''Contarinia nasturtii'', the swede midge, is a small

fly Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwing ...

, the larvae of which infest brassica plants, causing twisting and distortion of the leaf stems and foliage including death of the growing point in seedlings, or damage to developing flower heads. It is native to Europe and Turkey, and has been introduced into North America where it is regarded as an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

Life cycle

Adult swede midges are yellowish-brown and up to long, and live for up to three days. During this time the female lays about one hundred eggs in several batches on the leaves of suitable

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

plants. The eggs need moisture to hatch and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e emerge in between one and ten days at respectively. They feed for between one and three weeks, again depending on temperature, and produce a gall. When fully grown they descend to the soil and either

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

te in an oval cocoon at a depth of about or, in adverse weather conditions, become dormant in a globular cocoon buried deeper in the soil. The adults emerge one and a half to seven weeks after pupation and there are several generations each year. When the dormancy period is due to drought, development continues after wetting, but when it is due to low temperature, development restarts only after a prolonged period of cold weather. The larvae then make their way to the soil surface before burying themselves shallowly and forming an oval cocoon.

Host-attraction

A recent study found that ''C. nasturtii'', despite being crucifer-specialist, may not depend on the crucifer-specific glucosinolates.Boddum T, Molnár BP, Hill SR, Birgersson GÅO, Hansson BS, Abreha KB, Andreasson E and Hillbur Y (2018) Host Attraction and Selection in the Swede Midge (Contarinia nasturtii). Front. Ecol. Evol. 6:61. doi: 10.3389/fevo.2018.00061 Therefore, other volatile compounds emitted by crucifer plants may mediate the ''C. nasturtii'' host attraction.

Damage

Host plants for the swede midge include

cauliflower Cauliflower is one of several vegetables in the species ''Brassica oleracea'' in the genus ''Brassica'', which is in the Brassicaceae (or mustard) family. It is an annual plant that reproduces by seed. Typically, only the head is eaten – the ...

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 ...

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.&nb ...

Brussels sprout The Brussels sprout is a member of the Gemmifera cultivar group of cabbages (''Brassica oleracea''), grown for its edible buds. The leaf vegetables are typically 1.5–4.0 cm (0.6–1.6 in) in diameter and resemble miniature cabbages ...

kohlrabi Kohlrabi (pronounced ; scientific name ''Brassica oleracea'' Gongylodes Group (horticulture), Group), also called German turnip or turnip cabbage, is a Biennial plant, biennial vegetable, a low, stout cultivar of wild cabbage. It is a cultivar o ...

and a number of wild plants in the brassica family including shepherd’s purse, field penny-cress, field peppergrass and

yellow rocket ''Barbarea'' (winter cress or yellow rocket) is a genus of about 22 species of flowering plants in the family Brassicaceae, native to temperate regions of the Northern Hemisphere, with the highest species diversity in southern Europe and southwe ...

. When a seedling or young plant is attacked, the larvae conglomerate and secrete saliva which softens the plant cuticle and epidermis, sucking in the resulting fluid. On a leaf stalk, this damages the tissues and results in the formation of a corky gall. The undamaged side of the stalk continues to grow normally which results in twisting and distortion. The growing point can be completely killed and secondary bacterial infections can occur. If the infection occurs in the flowering stage of cauliflower, it causes a stunted, multi-branched, tuft-like appearance of the flower-head.

Distribution

''Contarinia nasturtii'' is native to Europe and Turkey. It was first detected in Canada in 1996 and is now present in

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

and

Prince Edward Island Prince Edward Island (PEI; ) is one of the thirteen Provinces and territories of Canada, provinces and territories of Canada. It is the smallest province in terms of land area and population, but the most densely populated. The island has seve ...

. In the United States it was detected in the western part of

New York state New York, officially the State of New York, is a state in the Northeastern United States. It is often called New York State to distinguish it from its largest city, New York City. With a total area of , New York is the 27th-largest U.S. stat ...

in 2004 and is now also known from

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

, and

Vermont Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...

. It is regarded as an

in North America.

References

External links

Images representing ''Contarinia nasturtii''
at

BOLD In typography, emphasis is the strengthening of words in a text with a font in a different style from the rest of the text, to highlight them. It is the equivalent of prosody stress in speech. Methods and use The most common methods in W ...

{{Taxonbar, from=Q1778497 Diptera of Europe Cecidomyiinae Insects described in 1888 Taxa named by Jean-Jacques Kieffer