Information

What is the conical mouthpart of a soldier termite and what does it do?

What is the conical mouthpart of a soldier termite and what does it do?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

I'm trying to get a visual understanding of termite anatomy and I'm getting quite confused on the protruding mouthpart area (it looks like a beak) located between the pincers.

What does it do / what is it for? It does not look like a chewing mouthpart.

Further, is it related to the mouthparts of the worker / females termites?

Oddly enough, I found "Conehead" termites with what appears to be a far more profound version of this part (though it might not be) and again I see no purpose for it.

Is there a place on the internet where the breakdown of termites can be found? This would be very useful.

What is between the pincers?


This is actually the termite's labrum. Its quite big in termites. Does not have value in telling male from female.


What is the conical mouthpart of a soldier termite and what does it do? - Biology

Summer Termite Promotion Terms & Conditions: The promotion is valid from 19 October 2020 until 31 March 2021. To qualify for the&hellip

How pests can damage your home

Pests chewing away an investment can be a recurring nightmare for homeowners. There are many ways pests can cause structural&hellip

Top 11 termite facts you (probably) didn’t know

Termites are interesting critters. There are millions of facts that could have made our list but here is our list&hellip


Worker Defensive Behavior Associated with Toxins in the Neotropical Termite Neocapritermes braziliensis (Blattaria, Isoptera, Termitidae, Termitinae)

Termite societies are abundant in the tropics, and are therefore exposed to multiple enemies and predators, especially during foraging activity. Soldiers constitute a specialized defensive caste, although workers also participate in this process, and even display suicidal behavior, which is the case with the species Neocapritermes braziliensis. Here we describe the morphology, mechanisms of action, and proteomics of the salivary weapon in workers of this species, which due to the autothysis of the salivary glands causes their body rupture, in turn releasing a defensive secretion, observed during aggressiveness bioassays. Salivary glands are paired, composed of two translucent reservoirs, ducts and a set of multicellular acini. Histological and ultrastructural techniques showed that acini are composed of two types of central cells, and small parietal cells located in the acinar periphery. Type I central cells were abundant and filled with a large amount of secretion, while type II central cells were scarce and presented smaller secretion. Parietal cells were often paired and devoid of secretion. The gel-free proteomic approach (shotgun) followed by mass spectrometry revealed 235 proteins in the defensive secretion, which were classified into functional groups: (i) toxins and defensins, (ii) folding/conformation and post-translational modifications, (iii) salivary gland detoxification, (iv) housekeeping proteins and (v) uncharacterized and hypothetical proteins. We highlight the occurrence of neurotoxins previously identified in arachnid venoms, which are novelties for termite biology, and contribute to the knowledge regarding the defense strategies developed by termite species from the Neotropical region.

This is a preview of subscription content, access via your institution.


Ecology of termites from the genus Nasutitermes (Termitidae: Nasutitermitinae) and potential for science-based development of sustainable pest management programs

The genus Nasutitermes is among the most abundant wood-feeding Termitidae and an extremely diverse and heterogeneous group in terms of its biogeography and morphology. Despite the major role of several Nasutitermes species as structural pests, the phylogenetic status of this genus is still unclear, along with a confused taxonomy and species identification remaining difficult. The first aim of this review was thus to gather and discuss studies concerning the taxonomic status of the genus Nasutitermes in order to clarify this crucial point. Then, our goal was to gain new insights into the management of N. corniger, considered to be the most economically detrimental pest of this genus in South America and a Nasutitermes model species, while filtering available information concerning its biology through the prism of termite control, as well as critically examine the existing methods. We indeed strongly believe that increasing our knowledge of this species’ biological strategies is the key to progress in the challenging question of their sustainable management.

This is a preview of subscription content, access via your institution.


Termites In Brazil Built Millions Of Huge Mounds, The Size Of Minnesota

A termite mound field in Brazil. The mounds are found in dense, low and dry forest caatinga vegetation.

In northeastern Brazil, in a forest so dry that the trees blanch bone-white, termites have been busy at work for millennia. The only external signs of their labor are dirt mounds, garbage dumps from their underground excavations. Dirt and garbage normally inspire as much awe as toenail clippings - but these are truly marvelous slag piles.

The conical mounds, each about 8 feet tall and 30 feet wide, erupt from the ground at regular intervals, spaced about 60 feet from each of six neighbors. From the air, the pattern evokes a checkerboard or the hexagonal combs in a beehive. A satellite map, via Google Earth, indicates the mounds cover more than 88,000 square miles, an area larger than Minnesota.

"Imagine it being a city," said Stephen J. Martin, an entomologist and expert in social insects at Britain's University of Salford. "We've never built a city that big." And the centimeter-long termites, Syntermes dirus, did it grain by grain.

In total, the earth excavated by termites equals the volume of 4,000 Pyramids of Giza, as Martin and his co-authors report in a study published Monday in the journal Current Biology. They collected samples from the centers of 11 mounds, and by measuring radiation in the mineral grains, determined the oldest mound tested is about 3,800 years old. Perhaps others are older. Based on satellite images and spot-checks across thousands of kilometers, the scientists estimate 200 million mounds dot the landscape.

If the forest cover vanished, exposing the mounds in all their splendor, this place would be celebrated as a natural "wonder of the Earth," Martin said.

Yet tucked under trees and thorny brush, the mounds can be hard to spot. Martin failed to notice them at first. He'd traveled to the Brazilian dry forest, called the caatinga, in pursuit of honeybees. Only after miles of driving, where the road sliced through the trees to reveal the mounds' gumdrop shape, did he see them. These were termite mounds, the local residents told Martin.

"No, that can't be right - there's too many of them," he recalled thinking. Back in Britain, colleagues told him the mounds must be lake sediment or another geological feature.

The locals, of course, were correct, as Martin found out when he returned. Miles from any major city, while walking near a swimming hole, the entomologist bumped into another biologist, named Roy Funch.

