Tegeticula Intermedius
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''Tegeticula intermedia'' is a
moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...
of the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Prodoxidae The Prodoxidae are a family of moths, generally small in size and nondescript in appearance. They include species of moderate pest status, such as the Lampronia capitella, currant shoot borer, and others of considerable ecological and evolutionar ...
. Along with other moth species, it is commonly known as a yucca moth. ''T. intermedia'' lives in North America, particularly the United States. The moth resides in the southwest, the
Great Plains The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...
, the Southeast, and mid-Atlantic. It also has been found much farther north in regions of Canada like
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
and Alberta. There are also notable populations present in
New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...
. Their habitats are diverse and vary in terms of climate, landscape, and other factors. The moth lives in sand dunes, forests (pine, pinyon, oak), glades, grassland, desert, and forests from the East Coast to the Southwest. Yucca moths have developed a strong mutualism with the yucca plant, such that both depend on each other for survival. The yucca moths and yucca plants have coevolved over millions of years. However, ''Tegeticula intermedia'' differs from most yucca moths in that it exhibits cheating behavior by laying eggs without pollinating the yucca plant. __TOC__


Geographic range

''T. intermedia'' primarily lives within the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
in the Southwest and Great Plains. However, it also has managed to maintain populations in the Southeast, including
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
, Georgia, and Virginia. It has additionally been found in Ontario and Alberta, Canada. The latest research suggests that ''T. intermedia'' originated from the Southwestern region of the United States, approximately located in present New Mexico. It then followed the yucca plant as it propagated eastward and into the south, particularly in Florida. The sister species to ''T. intermedia'', '' Tegeticula cassandra'', also exhibits cheating behavior in pollination and is restricted to the Southeastern United States. This led some scientists to believe that ''T. intermedia'' originated from this region, known as the "out-of-Florida hypothesis." However, recent
mtDNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in ...
analysis suggests that the species did in fact originate in the West.


Habitat

Yucca moths such as ''T. intermedia'' tend to live where their partner
yucca ''Yucca'' ( , YUCK-uh) is both the scientific name and common name for a genus native to North America from Panama to southern Canada. It contains 50 accepted species. In addition to yucca, they are also known as Adam's needle or Spanish-bayon ...
plants do. ''T. intermedia'' has been found to reside in a diverse array of environments including shrub deserts, coastal dunes, prairies, forests (
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
and
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
), and glades. This moth has an approximate vertical distribution from 0-1400m.


Food resources


Caterpillar

Larvae feed on a variety of plants within the yucca genus, depending on the region of the population. Some host species include ''
Yucca filamentosa ''Yucca filamentosa'', Adam's needle and thread, is a species of flowering plant in the family Asparagaceae native to the southeastern United States. Growing to tall, it is an evergreen shrub valued in horticulture. Description Usually trunkle ...
, Y. arkansana, and Y. flaccida.'' Larvae feed on yucca seeds within the fruit. Since there is an abundance of seeds within the fruit, the larva does not impinge too heavily upon the health of the yucca plant or compete too strongly with other pollinator species of yucca moths. These seeds are the only known food source to the yucca moth larvae. The larvae of ''T. intermedia'' superficially crawl towards the ovary so they can burrow past the wall and commence feeding upon the developing seeds. They then escape from the flower, falling to the ground to burrow and cocoon.


Adult

Adults have such short lifespans that they do not need to eat to achieve their reproductive goals. Although they do have mouth parts or tentacles, these are used for collecting pollen than for feeding.


Parental care


Host plant selection for egg laying

The host yucca plant regulates the number of eggs laid by selectively abscessing flowers that are overburdened with eggs. The plant selects which flowers to abscess by assessing its weight due to the excess of eggs and by recognizing severe ovule damage due to excessive oviposition. In ''T. intermedia,'' the moth avoids ovipositing into the
ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...
directly. Thus, the plant does not perceive ovule damage, and will not abort the flower.


