Misplaced Pages

#752247

59-424: Trialeurodes is a large genus of whiteflies in the family Aleyrodidae . This Hemiptera article related to members of the insect suborder Sternorrhyncha is a stub . You can help Misplaced Pages by expanding it . Aleyrodidae Aleurodicinae Aleyrodinae Udamoselinae † Bernaeinae Aleurodidae Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise

118-494: A defense to gooseberries or tomatoes. They provide root chemicals that deter whiteflies. A study intercropping French marigolds with short-vine tomatoes in glasshouse growing conditions achieved some control of whiteflies when the plants were grown together from the beginning of the growing season; however, limonene dispensers were more effective. Zinnias , conversely, attract predators that consume whiteflies, including hummingbirds and predatory wasps and flies. Other plants with

177-417: A dormant state in the wild and shipped for use in pest control; however, they may not stay in the location where they are released. They do live for about a year and will continuously lay eggs and reproduce. Spraying the bugs' wings with a sticky substance before release may hinder their ability to fly. Some promising claims have been made that mesh or film that excludes ultraviolet of certain wavelengths from

236-596: A floury, dusted appearance, hence names such as Aleyrodidae, Aleurodidae and Aleuroduplidens ; the root refers to the Ancient Greek : αλευρώδης (aleurodes) meaning "floury". However, not all species are white; for example, Aleurocanthus woglumi is slaty black. The legs of Aleyrodidae are well developed and fairly long, but gracile , and in contrast to Psyllidae , not adapted to leaping. The tarsi have two segments of roughly equal length. The pretarsus has paired claws, with an empodium between—in some species

295-429: A greater number of segments is required to achieve the same kinds of movements that are possible in vertebrate animals, which have rotational ball-and-socket joints at the base of the fore and hind limbs. The appendages of arthropods may be either biramous or uniramous . A uniramous limb comprises a single series of segments attached end-to-end. A biramous limb, however, branches into two, and each branch consists of

354-493: A greenhouse interfere severely with the ability of whitefly and various other greenhouse pests, to find their food plants. It is not yet clear, assuming that the effect is substantially of value, how readily pests in such circumstances might develop behavioural tolerance to such control measures. A number of plants can be intercropped with vegetables, in a garden setting, serving as companion plants to protect against whiteflies. For example, nasturtiums are thought to provide

413-478: A larval stage after they hatch for one to three weeks. The adult insects can fly and will feed only on pollen, honey, and nectar to reproduce. Repeated application may be necessary and the eggs could be eaten before they hatch by their natural predators, such as ants or mature green lacewings. Ladybirds are also used. They eat mostly insect eggs, but will also feed on beetle larvae , aphids, scale insects, and young caterpillars . Adults are often collected when in

472-424: A median bristle or empodium , meaning the meeting place of the pulvilli. On the underside of the tarsal segments, there frequently are pulvillus-like organs or plantulae . The arolium, plantulae and pulvilli are adhesive organs enabling their possessors to climb smooth or steep surfaces. They all are outgrowths of the exoskeleton and their cavities contain blood. Their structures are covered with tubular tenent hairs,

531-636: A series of segments attached end-to-end. The external branch (ramus) of the appendages of crustaceans is known as the exopod or exopodite , while the internal branch is known as the endopod or endopodite . Other structures aside from the latter two are termed exites (outer structures) and endites (inner structures). Exopodites can be easily distinguished from exites by the possession of internal musculature. The exopodites can sometimes be missing in some crustacean groups ( amphipods and isopods ), and they are completely absent in insects. The legs of insects and myriapods are uniramous. In crustaceans,

590-414: A similar function include the hummingbird bush , pineapple sage , and bee balm . Each of these plants also conceals the scent of nearby plants, making their detection by some pest insects more difficult, as do most other mints. Arthropod leg Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for

649-422: A tarsal claw. Myriapod legs show a variety of modifications in different groups. In all centipedes, the first pair of legs is modified into a pair of venomous fangs called forcipules. In most millipedes, one or two pairs of walking legs in adult males are modified into sperm-transferring structures called gonopods . In some millipedes, the first leg pair in males may be reduced to tiny hooks or stubs, while in others

