光周期对浙北地区桑螟滞育的影响

桑螟对光周期的感应效应试验证明 ,桑螟进入越冬状态是由短期光照引起的兼性滞育 ,3、4龄虫期是光感应的重要阶段 ,完全滞育与非滞育 ,只有在一定的连续光照条件下才产生 ;在温度 2 4 6℃时桑螟的临界光周期时数为 13h 40min ,浙江省湖州地区桑螟的临界日长日期为 9月 5日。初步探明湖州地区 (30°5 3′)第 4代桑螟发生分化而形成局部世代及世代演变的原因。

Effect of Photoperiod on Diapause of Diaphania pyloalis in North District of Zhejiang Province

The experiments of the effect of mulberry pyralid,Diaphania pyloails W.on photoperiodical perception evidenced that overwintering of the mulberry pryalid was facultative diapause which was caused by short illumination.The third and fourth instars of the mulberry pyralid were the most important stage for the photoperiodical perception.The complete diapause or non-diapause were produced under the conditions of certain continuous illumination.The critical hours of the mulberry pyralid at the temperature of 24.6 ℃ was 13 h and 40 min.The critical day of the mulberry pyralid diapause was fifth of September in Huzhou area,Zhejiang Province.The reasons of part-generation resulting from the differentiation of the fourth generation and the generation evolution of the mulberry pyralid in Huzhou distrct(N.L.30°53′)have been preliminarily explained.