棉铃虫种群消长及影响因子

耕作制度的改变,为棉铃虫种群数量上升提供了良好的食物源和生态环境;大面积使用化学农药,不仅削弱了天敌的控害作用,也提高了棉铃虫的抗药性;气候变暖,适宜于棉铃虫数量上升。因此,棉铃虫种群增加,棉花、玉米、小麦、豆类、瓜菜等受害也明显加重。要控制棉铃虫的发生程度,首先要防治棉田外一代幼虫和卵,减少一代种群数量;对二代棉铃虫,宜有选择地使用化学农药和生物农药进行防治,并充分发挥天敌的自然控制力,以减少种群数量;三代、四代棉铃虫主要危害作物繁殖器官,直接影响作物的产量和品质,以物理诱杀和玉米诱集带集中诱杀为主,既可控制其危害,又对其天敌无负面影响;五代棉铃虫虽对当年作物产量影响不大,但其种群数量直接影响下一年一代发生量,因此应及时喷施病毒类等生物性药剂,降低其越冬种群,同时也保护自然天敌安全越冬。

Growth and Decline of Population and Effect Factors on Helicoverpa Armigera

With the change of the cultivation system,the better food-sources and ecological conditions result in the increasing population number of helicoverpa armigera.The chemical pesticide are utilizing in more and more plantation,these impair the controlling of its natural enemy,and enhance the resistance to drugs of helicoverpa armigera.The warming of climate leads to the increase of helicoverpa armigera.Followed,cotton,corn,wheat,legume,melon and vegetables,etc,all suffer seriously.To control the occurrence of helicoverpa armigera,there are several methods to perform.Firstly,to prevent the first-generation larva and nit out of field,the aim is to decrease the number of first-generation.Secondly,to make use of chemical pesticide and biological pesticide selectively for secondly-generation helicoverpa armigera,the aim is to protect the natural enemy of the pest.Thirdly,to kill the pest centralized with physical methods for third-generation and fourth-generation helicoverpa armigera,it effect crop's organ of multiplication.Correspondingly,The natural enemy is protected.Although fifth-generation pests affect the yield little in this harvest,it induces the pest number of the next year.The biological pesticide is used timely after harvest,and this can decrease the pest,which live through the winter.