Psylliodes chrysocephala

(Linnaeus, 1758)

cabbage-stem flea beetle, cabbage stem flea beetle

Psylliodes chrysocephala, the cabbage-stem flea beetle, is a small flea beetle native to the Western Palaearctic and introduced to Canada. It is a major agricultural pest of winter oilseed rape (Brassica napus) in northern Europe, with feeding on leaves and larvae mining within petioles and stems. The exhibits an obligatory summer period to survive heat and desiccation stress, with complex physiological and genetic mechanisms regulating this dormancy. Management has become increasingly difficult due to neonicotinoid bans and rising resistance.

Psylliodes chrysocephala by (c) Paul Cook, some rights reserved (CC BY), uploaded by Paul Cook. Used under a CC-BY license.

Psylliodes chrysocephala by no rights reserved, uploaded by Peter Gabler. Used under a CC0 license.

Psylliodes chrysocephala by (c) anasacuta, some rights reserved (CC BY), uploaded by anasacuta. Used under a CC-BY license.

Pronunciation

How to pronounce Psylliodes chrysocephala: /psɪˈlaɪoʊdiːz ˌkraɪsoʊˈsɛfələ/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from by three key characters: absence of angles on the pronotum, equally coarse punctation on and , and first front tarsal segment equal in length to third. The orange-red hind with darkened apices and metallic blue coloration are helpful field characters, though coloration is variable.

Images

Habitat

Agricultural and semi-natural containing Brassicaceae plants; strongly associated with cultivated and wild members of the mustard . Found in winter oilseed rape fields, on cabbages, cauliflowers, turnip rape, watercress, radish, mustards, and nasturtium. aestivate during summer in sheltered locations to avoid heat and desiccation.

Distribution

Native to Western Palaearctic including Macaronesia, Cape Verde, and North Africa; introduced to Canada. In England, historically most abundant in Buckinghamshire, Cambridgeshire, Huntingdonshire, and Northamptonshire with localized occurrences in 13 other counties.

Seasonality

active from late summer through spring; mate in late August with oviposition from late September through mid-April. Larvae develop through winter and spring, pupating in early summer. New adults emerge from May. Obligatory summer period from approximately June to August.

Diet

feed on leaves of Brassicaceae; larvae mine within petioles and stems of plants. Feeding stimulated by glucosinolates and sugars, though glucosinolates are not prerequisite for feeding.

Host Associations

Brassica napus - primary winter oilseed rape, major crop pest
Brassica nigra - black mustard
Brassica oleracea - cabbages, cauliflowers
Brassica rapa - turnip rape
Nasturtium officinale - watercress
Raphanus sativus - radish
Sinapis alba - white mustard; shows larval
Sinapis arvensis - wild mustard
Tropaeolum majus - common nasturtium

Life Cycle

laid in soil beneath plant at 1-5 cm depth, in small clusters; single female may lay up to 1000 eggs. Eggs hatch after approximately 60 days (240 above 3.2°C). Larvae feed internally in stems and petioles for several weeks, completing development in about 4 weeks with 20-fold size increase. Fully developed larvae emerge and pupate in soil. New appear from May, may enter period after harvest of mature rape plants, then mate in late summer with some adults .

Behavior

possess enlarged hind enabling -like jumping. Exhibits obligatory summer as adults to survive heat and desiccation stress, involving dramatic metabolic suppression, reserve reduction, and lipid reserve increase. Females attracted to volatile organic compounds from mechanically damaged oilseed rape plants; males show no such response, indicating in olfactory sensitivity. Antennal contact chemosensilla respond to cruciferous including glucosinolates. Mating involves active antennal movement by males at beginning and end of copulation.

Ecological Role

Significant agricultural pest causing yield losses; larvae do not appear to substantially reduce yields despite being present in plants. Natural enemies present but effects quantified. cycles with peaks at approximately seven-year intervals reported in central Europe.

Human Relevance

Major pest of winter oilseed rape in northern Europe; most important establishment pest of rape in UK with potential yield losses up to 20% reported historically, though recent data suggests lower actual losses. Management complicated by neonicotinoid bans and resistance development. Subject of research into interference-based control methods and strategies.

Similar Taxa

Psylliodes luridipennisLundy Cabbage Flea Beetle, to Lundy Island; distinguished by distribution and plant specificity
Other Psylliodes speciesDifferentiated by pronotal angles, punctation , and front tarsal segment proportions

More Details

Physiological research

Subject of extensive research on transporters (Tret-1 and Tret-2) regulating energy metabolism during ; microRNA shown to regulate obligatory aestivation with 25% of miRNAs differentially abundant during dormancy

Pest management challenges

strategies limited by lack of cultivars, time-consuming monitoring methods, absence of threshold models based on plant physiological , and lack of registered non-synthetic alternatives

Host plant resistance

Larval appears absent in Brassica napus possibly due to domestication bottlenecks, but present in Sinapis alba, offering potential for resistance breeding