Thrips

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Thrips (order Thysanoptera ) is minutes (longest 1 mm or less), slender insects with tufted wings and a unique asymmetrical mouth. Different thrip species feed mostly on the plant by piercing and sucking its contents, although some are predators. Around 6,000 species have been described. They fly only weakly and their feathered wings are unsuitable for conventional flight; instead, thrips exploit unusual, clap and throw mechanisms, to create elevators using unstable circulatory patterns with transient vortices near the wings.

Many species of thrips are important commercial plant pests. Some species serve as vectors for more than 20 viruses that cause plant diseases, especially Tospovirus. Some thrip species are useful as pollinators or as predators of insects or other mites. Under the right conditions, as in greenhouses, many species can increase exponentially in population size and form large herds because of the lack of natural predators coupled with their ability to reproduce asexually, making them irritating to humans. Their identification into species by standard morphological characters is often challenging.

Video Thrips

Etimologi

The mention of the first recorded thrip is from the 17th century and a sketch was made by Philippo Bonanni, a Catholic priest, in 1691. Swedish entomologist Baron Charles De Geer described two species in the genus Physapus in 1744 and Linnaeus in 1746 added a third species and called this group of insects as Thrips . In 1836, Irish entomologist Alexander Henry Haliday described 41 species in 11 genera and proposed the name of the Thysanoptera order. The first monograph on the group was published in 1895 by Heinrich Uzel who is considered the father of the Thysanoptera study.

The generic and English name thrips is a direct transliteration of the ancient Greek ????, thrips , which means "woodworm". Like some other animal names such as sheep, deer and deer, the word thrips is singular and plural, so there may be many thrips or single thrips. Other common names for thrips include thunderflies, thunderbugs, storm flies, thunderblight, storm bugs, cornflies, cornflies, corn fleas, bug spots, harvest bugs and physopoda. The older group name "physopoda" is by referring to the bladder like tips to the foot tarsi. The name of the Thysanoptera order is built from the ancient Greek word ???????, thysanos , "fringe or fringe", and ??????, pteron i>, "wings", to the wing of the insects.

Maps Thrips

Morphology

Thrips are small hemimetabolic insects with distinctive cigar-shaped bauplan. They are elongated with transversal transverse body. Its size ranges from 0.5 to 14 mm (0.02 to 0.55 inches) long for larger predator thrips, but most thrips have a length of 1 mm. Thrips with flight capability have two pairs of rope-like wings with feather edges. The wings are folded back into the body at rest. Their feet usually end up in two tarsal segments with a bladder-like structure known as "arolium" in pretarsus. This structure can be changed by means of hemolymph pressure, allowing insects to walk on vertical surfaces. They have compound eyes consisting of a small amount of ommatidia and three ocelli or simple eyes on the head.

Thrips have unique asymmetric mouths for the group. Unlike Hemiptera (the real bug), the thrips' right jaw is reduced and the rest - and in some species completely absent. The left mandible is used briefly to cut food crops; Injectable saliva and maxillary stylet, which form the tube, are then inserted and the semi-digested food is pumped from the ruptured cells. This process causes the cells to crumble or collapse, and typical silver or bronze scars on the surface of the stems or leaves where the thrips are fed.

Thysanoptera is divided into two subordos, Terebrantia and Tubulifera; this can be distinguished by morphological, behavioral, and developmental characteristics. Tubulifera consists of one family, Phlaeothripidae; members can be identified by a tubular-shaped abdominal segment, laying on leaf surfaces, and three "cocoon" stages. In Phlaeothripidae, males are often larger than females and various sizes can be found in a population. The largest recorded phlaeothripid species is about 14mm long. Females from eight Terebrantia families all have eponymous-like ovipositors (see terebra) in the antisecond stomach segment, laying eggs within the plant tissue, and have two "cocoon" stages. In most Terebrantia, males are smaller than females. The Uzelothripidae family has one species and is unique in having a whip-like terminal antenna segment.

