Phenological model for Sesamia nonagrioides (Lepidoptera : Noctuidae)

The development time of different stages of Sesamia nonagrioides Lefevbre w as studied in the laboratory at constant temperatures in the range 10-36 de greesC. The relationship between the developmental rate (1/d) and the tempe rature (degreesC) was determined using both linear and nonlinear (Logan typ e III) models. The fit of the linear regression in the temperature range 15 -27.5 degreesC and Logan type III equation was good (R-2 > 0.97). The lower developmental threshold, calculated using the linear model, was t(b) = 12 degreesC. The nonlinear model gave a higher threshold of T-max = 36 degrees C, and an optimal developmental temperature of T-max = 30 degreesC. The nig hts of S. nonagrioides were studied in Lleida, Spain, from 1984 to 1997, an d the number of degree-days required for their occurrence was calculated. A relationship between the degree-days required for the first night calculat ed ly the averaging method and the degree-days required for estimated diapa use termination was obtained (R-2 = 0.84). This relationship allowed the pr ediction of the first night occurrence in the field. The degree-days requir ed for the second and third generations were then calculated as 730 and 491 , respectively.