80-433: Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved venom apparatus , such as fangs or a stinger , in a process called envenomation . Venom is often distinguished from poison , which is a toxin that is passively delivered by being ingested, inhaled, or absorbed through
160-408: A pupal stage and undergo complete metamorphosis . The majority of species are terrestrial, including a number of important agricultural pests, but some are found in freshwater habitats. These include the water boatmen , backswimmers , pond skaters , and giant water bugs . Hemiptera belong to the insect superorder Paraneoptera , which includes lice ( Psocodea ), thrips ( Thysanoptera ), and
240-423: A chemical arms race. Predator/prey pairs are expected to coevolve over long periods of time. As the predator capitalizes on susceptible individuals, the surviving individuals are limited to those able to evade predation. Resistance typically increases over time as the predator becomes increasingly unable to subdue resistant prey. The cost of developing venom resistance is high for both predator and prey. The payoff for
320-673: A double layer of grains, coarser on the outside. The Amazon rain forest cicada Hemisciera maculipennis displays bright red deimatic flash coloration on its hindwings when threatened; the sudden contrast helps to startle predators, giving the cicada time to escape. The coloured patch on the hindwing is concealed at rest by an olive green patch of the same size on the forewing, enabling the insect to switch rapidly from cryptic to deimatic behaviour. Some hemipterans such as firebugs have bold aposematic warning coloration, often red and black, which appear to deter passerine birds. Many hemipterans including aphids, scale insects and especially
400-443: A greater or lesser degree. The nymphs moult several times as they grow, and each instar resembles the adult more than the previous one. Wing buds grow in later stage nymphs; the final transformation involves little more than the development of functional wings (if they are present at all) and functioning sexual organs, with no intervening pupal stage as in holometabolous insects. Many aphids are parthenogenetic during part of
480-620: A herbaceous plant. Phloem sap, which has a higher concentration of sugars and nitrogen, is under positive pressure unlike the more dilute xylem sap. Most of the Sternorrhyncha and a number of Auchenorrhynchan groups feed on phloem. Phloem feeding is common in the Fulgoromorpha, most Cicadellidae and in the Heteroptera. The Typhlocybine Cicadellids specialize in feeding on non-vascular mesophyll tissue of leaves, which
560-404: A jam jar in and out. Stridulatory sounds are produced among the aquatic Corixidae and Notonectidae (backswimmers) using tibial combs rubbed across rostral ridges. Hemipterans are hemimetabolous , meaning that they do not undergo metamorphosis , the complete change of form between a larval phase and an adult phase . Instead, their young are called nymphs , and resemble the adults to
640-453: A protective mucus that acts as a chemical camouflage or macromolecular mimicry preventing "not self" recognition by the sea anemone and nematocyst discharge. Clownfish may acclimate their mucus to resemble that of a specific species of sea anemone. Toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms . They occur especially as proteins , often conjugated . The term
720-530: A safe level. In Europe, the European Food Safety Authority produced risk assessments for more than 4,000 substances in over 1,600 scientific opinions and they provide open access summaries of human health, animal health and ecological hazard assessments in their OpenFoodTox database. The OpenFoodTox database can be used to screen potential new foods for toxicity. The Toxicology and Environmental Health Information Program (TEHIP) at
800-488: A single species. This kind of polymorphism tends to be helpful when habitats are temporary with more energy put into reproduction when food is available and into dispersal through flight when food becomes scarce. In aphids, both winged and wingless forms occur with winged forms produced in greater numbers when food resources are depleted. Aphids and whiteflies can sometimes be transported very long distances by atmospheric updrafts and high altitude winds. Wing-length polymorphism
880-462: A sting. In bees and wasps , the stinger is a modified ovipositor (egg-laying device). In Polistes fuscatus , the female continuously releases a venom that contains a sex pheromone that induces copulatory behavior in males. In wasps such as Polistes exclamans , venom is used as an alarm pheromone, coordinating a response from the nest and attracting nearby wasps to attack the predator. In some species, such as Parischnogaster striatula , venom
