二化螟越冬幼虫滞育后发育起点温度与有效积温

在室内15、20、25℃和30℃的恒温条件下,对南昌二化螟田间越冬幼虫滞育后发育起点温度和有效积温进行了研究。在上述各温度条件下,50%个体化蛹时间分别为66.3、41.8、26.0 d和19.9 d。由回归方程估算出二化螟越冬幼虫滞育后发育起点温度和有效积温分别为(9.3±1.1)℃和(411.0±14.2)日.度。田间自然条件下,越冬幼虫在4月初始蛹,5月下旬终蛹,1998、2004年和2005年田间累积50%越冬幼虫化蛹时的有效积温分别为377.8、417.5日.度和375.4日.度,3年平均为390.2日.度。利用该理论有效积温,参照当年2~4月的气温,可预测田间越冬幼虫50%个体化蛹的时间。

Threshold and effective accumulative temperatures for post-diapause development of the over-wintering larvae of Chilo suppressalis

Threshold temperature and effective accumulative temperature for post\|diapause development of the over\|wintering larvae of the rice stem borer, Chilo suppressalis, in Nanchang were determined by exposing diapause\|terminated larvae to different constant temperatures (15, 20, 25 ℃ and 30 ℃). The mean numbers of days required for 50% pupation under each temperature were 66.3, 41.8, 26.0 days and 19.9 days, respectively. Post\|diapause developmental rate was regressed to temperature, and threshold and effective accumulative temperatures for post\|diapause development of over\|wintering rice stem borer larvae were calculated as (9.3±1.1)℃ and (411.0±14.2)day\|degrees. Under natural conditions, over\|wintering larvae pupated from early April to late May. In 1998, 2004 and 2005, 50% over\|wintering larvae pupated at 377.8, 417.5 day\|degrees and 375.4 day\|degrees, respectively, with a mean sum of (390.2±13.7) day\|degrees above the threshold of 9.3 ℃ in three years. These results suggest that the pupation date for 50% over\|wintering individuals could be estimated by using the theoretical effective accumulative temperature and the natural temperatures between February and April.