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''Pieris rapae'' is a small- to medium-sized
butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises ...
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
of the whites-and-yellows family
Pieridae The Pieridae are a large family of butterflies with about 76 genera containing about 1,100 species, mostly from tropical Africa and tropical Asia with some varieties in the more northern regions of North America and Eurasia.DeVries P. J. in L ...
. 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 caterpillar of this species, often referred to as the "imported cabbageworm", is a pest to crucifer crops such as cabbage, kale, bok choy and broccoli. ''Pieris rapae'' is widespread in Europe and
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
; it is believed to have originated in the
Eastern Mediterranean Eastern Mediterranean is a loose definition of the eastern approximate half, or third, of the Mediterranean Sea, often defined as the countries around the Levantine Sea. It typically embraces all of that sea's coastal zones, referring to commun ...
region of Europe, and to have spread across Eurasia thanks to the diversification of brassicaceous crops and the development of human trade routes. Over the past two centuries, it spread to North Africa, North America, New Zealand, and Australia, as a result of accidental introductions.


Description

In appearance it looks like a smaller version of the
large white ''Pieris brassicae'', the large white, also called cabbage butterfly, cabbage white, cabbage moth (erroneously), or in India the large cabbage white, is a butterfly in the family Pieridae. It is a close relative of the small white, '' Pieris ...
(''Pieris brassicae''). The upperside is creamy white with black tips on the forewings. Females also have two black spots in the center of the forewings. Its underwings are yellowish with black speckles. It is sometimes mistaken for a moth due to its plain appearance. The wingspan of adults is roughly .


Distribution and habitat

The species has a natural range across Europe, Asia, and North Africa. It was accidentally introduced to Quebec, Canada, around 1860 and spread rapidly throughout North America. The species has spread to all North American
life zones The life zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities. Merriam observed that the changes in these communities with an increase in latitude at a constant elevation a ...
from Lower Austral/Lower Sonoran to Canada. Estimates show that a single female of this species might be the progenitor in a few generations of millions. It is absent or scarce in desert and semidesert regions (except for irrigated areas). It is not found north of Canadian
life zone The life zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities. Merriam observed that the changes in these communities with an increase in latitude at a constant elevation a ...
, nor on Channel Islands off the coast of southern California. By 1898, the small white had spread to Hawaii; by 1929, it had reached New Zealand and the area around Melbourne, Australia, and found its way to Perth as early as 1943. It does not seem to have made it to South America. In Britain, it has two flight periods, April–May and July–August, but is continuously brooded in North America, being one of the first butterflies to emerge from the chrysalis in the spring and flying until hard freeze in the fall. The species can be found in any open area with diverse plant association. It can be seen usually in towns, but also in natural habitats, mostly in valley bottoms. Although an affinity towards open areas is shown, the small white is found to have entered even small forest clearings in recent years. The nominate subspecies ''P. r. rapae'' is found in Europe, while Asian populations are placed in the subspecies ''P. r. crucivora''. Other subspecies include ''atomaria'', ''eumorpha'', ''leucosoma'', ''mauretanica'', ''napi'', ''novangliae'', and ''orientalis''.


