J.M. DiTomaso, The Regents of the University of California

J.M. DiTomaso, The Regents of the University of California

Russian Knapweed

APPROVED BIOLOGICAL CONTROL AGENTS


Aulacidea acroptilonica

Aulacidea acroptilonica , or the Russian knapweed gall wasp, is a recently approved biological control agent for Russian knapweed.

Adults emerge in early April and females lay eggs in the meristematic tissue, inducing gall development of main and lateral shoots. There is one generation per year which is strongly female biased.

Jaapiella ivannikovi

Jaapiella ivannikovi , or the Russian knapweed gall midge, is another recently approved biological control agent for Russian knapweed. Female midges emerge in April and deposit their eggs on the surface of buds on the tips of the main and site shoots of Russian knapweed plants.

Larval feeding causes leaves to grow together and fuse, thereby stunting the shoot and creating a gall where larval development and pupation occur. Four to five partially overlapping generations, each lasting approximately one month, have been observed in the field.