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Evolution

The earliest thrip fossils are from the Permian ( Permothrips longipennis Martynov, 1935). At the beginning of the Cretaceous, true thrips become much more abundant. The surviving family of Merothripidae resembles the ancestral Thysanoptera, and may be basal in its order. There are currently more than six thousand recognized thrip species, grouped into 777 remaining genera and sixty fossils.

Phylogeny

Thrips are generally considered a group of brothers to Hemiptera (bugs).

The phylogeny of thrips family has been little studied. Initial analysis in 2013 of 37 species using 3 genes, as well as phylogeny based on ribosomal DNA and three proteins by 2012, supports monophyly from two subordos, Tubulifera and Terebrantia. In Terebrantia, Melanothripidae may be the brother of all other families, but other relationships remain unclear. In Tubulifera, Phlaeothripidae and its subfamily Idolothripinae are monophyletic. The two largest thrips subfamilies, Phlaeothripinae and Thripinae, are paraphyletic and need further work to determine their structure. The internal relationship of this analysis is shown in the cladogram.

Taxonomy

The following current family (2013) are recognized:

Subordo Terebrantia

Adiheterothripidae Shumsher, 1946 (11 genera)
Aeolothripidae Uzel, 1895 (29 genera) - striped thrips and wide-wing thrips
Fauriellidae Priesner, 1949 (four genera)
Hemithripidae Bagnall, 1923 (one genus of fossils, Hemithrips with 15 species)
Heterothripidae Bagnall, 1912 (seven genera, limited in the New World)
Jezzinothripidae zur Strassen, 1973 (included by some authors in Merothripidae)
Karataothripidae Sharov, 1972 (one fossil species, Karataothrips jurassicus )
Melanthripidae Bagnall, 1913 (six genera flower feeders)
Merothripidae Hood, 1914 (five genus, mostly Neotropical and eating on dry wood mushrooms) - large-footed thrips
Scudderothripidae zur Strassen, 1973 (included by some authors in Stenurothripidae)
Thripidae Stevens, 1829 (292 genera in four subfamilies, live flowers) - general thrips
Triassothripidae Grimaldi & amp; Shmakov, 2004 (two fossil genera)
Uzelothripidae Hood, 1952 (one species, Uzelothrips scabrosus )

Suborder Tubulifera

Phlaeothripidae Uzel, 1895 (447 genera in two subfamilies, hifa mushrooms and spore feeders)

Identify thrips for challenging species as the type is maintained as a slide preparation with varying quality over time. There is also a variability that causes many species to be misidentified. Molecular sequence-based approaches are increasingly applied to their identification.

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Biology

Feed

Thrips are believed to originate from mushroom ancestors during Mesozoic, and many groups still eat and inadvertently distribute fungal spores. It lives among leaf litter or on dead wood and is an important member of the ecosystem, their food is often added with pollen. Other species are primitive eusocials and form galls of plants and are other predators in mites and other thrips. Two species of Aulacothrips A. tenuis and A. levinotus , have been found as ectoparasites in aetalionid plants and membracid in Brazil.

Mirothrips arbitrator found in a paper wasp nest in Brazil. Eggs from the host include Mischocyttarus atramentarius , Mischocyttarus cassununga and Polist versicolor eaten by thrips. Thrips are also predators for different stages of coding moth life.

Much of the research focuses on the thrips of species that feed on economically significant crops. Some species are predatory, but most of them feed on pollen and chloroplasts harvested from the outer layers of epidermal cells and plant mesophyll. They prefer the tender parts of the plant, such as buds, flowers and new leaves. In addition to feeding on plant tissues, the common flower thrips feed on the pollen grains and on the eggs of the mites. When dietary supplements are larvae in this way, developmental and mortality times are reduced, and adult females who consume mite eggs increase their fecundity and longevity.