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#1732765543663960-601: A take-off velocity of up to 2.7 metres per second and an acceleration of up to 250 g. The instantaneous power output is much greater than that of normal muscle, implying that energy is stored and released to catapult the insect into the air. Cicadas, which are much larger, extend their hind legs for a jump in under a millisecond, again implying elastic storage of energy for sudden release. Instead of relying on any form of locomotion, most Sternorrhyncha females are sedentary or completely sessile, attached to their host plants by their thin feeding stylets which cannot be taken out of
1040-425: A toxin delivered via a bite, sting, etc.). Poison is a related but broader term that encompasses both toxins and toxicants; poisons may enter the body through any means - typically inhalation , ingestion , or skin absorption . Toxin, toxicant, and poison are often used interchangeably despite these subtle differences in definition. The term toxungen has also been proposed to refer to toxins that are delivered onto
1120-409: A variety of modes of locomotion including swimming, skating on a water surface and jumping, as well as walking and flying like other insects. Several families of Heteroptera are water bugs , adapted to an aquatic lifestyle , such as the water boatmen (Corixidae), water scorpions (Nepidae), and backswimmers (Notonectidae). They are mostly predatory, and have legs adapted as paddles to help
1200-536: A water surface, in the same way that a toy soap boat propels itself. Water bugs in the genus Microvelia ( Veliidae ) can travel at up to 17 cm/s, twice as fast as they can walk, by this means. Flight is well developed in the Hemiptera although mostly used for short distance movement and dispersal. Wing development is sometimes related to environmental conditions. In some groups of Hemiptera, there are variations of winged, short-winged, and wingless forms within
1280-464: A wide range of diseases, explored in over 5,000 scientific papers. In medicine, snake venom proteins are used to treat conditions including thrombosis , arthritis , and some cancers . Gila monster venom contains exenatide , used to treat type 2 diabetes . Solenopsins extracted from fire ant venom has demonstrated biomedical applications, ranging from cancer treatment to psoriasis . A branch of science, venomics , has been established to study
1360-422: A wide range of medical conditions including thrombosis , arthritis , and some cancers . Studies in venomics are investigating the potential use of venom toxins for many other conditions. The use of venom across a wide variety of taxa is an example of convergent evolution . It is difficult to conclude exactly how this trait came to be so intensely widespread and diversified. The multigene families that encode
1440-451: A wide variety of habitats, generally terrestrial, though some are adapted to life in or on the surface of fresh water (e.g. pondskaters , water boatmen , giant water bugs ). Hemipterans are hemimetabolous , with young nymphs that somewhat resemble adults. Many aphids are capable of parthenogenesis , producing young from unfertilised eggs; this helps them to reproduce extremely rapidly in favourable conditions. Humans have interacted with
1520-405: 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
1600-537: Is applied all over the body as an antimicrobial protection. Many caterpillars have defensive venom glands associated with specialized bristles on the body called urticating hairs . These are usually merely irritating, but those of the Lonomia moth can be fatal to humans. Bees synthesize and employ an acidic venom ( apitoxin ) to defend their hives and food stores, whereas wasps use a chemically different venom to paralyse prey, so their prey remains alive to provision
1680-411: Is even lower in amino acids and contains monosaccharides rather than sucrose , as well as organic acids and minerals. No digestion is required (except for the hydrolysis of sucrose) and 90% of the nutrients in the xylem sap can be utilised. Some phloem sap feeders selectively mix phloem and xylem sap to control the osmotic potential of the liquid consumed. A striking adaptation to a very dilute diet
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#17327655436631760-529: Is found in a few other reptiles such as the Mexican beaded lizard , the gila monster , and some monitor lizards, including the Komodo dragon . Mass spectrometry showed that the mixture of proteins present in their venom is as complex as the mixture of proteins found in snake venom. Some lizards possess a venom gland; they form a hypothetical clade, Toxicofera , containing the suborders Serpentes and Iguania and
