Бұрылып қанатты жәндіктер

Order of insects

The Strepsiptera (/s//t//ɹ//ɛ//p/'/s//ɪ//p//t//əɹ//ə/) are an order of insects with eleven extant families that include about 600 described species. They are endoparasites of 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. They are believed to be most closely related to beetles, from which they diverged 300–350 million years ago, but do not appear in the fossil record until the mid Cretaceous around 100 million years ago. The order is not well known to non specialists, and the nearest they have to a common name is stylops, in reference to the genus Stylops. The name of the order translates to "twisted wing", giving rise to other common names used for the order, twisted wing insects and twisted winged parasites. Adult males are rarely observed, although specimens may be lured using cages containing virgin females. Nocturnal specimens can also be collected at light traps. A similar organ exists in flies, though in that group the hindwings are modified instead, and the two groups are thought to have independently evolved the structures. The hindwings are generally fan shaped, and have strongly reduced venation. The antennae are flabellate, and are covered in specialised chemoreceptors, likely to detect females over long distances. Adult male Strepsiptera have eyes unlike those of any other insect, resembling the eyes found in the trilobite group 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.

The females of Stylopidia, which includes 97% of all described strepsipteran species and all modern strepsipteran families except Mengenillidae and Bahiaxenidae, are not known to leave their hosts and are neotenic in form, lacking wings, legs, and eyes, but have a well sclerotised cephalothorax (fused head and thorax). In the Stylopidia, the female's anterior region protrudes out between the segments of the hosts abdomen. In all strepsipterans the male mates by rupturing the female's cuticle (in the case of Stylopidia, this is in a deep narrow fissure of the cephalothorax near the birth canal). Sperm passes through the opening directly into the body in a process called traumatic insemination, which has independently evolved in some other insects like bed bugs. The offspring consume their mother from the inside in a process known as haemocoelous viviparity. Each female produces many thousands of planidium larvae. Larvae have legs and actively seek 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. Once inside the host, they undergo hypermetamorphosis and transform into 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. while Stylopidia targets only winged insects, with a large number of stylopidians targeting wasps and bees, while the largest family of strepsipterans, the Stylopidae, with over 27% of all described strepsipterans, targets bees exclusively.

The order, named by William Kirby in 1813, is named for the hindwings, which are held at a twisted angle when at rest (from Greek στρέφω (strephein), to twist; and πτερόν (pteron), wing). The forewings are reduced to halteres. 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, which have one pair of the wings modified into halteres, and failed to support their relationship to the beetles. Study of their evolutionary position has been problematic due to difficulties in phylogenetic analysis arising from long branch attraction. Most modern molecular studies find strepsipterans as the sister group of beetles (Coleoptera), with both groups together forming the clade Coleopterida. The most basal strepsipteran is the fossil Protoxenos janzeni discovered in Eocene aged Baltic amber, while the most basal living strepsipteran is Bahiaxenos relictus, the sole member of the family Bahiaxenidae. The earliest known strepsipteran fossils are those of Cretostylops engeli (Cretostylopdiae) and Kinzelbachilla ellenbergeri, Phthanoxenos nervosus and Heterobathmilla kakopoios (Phthanoxenidae), discovered in middle Cretaceous Burmese amber from Myanmar, around 99 million years old, which all lie outside the crown group, but are all more closely related to modern strepsiperans than Protoxenos is. The finding of a parasitic first instar in the same deposit indicates that the parasitic lifestyle of the group has likely existed nearly unchanged for 100 million years, though their evolutionary history prior to this remains a mystery. 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.