''Brachycaudus cardui'' is a species of

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

, commonly known as the thistle aphid or the plum-thistle aphid. It infests trees in the genus ''

Prunus ''Prunus'' is a genus of trees and shrubs, which includes (among many others) the fruits plums, Cherry, cherries, peaches, Peach#Nectarine, nectarines, apricots, and almonds. Native to the North American temperate regions, the neotropics of Sou ...

'' in the spring and autumn, and mostly plants in the aster family in the summer.

Description

The

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

wingless females of ''B. cardui'' have an oval or pear-shaped body and grow to a length of from . The colour may be green, yellowish, reddish or brown. The abdomen has a dark, shining patch on the dorsal surface, a fact which distinguishes this species from the otherwise similar plum leaf curl aphid (''

Brachycaudus helichrysi ''Brachycaudus helichrysi'' is a species of aphid first described by the German naturalist Johann Heinrich Kaltenbach in 1843. Its common names include leaf curl plum aphid, and leaf-curling plum aphid, and it is a serious pest of plum and da ...

'').

Nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ...

often have pinkish blotches on a dark green background.

Distribution

''B. cardui'' has a wide distribution in Europe, Asia, North Africa and North America.

Biology

The primary

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 ...

of ''B. cardui'' is plum, cherry, apricot, peach or damson, but during the summer months it moves to a secondary host. This is often a

thistle Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles can also occur all over the planton the stem and on the flat parts of the leaves ...

in the genera '' Carduus'' or ''

Cirsium ''Cirsium'' is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more precisely known as plume thistles. These differ from other thistle genera (''Carduus'', '' Sily ...

'' where it is commonly seen on the stems and flowerheads. Alternatively, other plants in the aster family or plants in the borage family (

Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the or ...

) may be used as secondary hosts. Winged individuals fly back to the primary hosts in the autumn. Colonies of ''B. cardui'' are usually attended by

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

s which feed on the honeydew the aphids produce and drive away

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

. Researchers found that in a damp meadow which contained

ragwort ''Jacobaea vulgaris'', syn. ''Senecio jacobaea'', is a very common wild flower in the family Asteraceae that is native to northern Eurasia, usually in dry, open places, and has also been widely distributed as a weed elsewhere. Common names inc ...

(''Jacobaea vulgaris'') but no ants, although winged ''B. cardui'' arrived at the site, they failed to establish colonies despite an abundance of the host plant. In an experimental habitat, colonies of ''B. cardui'' on ''J. vulgaris'' flourished when ants were present but died out if ants were excluded.

Damage

Infestation with ''B. cardui'' causes the margins of affected leaves to roll up. This aphid is a

vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

plum pox Plum pox, also known as sharka, is the most devastating viral disease of stone fruit from the genus ''Prunus''. The disease is caused by the plum pox virus (PPV), and the different strains may infect a variety of stone fruit species including pea ...

, a serious viral disease affecting plums, damsons, peaches, apricots and some other plants.

References

{{Taxonbar, from=Q10434154 Macrosiphini Hemiptera of Europe