尖翅小卷蛾的生物学特性

尖翅小卷蛾［Bactra lanceolana (Hübner)］是席草上的重要害虫，2004-2007年对浙南地区尖翅小卷蛾的生物学特性进行了系统研究。结果表明，尖翅小卷蛾越冬代成虫初见4月中旬初前后，全年发生7~8代，本田期发生4代，以第2代虫量最高，危害损失最重，其次是第3代和第1代，世代重叠，以幼虫在席草苗内越冬。成虫多在夜晚活动，有较强趋光性，但飞翔能力弱；停在草茎上，多数头朝下，尾朝上；雌雄性比1∶1.2，寿命长短与温度、湿度、雌雄性别等关系密切；成虫一般在原田活动，羽化、产卵多在晚上，以夜晚24:00前居多；羽化后当晚交尾，产卵前期多数1 d；卵粒大多产在粗壮植株中下部位、席草茎的凹槽上，自上而下产卵，亦有产在叶鞘上；卵一般在上午孵化，其孵化时间、孵化率高低、卵历期长短与温度、湿度有关。幼虫侵入、化蛹部位多在地面茎基部，中高龄幼虫还有转株为害的习性。

Observations on the bionomics of Bactra lanceolana

Bactra lanceolana (Hübner) is a major pest on Schoenoplectus trigueter (L.) Palla. However, the biology and morphology of this pest insect is still lacking. A systematic study on the biological characteristics of B. lanceolana was conducted in southern Zhejiang Province from 2004-2007. B. lanceolana had 7-8 generations per year, 4 of which occurred in the field. B. lanceolana larvae overwintered on the seedlings of S. trigueter and the overwintering adults appearred around mid April. The second generation in the field was the most disastrous, followed by the third and first generations. Adults were active during the night, showing strong positive phototaxis although they were weak flyers. On the stems of S. trigueter, the adults usually position themselves upside down. The female and male ratio was 1∶1.2. The life span of the adults was closely related to the temperature, humidity, gender and other factors. The adults were most frequently seen in the original field. Both eclosion and oviposition occurred at night, especially before midnight. Copulation occurred in the same night after eclosion. The eggs were usually laid on the middle or lower part of the thick stem or the concave part of the stem from top to bottom, although some were laid on the sheath occasionally. The eggs hatched in the morning. Egg period, hatching time and hatching rate were all related to temperature and humidity. Neonate larvae bore into the lower part of the stems. Mature larvae had the tendency of moving to a different plant. Pupation usually occurred around the lower part of the stems.