"He was walking up the river with a friend, and I was walking up the river to go swimming," said Funch, a co-author on the new paper. Martin "looked like, obviously, an outsider," so Funch, who also works as a tour guide, moseyed up, said hello and asked what brought Martin to Brazil. The termite mounds, Martin said, lamenting that nothing about them turned up in Google Scholar.

"I said, 'Hey, you just met the only guy in Brazil who's working on these mounds,'" Funch recalled. "So, you know, 'serendipitous' is putting it lightly."

Funch had traveled to Brazil in the 1970s with the Peace Corps. The beautiful mountains and hiking trails persuaded him to settle in the country's northeast, he said. He fell under the mounds' spell, too. The tallest, which Funch calls "grandmother mounds," reach 15 feet into the air. (Not all of them are still active.)

"I don't think anyone has ever seen such a modification of the landscape at such a huge scale by such tiny little creatures," he said.

In the 1980s, Funch, who describes himself as a "backwoods scientist" but has a PhD in botany, wrote about the termite mounds for a popular science magazine. He hoped to catch other researchers' attention. Nobody bit. Thirty years passed, and he decided to study them himself, until he teamed up with Martin.

These mounds, unlike the hives other termites build, are not nests or ventilation shafts. "We thought that the nests would be in the middle of the mounds," Funch said. "They weren't. They weren't even under the mounds." A single large tunnel, about 10 centimeters (about four inches) in diameter, rises through the center of the mound. The termites deliver their waste and plug the tunnel at the top.

"No one has ever found the queens' nests. We really don't know what's happening below the ground. Absolutely nothing," Funch said.

The mounds make uncooperative subjects. Soldier termites emerge when researchers disturb the dirt. They'll draw blood, Martin said. "They've got razor-sharp mandibles. They'll slice straight through the skin," he said. The nutrient-poor soil is a nightmare to dig up, baked hard as concrete in the heat.

Remoteness and poor soil are the very qualities that enable the termite mounds to endure. The area has long droughts, said University at Buffalo geographer Eun-Hye Yoo, an author of the study. (Yoo also met Funch in a Brazilian tourist town. "It's a good place to meet people," he said.) The climate, though not friendly to human agriculture, is stable. In this harsh environment, the termite kingdom flourishes.

"These termites have exploited this area and done very well for themselves," Martin said.

The wet season lasts for about a month. The caatinga leaps from brown to green and back again. The trees bloom, and just as quickly they shed their leaves. Within weeks, the forest floor is stripped bare of leaf litter. The termites take everything to eat. Martin suspects the litter sustains them for the rest of the year. Termites elsewhere farm fungus on leaf detritus, but there are no known fungus-growing termite species in South America.

The scientists do not have a definitive explanation for the mounds' unusual hexagonal spacing. The pattern is "absolutely striking and quite unusual in its scale. It's a beautiful example of large-scale self-organization," said Corina Tarnita, a mathematical biologist at Princeton University who was not involved with the new work. The only comparable pattern in nature so widely distributed, she said, are African fairy circles, rings in the brush that appear from Angola to South Africa.

But Martin proposed that, because these social insects "are very, very good at optimization" the six-pointed system may be the most efficient. Beneath the dirt, as seen by fiber-optic cable, is a large and interconnected tunnel system. The termites guide themselves by pheromones, the insect equivalent of a subway conductor.

"When you've got enough connections, it's very easy to find the nearest mound," Martin said. Only if a mound does not exist at the edge of the megacity will they begin to build a new one.

Tarnita cautioned that the mounds tested in this study were done so haphazardly. "It would be really important to have a systematic assessment of age that gives some sense of the relationship between a mound's age and that of its neighbors, or its neighbors' neighbors," she said.

Martin agrees there's plenty of work to do. No one knows how closely related the animals are at the far fringes of the empire. Their genetics are untested. And the colonies' rulers remain a mystery. "We'd love to get to the royal chamber," he said. He'd sacrifice a marvelous mound or two to a backhoe, for science.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)


DISCUSSION

Here, we report for the first time vibratory alarm signals in higher termites of the Southern African savannah. Major soldiers of M. natalensis produced a vibratory alarm signal with a pulse repetition rate of about 11 Hz. The sympatric living termite Odontotermes sp. also produced drumming signals but with a pulse repetition rate of 19 Hz. Both termite species were able to transmit the alarm signals over long distances. This ability is vital for termites that harvest in large groups and are frequently attacked by a variety of predators. Although long-distance alarm communication has been observed in Macrotermitinae before (Connétable et al., 1999 Röhrig et al., 1999), it was unclear exactly how the alarm was transmitted over long distances and whether subterranean galleries are used as communication channels.


Contents

Like most external features of arthropods, the mouthparts of hexapoda are highly derived. Insect mouthparts show a multitude of different functional mechanisms across the wide diversity of species considered insects. Certainly it is common for significant homology to be conserved, with matching structures formed from matching primordia, and having the same evolutionary origin. On the other hand, even structures that physically are almost identical, and share almost identical functionality as well, may not be homologous their analogous functions and appearance might be the product of convergent evolution.

Examples of chewing insects include dragonflies, grasshoppers and beetles. Some insects do not have chewing mouthparts as adults but do chew solid food when they feed while they still are larvae. The moths and butterflies are major examples of such adaptations.

Mandible Edit

A chewing insect has a pair of mandibles, one on each side of the head. The mandibles are caudal to the labrum and anterior to the maxillae. Typically the mandibles are the largest and most robust mouthparts of a chewing insect, and it uses them to masticate (cut, tear, crush, chew) food items. Two sets of muscles move the mandibles in the coronal plane: abductor muscles move insects' mandibles apart (laterally) adductor muscles bring them together (medially). This they do mainly in opening and closing their jaws in feeding, but also in using the mandibles as tools, or possibly in fighting note however, that this refers to the coronal plane of the mouth, not necessarily of the insect's body, because insects' heads differ greatly in their orientation.

