Temperature-Dependent Development of Aleyrodes proletella (Homoptera: Aleyrodidae) on Two Cultivars of Broccoli Under Constant Temperatures

Abstract

Laboratory experiments were conducted to estimate developmental rates and nymphal survival of Aleyrodes proletella Linnaeus (Homoptera: Aleyrodidae) on two broccoli Brassica oleracea L. variety italica Plenck cultivars (Marathon and Agripa) at eight constant temperatures (16, 18, 20, 22, 24, 26, 28, and 30ºC). The times required to complete development of egg and first instar decreased with increasing temperature, but the developmental times of second, third, fourth instars, all instars,and egg-adult period were greater at 30ºC than at 28ºC. The relationships between developmental rate of A. proletella and temperature were slightly influenced by broccoli cultivar. The optimal temperatures and thermal constant as well as the lower and upper thresholds of development for all immature stages were estimated by fitting the observed developmental rates versus temperature with a nonlinear model and two linear models. For all stages, graphs obtained by plotting the developmental rates against temperature could be described by the modiÞcation two of the Logan´s model. Overall, developmental times for immature stages and egg-adult periods were similar on both Agripa and Marathon cultivars. The most favorable temperature range for nymphal development seemed to be 28-29 (second and third instars) and 31-33ºC (fourth instar). Mean generation times (egg-adult)ranged from 19d ("Marathon" and "Agripa") at 28ºC to 47 ("Marathon") and 46d ("Agripa") at 16ºC.