Pieris rapae
Small white | |
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Female | |
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Male | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Family: | Pieridae |
Genus: | Pieris |
Species: | P. rapae
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Binomial name | |
Pieris rapae (Linnaeus, 1758)
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Synonyms | |
Papilio rapae Linnaeus, 1758 |
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,[note 1] on several continents as the small cabbage white, and in New Zealand as the white butterfly.[2] 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
Description
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Pieris_sp_3.jpg/220px-Pieris_sp_3.jpg)
![Cabbage White Butterfly (Pieris rapae) wings closed. Montgomery County, PA.](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Cabbage_White_Butterfly_%28Pieris_rapae%29.jpg/220px-Cabbage_White_Butterfly_%28Pieris_rapae%29.jpg)
In appearance it looks like a smaller version of the
Pieris rapae has a wingbeat frequency averaging 12.8 flaps per second.[5]
Distribution and habitat
![](http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Global_Invasion_History_of_Pieris_rapae.png/220px-Global_Invasion_History_of_Pieris_rapae.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Small_Whites_Mating.jpg/220px-Small_Whites_Mating.jpg)
The species has a natural range across Europe, Asia, and North Africa.
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.[12]
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
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Pieris.rapae.caterpillar.jpg/220px-Pieris.rapae.caterpillar.jpg)
Traditionally known in the
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Pieris_rapae_pupa.jpg/220px-Pieris_rapae_pupa.jpg)
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.[8] 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.[13]
Like its close relative the large white, 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.[18] Adult P. rapae can move many kilometers in individual flights. Adults have been observed to fly as much as 12 km in one flight.[12] On average, a female flies about 0.7 km per day and moves 0.45 km from where she starts.[8] 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.[8] Considered a serious pest, the caterpillar is known to be responsible for annual damage worth hundreds of thousands of dollars.[10]
The larvae are shown to disperse their damage on the plant.[19] 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.[19] 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.[20] 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.[21]
Survival rates do not differ depending on nutrition availability of host plant. Elevated plant nutrient levels decrease larval duration and increase larval growth rate.[20] 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.[20]
Adult feeding
Adult P. rapae use both visual and olfactory cues to identify flowers in their foraging flight.
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.[23] 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.[24]
Courtship and reproduction
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/58/Pieris_rapae_which_copulates_0928.jpg/220px-Pieris_rapae_which_copulates_0928.jpg)
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.[25] 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.[8] 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.[25]
Males seem to benefit from the sodium uptake through mud-puddling behaviour with an increase in reproductive success.
Host selection
All known host plants contain natural chemicals called
There are three phases to host selection by the P. rapae adult female butterfly: searching, landing, and contact evaluation.
Host plant searching behavior
Pre-mating females do not display host plant searching behavior. The behavior starts soon after mating.
Adult females may search for a suitable Brassicaceae over a range of 500 m to several kilometers.[27]
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
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/Senecio_tamoides_3.jpg/220px-Senecio_tamoides_3.jpg)
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.[26] 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.[26] 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.[29] 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.[30] 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.[30] This behavior may have evolved to exploit the original vegetation in the eastern Mediterranean where brassica plants originated.[21]
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.[31] The main issues with the weather are that strong winds can blow eggs from the leaves and strong rains can drown the caterpillars.[31]
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.[32] 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.[32] In this lab condition, larvae grows between 10 °C to 30.5 °C while showing maximal developmental rate at 30.5 °C.[32] 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
Parasitism
P. rapae caterpillars are commonly parasitized by a variety of insects. The four main parasitoids are braconid wasps
P. rapae pupae are frequently parasitized by Pteromalus puparum.[33]
Butterfly Life Cycle in Video (Pieris rapae, the common cabbage white)
Gallery
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Emerging from egg and first feedings.
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Second instar larvae eating. Speeded up 50 times to illustrate feeding behavior. This species first and second instar larvae’s nearly transparent body shows internal digestion.
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This species second instar larvae sheds skin in under 20 minutes.
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Larvae eating remainder of a leaf. Six hours speeded up one hundred times.
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Segments of the last two hours of the larvae shedding its 4th instar skin, after starting a few hours earlier.
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Fifth instar white cabbage larvae walking on broccoli stem and on glass, showing it laying down silk it then walks on.
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Parasitized larvae showing wasp larvae exiting its body, spinning cocoons. Playback at double speed. Adult wasps at normal speed.
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Larvae shedding skin, becoming a chrysalis. Recorded over fifteen hours. Closeups at two times speed. Other clips at ten times speed.
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Emerging from chrysalis into an adult.
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Butterflies flying. Later clips in slow motion.
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Male butterflies mud-puddling to concentrate salts for female reproduction.
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Butterflies depositing eggs under leaves. Each repeated in slow motion.
Notes
- ^ In Europe, "cabbage white" and "cabbage butterfly" refer instead to Pieris brassicae, also known as "large white"
References
- ^ "NatureServe Explorer 2.0 Pieris rapae Cabbage White". explorer.natureserve.org. Retrieved 3 October 2020.
- ISBN 978-0-9597663-5-6. Archived from the originalon 2010-05-25. Retrieved 2010-05-07.
- PMID 31506352.
- ^ "Butterflies of Canada - Cabbage White". 11 June 2014.
- S2CID 11346861.
- )
- ^ ISBN 978-0-385-04926-9.
- ^ ISBN 978-0-8047-1205-7.
- JSTOR 4536.
- ^ a b Holland, W. J. (1931). The Butterfly book. Garden City, New York: Doubleday, INC.
- ^ Gibbs, G. W. (1980). New Zealand butterflies identification and natural history. Auckland, New Zealand: Collins.
- ^ a b Klots, Alexander B. (1951). A Field guide to the Butterflies of North America, East of the Great Plains. Cambridge: The Riverside Press.
- ^ JSTOR 1459.
- ^ S2CID 18306617.
- S2CID 7947436.
- ^ ""Tiny black pints on the caterpillar"". Butterfly Identification. 2019-04-09. Retrieved 2021-05-04.
- ISBN 978-1-887247-06-1.)
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has generic name (help)CS1 maint: multiple names: authors list (link - S2CID 53182157.
- ^ S2CID 84852010.
- ^ .
- ^ S2CID 32329879.
- ^ S2CID 42519089.
- S2CID 21394740.
- S2CID 20010229.
- ^ ISBN 978-0-19-554124-3.
- ^ .
- ^ .
- ^ JSTOR 1939467.
- .
- ^ S2CID 12774590.
- ^ JSTOR 2401350.
- ^ S2CID 1052766.
- ^ .
Further reading
- Asher, Jim et al.: The Millennium Atlas of Britain and Ireland. Oxford University Press.
- Evans, W. H. (1932). The Identification of Indian Butterflies (2nd ed.). Mumbai, India: Bombay Natural History Society.
External links
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikispecies-logo.svg/34px-Wikispecies-logo.svg.png)
- Pieris project A worldwide citizen science project undertaking research on Pieris rapae
- Pieris rapae on the UF / IFAS Featured Creatures website
- Cabbage white, Butterflies of Canada