In carnivorous chewing insects, the mandibles commonly are particularly serrated and knife-like, and often with piercing points. In herbivorous chewing insects mandibles tend to be broader and flatter on their opposing faces, as for example in caterpillars.

In males of some species, such as of Lucanidae and some Cerambycidae, the mandibles are modified to such an extent that they do not serve any feeding function, but are instead used to defend mating sites from other males. In some ants and termites, the mandibles also serve a defensive function (particularly in soldier castes). In bull ants, the mandibles are elongate and toothed, used both as hunting and defensive appendages. In bees, that feed primarily by use of a proboscis, the primary use of the mandibles is to manipulate and shape wax, and many paper wasps have mandibles adapted to scraping and ingesting wood fibres.

Maxilla Edit

Situated beneath (caudal to) the mandibles, paired maxillae manipulate and, in chewing insects, partly masticate, food. Each maxilla consists of two parts, the proximal cardo (plural cardines), and distal stipes (plural stipites). At the apex of each stipes are two lobes, the inner lacinia and outer galea (plurals laciniae and galeae). At the outer margin, the typical galea is a cupped or scoop-like structure, located over the outer edge of the labium. In non-chewing insects, such as adult Lepidoptera, the maxillae may be drastically adapted to other functions.

Unlike the mandibles, but like the labium, the maxillae bear lateral palps on their stipites. These palps serve as organs of touch and taste in feeding and in the inspection of potential foods and/or prey.

In chewing insects, adductor and abductor muscles extend from inside the cranium to within the bases of the stipites and cardines much as happens with the mandibles in feeding, and also in using the maxillae as tools. To some extent the maxillae are more mobile than the mandibles, and the galeae, laciniae, and palps also can move up and down somewhat, in the sagittal plane, both in feeding and in working, for example in nest building by mud-dauber wasps.

Maxillae in most insects function partly like mandibles in feeding, but they are more mobile and less heavily sclerotised than mandibles, so they are more important in manipulating soft, liquid, or particulate food rather than cutting or crushing food such as material that requires the mandibles to cut or crush.

Like the mandibles, maxillae are innervated by the subesophageal ganglia.

Labium Edit

The labium typically is a roughly quadrilateral structure, formed by paired, fused secondary maxillae. [1] It is the major component of the floor of the mouth. Typically, together with the maxillae, the labium assists manipulation of food during mastication.

The role of the labium in some insects however, is adapted to special functions perhaps the most dramatic example is in the jaws of the nymphs of the Odonata, the dragonflies and damselflies. In these insects, the labium folds neatly beneath the head and thorax, but the insect can flick it out to snatch prey and bear it back to the head, where the chewing mouthparts can demolish it and swallow the particles. [2]

The labium is attached at the rear end of the structure called cibarium, and its broad basal portion is divided into regions called the submentum, which is the proximal part, the mentum in the middle, and the prementum, which is the distal section, and furthest anterior.

The prementum bears a structure called the ligula this consists of an inner pair of lobes called glossae and a lateral pair called paraglossae. These structures are homologous to the lacinia and galea of maxillae. The labial palps borne on the sides of labium are the counterparts of maxillary palps. Like the maxillary palps, the labial palps aid sensory function in eating. In many species the musculature of the labium is much more complex than that of the other jaws, because in most, the ligula, palps and prementum all can be moved independently.

The labium is innervated by the sub-esophageal ganglia. [3] [4] [5]

In the honey bee, the labium is elongated to form a tube and tongue, and these insects are classified as having both chewing and lapping mouthparts. [6]

The wild silk moth (Bombyx mandarina) is an example of an insect that has small labial palpi and no maxillary palpi. [7]

Hypopharynx Edit

The hypopharynx is a somewhat globular structure, located medially to the mandibles and the maxillae. In many species it is membranous and associated with salivary glands. It assists in swallowing the food. The hypopharynx divides the oral cavity into two parts: the cibarium or dorsal food pouch and ventral salivarium into which the salivary duct opens.

This section deals only with insects that feed by sucking fluids, as a rule without piercing their food first, and without sponging or licking. Typical examples are adult moths and butterflies. As is usually the case with insects, there are variations: some moths, such as species of Serrodes and Achaea do pierce fruit to the extent that they are regarded as serious orchard pests. [8] Some moths do not feed after emerging from the pupa, and have greatly reduced, vestigial mouthparts or none at all. All but a few adult Lepidoptera lack mandibles (the superfamily known as the mandibulate moths have fully developed mandibles as adults), but also have the remaining mouthparts in the form of an elongated sucking tube, the proboscis.

Proboscis Edit

The proboscis, as seen in adult Lepidoptera, is one of the defining characteristics of the morphology of the order it is a long tube formed by the paired galeae of the maxillae. Unlike sucking organs in other orders of insects, the Lepidopteran proboscis can coil up so completely that it can fit under the head when not in use. During feeding, however, it extends to reach the nectar of flowers or other fluids. In certain specialist pollinators, the proboscis may be several times the body length of the moth.

A number of insect orders (or more precisely families within them) have mouthparts that pierce food items to enable sucking of internal fluids. Some are herbivorous, like aphids and leafhoppers, while others are carnivorous, like assassin bugs and mosquitoes (females only).

Proboscis Edit

The defining feature of the order Hemiptera is the possession of mouthparts where the mandibles and maxillae are modified into a proboscis, sheathed within a modified labium, which is capable of piercing tissues and sucking out the liquids. For example, true bugs, such as shield bugs, feed on the fluids of plants. Predatory bugs such as assassin bugs have the same mouthparts, but they are used to pierce the cuticles of captured prey.

