''Psylliodes chrysocephala'' or ''Psylliodes chrysocephalus'', commonly known as the cabbage-stem flea beetle, is a species of

leaf beetle The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...

situated in the subfamily

Galerucinae The Galerucinae are a large subfamily of the leaf beetles (Chrysomelidae), containing about 15,000 species in more than 1000 genera, of which about 500 genera and about 8000 species make up the flea beetle tribe Alticini. The division into t ...

and the tribe

Alticini The flea beetle is a small, jumping beetle of the leaf beetle family (Chrysomelidae), that makes up the tribe Alticini which is part of the subfamily Galerucinae. Historically the flea beetles were classified as their own subfamily. Though m ...

(flea beetles).

Description

''P. chrysocephala'' measures 3.0–4.0 mm in length. It is variably coloured, but most often a dark metallic blue. Like all flea beetles it has large hind femora which it can use to jump. These are orange-red in colour with the hind femora darkened. It is differentiated from other members of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

through a lack of anterior angles on its

pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...

, the punctures on top of the head being as coarse as those on the

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

, and its first front tarsal segment being equal in length to its third. Psylliodes chrysocephala larva (31827378971).jpg, ''Psylliodes chrysocephala'' larva feeding in stem of '' Brassica napus'' Psylliodes chrysocephala (31906272736).jpg, ''P. chrysocephala'' pupa Cabbage-stem Flea Beetle (37130910672).jpg, Adult beetle

Distribution

It is native to the Western

Palaearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

, including Macaronesia, Cape Verde and North Africa and has been introduced into Canada.

Lifecycle

Adult beetles mate in late August on the leaves of host plants, with eggs first laid 5–10 days after copulation. Oviposition takes place from the end of September through winter until mid-April and a single female may lay up to 1000 eggs, deposited in small clusters in the soil beneath the host plant at depths of 1–5 cm. Larvae hatch after about 60 days and feed within the stem and leaves of the host plant. Fully developed larvae emerge in early summer and pupate in the soil. Newly emerged adults appear from May each year. Adults may enter an aestivation period over Summer after the harvest of mature rape plants. After mating in late summer, some adults will overwinter.

Behaviour and habitat

Colza (Gros plan) Cl J Weber01 (23566547692)

''P. crysocephala'' can be found in various habitats, depending on the availability of a host plant. It is particularly associated with wild and cultivated members of the plant family

Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...

. It has been directly associated with '' Brassica napus'', '' B. nigra'' (black mustard), '' B. oleracea'' (cabbages, cauliflowers), '' B. rapa'' (turnip rape), ''

Nasturtium officinale Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae. Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf ve ...

'' (watercress), ''

Raphanus sativus The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman times. Radishes are grown and consumed throughout the world, being mostly eaten raw ...

'' (radish), ''

Sinapis alba White mustard (''Sinapis alba'') is an annual plant of the family Brassicaceae. It is sometimes also referred to as ''Brassica alba'' or ''B. hirta''. Grown for its seeds, used to make the condiment mustard, as fodder crop, or as a green manu ...

'' (white mustard), '' S. arvensis'' (wild mustard), and ''

Tropaeolum majus ''Tropaeolum majus'', the garden nasturtium, nasturtium, Indian cress or monks cress, is a species of flowering plant in the family Tropaeolaceae, originating in the Andes from Bolivia north to Colombia. An easily-grown annual or short-lived per ...

'' (common nasturtium).

As an arable pest

It is a serious pest of rape in northern Europe. In central parts of Europe it has a cyclic appearance with peaks in populations at intervals of about seven years. In the UK, it is the most important establishment pest of rape, leading to yield losses of up to 20%.

References

External links

High reoslution images of ''Psylliodes crysocephala''
{{Taxonbar, from=Q586373 Agricultural pest insects Beetles of Europe Taxa named by Carl Linnaeus Alticini Beetles of North America Beetles described in 1758