NORTHERN CORN-ROOTWORM (COLEOPTERA, CHRYSOMELIDAE) TEMPERATURE REQUIREMENTS FOR EGG DEVELOPMENT

Temperature-dependent development of laboratory-wintered eggs of north ern corn rootworm, Diabrotica barberi Smith & Lawrence, was described using data from constant temperature laboratory experiments. Median de velopment of postdiapause eggs at constant temperatures of 15, 18, 20, 23, 25, 27, and 30 degrees C required 59, 30, 24, 17, 15.5, 14, and 1 4 d, respectively. Linear and nonlinear models were fitted to temperat ure versus developmental rate data. Variation in developmental rates a cross temperatures was modeled with a cumulative Weibull distribution. Mean developmental rate was linear between 15 and 27 degrees C, optim al at 27 degrees C, and decreased at 30 degrees C. The thermal thresho ld for development (10.9 degrees C) was determined by extrapolation wi th median egg hatch occurring after 238 DD (10.9).