Insecticide resistance in field populations of the sheep blowfly Lucilia cuprina (Wiedemann) in 1977

Abstract

A survey of insecticide resistance in Lucilia cuprina, the sheep blowfly, was conducted during 1977. The levels of organophosphorus resistance in samples collected from the Central West of New South Wales and Victoria were determined by testing diazinon against first instar larvae. Resistance factors varied from x4 to x 28. The allele(s) for resistance were present at a frequency close to 1.0 in 23 of the samples tested, while the remaining five samples contained the susceptible allele at an average frequency of 0.6. The frequency of the allele for dieldrin resistance, determined by treating adult females with the discriminating dose, was less than 0.02. A composite of field samples, following pressure from diazinon in the laboratory, increased its larval resistance factor to x45, indicating selection to high-order resistance. It is suggested that insecticides be used only at the onset of a fly wave to delay a similar response occurring in the field.