PINK-BOLLWORM (LEPIDOPTERA, GELECHIIDAE) MALE MOTH TRAP CATCHES IN GOSSYPLURE-BAITED TRAPS IN RELATION TO ACCUMULATED HEAT UNITS

Studies were conducted from 1981 to 1989 to examine the relationship between pink bollworm (PBW), Pectinophora gossypiella (Saunders), male moth trap catches in gossyplure-baited traps and heat units (degree days) in the Imperial Valley, California. Heat unit accumulations were based on 30.0/12.8-degrees-C (86/55-degrees-F) upper/lower temperature thresholds. Results showed that the number of PBW male moths/trap/night caught in gossyplure-baited traps from early March to 31 August were estimated by the equation: Y = -1.797 + 0.988E-03 X, where Y was Log10 [male moths/trap/night] and X was the number of accumulated degree days beginning 1 January each year (R2 = 0.717). Decreasing numbers of male moths/trap/night from 1 September to mid-November were estimated by the equation Y = -3.766 -0.398E-03 X, but the data fit was poor (R2 = 0.114) because results were confounded by decreasing temperatures beginning in early September. Results of the study suggest that trap catch data, as related to degree days, may be used to describe seasonal male moth trap catch increases as a reflection of increasing PBW populations. Further, male moth trap catches and degree day relationships provide the potential for developing an economic level decision-making tool.