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33-507: Zelandoperla is a genus of ‘long-tailed’ stoneflies endemic to New Zealand , placed within Southern Hemisphere family Gripopterygidae . Zelandoperla species occur in high-gradient, stoney streams throughout New Zealand, where they feed predominantly on biofilms . The currently recognised species are: Two additional described species ( Zelandoperla pennulata ; Zelandoperla tillyardi ) are now considered to be ecotypes of

66-451: A characteristic seasonal pattern . In temperate regions, photoperiod is the most reliable cues of seasonal change. This informs entry into reproductive diapause for many northern insects, including the fruit fly Drosophila montana . Depending on the season in which diapause occurs, either short or long days can act as token stimuli. Insects may also respond to changing day length as well as relative day length. Temperature may also act as

99-429: A completely immobile stage, such as the pupae and eggs, or it may occur in very active stages that undergo extensive migrations, such as the adult monarch butterfly , Danaus plexippus . In cases where the insect remains active, feeding is reduced and reproductive development is slowed or halted. Embryonic diapause , a somewhat similar phenomenon, occurs in over 130 species of mammals, possibly even in humans, and in

132-574: A regulating factor, either by inducing diapause or, more commonly, by modifying the response of the insect to photoperiod. Insects may respond to thermoperiod, the daily fluctuations of warm and cold that correspond with night and day, as well as to absolute or cumulative temperature. This has been observed in many moth species including the Indian mealmoth , where individuals diapause in different developmental stages due to environmental temperature. Food availability and quality may also help regulate diapause. In

165-504: A specific diapause stage, or be accompanied by color change. Enzymatic changes may take place in preparation for cold hardening . For example, only diapausing adults of the fire bug, Pyrrhocoris apterus , have the enzymatic complement that allows them to accumulate polyhydric alcohols , molecules that help to lower their freezing points and thus avoid freezing. Insects may also undergo behavioural changes and begin to aggregate, migrate , or search for suitable overwintering sites. During

198-622: Is relatively soft, and may include remnants of the nymphal gills even in the adult. Both nymphs and adults have long, paired cerci projecting from the tip of their abdomens. The name "Plecoptera" literally means " braided -wings", from the Ancient Greek plekein (πλέκειν, "to braid") and pteryx (πτέρυξ, "wing"). This refers to the complex venation of their two pairs of wings , which are membranous and fold flat over their backs. Stoneflies are generally not strong fliers, and some species are entirely wingless. A few wingless species, such as

231-405: Is required for the accumulation by the fat body of a storage protein that is associated with diapause. Diapause hormone regulates embryonic diapause in the eggs of the silkworm moth, Bombyx mori . DH is released from the subesophageal ganglion of the mother and triggers trehalase production by the ovaries . This generates high levels of glycogen in the eggs , which is converted into

264-416: Is typical as is reduced movement and feeding. In Polistes exclamans , a social wasp, only the queen is said to be able to undergo diapause. The sensitive stage is the period when stimulus must occur to trigger diapause in the organism. Examples of sensitive stage/diapause periods in various insects: The induction phase occurs at a genetically predetermined stage of life, and occurs well in advance of

297-646: The Carboniferous and Lower Permian geological periods, while true stoneflies are known from fossils only a bit younger. Their modern diversity, however, apparently is of Mesozoic origin. Plecoptera are found in both the Southern and Northern Hemispheres , and the populations are quite distinct, although the evolutionary evidence suggests species may have crossed the equator on a number of occasions before once again becoming geographically isolated. All species of Plecoptera are intolerant of water pollution , and

330-802: The Lake Tahoe benthic stonefly ( "Capnia" lacustra ) or Baikaloperla , are the only known insects, perhaps with the exception of Halobates , that are exclusively aquatic from birth to death. Some true water bugs (Nepomorpha) may also be fully aquatic for their entire lives, but can leave the water to travel. The nymphs (technically, "naiads") are aquatic and live in the benthic zone of well-oxygenated lakes and streams. A few species found in New Zealand and nearby islands have terrestrial nymphs, but even these inhabit only very moist environments. The nymphs physically resemble wingless adults, but often have external gills, which may be present on almost any part of

363-430: The desert locust , Schistocerca gregaria , a plant hormone called gibberellin stimulates reproductive development. During the dry season, when their food plants are in senescence and lacking gibberellin, the locusts remain immature and their reproductive tracts do not develop. The neuroendocrine system of insects consists primarily of neurosecretory cells in the brain , the corpora cardiaca, corpora allata and

