Common buckeye | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Family: | Nymphalidae |
Genus: | Junonia |
Species: | J. coenia |
Binomial name | |
Junonia coenia Hübner, 1822 | |
Junonia coenia, known as the common buckeye or buckeye, is a butterfly in the family Nymphalidae. Its range covers much of North America and some of Central America, including most of the eastern half of the US, the lower to middle Midwest, the Southwest (including most of California), southern Canada, and Mexico. Its habitat is open areas with low vegetation and some bare ground. Its original ancestry has been traced to Africa, which then experiences divergence in Asia. [2] The species Junonia grisea , the gray buckeye, is found west of the Rocky Mountains and was formerly a subspecies of Junonia coenia. [3] [4]
Caterpillars of these butterflies appear to prefer plants that produce iridoid glycosides, which are bitter compounds that release a hormone called gastrin that activates the digestive system (i.e. hunger); therefore, iridoid glycoside producing plants stimulate and attract their appetites particularly when found in plants like Plantago lanceolata . [5] [6] In fact, the presence of these metabolites may trigger oviposition behaviors in female butterflies so that descendant larval bodies may better incorporate iridoid glycosides. [7] Iridoid glycolyside metabolites appear to have a growth-stimulating effect on caterpillars but a growth-reducing effect on predators. Predators like ants, wasps, birds, and small animals prefer to feed on iridoid glycoside poor caterpillars rather than iridoid glycoside rich larvae, potentially due to these effects. [8] [9] Therefore, immunity of J. coenia larvae to predators like ants appears to be strongly related to the concentration of iridoid glycosides sequestered in their bodies. [10] However, too much iridoid glycosides in the diet can negatively affect the immune response of these larvae and lead to increased susceptibility to parasitism. [11]
Adult butterflies feed on flowers with certain pollinator cues: yellow flowers that are "pre-change", or flowers whose color has not been changed due to insect visitation or other factors. [12] Common buckeye caterpillars feed in isolation rather than relying upon grouping behaviors. [13] Vulnerability to the Junonia coenia densovirus is another concern for survivorship of common buckeye larvae. [14]
Common buckeye butterflies are colored mostly brown with some orange, black, white, blue, and magenta. The forewing features two proximal orange bars and a postmedian white band, which surrounds a prominent black eyespot and borders a smaller, more distal eyespot; both eyespots have a bluish center and each border a distal orange mark. The hindwing is mostly brown with an orange band towards the edge and a brown and white margin. It also has two eyespots, one larger and one smaller, each with a black and white outline 2 and 2.5 inches (5 - 6.5 cm). [15]
These caterpillars have a beautiful and complex color pattern. Their backs are mostly black with light-colored markings (white, gray, beige, or brownish, varying among individuals—see picture below), their sides have white markings and red-orange spots, and they have a brown underside. They have a mostly red-orange head with black markings on the face. They have spines running lengthwise along their back and sides, as many as 7 per segment. There is also a pair of small spines on the top of their head. These spines branch out (have smaller spines coming out of them) and appear a bit shiny-blue at the base. They also have 2 pairs of tiny white spines on each segment, near the bottom. The color patterns and spine forms are less pronounced in earlier instars. There are several other species that resemble these caterpillars in appearance, such as the painted lady, the Glanville fritillary, and the red admiral, which can be easily confused by an untrained observer. They can reach 4 cm (1 5/8 inches) in length. [15]
Like the more familiar monarchs, these caterpillars pupate by spinning a silk pad on a downward facing horizontal surface, attaching themselves with their rear end, and hanging in the form of the letter J for a day or so before shedding their skin to reveal the chrysalis. The chrysalis is mostly brown with beige markings, and has a prickly texture. It has a beige band near the top, another one at the "waist" (border between thorax and abdomen), and 4 pairs of beige dots running down its dorsal side. It is 18 mm long and 8 mm wide. When touched or handled excessively, it has a habit of wiggling its abdomen.
Junio probably arose from one African colonizing ancestor. In Asia, this diverged into J. atlites, J. iphita, and J. hedonia that resembled the African ancestor. These species then diverged into J. almanac, J. lemonias, and J. villida that began to differ morphologically from African ancestors. The Taxon Pulse Hypothesis is invoked to explain the vicariance as well as dispersal exhibited by this species where there is dispersal as the species expands until they find appropriate habitats. This then allows for speciation to occur in several isolated habitats. In Junonia the species may have expanded from Africa into Asia and then from Asia throughout “Australasia, Africa, and South America.” [2] In the 1930s established populations were recognized in Cuba and the Florida Keys. In the 1940s populations migrated inland from the coast of Florida and further into the southern United States. [16]
Caterpillars feed on a variety of plants including the narrowleaf plantain ( Plantago lanceolata ), the common greater plantain ( Plantago major ), blue toadflax, false foxglove, Mexican petunia (Ruellia species), the firecracker plant, and Cudweed.
