LABORATORY AND FIELD STUDIES ON THE CHEMICAL CONTROL OF THE CRUCIFER FLEA BEETLE, PHYLLOTRETA CRUCIFERAE (COLEOPTERA: CHRYSOMELIDAE), ON CRUCIFEROUS CROPS IN ONTARIO

The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is a pest of major economic importance on cruciferous crops in Canada. Laboratory and field tests were conducted to assess the effectiveness of insecticides which have been, or currently are used in Ontario, or which might have potential for its control. Twenty of 22 insecticides tested in the laboratory were toxic or moderately toxic by direct contact against adults. Carbofuran was 55 times and eight other insecticides 2.9 to 5.5 times more toxic than endosulfan. Of eight insecticides tested as soil treatments, diazinon, carbofuran, and dieldrin were most toxic to adults. All insecticides were less toxic in organic than in mineral soil. In field studies, concentrations of DDT and dieldrin typical of those found in mineral soils used for crucifer production in Ontario in the late 1960’s reduced crucifer flea beetle damage to radishes. As organochlorine insecticide residues decline a higher percentage of crucifer flea beetle population will survive necessitating greater emphasis on control. Two sprays of parathion, carbaryl, or endosulfan significantly reduced crucifer flea beetle damage to radishes in the early part of the growing season under moderate insect pressure. These control programs were less effective during warmer weather and(or) under severe crucifer flea beetle pressure. Soil applications of terbufos, carbofuran, and oxamyl protected cabbage grown in seed beds from attack. The latter was slightly phytotoxic. Planting–water treatments using azinphosmethyl, diazinon, and oxamyl protected cabbage transplants against early season crucifer flea beetle attack. On late cabbage, fensulfothion, azinphosmethyl, carbaryl, endosulfan, and chlorfenvinphos gave good protection.