川西北牧区四种主栽禾草粘虫危害的差异性分析

以被害率、病情指数、严重度、虫口密度、损失率等为指标,对川西北主要栽培的禾本科牧草老芒麦(Elgmus sibiricus L.)、(蘸)草(Phalaris arundinacea L.)、仲彬草[Kengyilla rigidula (Keng) J.L.]和燕麦(Avena sativa L.)进行粘虫(Mythimna separate Walker)危害调查与分析.结果表明,4种禾本科牧草在孕穗期、抽穗期受粘虫危害,粘虫危害老芒麦、(藕)草早于燕麦与仲彬草.4种禾本科牧草总被害率、病情指数、严重度存在极显著差异；虫口密度有极显著差异;技最大虫数、枝均虫数存在显著差异；粘虫虫龄组成与结构存在极显著差异；叶片面积损失率存在极显著差异；鲜草产量损失率为8.06％～18.65％,存在极显著差异;花序损失率存在极显著差异,种子产量损失率存在极显著差异.

Difference Analysis of Armyworm Infection on Four Main Cultivated Grasses in the Pastoral Areas of Northwest Sichuan

Elymus sibiricus L.,Phalaris arundinacea L.,Kengyilla rigidula(Keng)J.L.and Avena sativa L.,main cultivated grasses in the northwest Sichuan plateau,were used as research objects to investigate and analyze the damage of Mythimna separate Walker.The result showed that these grasses were easily infected by armyworms in the booting and heading stage.And the infection of E.sibiricus and P.arundinacea was earlier than that of A.sativa and K.rigidula.There was a very significant difference among the total infected rate,the disease index and severity(P<0.01) for those grasses.A greatly significant difference among population density for the grasses and a significant difference between the max insects per shoot and the number of insect per shoot were found.Meanwhile,there was a significant difference between insect instar and population structure on those grasses(P<0.01).A significant difference for leaf area loss resulted in a great fall of fresh grass yield(P<0.01),with the loss rate of fresh grass of 8.06%～18.65%.The difference for the loss rate of inflorescence also lead to a significant decrease of seed yield(P<0.01).