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 sp ecifically 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 Sep tember for defoliant or plant growth regulator application and 1 Novem ber for cotton stalk destruction and plowdown. In-season gossyplure-ba ited pink bollworm male moth activity monitoring and immature green co tton boil inspections for larval infestation were encouraged as decisi on making aids to determine the need for additional control action. Ma le pink bollworm moth catches in gossyplure-baited Lingren and delta s ticky traps were substantially reduced each year from 1990 to 1994 fol lowing 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 goss yplure-baited traps placed around the perimeter of the Imperial Valley suggest that pink bollworm moth migration into the valley occurred fr om 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.