SECTION 10

#1733086227753

708-445: A while, then undergoes changes within its skin, ceasing feeding and growing a new skin, forming what amounts to pupa. In doing so the insect does not shed the larval skin, which it retains as a protective puparium and which dries out. Meanwhile, the pupa within this skin develops into a pharate adult that usually is visible through the wall of the puparium. The puparium splits open as the imago forces its way out. This pupal stage

767-407: Is adapted for running ( cursorial ), rather than for digging, leaping, swimming, predation, or other similar activities. The legs of most cockroaches are good examples. However, there are many specialized adaptations, including: The embryonic body segments ( somites ) of different arthropods taxa have diverged from a simple body plan with many similar appendages which are serially homologous, into

826-816: Is advised. Specific insecticide information and guidance for the fig whitefly is available from the University of Florida. Care should be taken to ensure that the insecticide used will not kill the natural predators of whiteflies. For effective use of biological method after application of pesticide, plant washing is advised prior to release of predators or parasitoids. Pesticides used for whitefly control usually contain neonicotinoid compounds as active ingredients: clothianidin (commercial), dinotefuran (over-the-counter and commercial), imidacloprid (over-the-counter and commercial) and thiamethoxam (commercial). Neonicotinoids can be harmful if ingested. Rotation of insecticides from different families may be effective at preventing

885-840: Is analogous to the pupal forms of the Holometabola and it raises questions of terminology and concept. Some authorities argue that there is little functional, and no logically cogent basis for the distinction between the terms "larva" and "nymph". Some have long been in favour of dropping the term nymph entirely, and certainly apply the term "larvae" to the Aleyrodidae. In warm or tropical climates and especially in greenhouses, whiteflies present major problems in crop protection . Worldwide economic losses are estimated at hundreds of millions of dollars annually. Prominent pest species include: Although several species of whitefly may cause some crop losses simply by sucking sap when they are very numerous,

944-592: Is associated with sexual dimorphism in which one sex is markedly larger than the other. Such dimorphism is common in the Sternorrhyncha, in which the males of most scale insects for example are tiny compared to the female. Remarkably however, in some giant tropical species the males are much larger than the females. Like most of the mobile Sternorrhyncha, adult Aleyrodidae have well-developed antennae, which in most species in this family are seven-segmented. As in many Hemiptera, there are two ocelli , which generally in

1003-451: Is difficult and complex, as whiteflies rapidly develop resistance to chemical pesticides . The USDA recommends "an integrated program that focuses on prevention and relies on cultural and biological control methods when possible". While an initial pesticide application may be necessary to control heavy infestations, repeated applications may lead to strains of whiteflies that are resistant to pesticides, so only use of selective insecticides

1062-964: Is heavily infested. Pesticide use is not ideal in the case of controlling whitefly and widespread contamination can be costly; it is best to avoid this problem with aggressive preventive measures. Several predators and parasitoids may be effective in controlling whitefly infestations, including green lacewings , ladybirds , minute pirate bugs , big-eyed bugs , damsel bugs , Encarsia formosa and phytoseiid mites . Integrated management of whiteflies can as well be done using biopesticides based on microbials such as Beauveria bassiana (effective on larvae and adults) or Isaria fumosorosea . Green lacewing larvae have voracious appetites, so will attack whiteflies, as well as other pests, including aphids , mealybugs , spider mites , leafhopper larvae, moth eggs, scales , and thrips . They also can attack other insects, including caterpillars. They are available as eggs from commercial insectaries, and will stay in

1121-523: Is no longer used. Arachnid legs differ from those of insects by the addition of two segments on either side of the tibia, the patella between the femur and the tibia, and the metatarsus (sometimes called basitarsus) between the tibia and the tarsus (sometimes called telotarsus), making a total of seven segments. The tarsus of spiders have claws at the end as well as a hook that helps with web-spinning. Spider legs can also serve sensory functions, with hairs that serve as touch receptors, as well as an organ on

