Wood tiger
Arctia plantaginis, the wood tiger, is a moth of the family Erebidae. Several subspecies are found in the Holarctic ecozone south to Anatolia, Transcaucasus, northern Iran, Kazakhstan, Mongolia, China, Korea and Japan. One subspecies is endemic to North America.
This species was formerly a member of the genus Parasemia, but was moved to Arctia along with the other species of the genera Acerbia, Pararctia, Parasemia, Platarctia, and Platyprepia.
P. plantaginis males occur predominantly in two distinct color phenotypes: yellow and white. They are aposematic, meaning their colorations serve to deter predators from attacking. In populations of aposematic species, it is common to have a single coloration phenotype dominate, because predators better learn to avoid the more common phenotype and rare phenotypes suffer higher predation. Rare phenotypes are often selected against because predators are less familiar with their aposematic signal. Thus, other selective pressures exist to perpetuate weaker aposematic signals in exchange for other adaptive benefits. P. plantaginis has become a common model for studying the counteracting selective pressures of predation, mate choice, immune function, thermoregulation, and more.
Te
TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Ov
OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
A
starts withThis moth is extraordinarily variable. The wingspan is 32–38 mm. Normally, it has a black forewing in both sexes, with moderately broad, ivory yellow bands. In the male, the hindwing is yellow or white with an irregular marginal band, which is often interrupted, and two or three submarginal spots. The basal portion of the hindwing bears black streaks at the margin of the cell and before the anal margin. In the female, the hindwing is red above with the base strongly black. Numerous aberrations have been found and named, which often occur predominantly, and only exceptionally among typical specimens. Major aberrations are listed by Seitz, 1913.
There are populations throughout the globe, but most common in northern latitudes of North America and Eurasia. The North American populations range from Alaska to Manitoba, and south through the Rocky Mountain region to southern New Mexico, with isolated populations occurring in Arizona and the Sierra Nevada mountains of California and Nevada.
P. plantaginis prefer slightly moist areas, like meadows with nearby streams. Adults like to spend time close to lupine stands, which are meadows of plants from the genus Lupinus. It is estimated that over 250 annual and perennial species of this genus Lupinus are distributed throughout both montane and lowland habitats, with hugely diverse regions found in North and South America.
Males are, on average, smaller than females but experience a relatively similar rate of development. Generally a longer development time correlates with a larger pupal mass, and in females, pupal mass correlates with total lifetime eggs produced.
As a polyphagous species, the life history traits of P. plantaginis depend on its habitat and diet. In P. plantaginis, high anti-oxidant intake from their diet significantly increases their ability to encapsulate pathogens. Encapsulation is an important, innate immune response that occurs in invertebrates to protect against a variety of parasites and pathogens. The antioxidants serve to protect cells from damage incurred by the creation of free radicals resulting from the encapsulation reaction. In environments where the pathogen load is likely to be high, the food ingested by an individual moth is important in building its defense mechanisms.
Flight behavior in populations of P. plantaginis vary between color morphs and are under frequency dependent selection. In outdoor cage experiments of populations with various frequencies of yellow and white male morphs, researches found that white morphs were significantly more active and had longer periods of sustained activity than yellow morphs across all treatment groups. In groups with higher frequencies of yellow morphs, overall flying activity for both morphs was considerably lower. The data suggest that white male morphs invest less in producing costly warning signals and thus have more energy to invest in flight for both avoiding predation and finding mates. Yellow males, which in previous studies have been shown to be less sexually favored by females than whites, tend to be most active at peak female-calling periods.
Wood tiger moths are polyphagous, meaning their diet can vary significantly. Eating different host plants can result in different immune function and overall life history traits; one example of this is shown by wood tiger moth caterpillars that feed on ribwort plantain. These plant contain high levels of iridoid glycosides, which help caterpillars produce defensive chemicals. A 2015 study showed that the iridoid glycosides present in plantain-eating larvae is sufficient to deter both ants and parasitoids.
Yellow morphs are able to avoid predation more readily than white morphs; however, a laboratory study showed that yellow males had lower mating success compared to white males. This trade-off between reproductive success and predator avoidance could explain why two polymorphisms exist.
Females tend to attract males during the day, and they group together at dusk. It has been observed that once attracted to a group of females, male P. plantaginis will readily mate with females of a related species Arctica villa, most likely due to their similar sex pheromones. Similarly, female P. plantaginis are also attracted to male Artica villas.
