稻象甲是苏南地区的常见害虫,80年代以前对水稻危害甚微,自80年代以来危害逐年加重,近年已成为水稻生长前期的主要害虫。特别在推广小苗直栽的地方,受害更为严重,平均断叶率达57.4％。忽视药剂防治的地区,常造成栽秧后大田耕翻重栽。 通过大量调查和辅助性试验,初步探明稻象甲在本地区回升的主要原因有: 1.秋播和除草方式的改革,改善了稻象甲幼虫的生活环境。秋播方式由原来的耕翻播种改革为免、少耕播种,既使稻象甲幼虫免除了在播种过程中的机械损伤,又使其越冬条件大大改善,越冬基数大,死亡率低。大面积调查越冬后幼虫密度,免、少耕田块显著高于耕翻播种的田块:辅助试验中的免耕小区冬后平均幼虫密度达47.8头/0.11米~2,而耕翻小区仅32.4头/米~2。经t测验检验差异达极显著水平。化学除草代替耘耥除草,幼虫免除了耘耥过程的机械损伤和混浊水(或泥糊)造成的窒息作用。辅助试验耘耥1次的 Rice weevil is a common pest in southern Jiangsu Province. Before the 1980s, it had little harm to rice and its harm has been increasing year by year since the 1980s. It has become a major pest in the early stage of rice growth in recent years. Especially in the promotion of direct seedlings planted more seriously, the average off-leaf rate of 57.4%. Ignore the area of ​​chemical control, often resulting in field cultivation after transplanting replanted. Through a large number of surveys and auxiliary tests, the main reasons for the initial ascension of the rice weevil in the region are as follows: 1. The autumn sowing and weeding mode reforms have improved the living environment of the rice larvae. The autumn sowing mode was replaced by tillage sowing and sowing less. Even if the rice larvae were relieved of mechanical damage during sowing, their overwintering conditions were greatly improved, the overwintering base was large and the mortality rate was low. After a large area investigation, the density of larvae overwintered, the number of free-plowing and the small-plowing plots was significantly higher than that of tillage and transplanting plots. The mean larval density of no-tillage plots in the assisting experiment was 47.8 /0.11 m ~ 2 after winter, 32.4 head / m ~ 2. The t test test differences reached a significant level. In addition to chemical weeding to cultivate grass, the larvae eliminate the mechanical damage of the pit and the choking effect caused by turbid water (or mud). Auxiliary test Yun 耥 1 times