Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plant: wild or cultivated brassicas.
- Adult: it flies when the rape starts flowering and feeds principally on flower buds and pollen. It can cover distances reaching 3 km to reach the warmer zones or the cultivated fields.
Mating starts rapidly after its arrival in these favorable zones and the eggs are laid 2 or 3 at a time in buds of 2 to 3 mm in diameter, next to the anthers.
Maximum fecundity, 250 eggs. The overwintered adults gnaw the late buds and the extremities of the winter pods or the spring brassicas before hibernating.
- Egg: embryonic development lasts about 12 days.
- Larva: 2 instars. During the first instar, the larvae remain in the bud and feed on pollen; they attack the ovaries only when there are more than 5 larvae per bud. The second-instar larvae migrate to other buds then drop to the ground and pupate, each in an earthen cell at a depth of 2 to 3 cm.
The larval development lasts 27 to 30 days at 16 °C.
- Pupa: average length of pupation period, 15 to 22 days.
- 1 annual generation, possibly 2 in the meridional regions.
- The adults emerge from hibernation in May, over an extended period if the temperature is low, or suddenly if the weather is warm and dry for several days in a row. The new, young adults feed briefly, then bury themselves in the soil at the end of summer-autumn to overwinter.
Adults and larvae destroy a large number of flowers and flower buds and can be harmful to brassica seed crops. Damage is identical to and compounds that of the pollen beetle (Meligethes aeneus), which appears 3 or 4 weeks earlier.
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.