The Quino Checkerspot

Quino ButterflyThe Quino checkerspot, known scientifically as euphydryas editha quino, is a butterfly native to southern California and northwestern Mexico which is now endangered. Once well represented in the San Bernardino Mountains, it is now only rarely spotted there.
A member of the brush-footed butterfly family, Nymphalidae, the Quino checkerspot is a medium-sized butterfly with a wingspan of around one-and-one-quarter inches to one-and-a-half inches. The dorsal wing surface is a colorful checkerboard of brown, red and yellow spots. The Quino differs from other E. editha subspecies in that its spots tend to be a darker red.
It also differentiates itself through its size and larval and pupal phenotypes. The ventral side of the butterfly is dominated by a checkered red and cream pattern. Its abdomen has red stripes across the dorsal side. After a second molt, the Quino checkerspot is recognized by the dark black coloration and row of 8 to 9 orange tubercles on its back. Before the larvae first molt they are mostly yellowish. After first molt and before their second molt they are gray with black markings. The pupae are mottled black on a blue-gray background.
An obvious factor in the decline of the Quino checkerspot is urban development. Much of the historic scrub land that it occupied has been built over. The persisting habitat faces other threats. Invasive species, in the form of non-native plant life, along with fire suppression practices and overgrazing are three major hurdles facing the recovery of the Quino checkerspot. Nearly all of the blame lie in agricultural and urban development in southern California. Today, there are eight populations of the Quino known.
With its habitat having declined, the distribution and population of the Quino checkerspot has been greatly reduced during the last 100 years. Currently, the Quino checkerspot is consistently found in a very few locales, which are limited to Western Riverside County, southern San Diego County and northern Baja California, Mexico. The animal’s historic range once included much of coastal California south of Ventura County as well as the inland valleys south of the Tehachapi Mountains. Regardless, more than 75 percent of the butterfly’s original range has been lost. The range loss translates directly into population decline. Quino checkerspot butterfly populations appear to have decreased by more than 95 perectnt rangewide.
The Quino life cycle includes four distinct life stages: egg, larva (caterpillar), pupa (chrysalis), and adult, with the larval stage divided into 5 to 7 instars (periods be tween molts, or shedding skin). There is usually one generation of adults per year, although larvae may remain in diapause (summer dormancy) for multiple years prior to maturation.
Quino are exothermic (cold-blooded) and therefore require an external heat source to increase their metabolic rate to levels needed for normal growth and behavior. Within open, woody-canopy communities, larvae seek microclimates with high solar exposure for basking in order to speed their growth rate. Like most butterflies, adult Quino frequently bask and remain in sunny areas to increase their body temperature to the level required for normal active behavior.
Oviposition begins within a day of the female’s emergence, with females depositing masses of up to hundreds of eggs at the base of host plants. Most populations are monophagous, with females normally ovipositing on only one of several potential host species. Such plants include Plantago erecta and Orthocarpus densiflorus.
The eggs further develop into pre-diapause larvae whose goal is to enter diapause and reach the fourth instar before their annual host plants deteriorate with age. Thus, females try to enhance offspring survival by laying egg masses on cool moist slopes where host plant deterioration is most delayed. Once the larvae reach the diapause stage and become post-diapause larvae (pupae), they must grow by basking in the sunlight to regulate their body temperature. Larval body temperature is about 18 to 22 °F above ambient temperature, and the fastest growth rate occurs at 86-95 °F. They must receive enough exposure to the sun’s rays to terminate the diapause stage and become a fully-grown butterfly. Thus, the paradox is that these larvae no longer prefer the cool slopes of host plants they grew up on, as it produces shade to restrict growth.
Caterpillars in the genus Euphydryas are usually attacked by one to three parasitoid species, often by a species of Apanteles wasp (Braconidae), a species of Benjaminia wasp (Ichneumonidae), and a tachnid fly. Checkerspot butterflies have developed defense mechanisms to prevent predators from attacking. Larvae twitch in unison to repel predators, and, depending on the host plant of the population, the larvae, pupae, and adult butterflies are somewhat poisonous to vertebrates because they may ingest toxins from the plant.
Male Edith’s checkerspot butterflies exhibit polygyny and may mate with multiple females. Females, on the other hand, mate once or occasionally twice. Young females remain motionless on the ground in low vegetation for about an hour after emerging as an adult from the larva while their wings harden. During this time they cannot fly or easily reject courting males. Thus, the first mate to locate a female usually mates with her. Virgin females release a pheromone which attracts males. Hidden virgins are found by males after an average of fifty minutes.
There are at least two mechanisms evolved to prevent females from remating: physical and neurological/behavioral. The physical mechanism involves a literal physical barrier. When the male’s spermatophore is deposited into the female’s bursa copulatrix, the spermatophore has a long neck that can act as a mating plug to seal it and prevent further mating. When, however, second matings occur before the plug has hardened or if the plug erodes, the female lays eggs which have been predominantly fertilized by the sperm of the last male to mate, as the last sperm to enter and be stored in the spermatheca of the female is also usually the first to leave. The second, neurological, inhibition mechanism involves mate rejection behavior in which the female flaps and tries to escape. This behavior is stimulated by the neural sensation of bursal distention, which occurs in the presence of a spermatophore.
Most male reproductive effort is devoted to the acquisition of females, especially virgin females. Males often exhibit indiscriminate mate location behavior, which is characterized by males failing to distinguish between female conspecifics, that is, members of its own species, and other objects, frequently resulting in misdirected courtship or attempted copulation. In some cases, males become attracted to spider webs containing dead conspecifics, mistaking the motionless bodies in the webs for young females, and attempt copulation. This puts them at risk of death, showing that there is a risk of male mortality associated with indiscriminate mate location behavior. However, the benefit outweighs the cost, and indiscriminate mate location behavior prevails.
Edith’s checkerspot males sometimes form aggregations on patches of bare ground like ridges or peaks, and from these perches they dart after passing males and females of both their conspecifics and heterospecifics, and other species. This strategy is called perching. Another strategy is termed “patrolling” and consists of males wandering in search of mates. In years of low population density, the hilltopping behavior may become adaptive. In such instances, males concentrate in mating aggregations at the highest point of a slope and females must travel up the slope to mate. After mating, females return down the slope in order to minimize sexual harassment, and deposit eggs. Hilltopping occurs in small populations where there is a smaller chance for virgin females to encounter males before reaching the hilltop. Where populations are relatively dense; however, upslope movement may place these butterflies at a reproductive disadvantage.
-From Wikipedia

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