中文摘要：

为了解空心莲子草叶甲Agasicles hygrophila被引入中国20多年后其取食行为与取食能力是否发生改变,我们通过采集叶甲自然种群的成虫,在室内用空心莲子草Alternanthera philoxeroides饲养获得检测用叶甲各虫态与虫量进行室内定量检测,研究了空心莲子草叶甲自然种群各龄幼虫与成虫在不同密度下对空心莲子草的控害效果。结果显示：1龄幼虫喜食顶芽嫩叶,在每株接0.2和1头1龄幼虫密度下,空心莲子草仍有新叶和侧芽生成,生物量、株高与茎节数仍在增加;在5头/株的密度下,空心莲子草的生物量、叶片数和侧芽数均出现负增长;在10头/株的密度下,草的生物量、株高、叶片数、侧芽数和茎节数均表现为负增长。2龄幼虫优先取食顶芽嫩叶,也取食老叶与茎杆,在每株10头2龄幼虫的密度下,接虫7d后,40%的植株死亡。3龄幼虫取食叶片与茎秆,后期钻入茎秆中化蛹,在10头/株密度下,7d后,已引起52%的植株死亡,存活株的茎节数显著减少。成虫可24h连续取食植株的任何组织,0.2头/株的密度下,空心莲子草叶片与侧芽数量已呈现负增长;5头/株的密度下,空心莲子草的生物量、株高、叶片数、侧芽数与茎节数均呈现较大的负增长;10头/株的控草效果更加显著。

英文摘要：

To understand if the feeding behavior and capacity of Agasicles hygrophila changed after the insect has been introduced to China for more than 20 years,the controlling effects of all stages（larvae and adults） at different infestation densities on alligator weed,Alternanthera philoxeroides,were quantitatively detected in the laboratory,and in the detection tests the experimental larvae and adults were obtained from adults collected in fields and reared with A.philoxeroides.The results showed that the 1st instar larvae of A.hygrophila preferred to feed the top buds and tender leaves.A.philoxeroides plants still produced new leaves and axillary buds,and its biomass,plant height and number of stem nodes increased at the infestation densities of both 0.2 and 1 1st instar larvae of A.hygrophila per plant.The biomass,numbers of leaves and axillary buds exhibited negative growth at the infestation density of 5 1st instar larvae of A.hygrophila per plant.All measured parameters including biomass,plant height,and the numbers of leaves,stem nodes and axillary buds exhibited negative growth at the infestation densities of 10 1st instar larvae of A.hygrophila per plant.The 2nd instar larvae of A.hygrophila preferred to feed on the top bud and tender leaves and also fed on tough foliages and stems.Forty percent of experimental A.philoxeroides plants died at 7 d after infestation at the density of 10 2nd instar larvae of A.hygrophila per plant.The 3rd instar larvae fed both leaves and stems,and then pupated in the stems at the later stage.Fifty-two percent of experimental A.philoxeroides plants died at 7 d after infestation at the density of 10 3rd instar larvae per plant,and the number of stem nodes of surviving plants markedly decreased.The adults could continuously eat any tissues of the weed for 24 h.At the infestation density of 0.2 adults per plant,the numbers of leaves and axillary buds of the experimental plants revealed negative growth.At the infestation density of 5 adults per plant,the biomass,plant height,and th