三化螟主害代转变与防治对策研究

本研究探明新余市蒙山山麓稻区水稻栽培制度不合理,虫源田、过渡桥梁田大量存在,是造成三化螟种群上升的重要原因。水稻生育期提前,二代过渡桥梁田由迟熟早稻改为一季晚稻和二季晚稻秧田为主,幼虫滞育时间较长,以及螟虫营养条件改善,是导致主害代由四代转变为三代的直接原因。三代转化率低使四代三化螟种群数量下降,为害减轻。同时,针对该地区三化螟发生规律,阐明了调整栽培制度,消灭越冬虫源,提高栽培技术,减轻螟害的措施,以及“兼治一代,挑治二代,狠治三代”的药剂防治策略。提出了第四代三化螟预报中应注意的问题。

A Study on the Change of Main Injurious Generations of Scirophaga incrtulas and its Control

Studies showed that, the improper cultivation system, the sufficient source of the insects and the sufficient fields which conveyed the insects from one generation to anthor were the important reasons for the increase of Scirophaga incrtulas at the foot of Mengshan Mountain in Xingyu City. The direct reasons for the change from four generations into three generations were as follows: the growth period of rice shifted to an earlier date; the great amount of single cropping of late rice and double cropping of late rice seedlings were grown in the filds which conveyed the insects from one generation to anthor instead of late maturing early rice, the larva diapause period shorted and the nutriment improved. The low change rate of the third generation caused the decline of the population of S. incrlulas, reducing the damage, Also, in view of the generation change regulation of S. incrlulas in that area, the authors illuminated the control methods of adjusting cultivation system, eliminating source for insect overwintering and raising cultivation techniques, and put forward the chemical cuntrol tactics of controlling the first generation extensively, controlling the second generation selectively and controlling the third generation intensivlely. In addition , the authors pointed out some points worth noticing when the occurence of the fourth generation of S. incrlulase was predicted