Iridoid glycosides trigger feeding behaviors of J. coenia larvae in northern California, serving as attractants and as stimulants. It also allows for higher growth and survival rates that appear to be best promoted in the plant Plantago lanceolata , an invasive plant in California. In fact, leaves from this plant were preferred over artificial diets with just the iridoid glycosides, indicating the presence of additional sources in P. lanceolata that might play a role in food preferences. Naturally, J. coenia consider iridoid glycosides in the host plant selection for larvae. This inclination for iridoid glycosides may also reflect its role in oviposition and microhabitat selection. [5] Aucubin and catalpol are two other chemicals that can be stimulants and attractants for larval feeding behaviors. [7]
In the case of Lantana camara flowers, J. coenia preferentially feed on flowers in the yellow stage at a significantly higher rate that suggests associative learning. During early life stages, the butterfly feeds upon yellow and red flowers almost equally but over time focuses only on those flowers that are yellow and 'pre-change.' This is especially advantageous because the flower's color can be linked to its viability as well as the nectar reward that it can provide the pollinator. With this signal the pollinator can visit the right plant at the right time maximizing both its reproductive advantage as well as that of the flower. Moreover, the amount of nectar found within the flower can also influence the duration of a pollinator's visit to the plant. [12]
In the process of oviposition, contact chemoreception is an important sense used to detect allelochemicals on individual leaves that promote or discourage oviposition. Females detect iridoid glycosides found in plants like P. lanceolata as oviposition cues. Similarly, a mix of catalpol and aucubin, as well as catalpol alone, also promotes oviposition. In addition, the quantity of catalpol also seems to play a role in oviposition because females choose to lay eggs in regions that are most concentrated with catalpol. Just one iridoid glycoside molecule is enough to promote oviposition to the same degree that would be seen on a hostplant leaf. However, with that said, females did prefer plants with more iridoid glycosides. Larvae concentrate large amounts of iridoid glycosides, and theoretical explanations for this include protection from predators. Therefore, evolution would favor female J. coenia that can detect more iridoid glycosides on host plants so that larvae can incorporate that into their diet and thus gain better protective mechanisms for survival. [7]
Caterpillars tend to feed individually and in isolation. For example, even in the case that multiple caterpillars are feeding upon the same plant, they will not be doing so cooperatively or based in a group dynamic. [13] Caterpillars are generally not aggressive: they do not mind each other's presence and tend to abstain from fighting when running into one another.
Common buckeyes move to the south along with tailwinds directed to the north or northwest after the cold fronts from September or October. They are sensitive to the cold and cannot spend the winter in northern regions that will experience extreme cold temperatures. However, they will migrate back from the south during the spring. It was spotted in California in late summer, early fall of 2022. [15]
J. coenia appears to readily migrate on a local scale between patches that are connected by corridors over those that are not connected by corridors. They could also affect large scale immigration by making patches more accessible to immigrating butterflies if they are connected by corridors as opposed to if they are unconnected. As a result, this would play a role in increasing the population densities of these habitats, which would then affect resource availability for affected individuals. [17]
Predators for these organisms include ants, wasps, birds, and small animals. Predators appear to select larvae that feed on artificial diets deprived of iridoid glycoside (iridoid glycoside poor) rather than those that consume organic leaf material (iridoid glycoside rich larvae), which may indicate the role of iridoid glycoside consumption. This selection then favors larvae that have diets including iridoid glycosides as well as females who oviposition on those sites by providing offspring with necessary defense mechanisms. [9]
Prey which contain iridoid glycosides can affect invertebrate predators differently. Chemical differences as a result of leaf age can affect the development of these butterflies, which can then affect the quality of these butterflies as food sources for spiders. One such observation indicated that iridoid glycosides may diminish growth of predators so that predators select for caterpillars that do not feed on iridoid glycoside-rich substrates. Iridoid glycosides have been shown to stimulate growth in prey while decreasing growth in predators, which may then be responsible for its role in providing chemical protection to butterflies. [8]
The densovirus Junonia coenia infects the common buckeye larvae by focusing on targeting dividing cells in order to propagate. It consists of single stranded DNA genomes with a smooth, sphere-shaped capsid. It is from the family Parvoviridae and has been considered a potential insecticide, as is hypothesized for other one-species densoviruses. The Junonia coenia densovirus is unique in its separation of DNA strands for structural proteins versus nonstructural proteins. [14]
High intake of iridoid glycosides by J. coenia can have a negative effect on their immune response. This can then lead to higher susceptibility to parasitoids as well as a decreased ability to resist parasitism. Therefore, it is necessary to balance the chemical defense provided by these secondary metabolites with their immunological cost that correlates with increased risk of parasitism. Specifically, secondary metabolites may be hindering the immune response by operating through decreased melanization. This becomes even more problematic since parasitism is a prominent cause of mortality for caterpillars. This relationship exemplifies the vulnerable host hypothesis. [11]
Common predators of J. coenia larvae are ants, and chemical defense appears to be a strong survival mechanism for these organisms against predation. The concentration of iridoid glycoside sequestered by larvae seems to be a strong predictor for the decreased likelihood that they will be predated. [10]
In order to find a host plant for oviposition, females search for appropriate concentrations of catalpol or iridoid glycosides. Therefore, they practice drumming, which allows them to pierce the plant exterior and ‘taste’ the variety of allelochemicals that are present within its structure. This can be detected through the female J. coenia foretarsal chemoreceptors. [7]
Larvae also appear to weakly adopt automimicry as a survival strategy. In the presence of caterpillars that have sequestered iridoids (making them unpalatable to predators) and those that have not sequestered iridoids (making them palatable to predators), unpalatable caterpillars are able to escape predation. However, this trend is a weak example because it also may be the consequence of predators entirely avoiding this species of caterpillars rather than predators rejecting caterpillars. [10]
The common buckeye was featured on the 2006 United States Postal Service 24-cent postage stamp. [18]
Lepidoptera or lepidopterans is an order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organisms, making it the second largest insect order with 126 families and 46 superfamilies, and one of the most widespread and widely recognizable insect orders in the world.
