Lepidoptera
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A Giant Leopard Moth (Hypercompe scribonia)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Subclass: Pterygota
Infraclass: Neoptera
Superorder: Endopterygota
Order: Lepidoptera
Linnaeus, 1758
Suborders
Aglossata
Glossata
Heterobathmiina
Zeugloptera
Lepidoptera (pronounced /ˌlɛpɪˈdɒptərə/) is a large order of insects that includes moths and butterflies (called lepidopterans). It is one of the most speciose orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies and found virtually everywhere. Lepidoptera contains more than 180,000 species in 128 families and 47 superfamilies. The name is derived from Ancient Greek λεπίδος (scale) and πτερόν (wing). Estimates of species suggest that the order may have more species and is among the four largest, successful orders, along with the Hymenoptera, Diptera, and the Coleoptera.
Species of the order Lepidoptera are commonly characterized as being covered in scales, having two large compound eyes, and an elongated mouthpart called a proboscis. Almost all species have membranous wings, except for a few who have crossvein wings. The larvae are called caterpillars and are completely different in form, having a cylindrical body with a well developed head, mandible mouthparts, and from 0–11 (usually 8) legs.
The Lepidoptera have, over millions of years, evolved a wide range of wing patterns and coloration ranging from drab moths akin to the related order Trichoptera to the brightly colored and complex-patterned butterflies. Accordingly, this is the most recognized and popular of insect orders with many people involved in the observing, study, collecting, rearing and commerce of these insects. A person who collects or studies this order is referred to as a lepidopterist. Many species of the order are of economic interest by virtue of the silk they produce, and serve an important natural role through pollination.
Etymology
The word Lepidoptera comes from the Latin word for "scaly wing", from the Ancient Greek λεπίδος (Lepidos) meaning scale and πτερόν (pteron) meaning wing. Sometimes the term Rhopalocera is used to group the species that are butterflies, from the Ancient Greek ῥόπαλον (Rhopalon) and κέρας (kæras) meaning club and horn respectively; coming from the shape of the antennae of butterflies.
The origins of the common names of many species vary. The English word butterfly is from Old English buttorfleoge, with many variations in spelling. Other than that, the origin is unknown, however it could be derived from the pale yellow color of many species' wings (e.g., Yellow Sulfur: Pieridae) suggests the color of butter.(butterfly) The species of Heterocera are commonly called moths. The origins of the English word moth are more clear, which comes from Old English "moððe" (cf. Northumbrian "mohðe") from Common Germanic (compare Old Norse "motti", Dutch "Mot" and German "Motte" all meaning "moth"). Perhaps its origins are related to Old English "maða" meaning "maggot" or from the root of "midge" which until the 16th century was used mostly to indicate the larva, usually in reference to devouring clothes.(moth)
Distribution and diversity
Out of the more than 180,000 species described to date can be found virtually everywhere. Some 11,300 species are from North America, and 10,000 from Australia. Lepidoptera are found in a large variety of habitats, but almost always associated with higher plants, especially angiosperms (flowering plants).
Morphology and physiology
As in all insects, all species of Lepidoptera have an exoskeleton and segmented into three parts (head, thorax, abdomen) with scales and three pairs of legs. They also have two large compound eyes and an elongated mouthpart called a proboscis. Almost all species have membranous wings, except for a few who have crossvein wings. The larva are completely different in form, having a soft body with a well developed head, mandible mouthparts, and up to 11 pairs of legs (usually 8).
Morphology
Head
The adult head is segmented into six segments, though controversial[citation needed], and covered with hair-like scales. Lepidoptera have a long proboscis curled under their head, and have two large compound eyes which cover much of their head. These compound eyes are made of a large number of hexagonal facets, or lenses. Each facet is connected to a lens-like cylinder that is attached to nerves leading to the brain. Each facet subtends and forms the part of an ommatidium, or cluster of photoreceptor cells.
Lepidoptera have long, segmented antennae that act as olfactory organs. Lepidoptera antennae also have a Johnston's organ, a collection of sensory cells found in the pedicle (or second segment) of the antennae which perceives stretching between the pedicel and the rest of the antenna. In the case of Monarch butterflies, it has been shown that antennae are necessary for proper time-compensated Sun compass orientation during migration, that antennal clocks exist in monarchs, and that they likely provide the primary timing mechanism for sun compass orientation. In moths, males frequently have more feathery antennae than females, for detecting the female pheromones at a distance.
Caterpillars have very different heads than adult butterflies and moths, with a hard and well developed head cap for protection and mandible mouthparts designed to feed on plants.
Thorax
The thorax contains much of the insects means of locomotion, such as the legs and the wings. The thorax consists of three invisibly divided segments, namely the prothorax, metathorax and mesothorax. Adults have two pairs of membranous wings covered, usually completely, by minute scales. In some species, wings are reduced or absent (often in the female but not the male). The Trichoptera (caddisflies) which are a sister group of the Lepidoptera have scales, but also possess caudal cerci on the abdomen, a feature absent in the Lepidoptera.
Abdomen
The abdomen comprises about 9 segments, from segment 5 to 13 in larvae. The eleventh segment of the caterpillar's abdomen holds the anal clasps which are represented as the genitalia which protrudes in the case of some taxa.
Internal physiology
The digestive system of Lepidoptera consists of the proboscis, leading to the esophagus or gullet, and the stomach, over which is a large, bladder-like vessel called the proventriculus, a sort of crop preceding the true stomach, which is a cylindrical tube; the intestine is a slender tube (varying in shape in different genera) divided into the small intestine, the colon, and the rectum.
Polymorphism
Polymorphism is appearance of forms or "morphs" differing in color and number of attributes within a single species.:163 In Lepidoptera, polymorphism can be seen not only between individuals in a population, but also between the sexes, termed as sexual dimorphism, between geographically separated populations in geographical polymorphism and also between generations flying at different seasons of the year (seasonal polymorphism). It also includes the phenomenon of mimicry when mimetic morphs fly alongside non-mimetic morphs in a population of a particular species. Polymorphism occurs both at specific level with heritable variation in the overall morphological design of individuals as well as in certain specific morphological or physiological traits within a species.
Genetic polymorphism
Genetic polymorphism occurs when the morphs are a result of genetic determination only. The extreme case of genetic polymorphism is that of the papilionid Great Mormon (Papilio memnon), where four male forms and many as twenty-six female forms are reported. This species, and others in its genus, have been extensively studied for understanding the genetic basis for polymorphism and Batesian mimicry.
In the case of the Scarlet Tiger Moth Callimorpha (Panaxia) dominula (family Arctiidae), which is a diurnal moth occurs in continental Europe, western Asia and southern England, three forms occur in England : the typical homozygote; the rare homozygote (bimacula) and the heterozygote (medionigra). It was studied there by E.B. Ford, and later by P.M. Sheppard and their co-workers over many years. Data is available from 1939 to the present day, got by the usual field method of capture-mark-release-recapture and by genetic analysis from breeding in captivity. The records cover gene frequency and population-size for much of the twentieth century. In this instance the genetics appears to be simple: two alleles at a single locus, producing the three phenotypes. Total captures over 26 years 1939-64 came to 15,784 homozygous dominula (i.e. typica), 1,221 heterozygous medionigra and 28 homozygous bimacula. Now, assuming equal viability of the genotypes 1,209 heterozygotes would be expected, so the field results do not suggest any heterozygous advantage. It was Sheppard who found that the polymorphism is maintained by selective mating: each genotype preferentially mates with other morphs. This is sufficient to maintain the system despite the fact that in this case the heterozygote has slightly lower viability.
Sexual dimorphism
