The Strepsiptera are an endopterygote order of insects with nine extant families that include about 600 described species. They are endoparasites in other insects, such as bees, wasps, leafhoppers, silverfish, and cockroaches. Females of most species never emerge from the host after entering its body, finally dying inside it. The early-stage larvae do emerge because they must find an unoccupied living host, and the short-lived males must emerge to seek a receptive female in her host.
The order is not well known to non-specialists, and the nearest they have to a common name is "stylops". The name of the order translates to "twisted wing"', giving rise to another name used for the order, twisted-wing insects.
Males of the Strepsiptera have wings, legs, eyes, and antennae, though their mouthparts cannot be used for feeding. Many have mouthparts modified into sensory structures. To the uninitiated the males superficially look like flies. Adult males are very short-lived, usually surviving less than five hours, and do not feed. Females, in all families except the Mengenillidae, are not known to leave their hosts and are neotenic in form, lacking wings, legs, and eyes. Virgin females release a pheromone which the males use to locate them.
In the Stylopidia, the female's anterior region protrudes 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. The offspring consume their mother from the inside in a process known as hemocelous viviparity. Each female then produces many thousands of triungulin larvae that emerge from the brood opening on the head, which protrudes outside the host body. These larvae have legs and actively search out new hosts. Their legs are partly vestigial in that they lack a trochanter, the leg segment that forms the articulation between the basal coxa and the femur),
Strepsiptera of various species have been documented to attack hosts in many orders, including members of 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 eggs hatch inside the female, and the planidium larvae can move around freely within the female's haemocoel; this behavior is unique to these insects. The larvae escape through the female's brood canal, which communicates with the outside world. The larvae are very active, because they only have a limited amount of time to find a host before they exhaust their food reserves. These first-instar larvae have stemmata (simple, single-lens eyes). When the larvae latch onto a host, they enter it by secreting enzymes that soften the cuticle, usually in the abdominal region of the host. Some species have been reported to enter the eggs of hosts. Larvae of Stichotrema dallatorreanurn Hofeneder from Papua New Guinea were found to enter their orthopteran host's tarsus (foot). Once inside the host, they undergo hypermetamorphosis and become a less-mobile, legless larval form. They induce the host to produce a bag-like structure inside which they feed and grow. This structure, made from host tissue, protects them from the immune defences of the host. Larvae go through four more instars, and in each moult the older cuticle separates but is not discarded ("apolysis without ecdysis"), so multiple layers form around the larvae. Male larvae pupate after the last moult, but females directly become neotenous adults. The colour and shape of the host's abdomen may be changed and the host usually becomes sterile. The parasites then undergo pupation to become adults. Adult males emerge from the host bodies, while females stay inside. Females may occupy up to 90% of the abdominal volume of their hosts.
Adult male Strepsiptera have eyes unlike those of any other insect, resembling the schizochroal eyes found in the trilobite group known as the Phacopina. Instead of a compound eye consisting of hundreds to thousands of ommatidia, that each produce a pixel of the entire image - the strepsipteran eyes consist of only a few dozen "eyelets" that each produce a complete image. These eyelets are separated by cuticle and/or setae, giving the cluster eye as a whole a blackberry-like appearance.
Very rarely, multiple females may live within a single stylopized host; multiple males within a single host are somewhat more common. Adult males are rarely observed, however, although specimens may be lured using cages containing virgin females. Nocturnal specimens can also be collected at light traps.
Strepsiptera of the family Myrmecolacidae can cause their ant hosts to linger on the tips of grass leaves, increasing the chance of being found by the parasite's males (in case of females) and putting them in a good position for male emergence (in case of males).
The order, named by William Kirby in 1813, is named for the hind wings, which are held at a twisted angle when at rest (from Greek στρέϕειν (strephein), to twist; and πτερόν (pteron), wing). The fore wings are reduced to halteres (and initially were thought to be dried and twisted); this inspired the order name; Strepsiptera literally is the Greek plural for "twisted winged".