1840-502: Is found in many hemipterans: a filter chamber, a part of the gut looped back on itself as a countercurrent exchanger, which permits nutrients to be separated from excess water. The residue, mostly water with sugars and amino acids, is quickly excreted as sticky "honey dew", notably from aphids but also from other Auchenorrhycha and Sternorrhyncha. Some Sternorrhyncha including Psyllids and some aphids are gall formers. These sap-sucking hemipterans inject fluids containing plant hormones into
1920-455: Is higher. Rattlesnakes have responded locally by increasing the effectiveness of their venom. The kingsnakes of the Americas are constrictors that prey on many venomous snakes. They have evolved resistance which does not vary with age or exposure. They are immune to the venom of snakes in their immediate environment, like copperheads, cottonmouths, and North American rattlesnakes, but not to
2000-461: Is important to confirm usage if a common understanding is critical. Toxins are a subset of toxicants . The term toxicant is preferred when the poison is man-made and therefore artificial. The human and scientific genetic assembly of a natural-based toxin should be considered a toxin as it is identical to its natural counterpart. The debate is one of linguistic semantics . The word toxin does not specify method of delivery (as opposed to venom ,
2080-654: Is more nutritious than the leaf epidermis. Most Heteroptera also feed on mesophyll tissue where they are more likely to encounter defensive secondary plant metabolites which often leads to the evolution of host specificity. Obligate xylem feeding is a special habit that is found in the Auchenorrhyncha among Cicadoidea, Cercopoidea and in Cicadelline Cicadellids. Some phloem feeders may take to xylem sap facultatively, especially when facing dehydration. Xylem feeders tend to be polyphagous; to overcome
2160-408: Is notably rare in tree-living Hemiptera. Many Auchenorrhyncha including representatives of the cicadas, leafhoppers, treehoppers, planthoppers, and froghoppers are adapted for jumping (saltation). Treehoppers, for example, jump by rapidly depressing their hind legs. Before jumping, the hind legs are raised and the femora are pressed tightly into curved indentations in the coxae. Treehoppers can attain
2240-458: Is proven that reptile and platypus venom have independently evolved, it is thought that there are certain protein structures that are favored to evolve into toxic molecules. This provides more evidence of why venom has become a homoplastic trait and why very different animals have convergently evolved. Envenomation resulted in 57,000 human deaths in 2013, down from 76,000 deaths in 1990. Venoms, found in over 173,000 species, have potential to treat
2320-424: Is their "beak" in which the modified mandibles and maxillae form a "stylet" which is sheathed within a modified labium . The stylet is capable of piercing tissues and sucking liquids, while the labium supports it. The stylet contains a channel for the outward movement of saliva and another for the inward movement of liquid food. A salivary pump drives saliva into the prey; a cibarial pump extracts liquid from
2400-418: Is true of many aquatic species which are predatory, either as nymphs or adults. The predatory shield bug for example stabs caterpillars with its beak and sucks out the body fluids. The saliva of predatory heteropterans contains digestive enzymes such as proteinase and phospholipase , and in some species also amylase . The mouthparts of these insects are adapted for predation. There are toothed stylets on
2480-999: The Cnidaria , sea urchins among the Echinodermata , and cone snails and cephalopods , including octopuses , among the Molluscs . Venom is found in some 200 cartilaginous fishes, including stingrays , sharks , and chimaeras ; the catfishes (about 1000 venomous species); and 11 clades of spiny-rayed fishes ( Acanthomorpha ), containing the scorpionfishes (over 300 species), stonefishes (over 80 species), gurnard perches , blennies , rabbitfishes , surgeonfishes , some velvetfishes , some toadfishes , coral crouchers , red velvetfishes , scats , rockfishes , deepwater scorpionfishes , waspfishes , weevers , and stargazers . Some salamanders can extrude sharp venom-tipped ribs. Two frog species in Brazil have tiny spines around
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2560-492: The Early Devonian period. Hemipterans can dramatically cut the mass of affected plants, especially in major outbreaks. They sometimes also change the mix of plants by predation on seeds or feeding on roots of certain species. Some sap-suckers move from one host to another at different times of year. Many aphids spend the winter as eggs on a woody host plant and the summer as parthenogenetically reproducing females on
