Phyllotreta cruciferae

(Goeze, 1777)

crucifer flea beetle, canola flea beetle, rape flea beetle

is a flea beetle and significant agricultural pest of cruciferous crops, particularly canola, rapeseed, and other Brassica . are small, black, and shiny with enlarged hind adapted for jumping. The species overwinters as adults in leaf litter and topsoil, emerging in early spring to feed on plants. vary by region and year, with one to two annually depending on thermal accumulation.

Phyllotreta cruciferae (08) by Whitney Cranshaw, Colorado State University, Bugwood.org. Used under a CC BY 3.0 us license.

Phyllotreta cruciferae (05) by Whitney Cranshaw, Colorado State University, Bugwood.org. Used under a CC BY 3.0 us license.

Phyllotreta cruciferae (10) by Whitney Cranshaw, Colorado State University, Bugwood.org. Used under a CC BY 3.0 us license.

Pronunciation

How to pronounce Phyllotreta cruciferae: /ˌfɪloʊˈtɹiːtə ˈkɹuːsɪˌfɛriː/

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

Identification

Distinguished from similar flea beetles by its uniform black coloration without stripes or markings; Phyllotreta striolata has distinct longitudinal . The is slightly smaller than some . Jumping when disturbed is diagnostic for the . Examination of genitalia may be required for definitive separation from closely related .

Images

Appearance

are small, black, and shiny beetles approximately 2-3 mm in length. The body is compact and oval. Hind are enlarged, providing the jumping ability characteristic of flea beetles. are short and .

Habitat

Agricultural landscapes dominated by cruciferous crops; sites include leaf litter and the upper 2.5 cm of soil in windbreaks, fencerows, and cultivated areas. are restricted primarily to cruciferous vegetation during the growing season.

Distribution

Europe and Northern Asia (excluding China), North America (Canada and USA). Specific records from Austria, Belgium, Britain, Bulgaria, Czechoslovakia, Denmark, France, Germany, Greece, Hungary, Ireland, Italy, Netherlands, Poland, Portugal, Romania, Spain, Switzerland, Yugoslavia, Cyprus, India, Iran, Iraq, Israel, Jordan, Lebanon, Syria, Turkey, Algeria, Egypt.

Seasonality

emerge from sites in early spring. Peak adult movement occurs shortly after , primarily within 2 m of the ground and oriented toward plants. One to two per year depending on region and thermal conditions; single generation documented in southwestern Ontario in 1974, two generations in 1975.

Diet

Foliage of cruciferous plants ( Brassicaceae). Strong feeding preference for Brassica juncea (Indian mustard) and Sinapis alba (white mustard) among tested seedlings. Also feeds on B. napus, B. oleracea, B. rapa, Raphanus sativus, rutabaga, and Chinese cabbage. preference varies with seedling age.

Host Associations

Brassica juncea - preferred Indian mustard; strong feeding preference in laboratory and field studies
Sinapis alba - preferred White mustard; strong feeding preference
Brassica napus - Rapeseed/canola
Brassica oleracea - Cabbage, broccoli, kale
Brassica rapa - Turnip, field mustard
Raphanus sativus - Radish
Lepidium sativum - Garden cress
Microctonus vittatae - Braconid ; solitary endophagous of

Life Cycle

Overwinters as in leaf litter and topsoil. Preoviposition period ranges from 3.8 days at 32°C to 22 days at 20°C. to adult development requires 24 days at 30°C to 54 days at 20°C; developmental threshold approximately 11°C with 456 degree days required. Number of varies: one generation in cooler years/regions, two generations when thermal accumulation permits.

Behavior

jump readily when approached or disturbed, using enlarged hind legs. In autumn, beetles infest field borders and gradually move across fields, feeding and killing plants sequentially. Spring is followed by oriented movement toward plants, primarily at heights within 2 m of ground. Parasitized adults emerge earlier from sites than unparasitized individuals.

Ecological Role

Specialized herbivore of Brassicaceae; significant agricultural pest causing economic damage to canola and related crops. for Microctonus vittatae, which may regulate . Feeding damage skeletonizes leaves, causing bleached appearance before plant death.

Human Relevance

Major economic pest of canola, rapeseed, and vegetable Brassica crops. Feeding by creates characteristic shot-hole damage to leaves; heavy kill seedlings and reduce yield. Management includes clean to reduce sites, applications, and breeding. monitoring uses models with predictable to ±3.7 days.

Similar Taxa

Phyllotreta striolataSimilar size and ; distinguished by distinct longitudinal on , whereas P. cruciferae is uniformly black and shiny. P. striolata has narrower range.
Phyllotreta nemorumEuropean with similar ; may require examination of genitalia for definitive identification.
Bagrada hilarisDifferent (Pentatomidae) but similar range on Brassicaceae; much larger (5-7 mm), with distinctive color pattern, does not jump.

More Details

Thermal biology

Developmental thresholds of approximately 17°C for oviposition and 11°C for -to- development have been established. Heat unit summations from soil temperatures predict adult with high .

Plant resistance

High trichome on certain Brassica villosa accessions provides physical resistance by preventing beetles from settling to feed; this trichome-based resistance does not involve chemical deterrents.

Superparasitism effects

When multiple Microctonus vittatae larvae occur in a single , development of the surviving is prolonged compared to solitary .