1180-486: Is the fourth section of the typical insect leg. As a rule, the tibia of an insect is slender in comparison to the femur, but it generally is at least as long and often longer. Near the distal end, there is generally a tibial spur, often two or more. In the Apocrita , the tibia of the foreleg bears a large apical spur that fits over a semicircular gap in the first segment of the tarsus. The gap is lined with comb-like bristles, and

1239-645: Is unclear. The degree of separation is useful in recognising the species; for instance, one way to tell adult Bemisia from Trialeurodes is that the upper and lower parts of the compound eyes are connected by a single ommatidium in Bemisia , while in Trialeurodes they are completely separate. Both sexes have functional mouthparts and two pairs of membranous, functional wings; the rear wings are neither much reduced, nor modified into any such hooked or haltere -like structures as occur in some other Hemiptera such as many of

SECTION 20

#1733086227753

1298-459: The Apterygota , the legs of immature specimens are in effect smaller versions of the adult legs. A representative insect leg, such as that of a housefly or cockroach , has the following parts, in sequence from most proximal to most distal : Associated with the leg itself there are various sclerites around its base. Their functions are articular and have to do with how the leg attaches to

1357-507: The Cerylonidae have four tarsomeres on each tarsus. The distal segment of the typical insect leg is the pretarsus. In the Collembola , Protura and many insect larvae, the pretarsus is a single claw. On the pretarsus most insects have a pair of claws ( ungues , singular unguis ). Between the ungues, a median unguitractor plate supports the pretarsus. The plate is attached to the apodeme of

1416-570: The Coccoidea . The wing venation is reduced, like that of the Psyllidae, only generally much more so. In many genera there is only one conspicuous and unbranched vein in each wing; however, wings of larger species such as Udamoselis have less reduced venation, though their veins still are simple and few. The insects and their wings are variously marked or mottled according to species, and many species are covered with fine wax powder, giving most species

1475-605: The Scarabaeidae and Dytiscidae have thoracic legs, but no prolegs. Some insects that exhibit hypermetamorphosis begin their metamorphosis as planidia , specialised, active, legged larvae, but they end their larval stage as legless maggots, for example the Acroceridae . Among the Exopterygota , the legs of larvae tend to resemble those of the adults in general, except in adaptations to their respective modes of life. For example,

1534-420: The family Aleyrodidae , the only family in the superfamily Aleyrodoidea . More than 1550 species have been described. The Aleyrodidae are a family in the suborder Sternorrhyncha and at present comprise the entire superfamily Aleyrodoidea, related to the superfamily Psylloidea . The family often occurs in older literature as "Aleurodidae", but that is a junior synonym and accordingly incorrect in terms of

1593-431: The honeydew whiteflies secrete. This may also seriously impede the ability of farms to process cotton harvests. Whiteflies share a modified form of hemimetabolous metamorphosis , in that the immature stages begin life as mobile individuals, but soon attach to host plants. The stage before the adult is called a pupa , though it shares little in common with the pupal stage of holometabolous insects. Whitefly control

1652-446: The most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a Hox -gene , could result in parallel gains of leg segments. In arthropods, each of the leg segments articulates with the next segment in a hinge joint and may only bend in one plane. This means that

1711-410: The vasiform orifice on the dorsal surface of the caudal segment of the abdomen. This orifice is large and is covered by an operculum . The entire structure is characteristic of the Aleyrodidae and within the family it is taxonomically diagnostic because it varies in shape according to the species. Within the orifice beneath the operculum there is a tongue-like lingula. It appears to be involved in

1770-410: The Aleyrodidae are placed at the anterior margins of the compound eyes. The compound eyes themselves are rather remarkable: many have a distinct constriction between the upper and lower halves, and in some species there is a complete separation. Many insects' compound eyes are divided into functionally and anatomically distinct upper and lower regions, but the adaptation's purpose or origin in Aleyrodidae

