杀虫剂不同处理对二化螟为害、防治效果及水稻产量的影响

近年来,二化螟发生出现各代均偏重或大发生的新特点。为探索杀虫剂防治二化螟的新策略,采用田间小区试验在早晚稻田中分别研究5%氟虫腈加25%灭.水胺的不同施药时期和次数对二化螟幼虫的为害和防治效果及对水稻产量的影响。在试验地,二化螟第1和第2代发生在早稻田,第3和第4代发生在晚稻田。试验结果表明,在第1和第3代二化螟幼虫孵化高峰施药1次、隔10d再施药1次对早稻田和晚稻田的幼虫防效显著,分别达到了92.4%和92.6%。在早、晚稻田分别发生的第1和第3代2龄幼虫高峰期施药1次、同时在次代孵化高峰期再施药1次,均可显著降低虫伤株率和白穗株率,提高保穗效果,并显著提高单位面积上的水稻产量(3.98%~4.20%)。因此,对第1至第4代二化螟幼虫均进行1次药剂防治是二化螟各代均大发生的新形势下的防治策略。

Effects of different insecticide treatments on the damage by the striped stem borer, Chilo suppressalis,controlling efficiency and rice yield

A new trend in the occurrence of the striped stem borer (SSB), Chilo suppressalis, characterized by heavy infestation for all generations, appeared in the recent years. To explore a new insecticide-based controlling strategy for SSB, we designed field plot experiments in early and late rice cropping seasons to investigate the effects of timing and number of insecticide application on SSB damage, controlling efficiency and rice yield. In the experiment region, the first and the second generations of SSB occur in the early season rice field and, the third and the fourth, in the late season rice field. Results showed that spraying 5% Regent SC plus 25% Methomyl at the hatching peak of the 1st and 3rd generations coupled with a 2nd spray 10 d after the 1st spray significantly suppressed SSB larval populations, with controlling efficiency of 92.4% for early season rice and 92.6% for late season rice, respectively. The rates of damaged rice plants and dead panicles were significantly reduced and rice yield increased significantly by 3.98%～4.20% if the plots were sprayed with the insecticides once at the peak of 2nd instar larvae of the 1st and 3rd generation and with additional sprays at the hatching peak of the following generation. Therefore, the new strategy for controlling SSB is spraying for all the 1st to 4th generations.