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室内饲养观察稻纵卷叶螟(Cnaphalocrocis medinalis)5龄幼虫食量最大,第1、2代占总食叶量的68.42％和71.60％,4龄次之,第2、3代分别占总食叶量的18.30％和15.78％。因此,幼虫消灭在3龄以前可控制为害。对不同为害程度与水稻产量损失量关系进行了测定和分析,结果表明,第2代为害主要可使千粒重降低,同时对每穗粒数和空壳率也有较大影响。第3代为害主要表现在空壳率的上升和千粒重下降。第2代主要为害倒4、5叶,少量为害有一定的增产作用;而第3代主要为害剑叶和倒2叶,产量损失明显地大于第2代,是防治的关键世代。根据研究结果可得出不同世代、不同虫龄盛发期的动态经济阈值模型。
The fifth instar larvae of Cnaphalocrocis medinalis showed the highest food intake in indoor feeding. The first and second generations accounted for 68.42% and 71.60% of the total fresh leaves, followed by the fourth and second, respectively, The amount of 18.30% and 15.78%. Therefore, larval extinction can be controlled until the third instar. The relationship between the degree of damage and the loss of rice yield was measured and analyzed. The results showed that the damage of the second generation could mainly reduce the 1000-grain weight, and also had a significant impact on the number of grains per spike and the percentage of empty shell. The third generation of damage is mainly manifested in the increase of shell percentage and grain weight decline. The second generation of the main damage to fall 4,5 leaves, a small amount of damage have a certain role in increasing yield; and the third generation of the main damage to the flag leaf and 2 leaves, the yield loss was significantly greater than the second generation, is the prevention and control of the key generation. According to the research results, we can get the dynamic economic threshold model of different generation and different stages of insect age.