Pink Bollworm (Lepidoptera: Gelechiidae) Effects of Natural Infestation on Upland and Pima Cottons Untreated and Treated with Insecticide1

Abstract

Two upland cottons, Gossypium hirsutum L., and one American Pima colton, G. barbadense L., were grown for three seasons in unsprayed plots and in plots sprayed for control of pink bollworm (PBW), Pectinophora gossypiella (Saunders). PBW entrance holes per boll, forms (insects) per boll, and percent seed damage were higher in unsprayed than in sprayed plots. These measures of PBW infestation and plant damage were also higher in unsprayed plots of the two susceptible cultivars, ‘Deltapine 61’ (DPL-61) and ‘Pima S-5,’ than in the resistant breeding stock AET-5, except that ‘Pima S-5’ had the fewest entrance holes per boll. The green-boll and seed damage data were positively and highly significantly correlated inter se. The economic level of seed damage, as estimated by equatinga detectable decrease in cumulative lint yield with cumulative percent seed damage from sequential harvests, in unsprayed vs. sprayed plots, was 3 to 10% in DPL-61, 5 to 17% in Pima S-5, and above 17% in AET-5. Over the three seasons, lint yields in unsprayed plots were 84% (DPL-61), 73% (Pima S-5), and 101% (AET-5) of yields in sprayed plots.