but after the molt the position is reversed, the head being near the
tip of the abdomen and the caudal extremity at the juncture of the abdomen
and thorax. Parasitized leafhoppers
containing nearly mature Pipunculus
larvae may be easily recognized by the distended condition of the
abdomen. The larva emerges from the Typhlocyba nymph or adult through an
opening made between two segments of the abdomen and enters the soil to
pupate. In Pipunculus sp. the larvae were always found by Perkins (1905e) to
lie with the head directed frontwards, and emergence was through an opening
at the juncture of the thorax and abdomen.
In P. xanthocnemis Perk, parasitic in Liburnia, the emergence hole is in the mid-dorsal abdominal
area. The mature larvae of P. annulifemur
Brun. can jump similar to fruit fly larvae (Subramaniam 1922). Although most species pupate in soil, some
like P. cinerascens Perk. form puparia on foliage. The larva of P. xanthocerus Kow.
differs in having the integument heavily spinose rather than smooth, a trait
that persists in the puparium. Puparia of Pipunculidae are broadly oblong in outline, often with
a granular or rugulose sculpturing, and are red, black or brown in
color. The prothoracic cornicles are
very small in some species, and can barely be seen projecting through the
puparial wall. In other species, such
as P. cinerascens, they are borne at the apices of very large conical
processes. The posterior stigmatic
area is rounded in some species and depressed in others, with the spiracles
borne at the lateral margins. Each spiracles
usually has three openings, although there may be two in some species and in
others only one. The entire anterior
portion of the puparium is completely or partly forced off in two parts, the
dorsal one usually bearing the prothoracic cornicles, at eclosion. The transverse line of fracture is just
behind the anterior margin of the 2nd abdominal segment (Clausen
1940/62). In Chalarus and Verallia,
there is a modification in the manner of emergence from the puparium. The two anterior plates, which are forced
off, are broken further, the upper one into three parts and the lower into
two (Lundbeck 1922). In this way five
pieces are detached from the puparium compared to only two in Pipunculus. The prothoracic cornicles occur along the line of fracture and
are not a part of the median dorsal plate.
The relation between the five parts and the lines of fracture were
shown by De Meijere (1917) for an undetermined species. Swezey (1936) reported on the duration of the life cycle for
several species of Pipunculus. The combined egg and larval stages last 40
days and the pupal stage about one month.
The pupal stage is completed in 14-19 days in P. annulifemur. Pipunculidae is a small widespread family
with more than 407 species known as of 2000.
They are most abundant in the holarctic region. Important morphological characters include
a large head, hemispherical, with enormous compound eyes contiguous; veins
R-4+5 and M-1+2 nearly meeting at apex of wing; 1st anal cell closed before
margin of wing. The body is only 3-8
mm long. Their color is dull, gray or
black. They have not been used in
biological control. References: Please refer to <biology.ref.htm>, [Additional references
may be found at: MELVYL
Library] Aczel, M.
L. 1948. Acta Zool. Lilloana 6:
5-168. Coe, R.
L. 1966.
Handbook Ident. British Insects 10:
1-83. Cole, F.
R. 1969.
The Flies of Western North America.
Univ. Calif. Press, Berkeley & Los Angeles. 693 p. Hardy, E. D.
1943. Univ. Kansas Sci. Bull.
29: 3-231. Williams, J. R. 1957. Trans. Roy. Ent.
Soc. London 109: 65-110. |