Prediction of the Occurrence Trend of Rice Leaf Rollers in Five (3) Years in Anhui Province in 2007

First, the trend: five (3) generations of rice leaf curlers in the middle of the Yangtze River and Huai River and most of the south of the rice area will occur (5, more than 300 plexus larvae 300), the Yangtze River in the northern and Huaihuai will be partial emphasis on the rice area Occurrence (Level 4, 201-300 larvae) occurs locally. It is expected that most of the rice area during the height of the newly hatched larvae will appear from the end of July to the middle of August.

Second, forecast basis

1, the number of field debris is generally high.

Surveys conducted in the middle and late July period showed that the number of second-generation larvae of rice leaffolders was generally higher in the province. The total amount of residual insects in Huizhou District, Wangjiang County, Guichi District, Dongzhi County, Susong County, Fanchang County, and Fengyang County were 230, 298, 176, 220, 202, and 320 respectively. There were 248 heads, 271 heads, and 230 heads. The number of remnants had reached the level of emphasis, which was mostly the highest year in the same period since 2000. Among them, 176 heads and 220 heads were found in Taihu County and Shuyang County, respectively, which were 2.44 times and 3.0 times higher than the same period of the previous year. The number of residual insects in the fields of Ji County, Ningguo City, Ji County, Guangde County, Xuanzhou District, Wuhu County, Feidong County, Feixi County, Nanzhao District, and Changfeng County were 98.7, 64.8, and 123.1 respectively. 98.6 heads, 92 heads, 42.2 heads, 63.8 heads, 48.2 heads, 183 heads, and 58 heads. The amount of residual insects was significantly higher than in recent years. Of these, 49 were found in Yuexi County, 1.76 times more than in the same period of the previous year. The high residual amount of insects will provide a sufficient source of insects for the occurrence of five (3) generations of rice leaf roller.

2. During the period of occurrence of the five (3) generation rice leaf roller, the food is rich, and the microclimate in the field is beneficial to it. From the end of July to the beginning of August, most single-cropping rice is from booting to heading. The late-season rice is in the period of tillering. The rice larvae have better food conditions, and the field has a high degree of deforestation. The microclimate helps to alleviate the hot weather for egg hatching. And the adverse effects of younger larvae survival.