Laboratory of Protected Horticultural 17The influence of temperature and photoperiod on parasitism and female ratio of Microplitis pallidipes

Key Words：Microplitis pallidipes， temperature， photoperiod， the quadratic rotary combination design， parasitic rate， female ratio

Abstract：The influence of temperature and photoperiod on the parasitism rate of the larvae of Spodoptera litura Fabricius and the female ratio of Microplitis pallidipes Szepligeti was evaluated by quadratic orthogonal rotation regression design with two factors， producing two models. These models can provide a basis for optimizing the breeding environment of M. pallidipes. Main effects analysis showed that the relationship between temperature， photoperiod and parasitic rate was parabolic. When the coding value was zero， the parasitic rate became maximal. Temperature was a more important influence on female ratio than photoperiod. Interaction effects analysis showed a significantly negative relationship between temperature and photoperiod on the parasitic rate of S. litura larvae， however， the influence of temperature and photoperiod on the female ratio of M. pallidipes was not clear. The parasitism rate of S. litura reached its maximum (71.89%) at a temperature of 28℃ and photoperiod of L∶D＝12∶12 whereas the female ratio of M. pallidipes reached its maximum (0.57) at a temperature of 33.7℃ and a photoperiod of L∶D＝12∶12.