''Acyrthosiphon kondoi'', the blue alfalfa aphid or bluegreen aphid, is an

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 ...

in the superfamily Aphidoidea in the order

Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...

. It is a true bug and sucks sap from leguminous plants, particularly

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as w ...

(known as lucerne in most countries outside North America).

Description

The blue alfalfa aphid grows to a length of . It is very similar in appearance to the closely related

pea aphid ''Acyrthosiphon pisum'', commonly known as the pea aphid (and colloquially known as the green dolphin, pea louse, and clover louse), is a sap-sucking insect in the family Aphididae. It feeds on several species of legumes (plant family Fabaceae) w ...

(''Acyrthosiphon pisum''), but is often a more bluish shade of green. One significant difference from the pea aphid is that the blue alfalfa aphid has uniformly dark-coloured antennae. Both wingless and winged female forms occur, with the winged aphids being able to disperse and colonise new plants. Males also sometimes occur, are smaller than females, and are green with brown markings on head, thorax and abdomen.

Distribution

A native of Asia, the species has spread to other parts of the world including North America, South America, Australia and New Zealand; it was first detected in the United States in California in 1974 and had spread to Nebraska by 1979, Georgia and Kentucky by 1983 and Maryland by 1992. It is mainly a pest of plants in the family

Leguminosae The Fabaceae or Leguminosae,International Code of Nomenc ...

including

pea The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...

lentil The lentil (''Lens culinaris'' or ''Lens esculenta'') is an edible legume. It is an annual plant known for its lens-shaped seeds. It is about tall, and the seeds grow in pods, usually with two seeds in each. As a food crop, the largest pro ...

and

cowpea The cowpea (''Vigna unguiculata'') is an annual herbaceous legume from the genus ''Vigna''. Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia. It requires very few input ...

. Its host range in North America is very similar to that of the pea aphid, however, it is seen earlier in the spring and is more tolerant of cool weather than the pea aphid. As populations build up, they are increasingly affected by

entomopathogenic fungi An entomopathogenic fungus is a fungus that can kill or seriously disable insects. Typical life cycle These fungi usually attach to the external body surface of insects in the form of microscopic spores (usually asexual, mitosporic spores als ...

and

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

s, with populations peaking and stabilising. Hot summer weather, with temperatures averaging above , favours the plants' natural resistance mechanisms, and numbers of aphids reduce sharply.

Ecology

There are both winged and wingless adult females and both can produce live young by

viviparity 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 m ...

although some females also produce batches of eggs. Wingless forms are prolific and may have twelve or more generations in a season, producing young at the rate of seven nymphs per day. Winged forms produce many fewer young. These aphids may overwinter as eggs or as females, the latter moving from annual plants onto perennial legumes in the fall.

Economic importance

This aphid is a major pest of dwarf beans and

clover Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus ...

, where it feeds on leaves and stems. Where infection rates are high, yellowing, twisting, stunting and leaf drop may occur, young seedlings may die and plants regrowing after cutting are severely affected. This aphid does more damage to lucerne crops than does pea aphid, and yields of the crop may be severely reduced even at low population densities, particularly in spring and autumn. Further damage may also occur to the plants as a result of the accumulation of honeydew and the

sooty mould Sooty mold (also spelled sooty mould) is a collective term for different Ascomycete fungi, which includes many genera, commonly ''Cladosporium'' and ''Alternaria''. It grows on plants and their fruit, but also environmental objects, like fences, ...

that grows on it, and the aphid can be 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 ...

alfalfa mosaic virus Alfalfa mosaic virus (AMV), also known as ''Lucerne mosaic virus'' or ''Potato calico virus'', is a worldwide distributed phytopathogen that can lead to necrosis and yellow mosaics on a large variety of plant species, including commercially im ...

lucerne transient streak virus Lucerne transient streak virus (LTSV) is a pathogenic plant virus Plant viruses are viruses that affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate ...

and lucerne Australian latent virus in lucerne, as well as

cucumber mosaic virus ''Cucumber mosaic virus'' (CMV) is a plant pathogenic virus in the family ''Bromoviridae''. This virus has a worldwide distribution and a very wide host range, having the reputation of the widest host range of any known plant virus. It can be tra ...

bean yellow mosaic virus ''Bean yellow mosaic virus'' is a plant pathogenic virus in the genus ''Potyvirus'' and the virus family ''Potyviridae''. Like other members of the Potyvirus genus, it is a monopartite strand of positive-sense, single-stranded RNA surrounded by ...

and

watermelon mosaic virus ''Watermelon mosaic virus'' (WMV) also known as Marrow mosaic virus (Raychaudhuri and Varma, 1975; Varma, 1988), Melon mosaic virus (Iwaki et al., 1984; Komuro, 1962), and until recently Watermelon mosaic virus type 2 (WMV-2), is a plant pathogen ...

in other crops.

References

{{Taxonbar, from=Q10400827 Macrosiphini Agricultural pest insects Hemiptera of Asia