|Thrips tabaci (left); Frankliniella occidentalis (right)|
Thrips tabaci is a species of very small insect in the genus Thrips in the order Thysanoptera. It is commonly known as the onion thrips, the potato thrips, the tobacco thrips or the cotton seedling thrips.It is an agricultural pest that can damage crops of onions and other plants, and it can additionally act as a vector for plant viruses.
In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.
A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
Thrips is a genus of thrips.
In some populations, nearly all onion thrips are female, and males are very rare. 1 to 1.3 mm (0.04 to 0.05 in) long. The body is some shade of yellow, yellowish-brown or brown; the antennae have seven segments, the wings are well-developed and females have an ovipositor at the tip of the abdomen.The adult onion thrips is some
The ovipositor is an organ used by some animals for the laying of eggs. In insects an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typically its form is adapted to functions such as transmitting the egg, preparing a place for it, and placing it properly. In some insects the organ is used merely to attach the egg to some surface, but in many parasitic species it is a piercing organ as well.
The onion thrips is thought to have originated in the Mediterranean region but is now found on all continents except Antarctica.It infests a wide range of host plants that include onion, leek and garlic, brassicaceous plants such as cabbage, cauliflower and broccoli, asparagus, sugarbeet, melon, pumpkin, marrow and cucumber, strawberry, potato, tobacco, cotton and many fruiting and ornamental plants. Onion thrips was the first vector identified for tomato spotted wilt virus, being reported in 1927. There are now some identified populations of onion thrips that are not able to transmit tomato spotted wilt virus, possibly due to genetic spread in the global population.
In biology and medicine, a host is an organism that harbours a parasitic, a mutualistic, or a commensalist guest (symbiont), the guest typically being provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.
The female inserts her saw-like ovipositor into plant tissues and lays her eggs under the epidermis. The eggs are white at first, turning orange later, and hatch in four to five days. The larvae are white or yellowish and suck sap from the plant tissues. Two larval stages lasting about nine days in total are followed by the non-feeding prepupal and pupal stages which last four to seven days in total. The adult survives for two or three weeks during which time the females lay about eighty eggs. Most of the eggs are unfertilised and produced by parthenogenesis. In Hawaii, only about one in a thousand individuals is male,and in this location, it breeds throughout the year. In cooler climates it overwinters in plant debris and becomes active again in spring.
Parthenogenesis is a natural form of asexual reproduction in which growth and development of embryos occur without fertilization. In plants parthenogenesis is a component process of apomixis.
In populations from different areas, the ratio of males to females varies. A male to female ratio as high as 1 male to 2 females has been recorded from Central Spain, and 1 male to 6 females in Colorado. In contrast, counts as low as 1 male to 300 females have been recorded from Sudan, and in Hawaii a collection of over 5000 specimens held only 5 males in total. Some collections over the years from France, Japan, Taiwan and India have had no reported males at all. One study of the literature published in 1990 suggested a correlation between longitude and male population number, with the higher male counts occurring in the Western hemisphere.
The onion thrips is the most serious insect pest attacking onion crops in the tropics. The thrips rasp and pierce the surface of the plant with their mouthparts, mostly choosing young plant growth. They then add digestive juices and suck up the fluids that seep from the wounds. As the plant part grows, so do the damaged regions, leaving silvery streaks. The more thrips that are present, the greater the area of plant damaged, reducing the area of foliage available for photosynthesis. At the same time, more water is transpired and pathogens can find a way to gain entry. In severely damaged plants, leaves may wither and the whole plant may appear silvery; the crop ripens prematurely but the yield is greatly reduced.
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name photosynthesis, from the Greek φῶς, phōs, "light", and σύνθεσις, synthesis, "putting together". In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies all of the organic compounds and most of the energy necessary for life on Earth.
The onion thrips is a vector of certain plant viruses, including iris yellow spot tospovirus, strawberry necrotic shock virus, tobacco streak virus and tomato spotted wilt virus.It is also a vector of Alternaria porri , which causes the fungal disease known as purple blotch.
Whiteflies are small Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.
The silverleaf whitefly is one of several species of whitefly that are currently important agricultural pests. A review in 2011 concluded that the silverleaf whitefly is actually a species complex containing at least 24 morphologically indistinguishable species.
Paratrichodorus minor is a species of nematode in the family Trichodoridae, the stubby-root nematodes. It occurs in tropical and subtropical regions of the world. It damages plants by feeding on the roots and it is a vector of plant viruses. It is a pest of some agricultural crops.
Impatiens necrotic spot virus(INSV) is a plant pathogenic virus of the order Bunyavirales. It was originally believed to be another strain of Tomato spotted wilt virus but genetic investigations revealed them to be separate viruses. It is a single stranded RNA It has a tripartite genome and is largely spread by the insect vector of the western flower thrips. The virus infects more than 648 species of plant including important horticultural and agricultural species such as fuchsia, tomato, orchids, and lettuce. As the name implies, the main symptom on plants is necrotic spots that appear on the leaves. The INSV virus infects by injecting the RNA the virus contains into the cell which then starts using the cell resources to transcribe what the virus RNA states. Viral infection can often result in the death of the plant. The disease is mainly controlled by the elimination of the western flower thrip vector and by destroying any infected plant material.
Tobacco streak virus (TSV) is a plant pathogenic virus of the family Bromoviridae, in the genus Ilavirus. It has a wide host range, with at least 200 susceptible species. TSV is generally more problematic in the tropics or warmer climates. TSV does not generally lead to epidemics, with the exception of sunflowers in India and Australia, and peanuts in India.