2640-530: The Malpighian tubules in their proximal segment that produce mucopolysaccharides, which form the froth around spittlebugs, offering a measure of protection. Parental care is found in many species of Hemiptera especially in members of the Membracidae and numerous Heteroptera. In many species of shield bug, females stand guard over their egg clusters to protect them from egg parasitoids and predators. In
2720-591: The Psylloidea and Aleyrodoidea . Aphids and Coccoids appear in the Triassic . The Coleorrhyncha extend back to the Lower Jurassic . The Heteroptera first appeared in the Triassic . The present members of the order Hemiptera (sometimes referred to as Rhynchota) were historically placed into two orders, the so-called Homoptera and Heteroptera/Hemiptera, based on differences in wing structure and
2800-530: The Sternorrhyncha and Auchenorrhyncha , or partially hardened, as in most Heteroptera . The name "Hemiptera" is from the Greek ἡμι- ( hemi ; "half") and πτερόν ( pteron ; "wing"), referring to the forewings of many heteropterans which are hardened near the base, but membranous at the ends. Wings modified in this manner are termed hemelytra (singular: hemelytron ), by analogy with
2880-483: The United States National Library of Medicine (NLM) maintains a comprehensive toxicology and environmental health web site that includes access to toxins-related resources produced by TEHIP and by other government agencies and organizations. This web site includes links to databases, bibliographies, tutorials, and other scientific and consumer-oriented resources. TEHIP also is responsible for
2960-482: The honeydew that these hemipterans secrete. The relationship is mutualistic , as both ant and aphid benefit. Ants such as the yellow anthill ant, Lasius flavus , breed aphids of at least four species, Geoica utricularia , Tetraneura ulmi , Forda marginata and Forda formicaria , taking eggs with them when they found a new colony; in return, these aphids are obligately associated with the ant, breeding mainly or wholly asexually inside anthills. Ants may also protect
3040-599: The lovebug is a fly and the Maybug and ladybug are beetles . The term is occasionally extended to colloquial names for freshwater or marine crustaceans (e.g. Balmain bug , Moreton Bay bug , mudbug ) and used by physicians and bacteriologists for disease-causing germs (e.g. superbugs ). Most hemipterans feed on plants, using their sucking and piercing mouthparts to extract plant sap . Some are bloodsucking, or hematophagous , while others are predators that feed on other insects or small invertebrates . They live in
3120-435: The phosphodiester bonds of DNA ; and neurotoxins, which disrupt signalling in the nervous system. Snake venom causes symptoms including pain, swelling, tissue necrosis, low blood pressure, convulsions, haemorrhage (varying by species of snake), respiratory paralysis, kidney failure, coma, and death. Snake venom may have originated with duplication of genes that had been expressed in the salivary glands of ancestors. Venom
3200-452: The Hemiptera for millennia. Some species, including many aphids, are significant agricultural pests , damaging crops by sucking the sap. Others harm humans more directly as vectors of serious viral diseases. The bed bug is a persistent parasite of humans, and some kissing bugs can transmit Chagas disease . Some species have been used for biological control of insect pests or of invasive plants. A few hemipterans, have been cultivated for
3280-816: The Toxicology Data Network (TOXNET), an integrated system of toxicology and environmental health databases that are available free of charge on the web. TOXMAP is a Geographic Information System (GIS) that is part of TOXNET. TOXMAP uses maps of the United States to help users visually explore data from the United States Environmental Protection Agency 's (EPA) Toxics Release Inventory and Superfund Basic Research Programs . Hemiptera Hemiptera ( / h ɛ ˈ m ɪ p t ər ə / ; from Ancient Greek hemipterus 'half-winged')
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3360-414: The animal move through the water. The pondskaters or water striders (Gerridae) are also associated with water, but use the surface tension of standing water to keep them above the surface; they include the sea skaters in the genus Halobates , the only truly marine group of insects. Marangoni effect propulsion exploits the change in surface tension when a soap-like surfactant is released on to
