间作对甜玉米田主要害虫与天敌动态的影响

为明确甜玉米间作不同作物对害虫的控制作用,采用目测法系统调查了甜玉米单作、甜玉米与绿豆、菜豆、甘薯或花生间作生境玉米主要害虫和天敌种群发生动态,并比较了不同生境亚洲玉米螟的为害情况。间作生境中捕食性天敌蜘蛛和瓢虫类群的个体数量均明显增加,其中甜玉米间作绿豆或甘薯生境蜘蛛类群增长21%以上,瓢虫类群增长83%以上,显著高于甜玉米单作生境;不同生境间玉米螟赤眼蜂发生量差异不显著,对亚洲玉米螟卵的寄生率均达到86%以上。间作生境玉米生育期内亚洲玉米螟落卵量、斜纹夜蛾及玉米蚜发生量均与甜玉米单作无显著差异,但收获期甜玉米间作生境玉米螟为害率低于单作生境,其中以甜玉米间作绿豆生境最低,总蛀孔数和活虫数分别比单作生境下降55.72%和76.70%。表明间作不同作物对甜玉米田具有一定的控害增益作用。

Influence of intercropping on dynamics of insect pests, natural enemies and the damage of Ostrinia furnacalis in sweet corn field

In order to confirm the effect of pest control using intercropping with different crops, investigation was conducted to study the population dynamics of insect pests of maize and their natural enemies in the habitat of sweet corn monoculture or intercropping with other crops (mung bean, kidney bean, sweet potato or peanut) by the method of eyeballing. Damage by Asian corn borer (ACB), Ostrinia furnacalis (Guenée) between different habitats was also be analyzed and discussed. Results indicated that the amounts of two predator groups, spiders and ladybirds, increased in sweet corn intercropping habitats significantly. Individual number of spiders in the fields when sweet corn intercropped with mung bean and number of ladybirds in habitat of sweet corn intercropped with sweet potato were over 21% and 83% respectively more than that in sweet corn monoculture. The number of Trichogramma ostriniae Pang et Chen showed no significant difference between different habitats, with the parasitic rates of ACB eggs were over 86%. No significant differences was observed in number of ACB eggs, Spodoptera litura (Fabricius) or Rhopalosiphum maidis Fitch between sweet corn monoculture and intercropping habitats. However, the ACB damage rate in sweet corn intercropping habitats was less than that in sweet corn monoculture at harvest, with the least in sweet corn intercropped with mung bean habitat, in which the number of holes and larvae was decreased by 55.72% and 76.70% respectively. Study suggested that sweet corn intercropping with other crops could be beneficial to conservation of natural enemies and control of insect pests in some extents.