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Insect Order Strepsiptera
Strepsiptera, commonly known in older literature as
"twisted-winged parasites", form an insect order with nine families
making up about 600 species.
They are parasites of other insects; their hosts include bees,
wasps, leafhoppers, silverfish, and cockroaches.
Live adult Strepsiptera infected Polistes paper wasps photographed in the wild at DuPage
County, Illinois, and Vero Beach, Florida, USA.
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The anterior abdomens of three female
Strepsiptera in the family Stylopidae protrude from
under the abdominal segments of a paper wasp in the genus
Polistes. Female
Strepsiptera thus provide access to adult
males for purposes of reproduction, which is accomplished by
a process known as hypodermic insemination. In this
instance, the insects are acting as endoparasites, that is,
living inside the host's body.
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Strepsiptera Identifying
characteristics:
Minute size, ranging from 0.5 - 4.0 mm.
Front wings reduced to short, clublike
structures.
Hind wings membranous, fanshaped, with
few veins.
Bulging eyes on side of head.
Antennae 4- to 7-segmented with 1 to 3
distinctive elongate projections.
Females: Minute, saclike insects,
frequently lacking appendages.
Generally found and identified by
occurrence on parasitized host.
There are 11 genera and 56 species of
Strepsiptera in North America. Many
authorities use antennal and tarsal
characters of the males to place these
species into the four families listed
below. Other authorities lump all
species into the family Stylopidae and
include these insects within the order
Coleoptera.
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Paper wasp Polistes annularis with paper
brood cells. Single eggs are visible at the bottom
of each hexagonal cell.
The Strepsiptera, commonly known in
older literature as twisted-winged
parasites, are an order of insects with
nine families making up about 600
species. They are obligate endoparasites
on other insects; their hosts include
bees, wasps, leafhoppers, silverfish,
and cockroaches.
Male Strepsiptera have wings, legs,
eyes, and antennae, and look like flies,
though they generally have no useful
mouthparts. Females, in all families
except the Mengenillidae, never leave
their host and are neotenic in form,
lacking wings and legs. Males have a
very short adult lifetime (usually less
than five hours) and do not feed as
adults. Many of their mouth parts are
modified into sensory structures. Virgin
females release a pheromone which the
males search for. In the Stylopidia the
female has its anterior region extruding
out of the host body and the male mates
by rupturing the female's brood canal
opening which lies between the head and
prothorax. Sperm passes through the
opening in a process termed hypodermic
insemination. Each female produces many
thousands of triungulin larvae that
escape from its body and out of the host
into the soil and vegetation. These
actively search out new hosts. Their
hosts include members belonging to the
orders Zygentoma, Orthoptera, Blattodea,
Mantodea, Heteroptera, Hymenoptera, and
Diptera. In the Strepsipteran family
Myrmecolacidae, the males parasitize
ants while the females parasitize
Orthoptera.
Strepsiptera find and enter their insect
hosts as planidium larvae. The first
instar larvae have stemmata (simple,
single-lens eyes). They undergo
hypermetamorphosis and become a less
mobile legless larval form. In this
stage they feed within the host's body
cavity. The colour and shape of the
host's abdomen may be changed and the
host usually becomes sterile. The
parasites then undergo holometabolous
metamorphosis to become adults. Adult
males emerge out of the host body while
females stay inside. Females may occupy
up to 90% of the abdominal volume of
their hosts.
Male Strepsiptera have eyes unlike those
of any other insect, resembling the
schizochroal eyes found in the trilobite
group known as Phacopida. Instead of a
compound eye consisting of hundreds of
ommatidia, each of which sees one pixel,
the strepsipteran eyes consist of only a
few dozen ommatidia separated by cuticle
and/or setae, giving the eye a
blackberry-like appearance.
Multiple females may be seen within a
stylopized host. Males are extremely
rare. They may sometimes be seen at
light traps or may be lured using cages
containing virgin females.
--from Wikipedia
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This unfortunate paper wasp, Polistes
fuscatus, has 4 strepsiptera
protruding
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