Issus | |
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Issus coleoptratus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hemiptera |
Suborder: | Auchenorrhyncha |
Infraorder: | Fulgoromorpha |
Superfamily: | Fulgoroidea |
Family: | Issidae |
Subfamily: | Issinae |
Genus: | Issus Fabricius, 1803 |
Issus is a genus of planthoppers belonging to the family Issidae of infraorder Fulgoromorpha of suborder Auchenorrhyncha of order Hemiptera. Like most members of the order Hemiptera (popularly known as the "bug" or "true bugs" order) they live on phloem sap that they extract with their piercing, sucking mouth parts.
Planthoppers are the only animals known to possess a gear mechanism, [1] and Issus coleoptratus is the first type of planthopper to have the mechanism formally described. [2] [3] The mesh sector gears do not transform velocity or torque, and they do not convey much of the power; they only synchronize the jumping motion of the hind legs, preventing yaw (rotation).
The genus Issus includes small insects generally flightless with a stocky, brown body and forewings with strong pronounced ribs. They feed on phloem. Species of this genus are present in most of Europe, in the Near East, and in North Africa.
Planthoppers (of which there are over 12,000 known species) are the first animals found to possess a biological form of a mechanical gear, used in locomotion (crocodiles possess a heart valve with cog-like projections, but they have no cog-like function. [4] ) The existence of the gears in planthoppers had been known for decades, [5] but zoologist Gregory Sutton and his co-authors only recently characterized their functional significance by doing high-speed photography of Issus coleoptratus at Cambridge University. [2] The gears keep the hind legs in synchronization, allowing the bugs to jump accurately in a straight line, at an acceleration of nearly 400 g in two milliseconds. [2] Each leg has a 400-micrometer strip of tapered teeth, pitch radius 200 micrometers, with 10 to 12 fully interlocking spur-type gear teeth, including filleted curves at the base of each tooth, which reduces wear and the risk of shearing. [2] The gears aren't connected all the time. One is located on each of the juvenile insect's hind legs, and when it prepares to jump, the two sets of teeth lock together. As a result, the legs move in almost perfect unison for a straight jump, giving the insect more connected power as the gears rotate together to their stopping point and then unlock. [2]
The gears are found only in the nymph forms, and are found in all planthoppers, but they are lost during the final molt to the adult stage. [2] The juveniles repeatedly molt and grow new gears before adulthood. [2] Entomologist Malcolm Burrows has posited that the advantage of losing the gears after the last molt is that, if the gears were to be broken on an adult insect, this would be irreparable. [2] The legs of an adult planthopper are synchronized by a different mechanism, a series of protrusions that extend from both hind legs, and push the other leg into action. [2]
Before the planthopper nymph's hind leg mesh gears were discovered, it was assumed that only humans made and used gears. [3]
This genus include the following 29 species:
A gear or gearwheel is a rotating machine part typically used to transmit rotational motion and/or torque by means of a series of teeth that engage with compatible teeth of another gear or other part. The teeth can be integral saliences or cavities machined on the part, or separate pegs inserted inserted into it. In the latter case, the gear is usually called a cogwheel. A cog may be one of those pegs or the whole gear. Two or more meshing gears are called a gear train.
Hemiptera is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from 1 mm (0.04 in) to around 15 cm (6 in), and share a common arrangement of piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.
A planthopper is any insect in the infraorder Fulgoromorpha, in the suborder Auchenorrhyncha, a group exceeding 12,500 described species worldwide. The name comes from their remarkable resemblance to leaves and other plants of their environment and that they often "hop" for quick transportation in a similar way to that of grasshoppers. However, planthoppers generally walk very slowly. Distributed worldwide, all members of this group are plant-feeders, though few are considered pests. The infraorder contains two superfamilies, Fulgoroidea and Delphacoidea. Fulgoroids are most reliably distinguished from the other Auchenorrhyncha by two features; the bifurcate (Y-shaped) anal vein in the forewing, and the thickened, three-segmented antennae, with a generally round or egg-shaped second segment (pedicel) that bears a fine filamentous arista.
Siphanta acuta is a species of planthopper in the family Flatidae; this species is native to Australia, but is now found in various other parts of the world. About 10 mm long, they resemble small leaves and are generally found in trees. Its common names are Green Planthopper and Torpedo Bug.
Dictyopharidae is a family of planthoppers, related to the Fulgoridae. The family comprises nearly 760 species in more than 150 genera which are grouped into two subfamilies, Dictyopharinae and Orgeriinae.
Flatidae are a family of fulgoroid planthoppers. They are cosmopolitan in distribution and are distinguished from others in the superfamily by a combination of characters. Like all other planthoppers, they suck phloem sap of plants. Some species are known to communicate with vibrations through the plant stems. Communication may be with mates, or with ants that tend the nymphs, protecting them and gathering honeydew secretions. Adults of some species have brightly coloured forewings which are tougher and known as tegmina unlike the membranous hindwings which are used for flight. Although a few can be identified by their coloration, most species requires dissection and examination under a microscope with access to literature on already described species.
Issidae is a family of planthoppers described by Spinola in 1839, belonging to the order Hemiptera, suborder Auchenorrhyncha superfamily Fulgoroidea.
Nogodinidae is a family of planthoppers. They have membranous wings with delicate venation and can be confused with members of other Fulgoroid families such as the Issidae and Tropiduchidae. Some authors treat it as a subfamily of the Issidae.
Caliscelidae is a family of planthoppers, sap-sucking insects that belong to the order Hemiptera, suborder Auchenorrhyncha and superfamily Fulgoroidea. They are somewhat anomalous and have often been included within the family Issidae. Studies made in 2013 of the phylogeny of the Issidae and other groups using molecular techniques support the treatment of the group as a separate family. Sexual dimorphism can be marked. Some members of the family are called piglet bugs due to the shape of their snout. A particularly aberrant genus described in 2011 from India, Formiscurra, has males that resemble ants.
Issus coleoptratus is a species of planthopper belonging to the family Issidae.
Kinnaridae is a family of fulgoroid planthoppers. This is a small family with a little more than 20 genera and about a 100 species. The family was erected by Muir in 1925 and most members are found in the Oriental and Neotropical regions and only a few in the Nearctic and Palaearctic regions.
Delphacinae is a subfamily of delphacid planthoppers in the family Delphacidae. There are at least 1,700 described species in Delphacinae.
The Elicini are a tribe of planthoppers in the family Tropiduchidae. The type genus is Elica.
Achilidae is a family of planthoppers, sometimes called "achilids" in the order Hemiptera. There are at least 520 described species in Achilidae.
Thionia is a genus of planthoppers in the family Issidae. There are at least 60 described species in Thionia. However, several genera have been split off from Thionia reducing the number of species.
Elicinae is a subfamily of tropiduchid planthoppers in the family Tropiduchidae, with Elica the type genus.
Dictyopharinae is a subfamily of dictyopharid planthoppers in the family Dictyopharidae. There more than 100 genera and 500 described species in Dictyopharinae.
Agalmatium is a genus of planthoppers belonging to the family Issidae, subfamily Issinae.
Dictyophara europaea, is the type species of planthoppers belonging to the subgenus Dictyophara (Dictyophara): in the family Dictyopharidae, and tribe Dictyopharini.