Stylet Edit

In female mosquitoes, all mouthparts are elongated. The labium encloses all other mouthparts like a sheath. The labrum forms the main feeding tube, through which blood is sucked. Paired mandibles and maxillae are present, together forming the stylet, which is used to pierce an animal's skin. During piercing, the labium remains outside the food item's skin, folding away from the stylet. Saliva containing anticoagulants, is injected into the food item and blood sucked out, each through different tubes.

Labellum Edit

The housefly is a typical sponging insect. The labellum's surface is covered by minute food channels, formed by the interlocking elongate hypopharynx and epipharynx, forming a proboscis used to channel liquid food to the oesophagus. The food channel draws liquid and liquified food to the oesophagus by capillary action. The housefly is able to eat solid food by secreting saliva and dabbing it over the food item. As the saliva dissolves the food, the solution is then drawn up into the mouth as a liquid. [9]


Termites’ Cathedral Mounds

Thermal maps (right) superimposed on this termite mound show contrasting temperature profiles for night (left half) and day (right half).

Photographs courtesy of Hunter King and Sam Ocko


Thermal maps (right) superimposed on this termite mound show contrasting temperature profiles for night (left half) and day (right half).

Photographs courtesy of Hunter King and Sam Ocko

Looming meters tall , dotting hot climates on four continents, termite mounds have long mystified scientists. In each colony’s underground nest, the millimeter-sized insects store wood for food, cultivate the fungus that helps digestion, rear young, and tend to their queen. Yet the porous, cathedral-like mounds they build from soil and their own saliva and dung remain enigmatically empty.

In September, Harvard physicists published research asserting that the “cathedral” mounds built by Odontotermes obesus, in southern India, function as aboveground “lungs.” The mounds’ architecture features a large central chimney, where the temperature remains relatively constant, surrounded by thin outer flutes where temperatures fluctuate. During the daytime, these outer conduits heat up much more quickly than the internal chamber, forcing air up the flutes and down the chimney. At night, the process reverses, with air going up the chimney and down the flutes.

This process also ventilates the underground gallery where the colony lives and works. The scientists initially expected near-constant gas exchange that halted only when the convection cell reversed its direction twice a day. What they found when they measured carbon dioxide concentration levels surprised them. Because the top of the mound is hotter than the nest, keeping internal airflows due to convection small, the gas actually builds up during the day. But when the upper mound cools at night, relatively warmer air from the subterranean nest rises and diffuses through the walls. Stagnant air thus flushes out of the nest, reports researcher Sam Ocko: “We sometimes call it ‘the sneeze event.’”

A now-debunked but long-accepted theory, proposed in 1960 by Swiss entomologist Martin Lüscher, had claimed that the mound served as an air conditioner for the nest below, with the termites’ metabolic activity driving heated, stale air out from the center. (The Eastgate Centre in Harare, Zimbabwe, built in 1996, modeled its cooling and ventilation system on this supposed insect-inspired innovation.) More recently, SUNY biology professor J. Scott Turner—after years of research during which he pumped mounds with tracer gas, scanned them with lasers, and filled them with plaster—suggested a different hypothesis: that the mound manipulates external wind and the transient energy in its turbulence via intricate internal tunnels that “sloshed” fresh air in. In collaboration with Turner, Harvard’s de Valpine professor of applied mathematics, Lakshminarayanan “Maha” Mahadevan, and postdoctoral fellows Ocko and Hunter King, decided to try another approach—directly measuring the airflows inside a mound. (For more about Mahadevan’s work, see “The Physics of the Familiar,” March-April 2008, page 48.)

Easier said than done. In the mound, air moves slowly—and because “measuring slowly moving air is not something that people normally try to do,” King explains, commercial sensors couldn’t do the job. The complex geometry of the confined, opaque chambers posed an additional challenge. Then there were the mound’s residents: the colony’s soldiers rush to repel any intrusion, emitting a gluey, corrosive saliva onto the probe or attacking it with their mandibles. The team had to custom-design a sensor—something “very sensitive, calibrateable in these funny geometries, and very cheap, because you’re going to lose it every once in a while,” reports King—which they inserted into the mound after boring in with a hole saw.

They also adopted a strategy of what Ocko calls “hit-and-run measurements,” never lingering for more than five minutes and never poking into the same location twice, to avoid interrupting termite repairs. They also carried around a bucket of mound material and water for sealing the holes back up, “just as a courtesy,” says King. During their weeks in Bangalore, they bushwhacked through the forest to find more mounds to study, stomping to scare snakes out from underfoot. By the end, they’d taken around 80 measurements across 25 living and dead mounds. Investigating gas exchange was less hectic: King kept vigil for almost 24 hours by a mound, measuring carbon-dioxide levels every 15 minutes while snacking on the fruit of a nearby tamarind tree. (As termite lore goes, this is nothing: the poet who wrote the Ramayana is said to have meditated for so long that the insects built a mound around his body, and he had to be dug out by a passing sage.)

The resulting view into termite ventilation is particularly striking: the system uses oscillations, harnessing change itself. “Getting useful work out of a varying parameter, like temperature, is a novel mechanism,” King says, because “that’s not how things are usually engineered for humans,” who typically extract energy (whether from winds, waves, or the sun’s heat) from unidirectional flow.

To test whether these mechanisms are generalizable across species, the researchers are working on a paper about different mound-building termites, in Namibia. Their mounds endure more dramatic temperature extremes, Ocko reports, as well as daylong, full-sun exposure, which heats the sides of the mound unevenly. Additionally, this species produces a different mound shape—conical, without buttresses—and the reasons for the divergence in architecture remain unknown. “One question that we don’t have a good handle on is, why do some of them look one way, and some of them look another way?” says Ocko. “From an evolutionary perspective, are some strategies better at some times, and other strategies better in other places? Or is this some byproduct of termite behavior?”

Insights from termite behavior may prove useful to human engineers, from architects trying to design more efficient buildings to computer scientists interested in swarm intelligence. In the larger biological picture of how local decisions give rise to complex behavior, understanding the mound—knowing what solution these tiny, silent insects sought for their environment—is a vital piece.