1829-743: The Lower Cretaceous. The eggs of Aleyrodidae generally are laid near each other on the food plant, usually on a leaf, in spiral patterns or arcs, sometimes in parallel arcs. The egg is elongated, with one narrow end produced into a pedicel, which in some species is longer than the rest of the egg. After fertilisation the pedicel shrivels into a stalk. The details vary, but at least some species can reproduce parthenogenically by automixis . However, apparently all males are parthenogenically produced by arrhenotoky . The female however, can mate with her own male offspring, and thereafter produce eggs of both sexes. There generally are four larval instars . All

Trialeurodes - Misplaced Pages Continue

1888-465: The Odonata. In parasitic Hymenoptera, the base of the femur has the appearance of a second trochanter. In most insects, the femur is the largest region of the leg; it is especially conspicuous in many insects with saltatorial legs because the typical leaping mechanism is to straighten the joint between the femur and the tibia, and the femur contains the necessary massive bipennate musculature. The tibia

1947-445: The apices of which are moistened by a glandular secretion. The organs are adapted to apply the hairs closely to a smooth surface so that adhesion occurs through surface molecular forces. Insects control the ungues through muscle tension on a long tendon, the "retractor unguis" or "long tendon". In insect models of locomotion and motor control, such as Drosophila ( Diptera ), locusts ( Acrididae ), or stick insects ( Phasmatodea ),

2006-405: The building of tolerance to the product. Clothianidin and dinotefuran are of the same family. Spraying the leaves using insecticidal soap is another, environmentally friendly, option. Biological methods have also been proposed to control whitefly infestation, and may be paired with chemical methods. Washing the plant, especially the undersides of leaves, may help reduce the number of the pests on

2065-507: The coxa has two lobes where it articulates with the pleuron. The posterior lobe is the meron which is usually the larger part of the coxa. A meron is well developed in Periplaneta, the Isoptera, Neuroptera and Lepidoptera. The trochanter articulates with the coxa but usually is attached rigidly to the femur. In some insects, its appearance may be confusing; for example it has two subsegments in

2124-403: The empodium is a bristle, but in others it is a pad. The digestive system of the Aleyrodidae is typical of the Sternorrhyncha, including a filter chamber , and all active stages of the Aleyrodidae accordingly produce large quantities of honeydew; the anus is adapted to presentation of honeydew to symbiotic species, mainly ants; the honeydew emerges from the anus, which is inside an opening called

2183-575: The expulsion of honeydew, and in fact at one time was wrongly assumed to be the organ that produced the honeydew. In some species it protrudes from beneath the operculum, but in others it normally is hidden. The oldest members of the family belong to the Mesozoic subfamily Bernaeinae , known from the Middle/Upper Jurassic-Upper Cretaceous, the oldest representatives of the extant subfamilies Aleyrodinae and Aleurodicinae appear during

2242-408: The first antennae are uniramous, but the second antennae are biramous, as are the legs in most species. For a time, possession of uniramous limbs was believed to be a shared, derived character , so uniramous arthropods were grouped into a taxon called Uniramia . It is now believed that several groups of arthropods evolved uniramous limbs independently from ancestors with biramous limbs, so this taxon

2301-511: The first pair may be enlarged. Insects and their relatives are hexapods, having six legs, connected to the thorax , each with five components. In order from the body they are the coxa, trochanter, femur, tibia, and tarsus. Each is a single segment, except the tarsus which can be from three to seven segments, each referred to as a tarsomere . Except in species in which legs have been lost or become vestigial through evolutionary adaptation, adult insects have six legs, one pair attached to each of

2360-470: The flexor muscle of the ungues. In the Neoptera , the parempodia are a symmetrical pair of structures arising from the outside (distal) surface of the unguitractor plate between the claws. It is present in many Hemiptera and almost all Heteroptera . Usually, the parempodia are bristly (setiform), but in a few species they are fleshy. Sometimes the parempodia are reduced in size so as to almost disappear. Above

