Alternatives to DDT for the control of Oxycanus fuscomaculatus Walker (Lepidoptera: Hepialidae)

Abstract

Field trials to find an insecticide to replace DDT in the control of Oxycanm fucscomaculatus Walk. were conducted in north-western Tasmania during 1968. Chlorfenvinphos at 5, 10, and 15 oz active ingredient (a.i.) an acre and fenitrothion at 5.7, 11.4 and 17.1 oz a.i. an acre were applied in March, May, June, and August. 'Dursban' (R) (0,0diethyl 0-3,5,6,-trichloro-2- pyridyl phosphorothioate) applied at 15 oz a.i. an acre and bromophos applied at 12 oz a.i. an acre were also included in March and May trials. Increases in the rate of application of chlorfenvinphos and fenitrothion resulted in fewer surviving larvae for all except the August applications. No difference was shown between the overall effectiveness of fenitrothion and chlorfenvinphos at the dosage rates used but treatments with these two insecticides were more effective in March, May, and June than in August. The 'Dursban' and bromophos treatments gave control when applied and may warrant further investigation if they become commercially available for use against pests of pasture. It is concluded that of the 'currently available insecticides, fenitrothion applied at 17.1 oz a.i. per acre is a suitable replacement for DDT in the control of O. fucscomaculatus.