Contents

Reproductives

A female that has flown, mated, and is producing eggs is called a "queen". Similarly, a male that has flown, mated, and is in proximity to a queen is termed a "king". Research using genetic techniques to determine relatedness of colony members has shown the original idea that colonies are only ever headed by a monogamous royal pair is wrong. Multiple pairs of reproductives within a colony are commonly encountered. In the families Rhinotermitidae and Termitidae, and possibly others, sperm competition does not seem to occur (male genitalia are very simple and the sperm are anucleate), suggesting only one male (king) generally mates within the colony.

At maturity, a primary queen has a great capacity to lay eggs. In physogastric species, the queen adds an extra set of ovaries with each molt, resulting in a greatly distended abdomen and increased fecundity, often reported to reach a production of more than 2,000 eggs a day. The distended abdomen increases the queen's body length to several times more than before mating and reduces her ability to move freely, though attendant workers provide assistance. The queen is widely believed to be a primary source of pheromones useful in colony integration, and these are thought to be spread through shared feeding (trophallaxis).

The king grows only slightly larger after initial mating and continues to mate with the queen for life (a termite queen can live for 45 years). This is very different from ant colonies, in which a queen mates once with the male(s) and stores the gametes for life, as the male ants die shortly after mating.

The winged (or "alate") caste, also referred to as the reproductive caste, are generally the only termites with well-developed eyes, although workers of some harvesting species do have well-developed compound eyes, and, in other species, soldiers with eyes occasionally appear. Termites on the path to becoming alates (going through incomplete metamorphosis) form a subcaste in certain species of termites, functioning as workers ("pseudergates") and also as potential supplementary reproductives. Supplementaries have the ability to replace a dead primary reproductive and, at least in some species, several are recruited once a primary queen is lost.

In areas with a distinct dry season, the alates leave the nest in large swarms after the first soaking rain of the rainy season. In other regions, flights may occur throughout the year, or more commonly, in the spring and autumn. Termites are relatively poor fliers and are readily blown downwind in wind speeds of less than 2 km/h, shedding their wings soon after landing at an acceptable site, where they mate and attempt to form a nest in damp timber or earth.

Workers

Worker termites undertake the labors of foraging, food storage, brood and nest maintenance, and some defense duties in certain species. Workers are the main caste in the colony for the digestion of cellulose in food and are the most likely to be found in infested wood. This is achieved in one of two ways. In all termite families except the Termitidae, flagellate protists in the gut assist in cellulose digestion. [ citation needed ] However, in the Termitidae, which account for approximately 60% of all termite species, the flagellates have been lost and this digestive role is taken up, in part, by a consortium of prokaryotic organisms. This simple story, which has been in entomology textbooks for decades, is complicated by the finding that all studied termites can produce their own cellulase enzymes, and therefore might digest wood in the absence of their symbiotic microbes, although new evidence suggests these gut microbes make use of termite-produced cellulase enzymes. [ 1 ] Our knowledge of the relationships between the microbial and termite parts of their digestion is still rudimentary. What is true in all termite species, however, is the workers feed the other members of the colony with substances derived from the digestion of plant material, either from the mouth or anus. This process of feeding of one colony member by another is known as trophallaxis, and is one of the keys to the success of the group. It frees the parents from feeding all but the first generation of offspring, allowing for the group to grow much larger and ensuring the necessary gut symbionts are transferred from one generation to another. Some termite species do not have a true worker caste, instead relying on nymphs that perform the same work without differentiating as a separate caste. [ citation needed ]

Soldiers

The soldier caste has anatomical and behavioural specializations, providing strength and armour which are primarily useful against ant attack. The proportion of soldiers within a colony varies both within and among species. Many soldiers have jaws so enlarged that they cannot feed themselves, but instead, like juveniles, are fed by workers. The pantropical subfamily Nasutitermitinae have soldiers with the ability to exude noxious liquids through either a horn-like nozzle (nasus). Simple holes in the forehead called "fontanelles" and which exude defensive secretions are a feature of the family Rhinotermitidae. Many species are readily identified using the characteristics of the soldiers' heads, mandibles, or nasus. Among the drywood termites, a soldier's globular ("phragmotic") head can be used to block their narrow tunnels. Termite soldiers are usually blind, but in some families, particularly among the dampwood termites, soldiers developing from the reproductive line may have at least partly functional eyes.

The specialization of the soldier caste is principally a defence against predation by ants. The wide range of jaw types and phragmotic heads provides methods that effectively block narrow termite tunnels against ant entry. A tunnel-blocking soldier can rebuff attacks from many ants. Usually more soldiers stand by behind the initial soldier so once the first one falls another soldier will take the place. In cases where the intrusion is coming from a breach that is larger than the soldier's head, defense requires special formations where soldiers form a phalanx-like formation around the breach and bite at intruders or exude toxins from the nasus or fontanelle. This formation involves self-sacrifice because once the workers have repaired the breach during fighting, no return is provided, thus leading to the death of all defenders. Another form of self-sacrifice is performed by Southeast Asian tar baby termites (Globitermes sulphureus). The soldiers of this species commit suicide by autothysis—rupturing a large gland just beneath the surface of their cuticle. The thick yellow fluid in the gland becomes very sticky on contact with the air, entangling ants or other insects who are trying to invade the nest. [ 2 ] [ 3 ]

Termites undergo incomplete metamorphosis. Freshly hatched young appear as tiny termites that grow without significant morphological changes (other than wings and soldier specializations). Some species of termite have dimorphic soldiers (up to three times the size of smaller soldiers). Though their value is unknown, speculation is that they may function as an elite class that defends only the inner tunnels of the mound. Evidence for this is that, even when provoked, these large soldiers do not defend themselves but retreat deeper into the mound. On the other hand, dimorphic soldiers are common in some Australian species of Schedorhinotermes that neither build mounds nor appear to maintain complex nest structures. Some termite taxa are without soldiers perhaps the best known of these are in the Apicotermitinae.