Strepsiptera were once believed to be the sister group to the beetle families Meloidae and Ripiphoridae, which have similar parasitic development and forewing reduction; early molecular research suggested their inclusion as a sister group to the flies, in a clade called the halteria, which have one pair of the wings modified into halteres, and failed to support their relationship to the beetles. Further molecular studies, however, suggested they are outside the clade Mecopterida (containing the Diptera and Lepidoptera), but found no strong evidence for affinity with any other extant group. Study of their evolutionary position has been problematic due to difficulties in phylogenetic analysis arising from long branch attraction. The most basal strepsipteran is the fossil Protoxenos janzeni discovered in Baltic amber, while the most basal living strepsipteran is Bahiaxenos relictus, the sole member of the family Bahiaxenidae. The earliest known strepsipteran fossil is that of Cretostylops engeli, discovered in middle Cretaceous amber from Myanmar.
|Suggested phylogenetic position of the
The Strepsiptera have two major groups: the Stylopidia and Mengenillidia. The Mengenillidia include three extinct families (Cretostylopidae, Protoxenidae, and Mengeidae) plus two extant families (Bahiaxenidae and Mengenillidae; the latter is not monophyletic, however.) They are considered more primitive, and the known females (Mengenillidae only) are free-living, with rudimentary legs and antennae. The females have a single genital opening. The males have strong mandibles, a distinct labrum, and more than five antennal segments.
The other group, the Stylopidia, includes seven families: the Corioxenidae, Halictophagidae, Callipharixenidae, Bohartillidae, Elenchidae, Myrmecolacidae, and Stylopidae. All Stylopidia have endoparasitic females having multiple genital openings.
The Stylopidae have four-segmented tarsi and four- to six-segmented antennae, with the third segment having a lateral process. The family Stylopidae may be paraphyletic. The Elenchidae have two-segmented tarsi and four-segmented antennae, with the third segment having a lateral process. The Halictophagidae have three-segmented tarsi and seven-segmented antennae, with lateral processes from the third and fourth segments. The Stylopidae mostly parasitize wasps and bees, the Elenchidae are known to parasitize Fulgoroidea, while the Halictophagidae are found on leafhoppers, treehoppers, and mole cricket hosts.
Strepsipteran insects in the genus Xenos parasitize Polistes carnifex, a species of social wasps. These obligate parasites infect the developing wasp larvae in the nest and are present within the abdomens of female wasps when they hatch out. Here they remain until they thrust through the cuticle and pupate (males) or release infective first-instar larvae onto flowers (females). These larvae are transported back to their nests by foraging wasps.
Many insects which have been considered as pests, such as leafhoppers and cockroaches, have species-specific Strepsipteran endoparasites. Inoculation of a pest population with the corresponding parasitoid has been found to aid in minimizing the impact of these pests. This method is useful in agriculture as a means of avoiding addition of chemicals to crops for pest control.
Amphiesmenoptera is an insect superorder, established by S. G. Kiriakoff, but often credited to Willi Hennig in his revision of insect taxonomy for two sister orders: Lepidoptera (butterflies and moths) and Trichoptera (caddisflies). In 2017, a third fossil order was added to the group, the Tarachoptera.Trichoptera and Lepidoptera share a number of derived characters (synapomorphies) which demonstrate their common descent:
Females, rather than males, are heterogametic (i.e. their sex chromosomes differ).
Dense setae are present in the wings (modified into scales in Lepidoptera).
There is a particular venation pattern on the forewings (the double-looped anal veins).
