Temperature-dependent development and oviposition models of Spodoptera exigua Hübner (Lepidoptera: Noctuidae)

To develop temperature-dependent development and oviposition models of Spodoptera exigua Hübner, development and reproduction of S. exigua were investigated at ten constant temperatures (12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5 and 35°C), 60-70% RH, and a photoperiod of 14:10 (L:D) h. The development rates of immature stages increased with increasing temperatures. The relationship between the development rate for each life stage and temperature was fitted by a linear and six nonlinear developmental rate models (Logan-6, Lactin-1, 2, Briere-1, 2 and Sharpe and DeMichele), and was fitted best to the Briere-2 model (r2=0.97-0.99). The lower developmental threshold temperature was 12.91, 13.45, 11.54, 13.07 and 13.19°C for egg, 1st-3rd instar larva, 4th-6th instar larva, pupa, and total immature, respectively. The thermal constant required to complete the respective stage was 40.65, 89.29, 112.36, 100 and 322.58 DD. The normalized cumulative frequency distributions of development time for each life stage were fitted to the two-parameter Weibull function. The relationship of fecundity of adult female S. exigua and temperature was described by a nonlinear function, and its cumulative oviposition rate and survivorship were described by a two-parameter Wibull function, and a reverse logistic function, respectively. The temperature-dependent development and oviposition models of S.exigua developed in this study will be useful to develop a population dynamics model of S.exigua and to predict its seasonal population dynamics in fields.