榆掌舟蛾发生期观测及幼虫龄期测定

Observation on the Occurrence Period and Determination of the Larval Instar of Phalera takasagoensis Matsumura

通过多年持续灯诱监测,确定榆掌舟蛾Phalera takasagoensis Matsumura成虫发生期:7月上中旬为始见期,8月上中旬为高峰期,9月上中旬为终见期。采用饲养观察和林间调查相结合的方法,首次明确榆掌舟蛾幼虫有5龄型、6龄型和5~6龄混合型3种类型,8月上旬前孵化、8月下旬前后老熟的幼虫多为6龄型或兼有混合型,偶有5龄型; 8月下旬以后孵化幼虫、9月中下旬及以后老熟的幼虫均为5龄型。6龄型1~6龄头壳平均宽0.50、0.88、1.41、2.05、2.96、4.66 mm,幼虫历期28.3~43 d,平均32.3 d,各龄分别为4.2、5.2、5.4、5.9、4.4、7.2 d;5龄型1~5龄头壳平均宽0.52、0.90、1.53、2.68、4.37 mm,幼虫历期23.9~70 d,平均30.9 d,各龄分别为4.1、5.0、5.5、6.2、10.1 d;5龄型末龄幼虫历期最长达40.1 d,可耐-2℃短时低温;幼虫最早8月下旬老熟,最晚可危害至11月下旬。

The adult occurrence period of Phalera takasagoensis Matsumura was determined based on lamp induction monitoring for many years.The adults emerged in early and mid July,and reached the peak in early and mid August,ending in early September and mid September.Using indoor feeding and field investigation methods,3 types of larvae were identified for the first time:5 instars,6 instars and their mixed type.Most of the larvae hatched before the early August and the late mature larvae in late August were mostly 6 instars or mixed type,occasionally 5 instars type.the larvae hatched after late August and the mature larvae after mid September were all 5 instars type.The head width of 1~6 larvae of 6 instars type was 0.50,0.88,1.41,2.05,2.96 and 4.66 mm respectively.The larval calendar period was 28.3~43 d,with an average of 32.3 d.The duration of the larvae of each instar were 4.2,5.2,5.4,5.9,4.4,7.2 d,respectively.The head width of 1~5 larvae of 5 instars type was 0.52,0.90,1.53,2.68,4.37 mm respectively.The larval calendar period was 23.9~70 d,with an average of 30.9 d.The duration of the larvae of each instar were 4.1,5,5.5,6.2 and 10.1 d,respectively.The last instar larvae of the 5 instars type larvae had the longest duration of 40.1 d,which can withstand-2℃for a short time.The larvae mature in late August and can be harms to late November.