Pollination

Some flower-feeding thrips pollinate the flowers they eat, and some authors suspect that they may have been one of the first insects to develop a pollination relationship with their host plants. Scirtothrips dorsalis brings about commercially important commercial peppers. Darwin found that thrips can not be prevented by the net when he experiments with the larger pollinators away. Thrips setipennis is the only pollinator Wilkiea huegeliana , a small, singular tree or shrub in a rain forest in eastern Australia. T. setipennis serves as pollinator of obligations for other Australian rainforest plant species, including Myrsine howittiana M. variabilis. The genus Cycadothrips is the specialist pollinator of cycads, flowers that are adapted for pollination by small insects. Thrips is also the main pollinator of heathers in the Ericaceae family , and plays an important role in pollination of pointleaf manzanita. Electron microscopes show thrips carrying pollen that is attached to their backs, and their tufted wings are very capable of allowing them to fly from plant to plant.

Damage to plants

The most obvious contribution that makes thrips to their ecosystems is the damage they can cause during a meal. This impact can fall on a wide selection of prey items, because there are enough affinities of masters in the entire order, and even within a species, the varying loyalty levels of the perceived host remain. The Thripidae family is especially famous for members with a wide range of hosts, and the majority of thrips of pests are from this family. For example, Thrips tabaci damages the onion, potato, tobacco, and cotton.

Some species of thrips create galls, almost always in leaf tissues. This may occur as curls, rolls or folds, or as a change in tissue expansion causing distortion in the leaf blade. A more complex example causes roses, pockets, and horns. Most of these species occur in tropical and sub-tropical regions, and the structure of galls is a diagnostic of the species involved. Radiation of thrips species seems to occur in the Acacia trees in Australia; some of these species cause galls in the petiole, sometimes repairing two petioles together, while other species live in every gap available in the bark. At Casuarina in the same country, some species have invaded the stem, creating durable wooden games.

Social behavior

While poorly documented, chemical communication is believed to be important for the group. Anal secretory is produced in hindgut, and is released along the posterior setae as a predator predator. In Australia, aggregate thrips of male common flowers have been observed on the petals of Hibiscus rosa-sinensis and Gossypium hirsutum. ; females are attracted to these groups so it seems that men produce pheromones.

In phlaeothripids that eat mushrooms, males compete to protect and mate with females, and then retain egg mass. Men fight by flicking their opponents with their stomachs, and can kill with their foretharsal teeth. Small men may sneak into couples while larger males are busy fighting. In Merothripidae and in Aeolothripidae, men are again polymorphic with large and small forms, and may also compete for couples, so the strategy may be an ancestor among Thysanoptera.

Many thrips form galls on plants when feeding or laying down their eggs. Some bile-forming phlaeothripids, such as the genera Kladothrips and Oncothrips, form eusocial groups similar to ant colonies, with reproductive queens and unproductive soldier castes.

Flights

Most insects create lift through the mechanism of flight of rigid winged insects with stable aerodynamics; this creates a continuous vortex continuously as the wings move. The thrips hairy wings, however, produce lift by clapping and throwing, a mechanism invented by the Danish zoologist Torkel Weis-Fogh in 1973. At the tap of the cycle, the wings approaching each other on the backs of the insects, creating a circulation of air that forms vortices and produce useful power on the wings. The main edges of the wings are touching, and the wings rotate around their leading edge, uniting them in a "pat". Its wings are close, drawing air from among them, giving a more useful impulse. Wings spin around the rear edges to start "throwing", creating useful power. The edges move away, making the air rush between them and regulate the new vortices, producing more force on the wings. Vortices trailing edge but cancel each other with opposite flow. Weis-Fogh suggested that this cancellation could help the air circulation to grow faster, by turning off the Wagner effect which would otherwise counteract the growth of the circulation.

Clap and fling flight mechanism after Sane 2003

Dark circles and bold lines: wings (rachis and feathers); Black arrow (curved): flow; Blue arrow: induced velocity; Orange arrow: total force on wing

Apart from active flights, thrips, even those without wings, can also be picked up by the wind and transferred remotely. During warm and humid weather, adults can climb to the tip of the plant to jump and catch the air currents. Dissolution of wind-assisted species has been recorded over 1,600 km of sea between Australia and the South Island of New Zealand.