Life cycle

The small white will readily lay
eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
on both cultivated and wild members of the cabbage family, such as
charlock ''Sinapis arvensis'', the charlock mustard, field mustard, wild mustard, or charlock, is an annual or winter annual plant of the genus '' Sinapis'' in the family Brassicaceae. It is found in the fields of North Africa, Asia and Europe. ''Pieris ...
(''Sinapis arvensis'') and
hedge mustard ''Sisymbrium officinale'', the hedge mustard, (formerly ''Erysimum officinale'') is a plant in the family Brassicaceae. Description It is distinct from the mustard plants which belong to the genus ''Brassica''. ''S. officinale'' is similar to ot ...
(''
Sisymbrium officinale ''Sisymbrium officinale'', the hedge mustard, (formerly ''Erysimum officinale'') is a plant in the family Brassicaceae. Description It is distinct from the mustard plants which belong to the genus ''Brassica''. ''S. officinale'' is similar to ot ...
''). ''P. rapae'' is known to lay eggs singularly on the host plant. The egg is characterized by a yellowish color and 12 longitudinal ridges. The egg production peaks about a week after adulthood in lab and the female can live up to 3 weeks. Females tend to lay fewer eggs on plants in clumps than on isolated plants. It has been suggested that isothiocyanate compounds in the family Brassicaceae may have been evolved to reduce herbivory by caterpillars of the small white. However, this suggestion is not generally accepted because the small white has later been shown to be immune to the isothiocyanate forming reaction due to a specific biochemical adaptation. In contrast, the small white and relatives seem to have evolved as a consequence of this biochemical adaptation to the isothiocyanate-forming glucosinolates. Traditionally known in the United States as the imported cabbage worm, now more commonly the cabbage white, the caterpillars are bluish-green, with tiny black pints, a black ring around the spiracles, and a lateral row of yellow dashes, and a yellow middorsal line. Caterpillars rest on the undersides of the leaves, making them less visible to predators. Although the larval
instars An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or as ...
have not been fully studied, different instars are easily differentiated simply by comparing sizes, especially the head alone. During the first and second instar the head is entirely black; third instar has the clypeus yellow but the rest of the head black. In the fourth and fifth instar, there is a dark greenish-yellow dot behind each eye but with rest of the head black. However, the color of the caterpillar head does not necessarily indicate specific instar, as the time of color change is not fixed. In the larval stage, the small white can be a pest on cultivated
cabbage Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.&nbs ...
s,
kale Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a hea ...
, radish,
broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cl ...
, and horseradish. The larva is considered a serious pest for commercial growth of cabbage and other Brassicaceae. The pupa of ''P. rapae'' is very similar to that of ''P. napi''. It is brown to mottled-gray or yellowish, matching the background color. It has a large head cone, with a vertical abdomen and flared subdorsal ridge. The two (pupa of ''P. rapae'' and ''P. napi'') can be easily distinguished by comparing the proboscis sheath. In ''P. rapae'', the proboscis sheath extends far beyond the antennal sheath while in ''P. napi'', only a very short distance. Like its close relative the
large white ''Pieris brassicae'', the large white, also called cabbage butterfly, cabbage white, cabbage moth (erroneously), or in India the large cabbage white, is a butterfly in the family Pieridae. It is a close relative of the small white, '' Pieris ...
, the small white is a strong flyer and the British population is increased by continental immigrants in most years. Adults are diurnal and fly throughout the day, except for early morning and evening. Although there is occasional activity during the later part of the night, it ceases as dawn breaks. Adult ''P. rapae'' can move many kilometers in individual flights. Adults have been observed to fly as much as 12 km in one flight. On average, a female flies about 0.7 km per day and moves 0.45 km from where she starts. Males patrol all day around host plants to mate with females.


Behavior and ecology


Larva feeding

The ''P. rapae'' larva is voracious. Once it hatches from the egg, it eats its own eggshell and then moves to eat the leaves of the host plant. It bores into the interior of the cabbage, feeding on the new sprouts. The larvae adjust their feeding rate to maintain a constant rate of nitrogen uptake. They will feed faster in low nitrogen environment and utilize the nitrogen more efficiently (at the cost of efficiency in other nutrients) than larvae hatched on nitrogen high host plant. However, no significant difference in growth rate was observed between larvae in the two environments. Considered a serious pest, the caterpillar is known to be responsible for annual damage worth hundreds of thousands of dollars. The larvae are shown to disperse their damage on the plant. Larvae are shown to feed mostly during the day. They move around the plant mostly spending their time feeding. A feeding bout is immediately followed by a change in position, either to a new leaf or to another part of the same leaf. This dispersal of damage is seen as an adaptive behavior to hide the visual cues from predators that rely on vision. Even though ''P. rapae'' larvae are cryptic, they remain in the sun for the majority of the day, rather than hiding on the underside of the leaf. The condition of the host plant influences the larval growth significantly. Larval duration, pupal weights, adult weights, and larval growth rates were significantly altered by both plant nutrient availability and plant species. Larvae preferred Brassicaceae plants over other host plants. Larvae that have previously fed on crucifers will refuse nasturtium leaves to the point of starving to death. Within the family Brassicaceae, larvae show no significant difference in feeding behavior; larvae placed on kale show no difference from larvae placed on Brussels sprouts. Survival rates do not differ depending on nutrition availability of host plant. Elevated plant nutrient levels decrease larval duration and increase larval growth rate. The elevated nutrition level also decreased the fourth instar's consumption rate and increased its food utilization efficiencies. Larvae on cultivated host plant was observed to have higher growth efficiency than those fed in foliage of wild species. In short, larvae fed on high nutrition foliage show shorter duration of development, less consumption rate, higher growth rate and food processing efficiency.