3440-413: The aquatic Belostomatidae, females lay their eggs on the back of the male which guards the eggs. Protection provided by ants is common in the Auchenorrhyncha. Although many species of Hemiptera are significant pests of crops and garden plants, including many species of aphid and scale insects , other species are harmless. The damage done is often not so much the deprivation of the plant of its sap, but
3520-689: The biological origin as opposed to environmental or anthropogenic origins. Biotoxins can be classified by their mechanism of delivery as poisons (passively transferred via ingestion, inhalation, or absorption across the skin), toxungens (actively transferred to the target's surface by spitting, spraying, or smearing), or venoms (delivered through a wound generated by a bite, sting, or other such action). They can also be classified by their source, such as fungal biotoxins , microbial toxins , plant biotoxins , or animal biotoxins. Toxins produced by microorganisms are important virulence determinants responsible for microbial pathogenicity and/or evasion of
3600-428: The body surface of another organism without an accompanying wound . A rather informal terminology of individual toxins relates them to the anatomical location where their effects are most notable: On a broader scale, toxins may be classified as either exotoxins , excreted by an organism, or endotoxins , which are released mainly when bacteria are lysed . The term "biotoxin" is sometimes used to explicitly confirm
3680-513: The completely hardened elytra of beetles , and occur only in the suborder Heteroptera . In all suborders, the hindwings – if present at all – are entirely membranous and usually shorter than the forewings. The forewings may be held "roofwise" over the body (typical of Sternorrhyncha and Auchenorrhyncha ), or held flat on the back, with the ends overlapping (typical of Heteroptera ). The antennae in Hemiptera typically consist of four or five segments, although they can still be quite long, and
3760-471: The cost of physiological resistance is an increased chance of survival for prey, but it allows predators to expand into underutilised trophic niches. The California ground squirrel has varying degrees of resistance to the venom of the Northern Pacific rattlesnake . The resistance involves toxin scavenging and depends on the population. Where rattlesnake populations are denser, squirrel resistance
3840-404: The crown of their skulls which, on impact, deliver venom into their targets. Some 450 species of snake are venomous. Snake venom is produced by glands below the eye (the mandibular glands ) and delivered to the target through tubular or channeled fangs. Snake venoms contain a variety of peptide toxins, including proteases , which hydrolyze protein peptide bonds; nucleases , which hydrolyze
3920-496: The dangerous Chagas disease . The first known hemipteran to feed in this way on vertebrates was the extinct assassin bug Triatoma dominicana found fossilized in amber and dating back about twenty million years. Faecal pellets fossilised beside it show that it transmitted a disease-causing Trypanosoma and the amber included hairs of the likely host, a bat . Some species of ant protect and farm aphids (Sternorrhyncha) and other sap-sucking hemipterans, gathering and eating
4000-824: The disparity in the analyses is suggested to be the long branch attraction effect in phylogenetic analysis, due to rapidly evolving DNA regions. The cladogram shows Hemiptera's placement within Paraneoptera , as well as how Hemiptera's four suborders are related. English names are given in parentheses where possible. Other insects [REDACTED] (barklice, booklice, lice) [REDACTED] Thysanoptera (thrips) [REDACTED] (aphids, scale insects, etc) [REDACTED] (shield bugs, assassin bugs, etc) [REDACTED] (moss bugs) [REDACTED] Fulgoromorpha (planthoppers) [REDACTED] Cicadomorpha (cicadas, leafhoppers, spittlebugs, etc) [REDACTED] The defining feature of hemipterans
4080-620: The extraction of dyestuffs such as cochineal and carmine , and for shellac . Cicadas have been used as food, and have appeared in literature since the Iliad in Ancient Greece . Hemiptera is the largest order of hemimetabolous insects (not undergoing complete metamorphosis; though some examples such as male scale insects do undergo a form of complete metamorphosis ), containing over 95,000 named species. Other insect orders with more species are all holometabolous , meaning they have
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#17327655436634160-429: The fact that they transmit serious viral diseases between plants. They often produce copious amounts of honeydew which encourages the growth of sooty mould . Significant pests include the cottony cushion scale , a pest of citrus fruit trees, the green peach aphid and other aphids which attack crops worldwide and transmit diseases, and jumping plant lice which can be plant-specific and transmit diseases, as with
