ALFALFA CONSUMPTION BY ADULT CLOVER LEAF WEEVIL (COLEOPTERA, CURCULIONIDAE) AND DEVELOPMENT OF INJURY EQUIVALENTS FOR STUBBLE DEFOLIATORS

Experiments were conducted from 1990 through 1992 to determine consump tion rates and feeding duration of adult clover leaf weevils, Hypera p unctata (F.), to characterize the injury potential of this species dur ing alfalfa regrowth. Adults were fed for 29 d in 1990 and 18 d in bot h 1991 and 1992. The mean cumulative consumption per adult was 27.2 +/ - 1.6 cm(2) and 92.7 +/- 3.5 mg dry weight in 1991 and 24.6 +/- 0.9 cm (2) and 87.5 +/- 2.9 mg dry weight in 1992. The mean cumulative consum ption pattern was curvilinear for both dry weight and leaf area consum ption. Most consumption was within 11 d of adult eclosion. The peak co nsumption rate occurred approximate to 5 d after adult emergence. Beca use the highest consumption rates and the greatest percentage of defol iation were within the first 11 d of emergence, adult clover leaf weev ils potentially can delay regrowth of alfalfa stubble when adult emerg ence coincides with the 1st harvest. Further, because adult consumptio n patterns between clover leaf weevils and alfalfa weevils are similar , alfalfa stubble defoliation thresholds developed for alfalfa weevils and cutworms also can be used for clover leaf weevils. Injury equival ents (injury by 1 species in terms of another species) are determined for adult clover leaf weevils, larval variegated cutworm, Peridroma sa ucia (Hubner), and larval and adult alfalfa weevils, Hypera postica (G yllenhal).