ACTIVITY OF CHLORDIMEFORM AGAINST ORGANOCHLORINE RESISTANT AND SUSCEPTIBLE STRAINS OF HELIOTHIS SPP. (LEPIDOPTERA: NOCTUIDAE) FROM NEW SOUTH WALES

Abstract

Chlordimeform showed both ovicidal and larvicidal activity in the laboratory against eggs and first instar larvae of Heliothis armigera (Hiibner) and H. punctigera Wallengren. H. armigera eggs were less susceptible than those of H. punctigera but there was no significant difference between the susceptible and resistant strains of H. armigera. There were no significant differences in susceptibility to chlordimeform between first instar larvae of the three strains.Chlordimeform, first evaluated as an ovicide against Lepidoptera by Dittrich (l967), showed both contact and vapour activity. In laboratory work on Heliothis virescens (F.), Wolfenbarger et al. (1974) showed that complete mortality of eggs could be obtained using chlordimeform hydrochloride in water.Both H. puncrigera Wallengren and H. armigera (Hubner) damage cotton in N.S.W. (W. E. Wright, pers. comm. 1973). H. armigera has developed resistance to organochlorine insecticides in N.S.W., but there is no evidence of resistance in H. punctigera (Goodyer et al. 1975). Chlordimeform has been used commercially since 1973 against both species of Heliothis on cotton in New South Wales without precise evaluation.This paper reports laboratory results on the activity of chlordimeform against eggs, larvae that hatched from treated eggs, and first instar larvae of susceptible and organochlorine-resistant strains of Heliothis spp.The ovicidal work was done during the first three laboratory generations of three cultures started in spring 1973. These were H.punctigerafrom Bathurst, organochlorine-susceptible H. armigera from Windsor and organochlorine-resistant H. armigera from Wee Waa. The larvicidal work was also done during the first three laboratory generations of three cultures started in summer 1974 from the same areas. All testing and culturing was done at 27OC f 1.5 O C ; 14 h light: 10 h dark; the relative humidity was not regulated. All larvae were reared on the diet developed by Patana (1969) and adults were fed 10% sucrose solution.Eggs laid on Whatman ashless filter paper during the previous night were used for the ovicidal test. Squares, side 2 cm, bearing at least 20 eggs, were treated with 50 p1 of acetonic solution of an emulsifiable concentrate of chlordimeform (Acaron @50%) or with acetone for the controls. The numbers of eggs were counted shortly after treatment. After drying each paper square was placed on top of a small amount of Patana's diet in a labelled glass phial, 10 cm x 2.5 cm diameter. The phial was closed with a layer of paper towelling and a cork in which an 0.5 cm diameter hole had been made. The numbers of unhatched eggs (eggs in which the chorion had not been broken) and surviving larvae were counted three d after hatching. The surviving larvae did not eat the unhatched eggs, although they did eat the chorion of the egg from which they hatched. The method was selected to determine both egg mortality and mortality of the larvae that hatched from treated eggs. Three replicates, that is a total of at least 60 eggs, per dose we...

The Biology and Ecology of Heliothis-Armigera (Hubner) and Heliothis-Punctigera Wallengren (Lepidoptera, Noctuidae) in Australia - What Do We Know

“…Other concerns have been with the efficacy of certain chemicals or combinations of sprays (Braithwaite 1957;Clift 1976Clift , 1979Kay 1981b;Wilson 1981b) and spray formulations (MacQuillan et al 1976;Davies et al 1982). Associated with these spray trials and recommendations has been the necessity to monitor the development of resistance, most notably to DDT (Twine and Kay 1973;Wilson 1974;Goodyer et al 1975;Kay 1977;Kerr 1977;Goodyer and Greenup 1980).…”