4240-533: The families Varanidae , Anguidae , and Helodermatidae . Euchambersia , an extinct genus of therocephalians , is hypothesized to have had venom glands attached to its canine teeth. A few species of living mammals are venomous, including solenodons , shrews , the European mole , vampire bats , male platypuses , and slow lorises . Shrews have venomous saliva and most likely evolved their trait similarly to snakes. The presence of tarsal spurs akin to those of
4320-518: The food chambers of their young. The use of venom is much more widespread than just these examples; many other insects, such as true bugs and many ants , also produce venom. The ant species Polyrhachis dives uses venom topically for the sterilisation of pathogens. There are venomous invertebrates in several phyla , including jellyfish such as the dangerous box jellyfish , the Portuguese man-of-war (a siphonophore) and sea anemones among
4400-457: The heteropteran Oncopeltus fasciatus when it consumes milkweeds , while the coreid stinkbug Amorbus rubiginosus acquires 2- hexenal from its food plant, Eucalyptus . Some long-legged bugs mimic twigs, rocking to and fro to simulate the motion of a plant part in the wind. The nymph of the Masked hunter bug camouflages itself with sand grains, using its hind legs and tarsal fan to form
4480-459: The host immune response . Biotoxins vary greatly in purpose and mechanism, and can be highly complex (the venom of the cone snail can contain over 100 unique peptides , which target specific nerve channels or receptors). Biotoxins in nature have two primary functions: Some of the more well known types of biotoxins include: Many living organisms employ toxins offensively or defensively. A relatively small number of toxins are known to have
4560-426: The life cycle, such that females can produce unfertilized eggs, which are clones of their mother. All such young are females ( thelytoky ), so 100% of the population at these times can produce more offspring. Many species of aphid are also viviparous : the young are born live rather than laid as eggs. These adaptations enable aphids to reproduce extremely rapidly when conditions are suitable. Hemipterans make use of
4640-438: The mandibles able to cut into and abrade tissues of their prey. There are further stylets on the maxillae, adapted as tubular canals to inject saliva and to extract the pre-digested and liquified contents of the prey. A few hemipterans are haematophagic ectoparasites ), feeding on the blood of larger animals. These include bedbugs and the triatomine kissing bugs of the assassin bug family Reduviidae , which can transmit
4720-636: The many toxins that they contain; some venoms are complex mixtures of toxins of differing types. Major classes of toxin in venoms include: Venom is widely distributed taxonomically, being found in both invertebrates and vertebrates, in aquatic and terrestrial animals, and among both predators and prey. The major groups of venomous animals are described below. Venomous arthropods include spiders , which use fangs on their chelicerae to inject venom , and centipedes , which use forcipules — modified legs — to deliver venom, while scorpions and stinging insects inject venom with
4800-582: The mouthparts of Siphonaptera , some Diptera and Thysanoptera superficially resemble the rostrum of the Hemiptera, but on closer inspection the differences are considerable. Aside from the mouthparts, various other insects can be confused with Hemiptera, but they all have biting mandibles and maxillae instead of the rostrum. Examples include cockroaches and psocids , both of which have longer, many-segmented antennae, and some beetles , but these have fully hardened forewings which do not overlap. The forewings of Hemiptera are either entirely membranous, as in
4880-471: The negative pressure of xylem requires a special cibarial pump. Phloem feeding hemiptera typically have symbiotic micro-organisms in their gut that help to convert amino acids . Phloem feeders produce honeydew from their anus. A variety of organisms that feed on honeydew form symbiotic associations with phloem-feeders. Phloem sap is a sugary liquid low in amino acids, so insects have to process large quantities to meet their nutritional requirements. Xylem sap