Tomato yellow leaf curl virus(TYLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. TYLCV causes the most destructive disease of tomato, and it can be found in tropical and subtropical regions causing severe economic losses. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci, commonly known as the silverleaf whitefly or the sweet potato whitefly. The primary host for TYLCV is the tomato plant, and other plant hosts where TYLCV infection has been found include eggplants, potatoes, tobacco, beans, and peppers. Due to the rapid spread of TYLCV in the last few decades, there is an increased focus in research trying to understand and control this damaging pathogen. Some interesting findings include virus being sexually transmitted from infected males to non-infected females, and an evidence that TYLCV is transovarially transmitted to offspring for two generations.
The western flower thrips [Frankliniella occidentalis (Pergande)] is an invasive pest insect in agriculture. This species of thrips is native to the Southwestern United States but has spread to other continents, including Europe, Australia, and South America via transport of infested plant material. It has been documented to feed on over 500 different species of host plants, including a large number of fruit, vegetable, and ornamental crops. The adult male is about 1 mm long; the female is slightly larger, about 1.4 mm in length. Most western flower thrips are female and reproduce by arrhenotokous parthenogenesis; i.e. females can produce males from unfertilized eggs, but females arise only from fertilized eggs. Males are rare, and are always pale yellow, while females vary in color, often by season, from red to yellow to dark brown. Each adult is elongated and thin, with two pairs of long wings. The eggs are oval or kidney-shaped, white, and about 0.2 mm long. The nymph is yellowish in color with red eyes.
The Orthotospoviruses are a genus of negative RNA virus found within the family Tospoviridae of the order Bunyavirales. The genus takes its name from the discovery of tomato spotted wilt virus (TSWV) in Australia in 1919. It remained the only member of the family until the early 1990s when genetic characterisation of viruses discovered in plants became more common. There are now at least twenty viral species in the family with more being recorded and described on a relatively regular basis. Together, these viruses have been documented infecting over eight hundred different plant species from 82 different families.
The chilli thrips or yellow tea thrips, Scirtothrips dorsalis Hood, is an extremely successful invasive species of pest-thrips which has expanded rapidly from Asia over the last twenty years, and is gradually achieving a global distribution. It has most recently been reported in St. Vincent (2004) Florida (2005), Texas (2006), and Puerto Rico (2007). It is a pest of economic significance with a broad host range, with prominent pest reports on crops including pepper, mango, citrus, strawberry, grapes, cotton, tea, peanuts, blueberry, and roses. Chilli thrips appear to feed preferentially on new growth, and infested plants usually develop characteristic wrinkled leaves, with distinctive brown scarring along the veins of leaves, the buds of flowers, and the calyx of fruit. Feeding damage can reduce the sale value of crops produced, and in sufficient numbers, kill plants already aggravated by environmental stress. This thrips has also been implicated in the transmission of three tospoviruses, but there is some controversy over its efficiency as a vector.
Heliothis virescens, commonly known as the tobacco budworm, is a moth of the Noctuidae family found throughout the eastern and southwestern United States along with parts of Central America and South America.
Thrips palmi is an insect from the genus Thrips in the order Thysanoptera. It is known commonly as the melon thrips.
The Thripinae are a subfamily of thrips, insects of the order Thysanoptera. The Thripinae belong to the common thrips family Thripidae and include around 1,400 species in 150 genera. A 2012 molecular phylogeny found that the Thripinae was paraphyletic; further work will be needed to clarify the relationships within the group.
Frankliniella tritici, the eastern flower thrips, is a species of thrips in the genus Frankliniella. F. tritici inhabits blossom, such as dandelion flowers. They can directly damage plants, grasses and trees, in addition to commercial crops, and as a vector for tospoviruses, a form of plant virus, it particularly affects small fruit production in the United States, including strawberries, grapes, blueberries and blackberries. It can also affect alfalfa, oats, beans and asparagus crops. The species features strap-like wings edged with long hairs, a design which increases aerodynamic efficiency in very small arthropods; the reduced drag means the insect uses less energy. They extract nutrients directly from individual plant cells, and may also digest cells of fungi in the leaf litter.
Dicyphus hesperus is a species of true bug in the family Miridae. It is a generalist predator of other insects and also feeds on plant tissues. It is native to North America and has been used there in biological control of agricultural pests, especially whitefly on tomatoes.
Thrips simplex is a species of insect in the genus Thrips in the order Thysanoptera. It is commonly known as the gladiolus thrips and infests gladiolus plants as well as various other monocotyledonous plants such as lilies, irises and freesias.
The common blossom thrips is a species of thrips in the family Thripidae. It is found in many parts of the world and is an important pest insect in agriculture.
Pepper leaf curl virus(PepLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. PepLCV causes severe disease especially in pepper. It can be found in tropical and subtropical regions such as Thailand and India, but has also been detected in countries such as the United States and Nigeria. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci. The primary host for PepLCV are several Capsicum spp.. PepLCV has been responsible for several epidemics and causes severe economic losses. It is the focus of research trying to understand the genetic basis of resistance. Currently, a source of resistance to the virus has been identified in the Bhut Jolokia pepper.
Tomato spotted wilt virus (TSWV) is a spherical negative-sense RNA virus that has a diameter between 80-110nm.