Adult feeding

Adult ''P. rapae'' use both visual and olfactory cues to identify flowers in their foraging flight. The cabbage butterfly prefers purple, blue and yellow flowers over other floral colors. Some flowers, like ''
Brassica rapa ''Brassica rapa'' is a plant species growing in various widely cultivated forms including the turnip (a root vegetable); napa cabbage, bomdong, bok choy, and rapini. ''Brassica rapa'' subsp. ''oleifera'' is an oilseed which has many common nam ...
'', have a UV guide for aiding nectar search for the butterfly where the petals reflect near UV light whereas the center of the flower absorbs UV light, creating a visible dark center in the flower when seen in UV condition. This UV guide plays a significant role in ''P. rapae'' foraging. The adult flies around feeding from nectars of the plant. The adult looks for certain colors among green vegetation (purple, blue, and yellow preferred to white, red and green) and extend the proboscis before landing. It probes for nectar after landing. The butterfly identifies the flower through vision and odor. Chemical compounds such as Phenylacetaldehyde or 2-Phenylethanol was shown to provoke reflex proboscis extension. The search for nectar is also limited by the memory constraint. An adult butterfly shows a flower constancy in foraging, visiting flower species that it has already experienced. The ability to find nectar from the flower increased over time, showing a certain learning curve. Furthermore, the ability to find nectar from the first flower species decreased if the adult butterfly started to feed nectar from other plant species.


Courtship and reproduction

The male, when it spots a female, zigzags up, down, below, and in front of her, flying until she lands. The male flutters, catches her closed forewings with his legs, and spreads his wings. This causes her to lean over. He usually flies a short distance with her dangling beneath him. An unreceptive female may fly vertically or spread her wings and raise the abdomen to reject the male. Most host plants of ''P. rapae'' contain mustard oils and females use these oils to locate the plants. Females then lay the eggs singly on host leaves. In the northern hemisphere, adults appear as early as March and they continue to brood well into October. Spring adults have smaller black spots on its wings and are generally smaller than summer adults.


