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Lepidopteran



Lepidoptera (/ˌlɛpəˈdɒptərə/ lep-ə-DOP-tər-ə) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families[1] and 46 superfamilies,[2] 10 percent of the total described species of living organisms.[2][3] It is one of the most widespread and widely recognizable insect orders in the world.[4] The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought,[5] and is among the four most species-rich orders, along with the Hymenoptera, Diptera, and Coleoptera.[4]




lepidopteran



Some lepidopteran species exhibit symbiotic, phoretic, or parasitic lifestyles, inhabiting the bodies of organisms rather than the environment. Coprophagous pyralid moth species, called sloth moths, such as Bradipodicola hahneli and Cryptoses choloepi, are unusual in that they are exclusively found inhabiting the fur of sloths, mammals found in Central and South America.[18][19]Two species of Tinea moths have been recorded as feeding on horny tissue and have been bred from the horns of cattle. The larva of Zenodochium coccivorella is an internal parasite of the coccid Kermes species. Many species have been recorded as breeding in natural materials or refuse such as owl pellets, bat caves, honeycombs or diseased fruit.[19]


As of 2007, there were roughly 174,250 lepidopteran species described, with butterflies and skippers estimated to comprise around 17,950, and moths making up the rest.[2][20] The vast majority of Lepidoptera are to be found in the tropics, but substantial diversity exists on most continents. North America has over 700 species of butterflies and over 11,000 species of moths,[21][22] while about 400 species of butterflies and 14,000 species of moths are reported from Australia.[23] The diversity of Lepidoptera in each faunal region has been estimated by John Heppner in 1991 based partly on actual counts from the literature, partly on the card indices in the Natural History Museum (London) and the National Museum of Natural History (Washington), and partly on estimates:[5]


Flight is an important aspect of the lives of butterflies and moths, and is used for evading predators, searching for food, and finding mates in a timely manner, as most lepidopteran species do not live long after eclosion. It is the main form of locomotion in most species. In Lepidoptera, the forewings and hindwings are mechanically coupled and flap in synchrony. Flight is anteromotoric, or being driven primarily by action of the forewings. Although lepidopteran species reportedly can still fly when their hindwings are cut off, it reduces their linear flight and turning capabilities.[56]


An "evolutionary arms race" can be seen between predator and prey species. The Lepidoptera have developed a number of strategies for defense and protection, including evolution of morphological characters and changes in ecological lifestyles and behaviors. These include aposematism, mimicry, camouflage, and development of threat patterns and displays.[77] Only a few birds, such as the nightjars, hunt nocturnal lepidopterans. Their main predators are bats. Again, an "evolutionary race" exists, which has led to numerous evolutionary adaptations of moths to escape from their main predators, such as the ability to hear ultrasonic sounds, or even to emit sounds in some cases. Lepidopteran eggs are also preyed upon. Some caterpillars, such as the zebra swallowtail butterfly larvae, are cannibalistic.


Some species of Lepidoptera are poisonous to predators, such as the monarch butterfly in the Americas, Atrophaneura species (roses, windmills, etc.) in Asia, as well as Papilio antimachus, and the birdwings, the largest butterflies in Africa and Asia, respectively. They obtain their toxicity by sequestering the chemicals from the plants they eat into their own tissues. Some Lepidoptera manufacture their own toxins. Predators that eat poisonous butterflies and moths may become sick and vomit violently, learning not to eat those species. A predator which has previously eaten a poisonous lepidopteran may avoid other species with similar markings in the future, thus saving many other species, as well.[77][78] Toxic butterflies and larvae tend to develop bright colors and striking patterns as an indicator to predators about their toxicity. This phenomenon is known as aposematism.[79] Some caterpillars, especially members of Papilionidae, contain an osmeterium, a Y-shaped protrusible gland found in the prothoracic segment of the larvae.[77] When threatened, the caterpillar emits unpleasant smells from the organ to ward off the predators.[80][81]


Camouflage is also an important defense strategy, which involves the use of coloration or shape to blend into the surrounding environment. Some lepidopteran species blend with their surroundings, making them difficult to spot by predators. Caterpillars can exhibit shades of green that match its host plant. Others look like inedible objects, such as twigs or leaves. For instance, the mourning cloak fades into the backdrop of trees when it folds its wings back. The larvae of some species, such as the common Mormon (Papilio polytes) and the western tiger swallowtail look like bird droppings.[77][82] For example, adult Sesiidae species (also known as clearwing moths) have a general appearance sufficiently similar to a wasp or hornet to make it likely the moths gain a reduction in predation by Batesian mimicry.[83] Eyespots are a type of automimicry used by some butterflies and moths. In butterflies, the spots are composed of concentric rings of scales in different colors. The proposed role of the eyespots is to deflect attention of predators. Their resemblance to eyes provokes the predator's instinct to attack these wing patterns.[84]


