Phyllotreta albionica LeConte Coleoptera Chrysomelidae
Distribution. This native flea beetle is widely distributed in the western United States and Canada. It is found only as far east as Saskatchewan, Colorado, and New Mexico.
Host Plants. Cabbage flea beetle feeds principally on cruciferous plants. Vegetable crops attacked by this beetle include broccoli, Brussels sprouts, cabbage, cauliflower, kale, radish, rutabaga and turnip, but radish and turnip are most preferred. It also attacks alfalfa, sugarbeet, and tomato, but these events are unusual, or are cases of misidentification. Cabbage flea beetle feeds readily on cruciferous weeds.
Natural Enemies. Natural enemies are not well known, but Microctonus epitricis (Viereck) (Hymenop-tera: Braconidae) has been reared from cabbage flea beetle.
Life Cycle and Description. There is a single generation of this insect in Canada, but its biology has not been studied in detail elsewhere. Adults overwinter in leaf litter along fencerows and in woodlots. They become active in March and April and begin feeding on crucifers. Mating soon ensues, and egg laying commences after a pre-oviposition period of about 5-10 days. Adults live for about three months, continually feeding and depositing more eggs.
- The eggs are deposited beneath the host plants in the soil at a depth of about 2.5-5.0 cm. Clus ters of 15-20 eggs are common, and females deposit eggs over a three-week period. Fecundity is estimated at about 60 eggs per female, but this is likely an underestimate owing to laboratory rearing conditions. Eggs hatch in 15-20 days.
- Larvae are whitish, and are found feeding on the roots at depths of 5-15 cm. Larval development requires about four weeks, and can be found during May-July.
- As larvae are about to pupate, they characteristically move closer to the soil surface and create a small pupal chamber in the soil. The non-feeding pre-pupal period lasts about 10-12 days, and is followed by a pupal period of about 11 days.
- The adults of the summer generation emerge from the soil in August and begin feeding. Cabbage flea beetle is a shining blackish species, measuring 1.5-1.9 mm long. This beetle is easily confused with crucifer flea beetle, Phyllotreta cruciferae (Goeze), a more damaging species. However, cabbage flea beetle has a bronze luster, whereas crucifer flea beetle has a blue luster. Also, the fifth antennal segment is elongate in the female, and elongate and broad in the male cabbage flea beetle. The legs of cabbage flea beetle are brown except for the femora, which are black. The hind femora are enlarged. The antennae are black basally and reddish black toward the tip. The summer adults feed for about six weeks before seeking overwintering shelter.
The biology of this flea beetle was given by Chitten-den (1927), Burgess (1977, 1982), and Campbell et al. (1989).
Damage is caused principally by the adults in the form of small holes in the leaf surface. These beetles
are rarely abundant enough to damage anything but seedling plants. The larvae feed on the roots of cruci-fers, but they are not usually considered a problem, probably in view of their low numbers.
Management of this insect is similar to other cruci-fer-feeding flea beetles. Management has been discussed in detail in the section on crucifer flea beetle.
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