Termites are generally grouped according to their feeding behaviour. Thus, the commonly used general groupings are subterranean, soil-feeding, drywood, dampwood, and grass-eating. Of these, subterraneans and drywoods are primarily responsible for damage to human-made structures.

All termites eat cellulose in its various forms as plant fibre. Cellulose is a rich energy source (as demonstrated by the amount of energy released when wood is burned), but remains difficult to digest. Termites rely primarily upon symbiotic protozoa (metamonads) such as Trichonympha, and other microbes in their gut to digest the cellulose for them and absorb the end products for their own use. Gut protozoa, such as Trichonympha, in turn rely on symbiotic bacteria embedded on their surfaces to produce some of the necessary digestive enzymes. This relationship is one of the finest examples of mutualism among animals. Most so-called higher termites, especially in the Family Termitidae, can produce their own cellulase enzymes. However, they still retain a rich gut fauna and primarily rely upon the bacteria. Owing to closely related bacterial species, it is strongly presumed that the termites' gut flora are descended from the gut flora of the ancestral wood-eating cockroaches, like those of the genus Cryptocercus.

Some species of termite practice fungiculture. They maintain a “garden” of specialized fungi of genus Termitomyces, which are nourished by the excrement of the insects. When the fungi are eaten, their spores pass undamaged through the intestines of the termites to complete the cycle by germinating in the fresh faecal pellets. [ 4 ] [ 5 ] They are also well known for eating smaller insects in a last resort environment.


Contents

The first recorded mention of thrips 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 the Irish entomologist Alexander Henry Haliday described 41 species in 11 genera and proposed the order name of Thysanoptera. The first monograph on the group was published in 1895 by Heinrich Uzel who is considered the father of Thysanoptera studies. [3] [1]

The generic and English name thrips is a direct transliteration of the ancient Greek θρίψ , thrips, meaning "woodworm". [4] Like some other animal names such as sheep, deer, and moose, in English the word thrips is both the singular and plural forms, so there may be many thrips or a single thrips. Other common names for thrips include thunderflies, thunderbugs, storm flies, thunderblights, storm bugs, corn fleas, corn flies, corn lice, freckle bugs, harvest bugs, and physopods. [5] [6] [7] The older group name "physopoda" is with reference to the bladder like tips to the tarsi of the legs. The name of the order Thysanoptera is constructed from the ancient Greek words θύσανος , thysanos, "tassel or fringe", and πτερόν , pteron, "wing", for the insects' fringed wings. [8] [9] [10]

Thrips are small hemimetabolic insects with a distinctive cigar-shaped body plan. They are elongated with transversely constricted bodies. They range in size from 0.5 to 14 mm (0.02 to 0.55 in) in length for the larger predatory thrips, but most thrips are about 1 mm in length. Flight-capable thrips have two similar, strap-like pairs of wings with a fringe of bristles. The wings are folded back over the body at rest. Their legs usually end in two tarsal segments with a bladder-like structure known as an "arolium" at the pretarsus. This structure can be everted by means of hemolymph pressure, enabling the insect to walk on vertical surfaces. [11] [12] They have compound eyes consisting of a small number of ommatidia and three ocelli or simple eyes on the head. [13]

Thrips have asymmetrical mouthparts unique to the group. Unlike the Hemiptera (true bugs), the right mandible of thrips is reduced and vestigial – and in some species completely absent. [14] The left mandible is used briefly to cut into the food plant saliva is injected and the maxillary stylets, which form a tube, are then inserted and the semi-digested food pumped from ruptured cells. This process leaves cells destroyed or collapsed, and a distinctive silvery or bronze scarring on the surfaces of the stems or leaves where the thrips have fed. [15]

Thysanoptera is divided into two suborders, Terebrantia and Tubulifera these can be distinguished by morphological, behavioral, and developmental characteristics. Tubulifera consists of a single family, Phlaeothripidae members can be identified by their characteristic tube-shaped apical abdominal segment, egg-laying atop the surface of leaves, and three "pupal" stages. In the Phlaeothripidae, the males are often larger than females and a range of sizes may be found within a population. The largest recorded phlaeothripid species is about 14mm long. Females of the eight families of the Terebrantia all possess the eponymous saw-like (see terebra) ovipositor on the anteapical abdominal segment, lay eggs singly within plant tissue, and have two "pupal" stages. In most Terebrantia, the males are smaller than females. The family Uzelothripidae has a single species and it is unique in having a whip-like terminal antennal segment. [13]

The earliest fossils of thrips date back to the Permian (Permothrips longipennis). By the Early Cretaceous, true thrips became much more abundant. [16] The extant family Merothripidae most resembles these ancestral Thysanoptera, and is probably basal to the order. [17] There are currently over six thousand species of thrips recognized, grouped into 777 extant and sixty fossil genera. [18]

Phylogeny Edit

Thrips are generally considered to be the sister group to Hemiptera (bugs). [19]

The phylogeny of thrips families has been little studied. A preliminary analysis in 2013 of 37 species using 3 genes, as well as a phylogeny based on ribosomal DNA and three proteins in 2012, supports the monophyly of the two suborders, Tubulifera and Terebrantia. In Terebrantia, Melanothripidae may be sister to all other families, but other relationships remain unclear. In Tubulifera, the 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 relationships from these analyses are shown in the cladogram. [20] [21]

Taxonomy Edit

The following families are currently (2013) recognized: [21] [22] [13]