The earliest named lepidopteran taxon is Archaeolepis mane, a primitive moth-like species from the Early Jurassic, dated back to around 190 million years ago, and known only from three wings found in the Charmouth Mudstone of Dorset, UK. The wings show scales with parallel grooves under a scanning electron microscope and a characteristic wing venation pattern shared with Trichoptera (caddisflies).[107][108] Only two more sets of Jurassic lepidopteran fossils have been found, as well as 13 sets from the Cretaceous, which all belong to primitive moth-like families.[102]


Many more fossils are found from the Tertiary, and particularly the Eocene Baltic amber. The oldest genuine butterflies of the superfamily Papilionoidea have been found in the Paleocene MoClay or Fur Formation of Denmark. The best preserved fossil lepidopteran is the Eocene Prodryas persephone from the Florissant Fossil Beds.


In the so-called "macrolepidoptera", which constitutes about 60% of lepidopteran species, there was a general increase in size, better flying ability (via changes in wing shape and linkage of the forewings and hindwings), reduction in the adult mandibles, and a change in the arrangement of the crochets (hooks) on the larval prolegs, perhaps to improve the grip on the host plant.[102] Many also have tympanal organs, that allow them to hear. These organs evolved eight times, at least, because they occur on different body parts and have structural differences.[102]The main lineages in the macrolepidoptera are the Noctuoidea, Bombycoidea, Lasiocampidae, Mimallonoidea, Geometroidea and Rhopalocera. Bombycoidea plus Lasiocampidae plus Mimallonoidea may be a monophyletic group.[102] The Rhopalocera, comprising the Papilionoidea (butterflies), Hesperioidea (skippers), and the Hedyloidea (moth-butterflies), are the most recently evolved.[101] There is quite a good fossil record for this group, with the oldest skipper dating from 56 million years ago.[102]


The larvae of many lepidopteran species are major pests in agriculture. Some of the major pests include Tortricidae, Noctuidae, and Pyralidae. The larvae of the Noctuidae genus Spodoptera (armyworms), Helicoverpa (corn earworm), or Pieris brassicae can cause extensive damage to certain crops.[101] Helicoverpa zea larvae (cotton bollworms or tomato fruitworms) are polyphagous, meaning they eat a variety of crops, including tomatoes and cotton.[124] Peridroma saucia (variegated cutworms) are described as one of the most damaging pests to gardens, with the ability to destroy entire gardens and fields in a matter of days.[125]


The piggyBac (IFP2) short inverted terminal repeat transposable element from the cabbage looper Trichoplusia ni was tested for gene transfer vector function as part of a bipartite vector-helper system in the Mediterranean fruit fly Ceratitis capitata. A piggyBac vector marked with the medfly white gene was tested with a normally regulated piggyBac transposase helper at two different concentrations in a white eye host strain. Both experiments yielded transformants at an approximate frequency of 3-5%, with a total of six lines isolated having pigmented eyes with various levels of coloration. G1 transformant siblings from each line shared at least one common integration, with several sublines having an additional second integration. For the first transformant line isolated, two integrations were determined to be stable for 15 generations. For five of the lines, a piggyBac-mediated transposition was verified by sequencing the insertion site junctions isolated by inverse PCR that identified a characteristic piggyBac TTAA target site duplication. The efficient and stable transformation of the medfly with a lepidopteran vector represents transposon function over a relatively large evolutionary distance and suggests that the piggyBac system will be functional in a broad range of insects.


To determine the composition of the gut microbiota of two lepidopteran pests, Spodoptera littoralis and Helicoverpa armigera, we applied cultivation-independent techniques based on 16S rRNA gene sequencing and microarray. The two insect species were very similar regarding high abundant bacterial families. Different bacteria colonize different niches within the gut. A core community, consisting of Enterococci, Lactobacilli, Clostridia, etc. was revealed in the insect larvae. These bacteria are constantly present in the digestion tract at relatively high frequency despite that developmental stage and diet had a great impact on shaping the bacterial communities. Some low-abundant species might become dominant upon loading external disturbances; the core community, however, did not change significantly. Clearly the insect gut selects for particular bacterial phylotypes. 041b061a72


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