Host selection

All known host plants contain natural chemicals called glucosinolates, that are cues for egg laying. Host plants are: herb
Cruciferae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...
– '' Arabis glabra'', '' Armoracia lapthifolia'', '' Armoracia aquatica'', ''
Barbarea vulgaris ''Barbarea vulgaris'', also called wintercress (usual common name), or alternatively herb barbara, rocketcress, yellow rocketcress, winter rocket, yellow rocket, and wound rocket, is a biennial herb of the genus '' Barbarea'', belonging to the fa ...
'', '' Barbarea orthoceras'', ''
Barbarea verna ''Barbarea verna'' is a biennial herb in the family Brassicaceae. Common names include land cress, American cress, bank cress, black wood cress, Belle Isle cress, Bermuda cress, early yellowrocket, early wintercress, scurvy cress, creasy greens ...
'', ''
Brassica oleracea ''Brassica oleracea'' is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan. Its ...
'', ''
Brassica rapa ''Brassica rapa'' is a plant species growing in various widely cultivated forms including the turnip (a root vegetable); napa cabbage, bomdong, bok choy, and rapini. ''Brassica rapa'' subsp. ''oleifera'' is an oilseed which has many common nam ...
'', '' Brassica caulorapa'', ''
Brassica napus Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains a ...
'', ''
Brassica juncea ''Brassica juncea'', commonly brown mustard, Chinese mustard, Indian mustard, leaf mustard, Oriental mustard and vegetable mustard, is a species of mustard plant. Cultivar ''Brassica juncea'' cultivars can be divided into four major subgroup ...
'', '' Brassica hirta'', ''
Brassica nigra ''Brassica nigra'', or black mustard, is an annual plant cultivated for its dark-brown-to-black seeds, which are commonly used as a spice. It is native to tropical regions of North Africa, temperate regions of Europe, and parts of Asia. Desc ...
'', '' Brassica tula'', '' Cardaria draba'', ''
Capsella bursa-pastoris ''Capsella bursa-pastoris'', known as shepherd's purse because of its triangular flat fruits, which are purse-like, is a small annual and ruderal flowering plant in the mustard family ( Brassicaceae). It is native to eastern Europe and Asia mi ...
'' (females oviposit but larvae refuse it), '' Dentaria diphylla'', ''
Descurainia Sophia ''Descurainia sophia'' is a member of the family Brassicaceae. Common names include flixweed, herb-Sophia and tansy mustard. It reproduces by seeds. It is a dominant weed in dark brown prairie and black prairie soils of southern Alberta. Its s ...
'', ''
Eruca sativa Arugula (American English) or rocket (Commonwealth English) (''Eruca vesicaria''; syns. ''Eruca sativa'' Mill., ''E. vesicaria'' subsp. ''sativa'' (Miller) Thell., ''Brassica eruca'' L.) is an edible annual plant in the family Brassicaceae used a ...
'', '' Erysimum perenne'', '' Lobularia maritima'', ''
Lunaria annua ''Lunaria annua'', called honesty or annual honesty in English, is a species of flowering plant in the cabbage and mustard family Brassicaceae. It is native to the Balkans and south west Asia, and cultivated throughout the temperate world. Desc ...
'' (retards larval growth), ''
Matthiola incana ''Matthiola incana'' is a species of flowering plant in the cabbage family Brassicaceae. Common names include Brompton stock, common stock, hoary stock, ten-week stock, and gilly-flower. The common name stock usually refers to this species, thou ...
'', ''
Nasturtium officinale Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae. Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf ve ...
'', ''
Raphanus sativus The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman times. Radishes are grown and consumed throughout the world, being mostly eaten raw ...
'', '' Raphanus raphanistrum'', '' Rorippa curvisiliqua'', ''
Rorippa islandica ''Rorippa'' is a genus of flowering plants in the family Brassicaceae, native to Europe through central Asia, Africa, and North America. ''Rorippa'' species are annual to perennial herbs, usually with yellow flower A flower, sometimes known ...
'', ''
Sisymbrium irio ''Sisymbrium irio'', the London rocket, is a plant in the family Brassicaceae. It is an annual herb exceeding three feet in height with open, slender stem branches. The flowers are small with four pale yellow petals. The basal leaves are broad an ...
'', ''
Sisymbrium altissimum ''Sisymbrium altissimum'' is a species of '' Sisymbrium''. The plant is native to the western part of the Mediterranean Basin and is widely naturalized throughout most of the world, including all of North America. After maturity it forms a tumble ...
'', ''
Sisymbrium officinale ''Sisymbrium officinale'', the hedge mustard, (formerly ''Erysimum officinale'') is a plant in the family Brassicaceae. Description It is distinct from the mustard plants which belong to the genus ''Brassica''. ''S. officinale'' is similar to ot ...
'' (and var. ''leicocarpum''), '' Streptanthus tortuosus'', '' Thlaspi arvense'' (larvae grow slowly or refuse it);
Capparidaceae The Capparaceae (or Capparidaceae), commonly known as the caper family, are a family of plants in the order Brassicales. As currently circumscribed, the family contains 33 genera and about 700 species. The largest genera are ''Capparis'' (about 1 ...
: '' Cleome serrulata'', ''
Capparis sandwichiana ''Capparis sandwichiana'' is a species of flowering plant in the Capparaceae family endemic to the Hawaiian Islands. Common names include ''maiapilo'', ''pua pilo'', and Hawaiian caper. ''C. sandwichiana'' can be found on the main islands, Midwa ...
'';
Tropaeolaceae ''Tropaeolum'' , commonly known as nasturtium (; literally "nose-twister" or "nose-tweaker"), is a genus of roughly 80 species of annual and perennial herbaceous flowering plants. It was named by Carl Linnaeus in his book ''Species Plantarum' ...
: '' Tropaeolum majus'';
Resedaceae Resedaceae is a family of mostly herbaceous dicotyledonous plants comprising 107 known species in 8 to 12 genera: *'' Borthwickia'' - 1 species, sometimes placed in its own family Borthwickiaceae *'' Caylusea'' - 3 species *'' Forchhammeria'' - ...
: '' Reseda odorata''. There are three phases to host selection by the ''P. rapae'' adult female butterfly: searching, landing, and contact evaluation. A gravid female adult will first locate suitable habitats, and then identify patches of vegetation that contain potential host plants. The cabbage butterflies seem to limit their search to open areas and avoid cool, shaded woodlands even when host plants are available in these areas. Furthermore, gravid females will not oviposit during overcast or rainy weather. In laboratory conditions, high light intensity is required to promote oviposition. The females fly in a linear path independent of wind direction or position of the sun.