    Shumsher, 1946 (11 genera) Uzel, 1895 (29 genera) – banded thrips and broad-winged thrips Priesner, 1949 (four genera)
  • †HemithripidaeBagnall, 1923 (one fossil genus, Hemithrips with 15 species) Bagnall, 1912 (seven genera, restricted to the New World)
  • †Jezzinothripidaezur Strassen, 1973 (included by some authors in Merothripidae)
  • †Karataothripidae Sharov, 1972 (one fossil species, Karataothrips jurassicus) Bagnall, 1913 (six genera of flower feeders) Hood, 1914 (five genera, mostly Neotropical and feeding on dry-wood fungi) – large-legged thrips
  • †Scudderothripidae zur Strassen, 1973 (included by some authors in Stenurothripidae) Stephens, 1829 (292 genera in four subfamilies, flower living) – common thrips
  • †Triassothripidae Grimaldi & Shmakov, 2004 (two fossil genera) Hood, 1952 (one species, Uzelothrips scabrosus)
  • Suborder Tubulifera
    Uzel, 1895 (447 genera in two subfamilies, fungal hyphae and spore feeders)

The identification of thrips to species is challenging as types are maintained as slide preparations of varying quality over time. There is also considerable variability leading to many species being misidentified. Molecular sequence based approaches have increasingly been applied to their identification. [23] [24]

Feeding Edit

Thrips are believed to have descended from a fungus-feeding ancestor during the Mesozoic, [16] and many groups still feed upon and inadvertently redistribute fungal spores. These live among leaf litter or on dead wood and are important members of the ecosystem, their diet often being supplemented with pollen. Other species are primitively eusocial and form plant galls and still others are predatory on mites and other thrips. [9] Two species of Aulacothrips, A. tenuis and A. levinotus, have been found to be ectoparasites on aetalionid and membracid plant-hoppers in Brazil. [25]

Mirothrips arbiter has been found in paper wasp nests in Brazil. The eggs of the hosts including Mischocyttarus atramentarius, Mischocyttarus cassununga and Polistes versicolor are eaten by the thrips. [26] Thrips, especially in the family Aeolothripidae, are also predators, and are considered beneficial in the management of pests like the codling moths. [27]

Most research has focused on thrips species that feed on economically significant crops. Some species are predatory, but most of them feed on pollen and the chloroplasts harvested from the outer layer of plant epidermal and mesophyll cells. They prefer tender parts of the plant, such as buds, flowers and new leaves. [28] [29] Besides feeding on plant tissues, the common blossom thrips feeds on pollen grains and on the eggs of mites. When the larva supplements its diet in this way, its development time and mortality is reduced, and adult females that consume mite eggs increase their fecundity and longevity. [30]

Pollination Edit

Some flower-feeding thrips pollinate the flowers they are feeding on, and some authors suspect that they may have been among the first insects to evolve a pollinating relationship with their host plants. [31] Scirtothrips dorsalis carries pollen of commercially important chili peppers. [32] [33] [34] Darwin found that thrips could not be kept out by any netting when he conducted experiments by keeping away larger pollinators. [35] Thrips setipennis is the sole pollinator of Wilkiea huegeliana, a small, unisexual annually flowering tree or shrub in the rainforests of eastern Australia. T. setipennis serves as an obligate pollinator for other Australian rainforest plant species, including Myrsine howittiana and M. variabilis. [36] The genus Cycadothrips is a specialist pollinator of cycads, the flowers of which are adapted for pollination by small insects. [37] Thrips are likewise the primary pollinators of heathers in the family Ericaceae, [38] and play a significant role in the pollination of pointleaf manzanita. Electron microscopy has shown thrips carrying pollen grains adhering to their backs, and their fringed wings are perfectly capable of allowing them to fly from plant to plant. [37]

Damage to plants Edit

Thrips can cause damage during feeding. [39] This impact may fall across a broad selection of prey items, as there is considerable breadth in host affinity across the order, and even within a species, varying degrees of fidelity to a host. [28] [40] Family Thripidae in particular is notorious for members with broad host ranges, and the majority of pest thrips come from this family. [41] [42] For example, Thrips tabaci damages crops of onions, potatoes, tobacco, and cotton. [29] [43]

Some species of thrips create galls, almost always in leaf tissue. These may occur as curls, rolls or folds, or as alterations to the expansion of tissues causing distortion to leaf blades. More complex examples cause rosettes, pouches and horns. Most of these species occur in the tropics and sub-tropics, and the structures of the galls are diagnostic of the species involved. [44] A radiation of thrips species seems to have taken place on Acacia trees in Australia some of these species cause galls in the petioles, sometimes fixing two leaf stalks together, while other species live in every available crevice in the bark. In Casuarina in the same country, some species have invaded stems, creating long-lasting woody galls. [45]

Social behaviour Edit

While poorly documented, chemical communication is believed to be important to the group. [46] Anal secretions are produced in the hindgut, [47] and released along the posterior setae as predator deterrents [47] [48] In Australia, aggregations of male common blossom thrips have been observed on the petals of Hibiscus rosa-sinensis and Gossypium hirsutum females were attracted to these groups so it seems likely that the males were producing pheromones. [49]

In the phlaeothripids that feed on fungi, males compete to protect and mate with females, and then defend the egg-mass. Males fight by flicking their rivals away with their abdomen, and may kill with their foretarsal teeth. Small males may sneak in to mate while the larger males are busy fighting. In the Merothripidae and in the Aeolothripidae, males are again polymorphic with large and small forms, and probably also compete for mates, so the strategy may well be ancestral among the Thysanoptera. [13]

Many thrips form galls on plants when feeding or laying their eggs. Some of the gall-forming Phlaeothripidae, such as genera Kladothrips [50] and Oncothrips, [51] form eusocial groups similar to ant colonies, with reproductive queens and nonreproductive soldier castes. [52] [53] [54]

