Strepsiptera

views updated May 18 2018

Strepsiptera

Also known as twisted-winged parasites, strepsipterans are small insects which are internal parasites of other insects. Measuring between 0.02-0.16 in (0.5 and 4 mm) long, the males and females lead totally different lives. Males are free, winged insectsresembling some forms of beetlesand females are wingless, shapeless insects living as parasites. Strepsipterans live all over the world, except Antarctica.

Belonging to the largest class of animals in the worldthe class Insectathe superclass Hexapoda contains over 750,000 species. There are two subclasses within Hexapoda: (1) Apterygota (insects without wings) which contains two orders, and (2) Pterygota (insects with wings, accounting for 99.9% of all insect species) which contains twenty-eight orders. Further classification of strepsipterans is continuously being revised. Sometimes, they are considered to be a suborder of the order Coleoptera, an order containing beetles; however, often they are given their own orderthe order Strepsiptera. Currently, there are seven families within the order Strepsiptera, containing about 300 species of insects, 60 of which live in North America.

As mentioned before, the appearance and behavior of the male and female strepsipterans differ markedly. The female resembles a grub, having no wings, legs, eyes, or mouth. Also, her nervous system is very diminished. She generally attaches herself to another insect as a host. For instance, the female of the Stylopidae species attaches herself to the stomach of a wasp or bee. She burrows almost her entire body into her host, sticking out slightly. While she does not usually kill her host, her presence sterilizes it, causing it to have both male and female sexual organs, and alters its appearance otherwise.

The male strepsipteran is independent of any host, having antennae, wings, and large eyes. He darts about during his ten hour lifetime, continuously looking for a female to mate. She lures him with a special odor, since she is almost invisible within her host. He injects his sperm through a small hole located between her thorax and abdomen. The male dies soon after mating; when he dies, his forewings dry out and twist up like a corkscrew, giving these insects their common name.

After a few days, the female hatches about 1,500 tiny larvae that are born with eyes, mouths, and three pair of legs ending in suckers. Leaving their mother through an opening in her back, they continue to exist on the host bee (or other insect) until it lands on a flower. At this point, the offspring climb onto the flower and await another bee. Being consumed by a new bee, the young strepsipterans ride back to the hive. The bee regurgitates them when it stocks its nest with nectar, and the young strepsipterans are free to bore into the bee larvae and molt to their legless, inactive forms. Thus, the cycle begins again.

Strepsiptera

views updated Jun 08 2018

Strepsiptera

Also known as twisted-winged parasites , strepsipterans are small insects which are internal parasites of other insects. Measuring between 0.02-0.16 in (0.5 and 4 mm) long, the males and females lead totally different lives. Males are free, winged insects—resembling some forms of beetles—and females are wingless, shapeless insects living as parasites. Strepsipterans live all over the world, except Antarctica .

Belonging to the largest class of animals in the world—the class Insecta—the superclass Hexapoda contains over 750,000 species . There are two subclasses within Hexapoda: (1) Apterygota (insects without wings) which contains two orders, and (2) Pterygota (insects with wings, accounting for 99.9% of all insect species) which contains twenty-eight orders. Further classification of strepsipterans is continuously being revised. Sometimes, they are considered to be a suborder of the order Coleoptera, an order containing beetles ; however, often they are given their own order—the order Strepsiptera. Currently, there are seven families within the order Strepsiptera, containing about 300 species of insects, 60 of which live in North America .

As mentioned before, the appearance and behavior of the male and female strepsipterans differ markedly. The female resembles a grub, having no wings, legs, eyes, or mouth. Also, her nervous system is very diminished. She generally attaches herself to another insect as a host. For instance, the female of the Stylopidae species attaches herself to the stomach of a wasp or bee. She burrows almost her entire body into her host, sticking out slightly. While she does not usually kill her host, her presence sterilizes it, causing it to have both male and female sexual organs, and alters its appearance otherwise.

The male strepsipteran is independent of any host, having antennae, wings, and large eyes. He darts about during his ten hour lifetime, continuously looking for a female to mate. She lures him with a special odor, since she is almost invisible within her host. He injects his sperm through a small hole located between her thorax and abdomen. The male dies soon after mating; when he dies, his forewings dry out and twist up like a corkscrew, giving these insects their common name.

After a few days, the female hatches about 1,500 tiny larvae that are born with eyes, mouths, and three pair of legs ending in suckers . Leaving their mother through an opening in her back, they continue to exist on the host bee (or other insect) until it lands on a flower . At this point, the offspring climb onto the flower and await another bee. Being consumed by a new bee, the young strepsipterans ride back to the hive. The bee regurgitates them when it stocks its nest with nectar , and the young strepsipterans are free to bore into the bee larvae and molt to their legless, inactive forms. Thus, the cycle begins again.

Strepsiptera

views updated May 11 2018

Strepsiptera (stylops, twisted-wing parasite; phylum Arthropoda, class Insecta) An order of very small (adult males are 1–1.75 mm long), beetle-like insects almost all of which are parasites whose larval stages develop inside other insects. Adult males have a single pair of wings, comparable to the hind wings of other insects, the fore wings being reduced to structures resembling the halteres of Diptera. Females have no wings and in most species the female lives its entire life as an internal parasite of another insect, all but a small part of its body concealed inside its own last larval covering. Infestation causes changes in the body of the host (called ‘stylopization’) by which it can be distinguished from an uninfested individual, and causes the host to become infertile. There are nine families.

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