2419-675: The genus Bemisia . Bemisia tabaci and B. argentifolii transmit African cassava mosaic , bean golden mosaic, bean dwarf mosaic, bean calico mosaic , tomato yellow leaf curl , tomato mottle, and other Begomoviruses , in the family Geminiviridae . The worldwide spread of emerging biotypes, such as B. tabaci biotype B, also known as, 'B. argentifolii', and a new biotype Q, continue to cause severe crop losses which are expected to increase, demanding matching increases in pesticide use on many crops (tomatoes, beans, cassava, cotton, cucurbits, potatoes, sweet potatoes). Efforts to develop environmentally friendly integrated pest management systems, with

Trialeurodes - Misplaced Pages Continue

2478-669: The goal of reducing insecticide use, aim to re-establish the ecological equilibrium of predators , parasitoids , and microbial controls that were once in place. New crop varieties are also being developed with increased tolerance to whiteflies, and to the plant diseases carried by them. A major problem is that whiteflies and the viruses they carry can infect many host plants, including agricultural crops, palms, and weeds. These problems are complicated by difficulties in classifying and detecting new whitefly biotypes and begomoviruses. Proper diagnosis of plant diseases depends on using sophisticated molecular techniques to detect and characterize

2537-414: The growth of the fungi. However, by far their major importance as crop pests is their transmission of diseases of plants. Although there are a great many species of whiteflies, and the family is notorious for devastating transmission of crop viruses , the actual proportion of whiteflies which are responsible is very low. The most prominent disease vectors among the Aleyrodidae are a species complex in

2596-560: The insect cleans its antennae by drawing them through. The ancestral tarsus was a single segment and in the extant Protura , Diplura and certain insect larvae the tarsus also is single-segmented. Most modern insects have tarsi divided into subsegments (tarsomeres), usually about five. The actual number varies with the taxon , which may be useful for diagnostic purposes. For example, the Pterogeniidae characteristically have 5-segmented fore- and mid-tarsi, but 4-segmented hind tarsi, whereas

2655-431: The instars are more or less in the shape of a flattened ellipse fringed with bristles and waxy filaments. The first instar has functional legs, though short. Once it has inserted its stylets into the phloem to feed, it settles down and no longer uses its legs, and they degenerate after the first ecdysis . From then until it emerges as an adult, it remains attached to the plant by its mouthparts. The final instar feeds for

2714-607: The international standards for zoological nomenclature. Aleyrodidae are small insects, most species with a wingspan of less than 3 mm and a body length of 1 mm to 2 mm. Many are so small that their size complicates their control in greenhouses because they can only be excluded by screening with very fine mesh; in fact they can enter mesh so fine that many of their natural enemies cannot come in after them, so that unchecked whitefly populations in greenhouses rapidly become overwhelming. Some "giant whitefly" species exist, some of which may exceed 5 mm in size. This sometimes

2773-464: The legs of larval insects, particularly in the Endopterygota , vary more than in the adults. As mentioned, some have prolegs as well as "true" thoracic legs. Some have no externally visible legs at all (though they have internal rudiments that emerge as adult legs at the final ecdysis ). Examples include the maggots of flies or grubs of weevils . In contrast, the larvae of other Coleoptera , such as

2832-414: The legs of most immature Ephemeroptera are adapted to scuttling beneath underwater stones and the like, whereas the adults have more gracile legs that are less of a burden during flight. Again, the young of the Coccoidea are called "crawlers" and they crawl around looking for a good place to feed, where they settle down and stay for life. Their later instars have no functional legs in most species. Among

2891-461: The locos Norte City Agriculture Office discovered cauliflower Aleyrodidae infestation in Laoag due to changing weather . Whiteflies feed by tapping into the phloem of plants, introducing toxic saliva and decreasing the plants' overall turgor pressure . Since whiteflies congregate in large numbers, susceptible plants can be quickly overwhelmed. Further harm is done by mold growth encouraged by

