''Brevicoryne brassicae'', commonly known as the cabbage aphid or cabbage aphis, is a destructive

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

(plant louse) native to

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

that is now found in many other areas of the world.Hawaii Department of Entomology information page
/ref> The aphids feed on many varieties of produce, including

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.& ...

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the Brassicaceae, cabbage family (family Brassicaceae, genus ''Brassica'') whose large Pseudanthium, flowering head, plant stem, stalk and small associated leafy gre ...

(especially),

Brussels sprouts The Brussels sprout is a member of the Gemmifera cultivar group of cabbages (''Brassica oleracea''), grown for its edible buds. Etymology Though native to the Mediterranean region with other cabbage species, Brussels sprouts first appeared i ...

cauliflower Cauliflower is one of several vegetables cultivated from the species '' Brassica oleracea'' in the genus '' Brassica'', which is in the Brassicaceae (or mustard) family. Cauliflower usually grows with one main stem that carries a large, rou ...

and many other members of the genus ''

Brassica ''Brassica'' () is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, mustard plants, or simply brassicas. Crops from this genus are sometim ...

'', but do not feed on plants outside of the family

Brassicaceae Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...

. The insects entirely avoid plants other than those of Brassicaceae; even though thousands may be eating broccoli near strawberries, the strawberries will be left untouched.University of Minnesota extension
Cabbage aphids, from the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Brevicoryne'' of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Aphididae The Aphididae are a very large insect family in the aphid superfamily ( Aphidoidea), of the order Hemiptera. These insects suck the sap from plant leaves. Several thousand species are placed in this family, many of which are considered plant/cr ...

, are grayish-green, but a waxy covering gives them a grayish-white to powdery blue appearance.

Predator defense mechanism

Cabbage aphids produce a myrosinase (beta-thioglucoside glucohydrolase)

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

in head and thoracic

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

s; the aphids also uptake

glucosinolate Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise damaged. ...

s, particularly sinigrin, from the plants on which they feed, storing the glucosinolates in their

haemolymph Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph ce ...

. (Glucosinolates are natural defenses for plants in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Brassicales The Brassicales (or Cruciales) are an order (biology), order of flowering plants, belonging to the malvid group of eudicotyledons under the APG IV system. Well-known members of Brassicales include cabbage, cauliflower, Brussels sprout, broccoli, ...

against pests and

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s.) The combination of the glucosinolates and the myrosinase enzyme produces a violent chemical reaction that releases the

mustard oil Mustard oil can mean either the pressed oil used for cooking or a pungent essential oil, also known as volatile oil, of the mustard plant. The essential oil results from grinding mustard seed, mixing the grounds with water, and isolating the resu ...

chemical allyl isothiocyanate.Imperial College London (2007, July 12). Aphids Make 'Chemical Weapons' To Fight Off Killer Ladybirds. ScienceDaily. Retrieved November 20, 2007, from https://www.sciencedaily.com/releases/2007/07/070711105844.htm The defense mechanism has a dramatic negative effect on the survival of the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l ladybird predator '' Adalia bipunctata''. The chemical defence of the aphids has been likened to a " walking mustard oil bomb". The myrosinase from ''Brevicoryne brassicae'' appears to have

evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

separately from myrosinases found in plants, possibly a case of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. Aphid myrosinase appears to have greater similarity to animal beta-O-glucosidases than to plant myrosinases.

Pest control

Different varieties of

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s have varying resistance to ''Brevicoryne brassicae''. '' Diaeretiella rapae'' is a common

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

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 ...

of cabbage aphids. Other controlling insects include ladybird beetles, syrphid fly larvae, and

lacewing The Hemerobiiformia are a suborder of insects in the order Neuroptera that include most of the lacewings, antlions and their allies. The phylogeny of the Neuroptera was explored in 2014 using mitochondrial DNA sequences. The results indicate t ...

larvae. Some insecticidal soaps may be effective in treating aphid infestations.

References

External links

Images of cabbage aphids
* * {{Taxonbar, from=Q2634837 Macrosiphini Agricultural pest insects Insect vectors of plant pathogens Insects described in 1758 Hemiptera of Europe Taxa named by Carl Linnaeus