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斜纹夜蛾在自然条件下的发生危害期为7~10月,其食性杂,能取食大豆、甘薯、蔬菜等多种作物。近年来江苏、上海等地保护地草莓发展较快,新种田块周边植物种类多样,斜纹夜蛾虫源广,加上扣棚后棚温适宜,导致其危害期延长,对第一茬草莓的产量及商品性影响大。江苏、上海等地斜纹夜蛾一年发生5~6代,7~10月危害最重。在草莓上危害,前3代虫主要在繁苗期危害,第四代和第五代在草莓移栽后扣棚前危害,有些年份第六代虫在草莓扣棚后的11月中下旬至12月上旬也会严重发生。幼虫大量取食草莓叶片、花和果实,严重时花果被害率可达20%~30%,12月份草莓大棚内仍能诱捕到斜纹夜蛾成虫。
Spodoptera litura in the natural conditions of the occurrence of harm from July to October, its mixed diet, can eat soybeans, sweet potatoes, vegetables and other crops. In recent years, Jiangsu, Shanghai and other places to protect the rapid development of strawberries, new plant blocks around the diverse species of plants, Spodoptera litura insect wide, coupled with shed suitable after shed temperature, resulting in the extension of the damage period, the first strawberries Large impact on output and merchandise. Spodoptera litura in Jiangsu and Shanghai occur 5-6 generations a year, the most serious from July to October. On the strawberry damage, the first three generations of insects mainly in the danger of the second seedlings, the fourth and fifth generations of strawberry transplanting buckle shed before the harm, in some years the sixth generation of insects in the strawberry buckthorn in late November to late In early December will be serious. Larvae fed on strawberry leaves, flowers and fruits in large quantities. In severe cases, the damage rate of flowers and fruits could reach 20% -30%. In December, the adults could still be trapped in the strawberry greenhouse.