The Persistence and Toxicity of Insecticides under tropical Conditions. I.—The Persistence of γ BHC and its Toxicity to Tribolium castaneum (Hbst.)

Abstract

The persistence and toxicity to Tribolium castaneum (Hbst.) of initial deposits approximating to 10, 20 and 40 mg. per sq. ft. of γBHC were studied over a period of three weeks in a typical warehouse in Kano, Northern Nigeria. Chemical and biological assessments indicated that the lowest rate of application was inadequate for practical insect control whilst the other two rates showed very similar biological activity up to eight days after treatment. Thereafter small quantities persisted from applications at the highest rate for a further week but the resultant mortalities were inadequate for purposes of field control. It was concluded that to maintain control of T. castaneum, weekly applications of BHC would be required and that the rate of application should approximate to 20 mg. per sq. ft.