三种阔叶草坪草对斜纹夜蛾生长发育及营养利用的作用

Effects of three leafy turfgrasses on the development and nutrition utilization of Spodoptera litura(Lepidoptera:Noctuidae)

为了探讨斜纹夜蛾Spodoptera litura对草坪的为害,提供综合治理该虫的理论依据,室内利用白三叶草Trifolium repens、红三叶草T.pratense和马蹄金Dichondra repens 3种阔叶草坪草,分别饲喂斜纹夜蛾幼虫;应用编制实验种群生命表的方法,分析斜纹夜蛾种群生长发育的趋势;同时研究该幼虫对3种草坪草的趋性及营养利用。结果表明:斜纹夜蛾幼虫的趋性表现为白三叶草>红三叶草>马蹄金。该虫在3种草坪草上都能够完成生活史;2种三叶草饲喂的该虫幼虫存活率、化蛹率、成蛾率显著高于马蹄金,幼虫期和蛹期则显著短于马蹄金;3种草坪草饲喂的该虫产卵期和平均产卵量相互之间差异不显著,而马蹄金饲喂的产卵前期和雌成虫寿命则显著短于2种三叶草。3种草坪草饲喂的该虫净生长率(Ro)、世代平均周期(T)、内禀生长率(rm)、周限生长率(λ)、种群加倍时间(DT)及种群增长参数(I)都有差异,其中2种三叶草的各种群增长参数较接近。对5龄幼虫取食3种阔叶草坪草的营养指标测定结果显示:取食马蹄金的相对生长率显著高于取食红三叶草的;取食马蹄金的相对取食量和近似消化率显著高于取食三叶草的;取食马蹄金的食物利用率和食物转化率显著低于取食三叶草的;2种三叶草间无显著差异。综合分析认为,斜纹夜蛾最喜食三叶草,最容易在三叶草草坪上猖獗为害。

To understand damage of Spodoptera litura to lawn and provide basic information for integrated management of the pest, we investigated effects of feeding Trifolium repens, T. pratense and Dichondra repens on the growth and development of S. litura in the laboratory using a life table method and by evaluating the preference to grasses and the nutrition utilization of S. litura. The results indicated that the preference of the larva to the three grasses was T. repens 〉 T. pretense 〉 D. repens. S. litura could complete their life cycle on all the three turfgrasses. The survival rate of larvae, the pupation rate and the ratio of larvae developed to moth emergence when larvae fed on T. repens and T. pratense were significantly higher than that on D. repens. Larval and pupal durations when larvae fed on T. repens and T. pratense were significantly shorter than that on D. repens. The oviposition duration and mean fecundity did not show significantdifferences among treatments of the three turgrasses; however, the preoviposition period and life-span of female adults developed from larvae fed on D. repens were significantly shorter than those on T. repens and T. pretense. The net reproductive rate （ Ro ）, the mean generation time （T）, the intrinsic rate of increase （ rm ）, the finite increase rate （λ）, the doubling time （DT） and the index of population trend （I） showed significant differences among treatments of the three turfgrasses. But the population increase parameter of the moth fed on T. repens and T. pratense was similar. The nutrition indexes of 5th instar larvae on consumption of the threeturfgrasses indicated that the relative growth rate （RGR） in larvae feeding on D. repens was significantly higher than that on T. pratense; the relative consumption rate （RCR） and approximate digestibility （AD） in larvae feeding on D. repens were significantly higher than those on T. pratense and T. repens; and the efficiency of conversion of ingested food （ECI） and efficiency of conversion of digested food （ECD） in larvae feeding on D. repens were significantly lower than those on T. repens and T. pratense. The nutrition indexes of 5th instar larvae on consumption of T. repens and T. pretense showed no significant differences. Thus it was concluded that T. repens and T. pretense were the most suitable for S. litura, with possibility of the pest outbreak on the two grasses.