Flight Edit

Most insects create lift by the stiff-winged mechanism of insect flight with steady state aerodynamics this creates a leading edge vortex continuously as the wing moves. The feathery wings of thrips, however, generate lift by clap and fling, a mechanism discovered by the Danish zoologist Torkel Weis-Fogh in 1973. In the clap part of the cycle, the wings approach each other over the insect's back, creating a circulation of air which sets up vortices and generates useful forces on the wings. The leading edges of the wings touch, and the wings rotate around their leading edges, bringing them together in the "clap". The wings close, expelling air from between them, giving more useful thrust. The wings rotate around their trailing edges to begin the "fling", creating useful forces. The leading edges move apart, making air rush in between them and setting up new vortices, generating more force on the wings. The trailing edge vortices, however, cancel each other out with opposing flows. Weis-Fogh suggested that this cancellation might help the circulation of air to grow more rapidly, by shutting down the Wagner effect which would otherwise counteract the growth of the circulation. [55] [56] [57] [58]

Clap 1: wings close over back

Clap 2: leading edges touch, wing rotates around leading edge, vortices form

Clap 3: trailing edges close, vortices shed, wings close giving thrust

Fling 1: wings rotate around trailing edge to fling apart

Fling 2: leading edge moves away, air rushes in, increasing lift

Fling 3: new vortex forms at leading edge, trailing edge vortices cancel each other, perhaps helping flow to grow faster (Weis-Fogh 1973)

Apart from active flight, thrips, even wingless ones, can also be picked up by winds and transferred long distances. During warm and humid weather, adults may climb to the tips of plants to leap and catch air current. Wind-aided dispersal of species has been recorded over 1600 km of sea between Australia and South Island of New Zealand. [13]

A hazard of flight for very small insects such as thrips is the possibility of being trapped by water. Thrips have non-wetting bodies and have the ability to ascend a meniscus by arching their bodies and working their way head-first and upwards along the water surface in order to escape. [59]

Lifecycle Edit

Thrips lay extremely small eggs, about 0.2 mm long. Females of the suborder Terebrantia cut slits in plant tissue with their ovipositor, and insert their eggs, one per slit. Females of the suborder Tubulifera lay their eggs singly or in small groups on the outside surfaces of plants. [60]

Thrips are hemimetabolous, metamorphosing gradually to the adult form. The first two instars, called larvae or nymphs, are like small wingless adults (often confused with springtails) without genitalia these feed on plant tissue. In the Terebrantia, the third and fourth instars, and in the Tubulifera also a fifth instar, are non-feeding resting stages similar to pupae: in these stages, the body's organs are reshaped, and wing-buds and genitalia are formed. [60] The adult stage can be reached in around 8–15 days adults can live for around 45 days. [61] Adults have both winged and wingless forms in the grass thrips Anaphothrips obscurus, for example, the winged form makes up 90% of the population in spring (in temperate zones), while the wingless form makes up 98% of the population late in the summer. [62] Thrips can survive the winter as adults or through egg or pupal diapause. [13]

Thrips are haplodiploid with haploid males (from unfertilised eggs, as in Hymenoptera) and diploid females capable of parthenogenesis (reproducing without fertilisation), many species using arrhenotoky, a few using thelytoky. [63] In Pezothrips kellyanus females hatch from larger eggs than males, possibly because they are more likely to be fertilized. [64] The sex-determining bacterial endosymbiont Wolbachia is a factor that affects the reproductive mode. [40] [63] [65] Several normally bisexual species have become established in the United States with only females present. [63] [66]

As pests Edit

Many thrips are pests of commercial crops due to the damage caused by feeding on developing flowers or vegetables, causing discoloration, deformities, and reduced marketability of the crop. Some thrips serve as vectors for plant diseases, such as tospoviruses. [67] Over 20 plant-infecting viruses are known to be transmitted by thrips, but perversely, less than a dozen of the described species are known to vector tospoviruses. [68] These enveloped viruses are considered among some of the most damaging of emerging plant pathogens around the world, with those vector species having an outsized impact on human agriculture. Virus members include the tomato spotted wilt virus and the impatiens necrotic spot viruses. The western flower thrips, Frankliniella occidentalis, has spread until it now has a worldwide distribution, and is the primary vector of plant diseases caused by tospoviruses. [69] Other viruses that they spread include the genera Ilarvirus, (Alpha|Beta|Gamma)carmovirus, Sobemovirus and Machlomovirus. [70] Their small size and predisposition towards enclosed places makes them difficult to detect by phytosanitary inspection, while their eggs, laid inside plant tissue, are well-protected from pesticide sprays. [61] When coupled with the increasing globalization of trade and the growth of greenhouse agriculture, thrips, unsurprisingly, are among the fastest growing group of invasive species in the world. Examples include F. occidentalis, Thrips simplex, and Thrips palmi. [71]

Flower-feeding thrips are routinely attracted to bright floral colors (including white, blue, and especially yellow), and will land and attempt to feed. It is not uncommon for some species (e.g., Frankliniella tritici and Limothrips cerealium) to "bite" humans under such circumstances. Although no species feed on blood and no known animal disease is transmitted by thrips, some skin irritation has been described. [72]

Management Edit

Thrips develop resistance to insecticides easily and there is constant research on how to control them. This makes thrips ideal as models for testing the effectiveness of new pesticides and methods. [73]

Due to their small sizes and high rates of reproduction, thrips are difficult to control using classical biological control. Suitable predators must be small and slender enough to penetrate the crevices where thrips hide while feeding, and they must also prey extensively on eggs and larvae to be effective. Only two families of parasitoid Hymenoptera parasitize eggs and larvae, the Eulophidae and the Trichogrammatidae. Other biocontrol agents of adults and larvae include anthocorid bugs of genus Orius, and phytoseiid mites. Biological insecticides such as the fungi Beauveria bassiana and Verticillium lecanii can kill thrips at all life-cycle stages. [74] Insecticidal soap spray is effective against thrips. It is commercially available or can be made of certain types of household soap. Scientists in Japan report that significant reductions in larva and adult melon thrips occur when plants are illuminated with red light. [75]


Watch the video: IFAattackFormosanSoldier (February 2023).