Leptidea sinapis, or the wood white butterfly of the family Pieridae, is a small white butterfly that is mainly found in England, Ireland, and Northern Europe. Since the species is currently depleting in size throughout England, it is primarily found in woodland pockets, such as the Haugh and Wigmore Woods of Herefordshire. L. sinapis is also found in Slovakia, the Czech Republic, Sweden, France, Spain and Ireland.
Habitat
The wood white is found in the midlands and southern parts of the United Kingdom, largely in the clearings among woodlands or nearby shrubbery. They can often also be found in areas where there is substantial shelter, such as abandoned railway tracks and cliffs near the sea shore, as well as meadows, forest edges and sparse forests up to 2,500 m above sea level. One of the most consistently populous regions of England in terms of L. sinapis is in Herefordshire, particularly the Haugh Wood and Wigmore Rolls woodlands. The wood white requires habitats with substantial vegetation and shrubbery in order to lay eggs and pupate, however they are very particular about the amount of shade in their habitat. Substantial habitat loss for wood whites occurs as a result of too much shrubbery or shade in their living environments. They select very specific food-plants within these habitats.
Host plant learning and selection for egg laying
Female wood whites lay the eggs on very specific food-plants (such as Lotus pedunculatus, Lathyrus pratensis, and Lotus corniculatus) that they select through chemoreception via receptors on their feet. They fly low and slowly over the shrubbery and test several plants by landing on them and using their chemoreceptors. The species is bivoltine, meaning that two generations hatch per year, during the months of late May through August.
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(MHNT)_Leptidea_sinapis_-_Foret_de_Bouconne,_France_-_male dorsal.jpg|Leptidea sinapis ♂
(MHNT)_Leptidea_sinapis_-_Foret_de_Bouconne,_France_-_male ventral.jpg|Leptidea sinapis ♂ △
(MHNT) Leptidea sinapis - Foret de Bouconne, France - female dorsal.jpg|Leptidea sinapis ♀
(MHNT) Leptidea sinapis - Foret de Bouconne, France - female ventral.jpg|Leptidea sinapis ♀ △
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Genetics
Speciation
Leptidea sinapis is one of three species in a cryptic species complex. The other members of the cryptic species complex are L. reali and L. juvernica. Similar species are L. morsei, L. duponcheli and L. amurensis. The two other related species that have been classified (L. reali and L. juvernica) do not exhibit cross-mating. DNA and mitochondrial studies have shown that the two taxa are definitively different; although they appear the same in wing coloration and external appearance, they can be differentiated by their genitalia. A population genetic study of male L. sinapis, L. reali and L. juvernica individuals showed no evidence for gene flow after divergence. L. reali is found in Italy, Spain, and France, while L. juvernica is found more in England and Ireland, and other Nordic countries. They appear to be niche separated—they utilize and inhabit different habitats. Male members of the two species try and mate with females of both species with equal frequency, but the females only mate with members of their own species. Researchers are attempting to understand the reason for the niche-separation of the two subspecies. The two species tend to lay eggs on the same plants, causing researchers to hypothesize that host-plant selection is not the primary reason for niche-separation and later speciation. The choice of host plant did not affect survival rates of either species to any significant degree, but the most common host plant for both larvae was L. pratensis.
Mating
Female-male interactions
Mate choice
There are two reproductively isolated species of wood white called L. sinapis and L. reali. These two species can mate with each other (heterospecific mating), but it is in their best interest, for the viability and fecundity of their offspring, that they mate only within their species (conspecific mating). Male members of the two species try and court or mate with females of both species with equal frequency, but the females only mate with members of their own species. This female choice has caused the two species to diverge and become reproductively isolated. There is a time and energy cost that the females bear when males of the opposite species attempt to mate with them—this cost has led to females occasionally acquiescing and mating with these males, leading to some degree of between-species hybridization.
Physiology
Flight
Adult wood whites fly slowly, and they appear to flutter. Males spend the majority of their lifetime flying low over shrubbery to find possible mates. Males have white-tipped antennae, while females have brown-tipped antennae.
Threats
Predators
Predators of the wood white eggs are largely unknown, but lead to 90-98% of all egg deaths.