The danger of flying for very small insects like thrips is the possibility of being trapped by water. Thrips have a body that does not wet the bed and has the ability to climb the meniscus by bending their bodies and working the way the first head and up along the water surface to escape.

Life cycle

Thrips spawn very small, about 0.2 mm. Women from the Terebrantia suborder cut the gap in the plant tissue with their ovipositor, and inserted their eggs, one per gap. Women from Tubulifera subordo lay their eggs individually or in small groups on the outer surface of the plant.

Thrips are hemimetabolous, morphed gradually into adult form. The first two instars, called larvae or nymphs, are like adults without small wings (often confused with springtails) without genitalia; this feeds on plant tissue. In Terebrantia, the third and fourth instar, and in Tubulifera also the fifth instar, is a non-eating break stage similar to pupa: at this stage, the organs are reshaped, and buds and genitals are formed. Adult stage can be achieved about 8-15 days; adults can live for about 45 days. Adults have winged and winged forms; in the thrips of grass Anaphothrips obscurus, for example, the winged form makes up 90% of the population in the spring (in the temperate zone), while the wingless form makes up 98% of the population at the end of the summer. Thrips can survive in winter as adults or through eggs or diapause pupa.

Thrips are haplodiploid with haploid stud (from infertile eggs, as in Hymenoptera) and diploid females capable of parthenogenesis (reproduction without fertilization), many species use arrhenotoky, some use thelytoky. The endosymbiont that determines sex Wolbachia is a factor affecting the reproductive mode. Some bisexual species have usually been established in the United States with only women.

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Human impact

As pest

Many thrips are commercial plant pests because of the damage caused by eating on the development of flowers or vegetables, causing discoloration, defects, and reduced plant selling power. Some thrips serve as vectors for plant diseases, such as tospoviruses. More than 20 viruses that infect plants are known to be transmitted by thrips, but on the other hand, fewer than a dozen of the described species are known tospovirus vectors. These enveloped viruses are considered one of the most destructive plant pathogens worldwide, with vector species that have a major impact on human farming. Members of the virus include the withered tomato virus that is visible and the virus where necrotic impatiens. Thrips of the western flower, Frankliniella occidentalis , have spread until now have worldwide distribution, and are the main vectors of plant diseases caused by tospoviruses. Their small size and tendency to enclosed places make them difficult to detect by phytosanitary examination, while their eggs, placed in plant tissue, are well protected from pesticide sprays. When combined with the increasing globalization of trade and the growth of greenhouse agriculture, thrips, not surprisingly, are the fastest-growing group of invasive species in the world. Examples include F. occidentalis , Thrips simplex , and Thrips palmi .

Flower-eating thrips are routinely attracted to the colors of bright flowers (including white, blue, and especially yellow), and will land and try to feed. This is unusual for some species (eg, Frankliniella tritici and Limberrips cerealium) to "bite" humans in such circumstances. Although no species eat blood and no animal disease is known to be transmitted by thrips, some skin irritations have been described.

Management

Thrips develops resistance to insecticides easily and there is constant research on how to control them. This makes ideal thrips a model for testing the effectiveness of pesticides and new methods.

Due to its small size and high reproduction rate, thrips are difficult to control using classical biological controls. Suitable predators should be small and slim enough to penetrate the gaps where thrips hide during breastfeeding, and they should also extend eggs and larvae extensively to be effective. Only two families of Hymenoptera parasitoids shrink eggs and larvae, Eulophidae and Trichogrammatidae. Other biocontrol agents from adults and larvae include anthocorid insects from the genus Orius , and phytoseiid mites. Biological insecticides such as the fungus Beauveria bassiana and Verticillium lecanii can kill thrips at all stages of the life cycle. An effective insecticide soap spray against thrips. It is commercially available or can be made from a certain type of household soap. Scientists in Japan report that significant reductions in larvae and adult melon thrips occur when the plant is illuminated with red light.

How To Get Rid Of Thrips Pests In Your Garden - YouTube