Reduction of pink bollworm (Lepidoptera: Gelechiidae) populations in the Imperial Valley, California, following mandatory short-season cotton management systems

A cotton management program in the Imperial Valley, California, was specifically designed to reduce pink bollworm, Pectinophora gossypiella (Saunders), populations in the area by optimizing the host-free period. The program established 1 March as the earliest planting date, 1 September for defoliant or plant growth regulator application and 1 November for cotton stalk destruction and plowdown. In-season gossyplure-baited pink bollworm male moth activity monitoring and immature green cotton boil inspections for larval infestation were encouraged as decision making aids to determine the need for additional control action. Male pink bollworm moth catches in gossyplure-baited Lingren and delta sticky traps were substantially reduced each year from 1990 to 1994 following the initiation of the management program in 1989. Fewer larvae per cotton boil occurred in the years from 1990 to 1992. Fiber quality of commercial cotton sampled was also improved from 1989 to 1994, as compared with the 1984 to 1988 average. Male moth trap catches in gossyplure-baited traps placed around the perimeter of the Imperial Valley suggest that pink bollworm moth migration into the valley occurred from surrounding cotton growing areas during the growing season. Highest numbers of moths were caught in perimeter traps directionally placed toward cotton growing areas in the Mexicali, Baja California, Mexico, and Bard-Winterhaven and Pale Verde, CA. Cotton production, in general, was reduced during 1989-1994 in these areas and may have contributed partially to reduced populations in Imperial Valley.