Heliothis as a pest of cotton

Abstract

Over the 10-year period 1948-1957, 13 trials with modern insecticides against Heliothis armigera (Hubn.) were conducted on both irrigated and rain-grown cotton in Central Queensland. Results from four of these trials show total yield increases after DDT applications which were successful in killing Heliothis armigera; the increase was economically significant in one instance only. During the 1955-56 season investigations were expanded to cover plant reaction to pest kills. Although goods kills of Heliothis and most other insects were obtained there was an increase in yields in the first pick but no differences among total yields. The killing of Heliothis caused the plants to hold larger percentages of early squares and bolls; later, however, fall from sprayed plants was sudden while that from unsprayed plants was gradual. Consequent replacement of squares and bolls was responsible for the levelling of total yields.