Host plant searching behavior

Pre-mating females do not display host plant searching behavior. The behavior starts soon after mating. Flight behavior of an ovipositing female of ''P. rapae'' follows the Markov process. Females foraging for nectar will readily abandon a linear path; they will show tight turns concentrating on flower patches. Females searching for host plant, however, will follow a linear route. As a result of directionality, the number of eggs laid per plant declines with increases in host plant density. The average move length declined as host plant density increases, but the decline is not enough to concentrate eggs on a dense host plant. Although females avoid laying eggs on plants or leaves with other eggs or larvae in a lab condition; this discrimination is not shown in field conditions. Adult females may search for a suitable Brassicaceae over a range of 500 m to several kilometers. Small differences in flight patterns have been observed in Canadian and Australian ''P. rapae'', indicating that there may be slight variation among different geographic populations.


Plant preference

Landing appears to be mediated primarily by visual cues, of which color is the most important. ''P. rapae'' in a lab environment showed no significant preference for the shape or size of the oviposition substrate. Gravid females responded most positively to green and blue/green colors for oviposition. The preference was shown for surfaces with maximal reflectance of 550 nm. In natural conditions, oviposition was preferred on larger plants, but this was not reflected in laboratory conditions. Younger plants often had yellow/green color while older plants display a darker and stronger green. Female butterflies preferred the older plants due to the attraction to the darker green color. However, larvae perform better on younger plants.


Behavior on plant

Once a gravid female lands on a plant, tactile and contact chemical stimuli are major factors affecting acceptance or rejection of the site for egg deposition. Once a female lands on a host plant, it will go through a "drumming reaction" or a rapid movement of the forelegs across the surface of a leaf. This behavior is believed to provide physical and chemical information about the suitability of a plant. ''P. rapae'' is shown to prefer smooth hard surfaces similar to a surface of an index card over rougher softer textures like blotting paper or felt. ''P. rapae'' use their chemoreceptors on their tarsi to search for chemical cues from the host plant. An adult female will be sensitive to number of glucosinolates, gluconasturtiin being the most effective glucosinolate stimulants for these sensilla.


Egg-laying behavior

A gravid female adult will lay disproportionate number of eggs on peripheral or isolated plants. A single larva is less likely to exhaust the whole plant, therefore laying eggs singly prevents the likelihood of larval starvation from resource exhaustion. This behavior may have evolved to exploit the original vegetation in the eastern Mediterranean where brassica plants originated. Age of butterflies appears to have no effect on their ability to select the source of highest concentration of oviposition stimulant. Additionally, it has been shown that the weather has a large impact on the eggs of ''P. rapae.'' The main issues with the weather are that strong winds can blow eggs from the leaves and strong rains can drown the caterpillars.