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#17327655436634960-947: The plant bugs from their natural enemies, removing the eggs of predatory beetles and preventing access by parasitic wasps. Some leafhoppers (Auchenorrhyncha) are similarly "milked" by ants. In the Corcovado rain forest of Costa Rica, wasps compete with ants to protect and milk leafhoppers; the leafhoppers preferentially give more honeydew, more often, to the wasps, which are larger and may offer better protection. Hemiptera form prey to predators including vertebrates, such as birds, and other invertebrates such as ladybirds . In response, hemipterans have evolved antipredator adaptations . Ranatra may feign death ( thanatosis ). Others such as Carpocoris purpureipennis secrete toxic fluids to ward off arthropod predators; some Pentatomidae such as Dolycoris are able to direct these fluids at an attacker. Toxic cardenolide compounds are accumulated by
5040-603: The plant quickly. Most hemipterans are phytophagous, using their sucking and piercing mouthparts to feed on plant sap. These include cicadas, leafhoppers, treehoppers, planthoppers, froghoppers, aphids, whiteflies, scale insects , and some other groups. Some are monophages , being host specific and only found on one plant taxon, others are oligophages , feeding on a few plant groups, while others again are less discriminating polyphages and feed on many species of plant. The relationship between hemipterans and plants appears to be ancient, with piercing and sucking of plants evident in
5120-454: The plant tissues inducing the production of tissue that covers to protects the insect and also act as sinks for nutrition that they feed on. The hackleberry gall psyllid for example, causes a woody gall on the leaf petioles of the hackleberry tree it infests, and the nymph of another psyllid produces a protective lerp out of hardened honeydew. Most other hemipterans are predatory , feeding on other insects, or even small vertebrates. This
5200-459: The planthoppers secrete wax to protect themselves from threats such as fungi, parasitoidal insects and predators, as well as abiotic factors like desiccation. Hard waxy coverings are especially important in the sedentary Sternorrhyncha such as scale insects, which have no means of escaping from predators; other Sternorrhyncha evade detection and attack by creating and living inside plant galls. Nymphal Cicadoidea and Cercopoidea have glands attached to
5280-441: The platypus in many non- therian Mammaliaformes groups suggests that venom was an ancestral characteristic among mammals. Extensive research on platypuses shows that their toxin was initially formed from gene duplication, but data provides evidence that the further evolution of platypus venom does not rely as much on gene duplication as was once thought. Modified sweat glands are what evolved into platypus venom glands. Although it
5360-440: The position of the rostrum . "Homoptera" was established as paraphyletic group and an obsolete name. The order is now divided into four suborders, Heteroptera , Sternorrhyncha , Auchenorrhyncha , and Coleorrhyncha . The earlier work was based on nuclear DNA , but later phylogenetic analysis using mitochondrial DNA suggests that Homoptera may be monophyletic after all, a sister group of Heteroptera . The cause of
5440-714: The potential to cause widespread sickness or casualties. They are often inexpensive and easily available, and in some cases it is possible to refine them outside the laboratory. As biotoxins act quickly, and are highly toxic even at low doses, they can be more efficient than chemical agents. Due to these factors, it is vital to raise awareness of the clinical symptoms of biotoxin poisoning, and to develop effective countermeasures including rapid investigation, response, and treatment. The term "environmental toxin" can sometimes explicitly include synthetic contaminants such as industrial pollutants and other artificially made toxic substances. As this contradicts most formal definitions of
5520-455: The prey. Both pumps are powered by substantial dilator muscles in the head. The beak is usually folded under the body when not in use. The diet is typically plant sap , but some hemipterans such as assassin bugs are predators . Both herbivorous and predatory hemipterans inject enzymes to begin digestion extra-orally (before the food is taken into the body). These enzymes include amylase to hydrolyse starch , polygalacturonase to weaken
5600-412: The proteins associated with venom and how individual components of venom can be used for pharmaceutical means. Venom is used as a trophic weapon by many predator species. The coevolution between predators and prey is the driving force of venom resistance, which has evolved multiple times throughout the animal kingdom. The coevolution between venomous predators and venom-resistant prey has been described as