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396-860: The embryos of many of the oviparous species of fish in the order Cyprinodontiformes . Diapause in insects is a dynamic process consisting of several distinct phases. While diapause varies considerably from one taxon of insects to another, these phases can be characterized by particular sets of metabolic processes and responsiveness of the insect to certain environmental stimuli. For example, Sepsis cynipsea flies primarily use temperature to determine when to enter diapause. Similarly, Chrysoperla plorabunda lacewings regulate their reproductive cycle using daylight length, with adults entering reproductive diapause when there are less than 12-13 hours of daylight. Diapause can occur during any stage of development in arthropods, but each species exhibits diapause in specific phases of development. Reduced oxygen consumption

429-420: The polymorphic Z. fenestrata . Stoneflies mostly Arctoperlaria : see text Plecoptera is an order of insects , commonly known as stoneflies . Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the most primitive groups of Neoptera , with close relatives identified from

462-769: The Euholognatha (meaning roughly "advanced Holognatha"), but the Scopuridae do not appear significantly closer to the Euholognatha than to the Systellognatha. In addition, not adopting the clades Antarctoperlaria and Holognatha allows for a systematic layout of the Plecoptera that adequately reproduces phylogeny, while retaining the traditional ranked taxa . Basal lineages ("Antarctoperlaria") Suborder Arctoperlaria Diapause Activity levels of diapausing stages can vary considerably among species. Diapause may occur in

495-420: The absence of JH, while larval diapause is often associated with its presence. In adults, absence of JH causes degeneration of flight muscles and atrophy or cessation of development of reproductive tissues, and halts mating behaviour. The presence of JH in larvae may prevent moulting to the next larval instar , though successive stationary moults may still occur. In the corn borer, Diatraea gradiosella , JH

528-523: The body. Nymphs can acquire oxygen via diffusing through the exoskeleton, or through gills located on behind the head, on the thorax, or around the anus. Due to their nymph's requirement for well oxygenated water, the species is very sensitive to water pollution. This makes them important indicators for water quality. Most species are herbivorous as nymphs, feeding on submerged leaves and benthic algae, but many are hunters of other aquatic arthropods. The female can lay up to one thousand eggs. It will fly over

561-412: The brain or by failure of the prothoracic glands to respond to prothoracicotropic hormone. The corpora allata is responsible for the production of juvenile hormone (JH). In the bean bug, Riptortus pedestris , clusters of neurons on the protocerebrum called the pars lateralis maintain reproductive diapause by inhibiting JH production by the corpora allata . Adult diapause is often associated with

594-670: The contrary). The Arctoperlaria, though, have been divided into two infraorders , the Euholognatha (or Filipalpia) and the Systellognatha (also called Setipalpia or Subulipalpia). This corresponds to the phylogeny with one exception: the Scopuridae must be considered a basal family in the Arctoperlaria, not assignable to any of the infraorders. Alternatively, the Scopuridae were placed in an unranked clade "Holognatha" together with

627-610: The end of unfavourable conditions and is followed by a state of quiescence from which the insect can arouse and begin direct development, should conditions change to become more favourable. This allows the insect to continue to withstand harsh conditions while being ready to take advantage of good conditions as soon as possible. Diapause in insects is regulated at several levels. Environmental stimuli interact with genetic pre-programming to affect neuronal signalling, endocrine pathways, and, eventually, metabolic and enzymatic changes. Environmental regulators of diapause generally display

660-468: The environmental conditions being avoided. These stimuli are important in preventing the insect from terminating diapause too soon, for instance in response to warm weather in late fall. In the Edith's checkerspot butterfly, individuals must receive enough sunlight in order to terminate the diapause stage and become a fully grown butterfly. Termination may occur at the height of unfavourable conditions, such as in

693-623: The environmental stress. This sensitive stage may occur within the lifetime of the diapausing individual, or in preceding generations, particularly in egg diapause. During this phase, insects are responsive to external cues called token stimuli, which trigger the switch from direct development pathways to diapause pathways. Token stimuli can consist of changes in photoperiod , thermoperiod , or allelochemicals from food plants. These stimuli are not in themselves favourable or unfavourable to development, but they herald an impending change in environmental conditions. The preparation phase usually follows

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726-485: The form of fallen trees may be more available following rainy seasons. Also, diapause may serve to synchronize mating seasons or reduce competition, rather than to avoid unfavourable climatic conditions. Diapause in the tropics poses several challenges to insects that are not faced in temperate zones. Insects must reduce their metabolism without the aid of cold temperatures and may be faced with increased water loss due to high temperatures. While cold temperatures inhibit