Erysimum, or wallflower, is a genus of flowering plants in the cabbage family, Brassicaceae. It includes more than 150 species, both popular garden plants and many wild forms. Erysimum is characterised by star-shaped and/or two-sided) trichomes growing from the stem, with yellow, red, pink or orange flowers and multiseeded seed pods.
Pieris rapae is a small- to medium-sized butterfly species of the whites-and-yellows family Pieridae. It is known in Europe as the small white, in North America as the cabbage white or cabbage butterfly, on several continents as the small cabbage white, and in New Zealand as the white butterfly. The butterfly is recognizable by its white color with small black dots on its wings, and it can be distinguished from P. brassicae by its larger size and the black band at the tip of its forewings.
The common blue butterfly or European common blue is a butterfly in the family Lycaenidae and subfamily Polyommatinae. The butterfly is found throughout the Palearctic and has been introduced to North America. Butterflies in the Polyommatinae are collectively called blues, from the coloring of the wings. Common blue males usually have wings that are blue above with a black-brown border and a white fringe. The females are usually brown above with a blue dusting and orange spots.
Diplacus aurantiacus, the sticky monkey-flower or orange bush monkey-flower, is a flowering plant that grows in a subshrub form, native to southwestern North America from southwestern Oregon south through most of California. It is a member of the lopseed family, Phrymaceae. It was formerly known as Mimulus aurantiacus.
Plantago lanceolata is a species of flowering plant in the plantain family Plantaginaceae. It is known by the common names ribwort plantain, narrowleaf plantain, English plantain, ribleaf, lamb's tongue, and buckhorn. It is a common weed on cultivated or disturbed land.
Heliconius charithonia, the zebra longwing or zebra heliconian, is a species of butterfly belonging to the subfamily Heliconiinae of the family Nymphalidae. It was first described by Carl Linnaeus in his 1767 12th edition of Systema Naturae. The boldly striped black and white wing pattern is aposematic, warning off predators. It is the state butterfly of Florida.
The Glanville fritillary is a butterfly of the family Nymphalidae. It is named for the naturalist who discovered it and the checkerboard pattern on its wings. These butterflies live in almost all of Europe, especially Finland, and in parts of northwest Africa. They are absent from the far north of Europe and parts of the Iberian Peninsula. To the east they are found across the Palearctic.
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Battus philenor, the pipevine swallowtail or blue swallowtail, is a swallowtail butterfly found in North America and Central America. This butterfly is black with iridescent-blue hindwings. They are found in many different habitats, but are most commonly found in forests. Caterpillars are often black or red, and feed on compatible plants of the genus Aristolochia. They are known for sequestering acids from the plants they feed on in order to defend themselves from predators by being poisonous when consumed. The adults feed on the nectar of a variety of flowers. Some species of Aristolochia are toxic to the larvae, typically tropical varieties. While enthusiasts have led citizen efforts to conserve pipevine swallowtails in their neighborhoods on the West coast, the butterfly has not been the subject of a formal program in conservation or protected in legislation. The butterfly is however of "Special Concern" in Michigan, which is on the Northern limit of its range.
Iridoids are a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They are biosynthetically derived from 8-oxogeranial. Iridoids are typically found in plants as glycosides, most often bound to glucose.
The variable checkerspot or Chalcedon checkerspot is a butterfly in the family Nymphalidae. It is found in western North America, where its range stretches from Alaska in the north to Baja California in the south and extends east through the Rocky Mountains into Colorado, Montana, New Mexico and Wyoming. The butterfly is usually brown or black with extensive white and yellow checkering and some red coloration on the dorsal wing. Adult wingspan is 3.2–5.7 cm (1.3–2.2 in). Adult butterflies feed on nectar from flowers while larvae feed on a variety of plants including snowberry (Symphoricarpos), paintbrush (Castilleja), Buddleja, Diplacus aurantiacus and Scrophularia californica.
Catalpol is an iridoid glucoside. This natural product falls in the class of iridoid glycosides, which are simply monoterpenes with a glucose molecule attached.
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Junonia grisea, also known as the gray buckeye, grey buckeye, or Western buckeye, is a species in the butterfly family Nymphalidae. It is found in North America, west of the Rocky Mountains. Like the common buckeye, the gray buckeye is a brown butterfly with eyespots on its wings that distract predators from its body.
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