The effects of herbicides on the chrysomelid beetle Gastrophysa polygoni (L.) in the laboratory and field.

The effects of the translocated herbicide 2,4-D upon the chrysomelid beetle Gastrophysa polygoni were investigated. Larvae feeding upon either host plant material or their own egg cases sprayed with herbicide suffered significantly higher mortalities than those larvae feeding upon unsprayed material. Application of 2,4-D did not effect hatching success, nor did contact with the chemical cause significant losses among larvae.

The use of 2,4-D in a mixture with CMPP in a field of spring barley significantly reduced host plant densities and numbers/m² of egg batches in sprayed areas of the field compared with unsprayed areas. The use of specific “anti-Polygonum” herbicides eradicated the host plants and thus populations of G. polygoni on a field scale.