759-528: The growth of fungi and bacteria , diapausing tropical insects still have to deal with these pathogens . Also, predators and parasites may still be abundant during the diapause period. Aggregations are common among diapausing tropical insects, especially in the orders Coleoptera , Lepidoptera , and Hemiptera . Aggregations may be used as protection against predation , since aggregating species are frequently toxic and predators quickly learn to avoid them. They can also serve to reduce water loss, as seen in

792-489: The induction phase, though insects may go directly from induction to initiation without a preparation phase. During this phase, insects accumulate and store molecules such as lipids , proteins , and carbohydrates . These molecules are used to maintain the insect throughout diapause and to provide fuel for development following diapause termination. Composition of the cuticle may be altered by changing hydrocarbon composition and by adding lipids to reduce water loss, making

825-697: The maintenance phase, insects experience lowered metabolism and developmental arrest is maintained. Sensitivity to certain stimuli which act to prevent termination of diapause, such as photoperiod and temperature , is increased. At this stage, insects are unresponsive to changes in the environment that will eventually trigger the end of diapause, but they grow more sensitive to these stimuli as time progresses. In insects that undergo obligate diapause, termination may occur spontaneously, without any external stimuli. In facultative diapausers, token stimuli must occur to terminate diapause. These stimuli may include chilling, freezing, or contact with water , depending on

858-460: The middle of winter. Over time, depth of diapause slowly decreases until direct development can resume, if conditions are favourable. Termination can also occur in specific time frames linked to reproductive periods, such as in the beetle Colaphellus bowringi : diapause ends for spring-reproducing beetles between late February and early April and for autumn-reproducing beetles between mid August and early October . Diapause frequently ends prior to

891-496: The nymphal form for one to four years, depending on species, and undergo from 12 to 36 molts before emerging and becoming terrestrial as adults. Before becoming adults, nymphs will leave the water, attach to a fixed surface and molt one last time. The adults generally only survive for a few weeks, and emerge only during specific times of the year when resources are optimal. Some do not feed at all, but those that do are herbivorous. Adults are not strong fliers and generally stay near

924-458: The organism resistant to desiccation. Diapausing puparia of the flesh fly , Sarcophaga crassipalpis , increase the amount of cuticular hydrocarbons lining the puparium, effectively reducing the ability of water to cross the cuticle. Photoperiod is the most important stimulus initiating diapause. The initiation phase begins when morphological development ceases. In some cases, this change may be very distinct and can involve moulting into

957-431: The polyhydric alcohols glycerol and sorbitol. Sorbitol directly inhibits the development of the embryos. Glycerol and sorbitol are reconverted into glycogen at the termination of diapause. Diapause in the tropics is often initiated in response to biotic rather than abiotic components . For example, food in the form of vertebrate carcasses may be more abundant following dry seasons, or oviposition sites in

990-426: The presence of their nymphs in a stream or still water is usually an indicator of good or excellent water quality. Stoneflies have a generalized anatomy, with few specialized features compared to other insects. They have simple mouthparts with chewing mandibles , long, multiple-segmented antennae , large compound eyes , and two or three ocelli . The legs are robust, with each ending in two claws. The abdomen

1023-469: The prothoracic glands. There are several key hormones involved in the regulation of diapause: juvenile hormone (JH), diapause hormone (DH), and prothoracicotropic hormone (PTTH) . Prothoracicotropic hormone stimulates the prothoracic glands to produce ecdysteroids that are required to promote development. Larval and pupal diapauses are often regulated by an interruption of this connection, either by preventing release of prothoracicotropic hormone from

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1056-462: The stream or lake they hatched from. Traditionally, the stoneflies were divided into two suborders , the "Antarctoperlaria" (or "Archiperlaria") and the Arctoperlaria . However, the former simply consists of the two most basal superfamilies of stoneflies, which do not seem to be each other's closest relatives. Thus, the "Antarctoperlaria" are not considered a natural group (despite some claims to

1089-418: The water and drop the eggs in the water. It also may hang on a rock or branch. Eggs are covered in a sticky coating which allows them to adhere to rocks without being swept away by swift currents. The eggs typically take two to three weeks to hatch, but some species undergo diapause , with the eggs remaining dormant throughout a dry season, and hatching only when conditions are suitable. The insects remain in

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