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DIPTERA -- <Juveniles> [Latest Classification] Please refer also to the following
links for details on this group: DIPTERA = Link 1, Photos-1, Photos-2 Host
Preferences Reproduction Life Cycle Principal
Families References Introduction As with the Hymenoptera, by the 4th decade of the 20th Century
there already existed an extensive literature concerning the exceptional diversity
in habits and forms within the order Diptera (Clausen 1940). Their economic importance judged from the
attack on other insects, ranks Diptera next to Hymenoptera in the number of
species and in the effectiveness of attack.
The Tachinidae are outstanding among the parasitic families followed
by others that consistently have this habit being Cyrtidae, Pipunculidae,
Nemestrinidae, Conopidae and Pyrgotidae.
The Bombyliidae are mostly parasitic but there are many predaceous
species also. Parasitic representatives
occur in many families that are predominantly not entomophagous, such as the
Agromyzidae, Phoridae, Cecidomyiidae, Calliphoridae and Anthomyiidae. Predaceous families known for their attack
on crop pests are Asilidae, Tabanidae, Syrphidae and Ochthiphilidae, but many
others also have species with predaceous habits. Host
Preferences
Most parasitic Diptera are primary parasitoids of plant pests and
are considered very beneficial.
However in the Tachinidae exceptions are those that attack adult
Carabidae and Apidae and some spiders.
The Pipunculidae, Pyrgotidae and Nemestrinidae are almost entirely
beneficial. Parasitic Bombyliidae are
most harmful because they attack larvae and pupae of beneficial Tachinidae
and Hymenoptera, which counteracts their value as infrequent parasitoids of
Coleoptera and Lepidoptera. The
Conopidae may be considered injurious because they attack Vespoidea, and the
Cyrtidae similarly are harmful because of their spider parasitization. Groups that are predaceous as larvae are
usually beneficia, as is the case with adults having predaceous habits. Many different kinds of insects are prey
of asilids and other large flies, which ranges from scarab beetles to small
flies, and thus it is difficult to evaluate their effect. Generally, the food sources of adult
predaceous Diptera are determined by size and ease of capture and by their
relative abundance in the predators' environment. Host preferences of parasitic species vary, with larvae of
Lepidoptera being preferred followed by larvae and adults of Coleoptera. These two orders are attacked primarily by
Tachinidae. Other hosts that are
infrequently attacked include dipterous larvae, hymenopterous larvae and
adults, hemipterous, homopterous and orthopterous adults and occasionally
nymphs, nymphs and adults of Dermaptera, nymphs of Trichoptera and the
Isopoda and Arachnida (Clausen 1940/1962). Predators are commonly found in the Syrphidae attacking
Aphididae, Coccidae and other Homoptera; Asilidae, the larvae of which prey
on various insects in soil; and Bombyliidae, Calliphoridae, Sarcophagidae and
Anthomyiidae, many of which are predators of acridid egg masses. Occasionally species of Drosophilidae,
Phoridae and Sarcophagidae develop in the egg sacs of spiders. Predaceous aquatic types feed on a variety
of insects and other minute animals in their surroundings. The habits of these were already known in
great detail by the 1930's as shown by the memoirs of Johannsen (1934-1937),
published under the title "Aquatic Diptera." Clausen (1940) provided a general
statement on the habits of entomophagous dipterous larvae, grouping them into
either predominantly parasitic or predatory and predatory only. He noted that there may be a difference of
opinion as to which habit predominates in a particular family. In the Bombyllidae, e.g., the number of
species parasitic larvae of Hymenoptera and others probably exceeds that
which is predaceous in egg masses, although the population of the latter may
be larger. Food requirements of adult Diptera is extremely variable. Parasitic species feed generally at
blossoms and on various plant exudations, as well as on honeydew secreted by
other insects, and a few species are known to imbibe the blood of their hosts
upon which they lay their eggs.