5680-728: The skin, and toxungen , which is actively transferred to the external surface of another animal via a physical delivery mechanism. Venom has evolved in terrestrial and marine environments and in a wide variety of animals: both predators and prey, and both vertebrates and invertebrates . Venoms kill through the action of at least four major classes of toxin, namely necrotoxins and cytotoxins , which kill cells; neurotoxins , which affect nervous systems; myotoxins , which damage muscles; and haemotoxins , which disrupt blood clotting . Venomous animals cause tens of thousands of human deaths per year. Venoms are often complex mixtures of toxins of differing types. Toxins from venom are used to treat
5760-576: The suborder Heteroptera . Entomologists reserve the term bug for Hemiptera or Heteroptera, which does not include other arthropods or insects of other orders such as ants , bees , beetles , or butterflies . In some varieties of English, all terrestrial arthropods (including non-insect arachnids , and myriapods ) also fall under the colloquial understanding of bug . Many insects with "bug" in their common name , especially in American English , belong to other orders; for example,
5840-401: The tarsi of the legs have two or three segments. Many hemipterans can produce sound for communication. The "song" of male cicadas, the loudest of any insect, is produced by tymbal organs on the underside of the abdomen, and is used to attract mates. The tymbals are drumlike disks of cuticle, which are clicked in and out repeatedly, making a sound in the same way as popping the metal lid of
5920-522: The tentacles of venomous sea anemones (an obligatory symbiosis for the fish), and are resistant to their venom. Only 10 known species of anemones are hosts to clownfish and only certain pairs of anemones and clownfish are compatible. All sea anemones produce venoms delivered through discharging nematocysts and mucous secretions. The toxins are composed of peptides and proteins. They are used to acquire prey and to deter predators by causing pain, loss of muscular coordination, and tissue damage. Clownfish have
6000-449: The term "toxin", it is important to confirm what the researcher means when encountering the term outside of microbiological contexts. Environmental toxins from food chains that may be dangerous to human health include: In general, when scientists determine the amount of a substance that may be hazardous for humans, animals and/or the environment they determine the amount of the substance likely to trigger effects and if possible establish
6080-406: The tough cell walls of plants, and proteinases to break down proteins. Although the Hemiptera vary widely in their overall form, their mouthparts form a distinctive "rostrum". Other insect orders with mouthparts modified into anything like the rostrum and stylets of the Hemiptera include some Phthiraptera , but for other reasons they generally are easy to recognize as non-hemipteran. Similarly,
6160-402: The toxins of venomous animals are actively selected , creating more diverse toxins with specific functions. Venoms adapt to their environment and victims, evolving to become maximally efficient on a predator 's particular prey (particularly the precise ion channels within the prey). Consequently, venoms become specialized to an animal's standard diet. Venoms cause their biological effects via
6240-800: The true bugs of Hemiptera. Within Paraneoptera, Hemiptera is most closely related to the sister clade Thysanoptera. The fossil record of hemipterans goes back to the Carboniferous ( Moscovian ). The oldest fossils are of the Archescytinidae from the Lower Permian and are thought to be basal to the Auchenorrhyncha . Fulgoromorpha and Cicadomorpha appear in the Upper Permian , as do Sternorrhyncha of
6320-429: The venom of, for example, king cobras or black mambas. Among marine animals, eels are resistant to sea snake venoms, which contain complex mixtures of neurotoxins, myotoxins, and nephrotoxins, varying according to species. Eels are especially resistant to the venom of sea snakes that specialise in feeding on them, implying coevolution; non-prey fishes have little resistance to sea snake venom. Clownfish always live among
6400-869: Was first used by organic chemist Ludwig Brieger (1849–1919), derived from toxic . Toxins can be small molecules , peptides , or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors . They vary greatly in their toxicity , ranging from usually minor (such as a bee sting ) to potentially fatal even at extremely low doses (such as botulinum toxin ). Toxins are often distinguished from other chemical agents strictly based on their biological origin. Less strict understandings embrace naturally occurring inorganic toxins, such as arsenic . Other understandings embrace synthetic analogs of naturally occurring organic poisons as toxins, and may or may not embrace naturally occurring inorganic poisons. It
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