''Issus'' is a genus of planthoppers belonging to the family

Issidae Issidae is a family of planthoppers described by Spinola in 1839, belonging to the order Hemiptera, suborder Auchenorrhyncha superfamily Fulgoroidea. Distribution Species of this family are present throughout the Northern Hemisphere. Descrip ...

of infraorder Fulgoromorpha of suborder

Auchenorrhyncha The Auchenorrhyncha suborder of the Hemiptera contains most of the familiar members of what was called the "Homoptera" – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and scale insects are the othe ...

of order Hemiptera. Like most members of the order Hemiptera (popularly known as the "bug" or "true bugs" order) they live on

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is c ...

sap that they extract with their piercing, sucking mouth parts. Planthoppers are the only animals known to possess a

gear A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic ...

mechanism, and ''

Issus coleoptratus ''Issus coleoptratus'' is a species of planthopper belonging to the family Issidae. Distribution and habitat This common species can be found in the western Palearctic realm, in the Near East, and in North Africa. These insects live on shrubbe ...

'' is the first type of planthopper to have the mechanism formally described. The mesh sector

s 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) A yaw rotation is a movement around the yaw axis of a rigid body that changes the direction it is pointing, to the left or right of its direction of motion. The yaw rate or yaw velocity of a car, aircraft, projectile or other rigid body is the a ...

Description

The genus ''Issus'' includes small insects generally flightless with a stocky, brown body and forewings with strong pronounced ribs. They feed on

. Species of this genus are present in most of

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

, in the Near East, and in

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

Gear mechanism

Planthoppers (of which there are over 12,000 known species) are the first animals found to possess a biological form of a mechanical

, used in locomotion (crocodiles possess a heart valve with cog-like projections, but they have no cog-like function.) The first formal description of this mechanism was in the species ''Issus coleoptratus''. 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. Each leg has a 400-micrometer strip of tapered teeth, pitch radius 200 micrometers, with 10 to 12 fully interlocking spur-type

teeth, including filleted curves at the base of each tooth, which reduces wear and the risk of shearing. 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. The existence of the gears in planthoppers had been known for decades, 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. The gears are found only in the nymph forms of all planthoppers, and are lost during the final molt to the adult stage. The juveniles repeatedly molt and grow new gears before adulthood. It is suspected that the gears are lost after the last molt into an adult because if broken in an adult they would be irreparable, crippling the insect for life. 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. Before the planthopper nymph's hind leg mesh gears were discovered, it was assumed that only humans made and used gears.

List of species

This genus include the following 29 species: *'' Issus analis'' Brullé, 1832 *'' Issus bellardi'' Melichar, 1906 *'' Issus bimaculatus'' Melichar, 1906 *'' Issus cagola'' Remane, 1985 *'' Issus cagracala'' Remane, 1985 *'' Issus cahipi'' Remane, 1985 *'' Issus canalaurisi'' Sergel, 1986 *'' Issus canariensis'' Melichar, 1906 *'' Issus capala'' Remane 1985 *'' Issus capapi'' Remane1985 *'' Issus cinereus'' (Olivier, 1791) *'' Issus climacus'' Fieber, 1876 *''

'' (Fabricius, 1781) *'' Issus distinguendus'' Lindberg, 1954 *'' Issus fieberi Melichar'' 1906 *'' Issus fissala Fieber'' 1876 *'' Issus gracalama'' Remane, 1985 *'' Issus gratehigo'' Remane, 1985 *'' Issus hipidus'' Remane, 1985 *'' Issus lauri'' Ahrens, 1818 *'' Issus maderensis'' Lindberg, 1956 *'' Issus muscaeformis'' (Schrank, 1781) *'' Issus padipus'' Remane, 1985 *'' Issus paladitus'' Remane, 1985 *'' Issus palama'' Remane, 1985 *'' Issus pallipes'' Lucas, 1853 *'' Issus pospisili'' Dlabola, 1958 *'' Issus rarus'' Lindberg, 1954 *'' Issus truncatus'' Fieber, 1876

References

External links

Fauna EuropaeaBiolib
{{Taxonbar, from=Q10538025 Issinae Auchenorrhyncha genera Hemiptera of Europe

Description

Gear mechanism

List of species

See also

References

External links