Hcliothisarmigera damaged cotton in the Nainoi Valley in summer-autumn 1973. In laboratory studies larvae exhibited several hundredfold resistance to DDT. 15-fold to DDT/chlorcam (1:2) mixture and 30-fold to endrin compared with a susceptible strain from Bathurst. The Namoi Valley larvae were found to be 5 times less susceptible than Bathurst larvae to parathion methyl, a difference which may be no more than normal variation between non-resistant strains. No resistance to insecticides was demonstrated in H.

No abstract

No abstract

The susceptibility of nymphs and adults of Nysius vinitor Bergroth and N. clevelandensis Evans to malathion, fenitrothion, carbaryl and DDT was determined by placing the insects on filter papers impregnated with a series of insecticide concentrations. The Id-p data obtained were similar for both species and a further 17 insecticides were tested against N. vinitor adults. Promecarb, mevinphos, ethyl-parathion, naled, methidathion and diazinon were the most effective chemicals tested. IntroductionNysius spp. are important pests of fruits, vegetables and summer crops in many parts of the world. Eleven species have been recorded as injurious to cultivated crops (Evans 1936). The most important species in Australia are the Rutherglen bug, Nysius vinitor Bergroth, and the grey cluster bug, N . clevelandensis Evans. Both occur in all the mainland states; N. vinitor is also present in Tasmania (Woodward 1964).Many Australian farmers have altered their activities over the past 10 years to meet an increasing demand for summer crops. In 1968-69 these crops, especially sunflower, Helianthus annuus L., and safflower, Carthumus tinctorius L., were extensively damaged by N . vinitor.Few data are available on the response of these insects to insecticides and In this study a range of insecticides was screened in the laboratory to obtain log doseprobability (Id-p) lines. This information will aid in choosing the best compounds for field testing.

Three strains of Indian meal moth, Pludia intevpuncfella, were collected in 1975 from stored foodstuffs and grain storages in New South Wales and their responses to 24 insecticides were compared with a laboratory reference strain. The strains showed 68-, 74.4-and 72.3-fold resistance to endrin, :-53-fold to dieldrin, 12.5-, 14.2-and 11.5-fold resistance to lindane, and > 42-fold resistance to DDT. One strain from Tamworth (strain T) displayed more than 260-fold resistance to malathion and two strains (R and M) showed 25-and 24-fold resistance to malathion. The three strains also had resistance to dichlorvos (2.9 to 3.6-fold), diazinon (7.0 to 9.7-fold), pirimiphos-methyl (4.5 to 4.8-fold) and fenitrothion (7.2 to 8.6-fold). Pre-treatment with triphenyl phosphate overcame most of the malathion resistance of strain T, reducing the resistance factor by more than 97% to 7.4, compared with only 20% and 17% reductions in strains R a n d M to 20. None of the strains was resistant to pyrethrins, synthetic pyrethroids or the carbamate, methomyl.