Oviposition

Although most yucca moths deposit their eggs in the ovule of the flower, ''Tegeticula'' employs different methods of laying eggs. ''T. intermedia'' employs superficial
oviposition The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
, meaning that the yucca moth lays its eggs very slightly beneath the plant tissue, so as not to damage the yucca ovule. This strategy allows the moth to bypass the yucca plant's regulation of the number of eggs it hosts, leading to exploitation of the plant. Oviposition takes place in the fruit of the yucca.


Life cycle


Egg

Yucca moths' mate in the spring when the yucca flowers are in bloom. They then mate on the yucca flower, usually in the evening when the flower will be open. Then, the female moth will lay eggs in the wall of the fruit of the yucca, typically around 6- to 20-day-old fruits. ''T. intermedia'' is unique in that it will superficially oviposit eggs one at a time so as to deceive the yucca plant.


Caterpillar

Once laid, the larvae will hatch quickly in only a few days' time. During early
instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...
s the larvae feed inside the fruit on the developing seeds. Later in their development, the matured instars leave the fruit, preferably after a rainstorm or during wet conditions to make escape easier.


Pupa

The larvae fall to the ground, burying themselves in a cocoon one to two dozen centimeters below ground during
pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...
tion.


Adult

The adult moths will emerge in the following spring to restart the life cycle.


Protective behavior

''T. intermedia'' is a predominantly white colored insect. Mild color variation occurs in different regions. The white color allows the moth to blend in with the yucca flower,
camouflaging Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
it from predators.


Genetic hybridization

Hybridization is when two different species or genetically different varieties of the same species are able to breed and produce offspring together. The offspring may have limited reproductive capability''.'' ''T. intermedia'' has successfully been able to mate with a similar moth, '' Tegeticula cassandra.'' Both have incredibly similar superficial ovipositor and
aedeagus An aedeagus ( or aedeagi) is a reproductive organ of male arthropods through which they secrete sperm from the testes during copulation (zoology), copulation with a female. It can be thought of as the insect equivalent of a mammal's penis, th ...
physiology. However, ''T. intermedia'' has not been found to have hybridized with any species with a
locule A locule (: locules) or loculus (; : loculi) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usually refers to a chamber within an ovary ...
ovipositor. Research suggests that it is thus the similarity in ovipositor that allows two different species to hybridize.


Physiology

''T. intermedia'' has a modest
wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the opposite wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingsp ...
of around 25 mm. The fore wings can occasionally have a slight tan color, but the body of the moth is predominately white. The hind wings are a soft, light grey and brown color. These moths tend to be lighter in more southern populations. Female moths have special tentacles as mouth parts (although it does not eat as an adult) which it uses to scrape pollen from a yucca anther into a relatively large, sticky ball that can be as big as 10% of her body mass.


Olfaction

Female yucca moths use their antennae to sense if a flower has already been visited, and presumably oviposited on, by another female by detecting trace
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s left behind. If detected, the female leaves and finds another flower that hopefully has not been pollinated yet.


Parasitism


With plants

Yucca moths get their name for the intense, obligate mutualism they share with the
yucca ''Yucca'' ( , YUCK-uh) is both the scientific name and common name for a genus native to North America from Panama to southern Canada. It contains 50 accepted species. In addition to yucca, they are also known as Adam's needle or Spanish-bayon ...
genus that has
evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
over millions of years. The yucca moth is the only insect capable of pollinating the yucca plant. Likewise, the yucca plant is the only biological resource that sustains the moth. Both are so deeply interdependent on each other for survival that in most cases one local population extinction event of either the plant or moth would lead to an extinction of the complementary species. However, ''Tegeticula intermedia'' is a cheater species of yucca moth that parasitizes the yucca plant. It has evolved to superficially oviposit to avoid detection by the yucca that would allow it to lay many eggs without inducing flower abortion. The key trait of this species is that it lays eggs without pollinating the yucca. It enjoys the benefits of reproducing without the costs of aiding yucca reproduction at the expense of the host.


References


External links

* http://tolweb.org/Tegeticula_intermedia/12474 (includes pictures of species and range map) {{Taxonbar, from=Q7694713 Moths described in 1892 Prodoxidae