Adults of groups with predaceous larvae may themselves be predaceous,
as is found in Asilidae, Rhagionidae, Therevidae and Dolichopodidae. However, those of other groups where the
larvae are not highly entomophagous, may feed almost entirely on insect
food. Among the latter are the
Empididae, Mydaidae, Ceratopogonidae and Scatophagidae. Reproduction
The first attempt to systematize the subject of dipterous
reproduction was by Townsend (1908), who proposed five groups for Tachinidae,
based on placement of the eggs or larvae with respect to the host. Pantel (1910) followed with studies on the
parasitic species of the order, but with special emphasis on Tachinidae. He increased these groups to 10, using as
a basis the reproductive system of the female, the type of egg laid, the
stage of incubation at the time of oviposition, and the placement of the egg
or larva. These groupings still
largely hold and are summarized as follows: 1. Egg macrotype, broadly
oval, flattened ventrally, the chorion thick and rigid dorsally and thin
ventrally, size proportioned to that of female; deposited on the host body;
posterior uterus of gravid female short and broad, occasionally long and
narrow (Thrixion). Example = Meigenia floralis Meig. 2. Egg microtype, chorion
as previous (#1), size largely independent of that of female; laid on food of
the host and ingested by latter; posterior uterus moderately to very long,
adapted for partial incubation of a large number of eggs. Example = Gonia atra Meig. 3. Egg large, elongate,
not flattened or pedicellate, the chorion thin and flexible; posterior uterus
an incubating organ containing a moderate number of eggs; females lacking
chitinized piercing organ; larviporous.
Example = Miltogramma spp., Sarcophaga spp. 4. Egg with very thin,
uniform chorion; ovarioles 50-150, posterior uterus long and coiled, with
eggs lying transversely in several series; 1st instar larva with cuticular
armature for protection, indicating a free-living period; larva laid by
female near host, usually on its food plant.
Example = Echinomyia fera L. 5. Egg and larva as in
previous (#4), but the ovaries less numerous, the posterior uterus very long,
slender and coiled (Glaucophana, Bigonicheta) or moderately long and
distended, the eggs lying transversely in regular series (Bigonicheta) or longitudinally and
irregularly; larva laid in host vicinity.
Example = Bigonicheta setipennis Fall. 6. Egg and larva as in
#4, with the chorion slightly thicker dorsally; larva without a specialized
cuticular armature; ovarioles 15-55, posterior uterus of medium length, in
1-2 corkscrew coils, and somewhat distended, with eggs lying transversely or
longitudinally; fully incubated egg laid on host body. Example = Cryptophlebia ruricola Meig. 7. Female with piercing
organ, distinct from ovipositor, for perforating skin of host; egg not
narrowed at posterior pole; posterior uterus slender, elongate,
intestiniform, serving as an incubating organ, the eggs lying transversely in
a single series. Example = Compsilura
concinnata Meig. 8. As previous (#7)
except that ovipositor itself serves as the piercing organ. Example = Cercomyia curvicauda
Fall. 9. Female with piercing organ
variably formed and functional; egg much narrowed at posterior pole;
posterior uterus short and does not serve for incubation. Example = Hyalomyia, Oxyptera, Conops. 10. Egg with a pedicel at
posterior pole, serving for adhering to host; ovarioles of moderate number
and posterior uterus intermediate between the simple and incubating
forms. Example = Carcelia cheloniae
Rond. Townsend (1934) further extended this classification through the
Muscoidea, enumerating 39 habit groups, the majority of which comprise some
entomophagous species. He includes
additionally characters of the 1st instar larva. However, this arrangement is of greater value to a taxonomist
and to the specialist of insect parasitology than to researchers working on
biologies of specific parasitoids or predators. Pantel's earlier arrangement is simpler and quite
satisfactory. Clausen (1940) conceded
that this classification would need revision and extension it if were to
include all parasitic groups of Diptera, and further still if it were to
include predaceous forms. Considering
only parasitic species, the Conopidae, Pipunculidae, Pyrgotidae and
Agromyzidae (Chryptochaetum) seem
to fall into groups 7-9, for the species consistently insert their eggs into
the host body. However, most
Conopidae have stalked eggs. Most
parasitic Phoridae have the same oviposition habit, but some deposit eggs
externally; yet females are still able to puncture the host with the
ovipositor. The parasitic
Cecidomyiidae that have stalked eggs do not fall into any of the 10 groups,
nor do the Cyrtidae, Nemestrinidae and Bombyliidae. The parasitic species show a wide range in reproductive capacity,
this being related to hazards encountered by the eggs and young larvae before
the latter gain access to the host body cavity. Species depositing their eggs or larvae in or directly on the
host body usually are limited to a few hundred, and several species are known
to produce less than 100. Those which
lay them in the general area of the host produce 1-2,000, the latter
including most Bombyliidae and many Tachinidae. When oviposition is entirely apart from the host or where the
eggs must be consumed by the host, the hazards are increased and thus a
higher reproductive capacity is required.