Larval growth

Larvae feeding and growth is highly dependent on their body temperature. While the larvae survives from as low as 10°C, the growth of larvae changes with changing temperature. From 10°C to 35°C, growth increases, but declines rapidly at temperatures higher than 35°C. Past 40°C, larvae start showing substantial mortality. The diurnal variation of temperature can be extensive with daily range of more than 20°C on some sunny days and clear nights. Larvae are able to respond well to a wide range of temperature condition, which allows them to inhabit various locations in the world. In natural conditions, larvae shows fastest growth at temperatures close to 35°C. however, in constant temperature conditions in laboratory, larvae shows mortality at 35°C. In this lab condition, larvae grows between 10°C to 30.5°C while showing maximal developmental rate at 30.5°C. The difference between lab and natural condition is due to routine temperature changes on the scale of minutes to hours under field conditions.


Predation

Studies in Britain showed that birds are a major predator in British town and city environments (such as in gardens) while arthropods had larger influence in rural areas. Bird predators include the
house sparrow The house sparrow (''Passer domesticus'') is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pale brown and grey, a ...
(''Passer domesticus''), goldfinch (''Carduelis carduelis'') and
skylark ''Alauda'' is a genus of larks found across much of Europe, Asia and in the mountains of north Africa, and one of the species (the Raso lark) endemic to the islet of Raso in the Cape Verde Islands. Further, at least two additional species are ...
(''Alauda arvensis''). Caterpillars are cryptic, coloured as green as the host plant leaves and they rest on the undersides of the leaves, thus making them less visible to predators. Unlike the large white, they are not distasteful to predators like birds. Like many other "white" butterflies, they
overwinter Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activi ...
as a pupa. Bird predation is usually evident only in late-instar larvae or on overwintering pupae.


Parasitism

''P. rapae'' caterpillars are commonly parasitized by a variety of insects. The four main parasitoids are bracconid wasps ''
Cotesia rubecula ''Cotesia rubecula'' is a parasitoid wasp from the large wasp family Braconidae. Description Black in adulthood with a body less than 1/4 of an inch long, ''C. rubecula'' has long, extending antenna about the same size as its body. Dis ...
'' and ''
Cotesia glomerata ''Cotesia glomerata'', the white butterfly parasite, is a small parasitoid wasp species belonging to family Braconidae. It was first described by Carl Linnaeus in his 1758 publication 10th edition of Systema Naturae. Description The adult ...
'', and flies '' Phryxe vulgaris'', and '' Epicampocera succinata''. ''
Cotesia rubecula ''Cotesia rubecula'' is a parasitoid wasp from the large wasp family Braconidae. Description Black in adulthood with a body less than 1/4 of an inch long, ''C. rubecula'' has long, extending antenna about the same size as its body. Dis ...
'' and ''
Cotesia glomerata ''Cotesia glomerata'', the white butterfly parasite, is a small parasitoid wasp species belonging to family Braconidae. It was first described by Carl Linnaeus in his 1758 publication 10th edition of Systema Naturae. Description The adult ...
'', previously in the genus '' Apanteles'', were introduced in North America from Asia as
biocontrol Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...
s. ''C. rubecula'' lays its eggs in the 1st and 2nd instar caterpillars. The larvae then grow within the caterpillar and continue to feed on the caterpillar until they are almost fully grown, and at that point the caterpillar is killed. It is important to note that only one larva develops per host and the rate of ''C. rubecula ''is largely independent of ''P. rapae ''population size. ''C. glomerata'' is similar to ''C. rubecula'' in that both parasitize the host in either the 1st or 2nd instar. The main difference is that ''C. glomerata'' always kill the host in the 5th instar and multiple larvae can be raised within one host. ''P. rapae'' pupae are frequently parasitized by '' Pteromalus puparum''.


Notes


References


Further reading

* Asher, Jim ''et al.'': ''The Millennium Atlas of Britain and Ireland''. Oxford University Press. *


External links


Pieris project
A worldwide citizen science project undertaking research on ''Pieris rapae''

on the UF / IFAS Featured Creatures website
Cabbage white
Butterflies of Canada {{Authority control rapae Butterflies of Africa Butterflies of Asia Butterflies of Europe Pieridae of South America Butterflies of Indochina Butterflies described in 1758 Taxa named by Carl Linnaeus