大螟幼虫田间扩散及成虫飞行能力研究

Studies on larval dispersal ability in the field and adult flight capacity of the pink stem borer,Sesamia inferens

大螟的抗性演化将成为制约Bt水稻产业化发展的关键因素,为实施预防性的害虫抗性治理策略,明确大螟成、幼虫的运动习性具有非常重要的意义,本文通过田间调查和飞行磨测试的方法研究了大螟幼虫在田间的迁移扩散行为和成虫的飞行能力。结果表明,大螟幼虫在不同水稻穴之间及同一水稻穴内的不同分蘖间均存在频繁的迁移扩散,且其在分蘖期水稻上的迁移扩散能力显著高于孕穗期水稻。在整个幼虫发育过程中,大螟在分蘖期和孕穗期水稻上的平均迁移扩散距离分别为62.29cm和51.02cm,最大扩散距离为120cm。吊飞结果表明,大螟的有效飞行时间为4～5d,能多次飞行,约有75.5%的个体累计飞行距离≤5km。因此,对于幼虫扩散能力相对较强、成虫飞行能力相对较弱、求偶前期相对较短的大螟来说,建议其抗性治理策略应设置为分区种植的庇护所,且庇护所与Bt稻田的距离最好不超过5.0km。

The resistance evolution of Sesamia inferens is one of the important factors to limit the commercial use of Bt rice. It is necessary to clarify the locomotor characters of S. inferens in order to implement precautionary in- sect resistance management strategy. In this study, the larval dispersal in the field as well as adult flight capacity of S. inferens was conducted by field investigation and tethered flight tests. The results showed that the larvae ex- hibit extensive movement among rice hills and tillers in plots of transplanted rice, during the course of larval de- velopment. Moreover, larval dispersal rate and distance during the rice tillering stage were significantly higher than that at the booting stage. The average dispersal distances of larvae were 62.29 cm and 51.02 cm during the rice tillering and booting stages, respectively, while the maximum movement was 120 cm. The tethered flight tests showed that the effective flight time of S. inferens was four to five days and it could fly continuously for several times. Accumulative flight distances of 75.5% individuals were ≤5 kin. Therefore, the external refuge rather than seed mixtures of Bt and non-Bt rice should be considered for resistance management and the distance between refuge and Bt rice field should not be over 5.0 kin, in view of S. inferens with relative higher larval dispersal abili- ty, comparatively low flight capacity and short pre-calling stage.