Brachypterolus pulicarius adults. R.Richard, USDA-APHIS

Brachypterolus pulicarius (L.) (Coleoptera: Nitidulidae)

by Rich Hansen, USDA-APHIS-PPQ, Forestry Sciences Lab, Montana State University, Bozeman, MT 59717-0278.

Dalmatian toadflax infestation: W.Hartung, NRCS; and plant (inset): R.Hansen, USDA-APHIS

Brachypterolus pulicarius was accidentally introduced into North America beginning prior to 1920, presumably as a contaminant of imported ornamental toadflax plants. B. pulicarius is now widely distributed in the US and Canada on yellow toadflax, but is apparently less abundant on Dalmatian toadflax. (Background information about Dalmation toadflax and yellow toadflax is available.)

Appearance

Brachypterolus pulicarius adults are black, oval beetles about 2 mm in length and are found feeding on young toadflax shoots and flower buds. Larvae are 1-4 mm long with short legs and are creamy-white in color; they are found within toadflax flowers and developing fruits.

Habitat

Grasslands, pastures, agricultural fields, and roadsides infested with yellow or Dalmatian toadflax.

Pests attacked

B. pulicarius attacks both yellow and Dalmatian toadflax. Host specificity tests have not been conducted with this insect, so its general host range is unclear. Occasionally, adult beetles may be found on flowers of other species, including dandelion, apple, strawberry, and wild mustards, but no further development is possible on these plants.

Life cycle

Adult beetles emerge from the soil in late spring and are present through mid-summer, feeding on young toadflax shoot tips and, perhaps, on flower buds. After mating, female beetles lay eggs in toadflax flowers.

Young larvae feed on pollen, anthers, and ovaries within the flowers, while older larvae also consume developing seeds. Larvae move freely from flower to flower as they consume floral tissues and seeds. By late summer, mature larvae leave flowers and developing fruits and enter the soil to pupate.

Winter is spent in the pupal stage. There is the one generation per year in the northern US and Canada, though some European reports suggest that two generations are possible.

Relative effectiveness

Flower- and fruit-feeding by B. pulicarius larvae may reduce toadflax seed production by more than 75%, but long-term effects on toadflax density are not yet known.

Pesticide susceptibility

Not yet known.

Conservation

Specifics are unknown. For general information about conservation of natural enemies, see Conservation in the Tutorial section on this site, or the Volume II, No. 1 Feature Article on conservation in the Midwest Biological Control News Online.

Commercial availability

Brachypterolus pulicarius adults may be readily collected from stands of yellow toadflax throughout much of the northern US and Canada.

References

Harris, P. 1961. Control of toadflax by Brachypterolus pulicarius (L.) (Coleoptera: Nitidulidae) and Gymnetron antirrhini (Payk.) (Coleoptera: Curculionidae) in Canada. Can. Entomol. 93: 977-981.

McClay, A.S. 1992. Effects of Brachypterolus pulicarius (L.) (Coleoptera: Nitidulidae) on flowering and seed production of common toadflax. Can. Entomol. 124: 631-636.

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