大豆田双斑萤叶甲成虫发生动态及其经济阈值

Occurrence regularity and economic threshold of Monolepta hieroglyphica adults in soybean fields

为明确双斑萤叶甲Monolepta hieroglyphica(Motschulsky)成虫危害对大豆产量损失的影响及其经济阈值,采用田间系统调查和小区罩网接虫方法,研究了不同虫口密度下大豆产量性状的变化规律。结果表明,在长春地区,双斑萤叶甲成虫在大豆田间发生危害的高峰期为7月26日到8月22日,共40 d,随着该害虫虫口密度上升,大豆植株有效结荚数降低,瘪荚率上升,百粒重下降,同时大豆的产量显著降低。双斑萤叶甲成虫密度与大豆瘪荚率的关系符合逻辑斯蒂模型y=8.720/(1+e^((0.718 9-0.026 0x))),与百粒重之间的关系符合二次曲线模型y=19.608 5-0.155x+0.002 4x^2,与大豆产量的关系符合修正指数模型(y=53.207 8+33.408 9×0.940 8x,p<0.000 1),与产量损失间的关系符合二次函数模型(y=-0.602 8+1.812 6x-0.025 8x^2,p<0.01)。目前,大豆生产中使用有效药剂2.5%高效氯氟氰菊酯EC(135m L/hm^2)和90%灭多威DP(180g/hm^2)防治双斑萤叶甲时,其经济危害允许水平分别为2.81%、2.91%,经济阈值分别为193.63头/百株和199.47头/百株。

To evaluate the effects of Monolepta hieroglyphica （Motschulsky） adults on the damage to soybean yield loss and the economic threshold of this pest, the agronomic yield characteristics of soybean influenced by M. hieroglyphica in different densities were tested with the method of systemic field investigation and plot grid connection. The results showed that the hazard summit period of M. hieroglyphica adults was during period of July 26 to August 22 in soybean fields, a total of 40 days. During this period, some agronomic yield characteristics of soybean changed, such as： reduced effective pod number, increased rate of empty pod, decreased 100 kernel weight, and the significantly decreased yield of soybean. The relationship of population density of M. hieroglyphica adult and rate of empty pod fitted well to the logistic growth model y=8.720/（1＋e^（0.7189-0.026 0x））. Equally, a quadratic curve model y=19.6085-0.155x＋0.0024x^2 indicated the relationship of population density of M. hieroglyphica adult and 100 kernel weight, and a modified exponential model y=53.2078＋33.4089×0.9408x（p〈0.0001） for soybean yield, a Quadratic function model y=-0.6028＋1.8126x-0.0258x^2 （p〈0.01） for rate of yield loss. Economic loss were 2.81% and 2.91%, and economic threshold were 193.63 bugs / 100 plants and 199.47 bugs / 100 plants, when lambda-cyhalothrin and methomyl were used for controling M. hieroglyphica in present soybean production.