Larvae have mouth structures and glands to make and manipulate silk.Thus these two extant orders are sisters, with Tarachoptera basal to both groups. Amphiesmenoptera probably evolved in the Jurassic. Lepidoptera differ from the Trichoptera in several features, including wing venation, form of the scales on the wings, loss of the cerci, loss of an ocellus, and changes to the legs.Amphiesmenoptera are thought to be the sister group of Antliophora, a proposed superorder comprising Diptera (flies), Siphonaptera (fleas) and Mecoptera (scorpionflies). Together, Amphiesmenoptera and Antliophora compose the group Mecopterida.Bahiaxenos
Bahiaxenos relictus is the sole member of the family Bahiaxenidae, a type of winged insect. It was only discovered and described in 2009 from relictual sand dunes associated with the Rio São Francisco in Bahia, Brazil. It is considered to be the most basal living member of the order Strepsiptera, so is the sister taxon to the remaining extant species. It is known from only a single male specimen, and its biology is unknown.Caenocholax
Caenocholax is a genus of twisted-winged insects in the family Myrmecolacidae. There are about seven described species in Caenocholax.Caenocholax fenyesi
Caenocholax fenyesi, the Fenyes' strepsiptera, is a species of twisted-winged insect in the family Myrmecolacidae. It is found in Central America, North America, and South America.Corioxenidae
The Corioxenidae are an insect family of the order Strepsiptera. Species in this family are parasites of heteropteran bugs including the Pentatomidae, Scutelleridae, Cydnidae, Coreidae, and Lygaeidae. The males lack mandibles. Three subfamilies within this family are recognized. The subfamilies are separated using morphology of the males, particularly on the basis of the number of tarsi and the presence of tarsal claws.
Corioxeninae Kinzelbach, 1970
Corioxenos Blair, 1936
Floridoxenos Kathirithamby and Peck, 1994
Loania Kinzelbach, 1970
Perissozocera Johnson, 1976
Australoxenos Kathirithamby, 1990
Blissoxenos Miyamoto & Kifune, 1984
Malayaxenos Kifune, 1981
Mufagaa Kinzelbach, 1980
Viridipromontorius Luna de Carvalho, 1985
Triozocerinae Kinzelbach, 1970
Triozocera Pierce, 1909
Dundoxenos Luna de Carvalho, 1956
Uniclavinae Kathirithamby, 1989
Uniclavus Kathirithamby, 1989
Proceroxenos Pohl, Katbeh-Bader & Schneider, 1996Dicondylia
The Dicondylia are a taxonomic group (taxon) that includes all insects except the jumping bristletails (Archaeognatha). Dicondylia have a mandible attached with two hinges to the head capsule (dicondyl), in contrast to the original mandible with a single ball joint (monocondyl).Elenchidae
The Elenchidae are an insect family in the order Strepsiptera.Elenchus (insect)
Elenchus is an insect genus in the family Elenchidae.Elenchus tenuicornis
Elenchus tenuicornis is an insect species in the genus Elenchus.Endopterygota
Endopterygota (from Ancient Greek endon “inner” + pterón, “wing” + New Latin -ota “having”), also known as Holometabola, is a superorder of insects within the infraclass Neoptera that go through distinctive larval, pupal, and adult stages. They undergo a radical metamorphosis, with the larval and adult stages differing considerably in their structure and behaviour. This is called holometabolism, or complete metamorphism.
The Endopterygota are among the most diverse insect superorders, with over 1 million living species divided between 11 orders, containing insects such as butterflies, flies, fleas, bees, ants, and beetles.They are distinguished from the Exopterygota (or Hemipterodea) by the way in which their wings develop. Endopterygota (meaning literally "internal winged forms") develop wings inside the body and undergo an elaborate metamorphosis involving a pupal stage. Exopterygota ("external winged forms") develop wings on the outside their bodies and do not go through a pupal stage. The latter trait is plesiomorphic, however, and not exclusively found in the exopterygotes, but also in groups such as Odonata (dragonflies and damselflies), which are not Neoptera, but more basal among insects.