In this way the Tachinidae and Cyrtidae deposit 2-6,000 eggs. An extreme is shown by Echinomyodes which produces ca. 13,000
maggots (Clausen 1940/1962). Life Cycle
Life cycles among entomophagous Diptera range from ca. 10 days in
Metagonistylum and an almost
equally short time for various other Phoridae, Tachinidae, Syrphidae and
Sarcophagidae, to the annual cycle found in a great many of both the
parasitic and predaceous species and to a possibly obligatory 2-yr. cycle in
some Nemestrinidae. The egg stage is
almost always short, often owing to partial or complete uterine incubation,
and in many species hatching occurs in the uterus or immediately on
deposition of the egg. The shortest
larval period occurs among the parasitic species, some of which complete
feeding in 2-4 days, this brief period also being found in a few
predators. However, there is no
uniformity in this respect for many species remain inactive within the host
for long periods of time. The pupal
stage similarly shows much variation, ranging from one week to almost a
year. The normal cycle of many
species may not be completed, being interrupted by adverse conditions. This results in some or all individuals
entering diapause, that may extend to over several years. The adult life is correlated with the kind
of reproduction, but in most species it extends to 1-2 months (Clausen
1940/1962). For a detailed discussion of immature stages of Diptera, please
refer to Clausen (1940/1962).
References: Please refer to <biology.ref.htm>, [Additional references
may be found at: MELVYL
Library] Blagoderov, V. A., E. D. Lukashevich & M. B.
Mostovski. 2002. "Order Diptera Linné, 1758. The true flies". In A.
P. Rasnitsyn & D. L. J. Quicke. History of Insects. Kluwer
Academic Publishers. Blagoderov,
V.A., Lukashevich, E.D. & Mostovski, M.B. 2002. Order Diptera. In: Rasnitsyn,
A.P. and Quicke, D.L.J.
The History of Insects, Kluwer Publ., Dordrecht, Boston, London,
pp. 227–240. Brown, B.V.,
Borkent, A., Cumming, J.M., Wood, D.M., Woodley, N.E., and Zumbado, M.
(Editors) 2009 Manual of Central American Diptera. Volume 1 NRC
Research Press, Ottawa ISBN 978-0-660-19833-0 Christian Thompson, F. C.. "Sources for the
Biosystematic Database of World Diptera (Flies)" (PDF). United States
Department of Agriculture, Systematic Entomology Laboratory. Colless, D.H.
& McAlpine, D.K.1991 Diptera (flies) , pp. 717–786. In: The
Division of Entomology. Commonwealth
Scientific and Industrial Research Organisation, Canberra (spons.), The
insects of Australia.Melbourne Univ. Press, Melbourne. Griffiths,
G.C.D. The phylogenetic classification of Diptera Cyclorrhapha,
withspecial reference to the structure of the male postabdomen. Ser. Ent. 8, 340 pp. [Dr. W. Junk,
N. V., The Hague] (1972). Hennig, W.
1954a. Diptera (Zweifluger). Handb. Zool. Berl. 4 (2 ) (31):1-337. General introduction with key to
World Families. In German. Hennig, W.
1954b. Flugelgeader und System der Dipteren
unter Berucksichtigung der aus dem Mesozoikum beschriebenen Fossilien. Beitr.
Ent. 4: 245-388 (1954). Hennig, W.
1948. Die Larvenformen der
Dipteren. 3. Teil. Akad.-Verlag, Berlin. 185 pp., 3
pls. Hoell, H.V., Doyen, J.T. & Purcell, A.H. 1998. Introduction
to Insect Biology and Diversity, 2nd ed.. Oxford University Press.
pp. 493–499. Oldroyd, H. The
Natural History of Flies. New York: W. W. Norton.1965. Rohdendorf, B.
B. 1964. Trans. Inst. Paleont., Acad. Sci. USSR,
Moscow, v. 100 "Taxon: Superorder
Antliophora". The Taxonomicon. Séguy, E.
1924-1953. Diptera: recueil
d'etudes biologiques et systematiques sur les Dipteres du Globe
(Collection of biological and systematic studies on Diptera of the World). 11
vols. Text figs. Part of Encyclopedie Entomologique, Serie B II:
Diptera. Seguy, E.
1950. La Biologie des Dipteres. pp. 609. 7 col + 3 b/w plates,
225 text figs. Wiegmann, B. M. & D. K. Yeates .1996. "Tree of
Life: Diptera". |