2950-408: The long tendon courses through the tarsus and tibia before reaching the femur. Tension on the long tendon is controlled by two muscles, one in the femur and one in the tibia, which can operate differently depending on how the leg is bent. Tension on the long tendon controls the claw, but also bends the tarsus and likely affects its stiffness during walking. The typical thoracic leg of an adult insect

3009-476: The main exoskeleton of the insect. Such sclerites differ considerably between unrelated insects. The coxa is the proximal segment and functional base of the leg. It articulates with the pleuron and associated sclerites of its thoracic segment, and in some species it articulates with the edge of the sternite as well. The homologies of the various basal sclerites are open to debate. Some authorities suggest that they derive from an ancestral subcoxa. In many species,

SECTION 50

#1733086227753

3068-411: The major harm they do is indirect. Firstly, like many other sap-sucking Hemiptera, they secrete large amounts of honeydew that support unsightly or harmful infestations of sooty mold . Recent studies suggest that insecticides can also be excreted through the honeydew leading to unintended effects. Secondly, they inject saliva that may harm the plant more than either the mechanical damage of feeding or

3127-572: The naming system used in the other groups. They are: coxa, basis, ischium, merus, carpus, propodus, and dactylus. In some groups, some of the limb segments may be fused together. The claw ( chela ) of a lobster or crab is formed by the articulation of the dactylus against an outgrowth of the propodus. Crustacean limbs also differ in being biramous, whereas all other extant arthropods have uniramous limbs. Myriapods ( millipedes , centipedes and their relatives) have seven-segmented walking legs, comprising coxa, trochanter, prefemur, femur, tibia, tarsus, and

3186-484: The plants and make their management by other methods more effective. Whiteflies are also attracted by the color yellow, so yellow sticky paper can serve as traps to monitor infestations. Dead leaves or leaves that have been mostly eaten by whiteflies can be removed and burned or carefully placed in closed bins to avoid reinfestation and spreading of the disease. Early detection in combination with hosing or vacuuming of diseased portions as well as removal of any section that

3245-501: The same structure as modern adult insect legs, and there has been a great deal of debate as to whether they are homologous with them. Current evidence suggests that they are indeed homologous up to a very primitive stage in their embryological development, but that their emergence in modern insects was not homologous between the Lepidoptera and Symphyta . Such concepts are pervasive in current interpretations of phylogeny. In general,

3304-529: The tarsus that serves as a humidity receptor, known as the tarsal organ . The situation is identical in scorpions , but with the addition of a pre-tarsus beyond the tarsus. The claws of the scorpion are not truly legs, but are pedipalps , a different kind of appendage that is also found in spiders and is specialised for predation and mating. In Limulus , there are no metatarsi or pretarsi, leaving six segments per leg. The legs of crustaceans are divided primitively into seven segments, which do not follow

3363-438: The three segments of the thorax. They have paired appendages on some other segments, in particular, mouthparts , antennae and cerci , all of which are derived from paired legs on each segment of some common ancestor . Some larval insects do however have extra walking legs on their abdominal segments; these extra legs are called prolegs . They are found most frequently on the larvae of moths and sawflies. Prolegs do not have

3422-492: The unguitractor plate, the pretarsus expands forward into a median lobe, the arolium . Webspinners ( Embioptera ) have an enlarged basal tarsomere on each of the front legs, containing the silk -producing glands. Under their pretarsi, members of the Diptera generally have paired lobes or pulvilli, meaning "little cushions". There is a single pulvillus below each unguis. The pulvilli often have an arolium between them or otherwise

3481-782: The viruses and whiteflies which are present in a crop. A team of researchers, extension agents and growers working together are needed to follow disease development, using dynamic modeling, to understand the incidence of disease spread. In 1997, tomato yellow leaf-curl begomovirus was discovered in Florida, USA. This is the worst viral disease transmitted by the whitefly, Bemisia argentifolii . The whitefly has also been shown to transmit almost 60 other viral plant diseases. In 2023 flower plantations in Naga, Camarines Sur were infested by whiteflies. Eggplant crops in Baler, Aurora were also affected. In 2024,

#752247