The earliest endopterygote fossils date from the Carboniferous.Halictophagidae
Halictophagidae are an insect family of the order Strepsiptera.Mesothorax
The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal), the mesosternum (ventral), and the mesopleuron (lateral) on each side. The mesothorax is the segment that bears the forewings in all winged insects, though sometimes these may be reduced or modified, as in beetles (Coleoptera) or Dermaptera, in which they are sclerotized to form the elytra ("wing covers"), and the Strepsiptera, in which they are reduced to form halteres. All adult insects possess legs on the mesothorax. In some groups of insects, the mesonotum is hypertrophied, such as in Diptera, Hymenoptera, and Lepidoptera), in which the anterior portion of the mesonotum (called the mesoscutum, or simply "scutum") forms most of the dorsal surface of the thorax. In these orders, there is also typically a small sclerite attached to the mesonotum that covers the wing base, called the tegula. In one group of insects, the Hemiptera, the dorsal surface of the thorax is typically formed primarily of the prothorax, but also in part by the enlarged posterior portion of the mesonotum, called the scutellum; in the Coleoptera, the scutellum may or may not be visible, usually as a small triangular plate between the elytral bases, thus similar in position to the Hemipteran scutellum. In Diptera and Hymenoptera the mesothoracic scutellum is also distinct, but much smaller than the mesoscutum.Myrmecolacidae
Myrmecolacidae is an insect family of the order Strepsiptera. There are four genera and about 98 species in this family. Like all strepsipterans, they have a parasitic mode of development with males parasitizing ants while the females develop inside Orthoptera. The sexes differ greatly in morphology making it very difficult to match females to the better catalogued museum specimens of males.Neoptera
Neoptera is a classification group that includes most orders of the winged insects, specifically those that can flex their wings over their abdomens. This is in contrast with the more basal orders of winged insects (the "Palaeoptera" assemblage), which are unable to flex their wings in this way.Pterygota
The Pterygota are a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless (that is, insect groups whose ancestors once had wings but that have lost them as a result of subsequent evolution).The pterygotan group comprises almost all insects. The insect orders not included are the Archaeognatha (jumping bristletails) and the Zygentoma (silverfishes and firebrats), two primitively wingless insect orders. Also not included are the three orders no longer considered to be insects: Protura, Collembola, and Diplura.Stylopidae
Stylopidae is a family of twisted-winged insects in the order Strepsiptera. There are about 15 genera and more than 330 described species in Stylopidae.Members of Stylopidae are parasitic insects. Host insects of this family that are afflicted are referred to as being "stylopized".Xenos
Xenos may refer to:
Xenos (Greek), a Greek word meaning "stranger" or "alien"
Xenos (insect), a genus of insects in the order Strepsiptera
Xenos (graphics chip), a custom graphics processing unit (GPU) designed by ATI, used in the Xbox 360 video game consoleXenos (insect)
Xenos is a genus of insects belonging to the family Stylopidae. The word derives from the Greek word for strange. A species of the genus is Xenos vesparum, first described by Pietro Rossi in 1793. The females are permanent entomophagous endoparasites of Polistes paper wasps. They dwell their whole lives in the abdomens of wasps.Xenos vesparum
Xenos vesparum is an insect species, whose females are permanent entomophagous endoparasites of Polistes paper wasps. They dwell their entire lifespan in the abdomen of the wasp. One particular species of social wasp it has been known to infect is Polistes gallicus. Younger members of a wasp colony tend to be targeted, although X. vesparum displays parasitic behavior in all stages of this host.According to Fabio Manfredini of Pennsylvania State University, co-author of an Animal Behaviour study of this insect's odd life cycle, published on 8 October 2011, the parasite infects a European worker wasp and completely alters its worker caste behaviour. The infected wasp begins to suffer nutritionally, then flies to meet with other infected wasps. The male parasite exits the wasp's abdomen and mates with the female parasites which stay inside their host. Wasps infected with the male parasite die. Wasps infected with the female parasite then fatten themselves up much like queen wasps do. They then fly to meet with other uninfected queen wasps. Then when the parasite is mature, the infected wasp flies to mingle with other uninfected wasps, thereby spreading brood and larvae into new environments.
Extant Strepsiptera families