在九段沙不同沙体和不同等级潮沟梯度下的5种主要植物群落中,在科和目层次上开展了昆虫多样性及其影响因素研究.调查区域共采集昆虫35444头,隶属于13目64科,按所含种数多少,主要的科有杆蝇科(42)、姬小蜂科(29)、金小蜂科(24)、茧蜂科(22)、姬蜂科(15)和缘腹细蜂科(12);主要的目有膜翅目(137)、双翅目(85)、鞘翅目(32)和半翅目(10).分析表明:(1)夏季昆虫的物种种数明显高于其他3个季节;(2)在上沙芦苇群落(夏季),低潮滩的昆虫个体数最多,其次是高潮滩,中潮滩的最小.低潮滩中杆长蝽科、秆蝇科、瓢虫科和蚁形甲科的个体数极明显地多于中潮滩和高潮滩;随着由低潮滩向高潮滩高程的变化,杆长蝽科和飞虱科的昆虫个体数由少变多趋势明显.中潮滩与低潮滩相比,与高潮滩的昆虫组成更相似;(3)在中沙(夏季),与芦苇群落相比,互花米草群落中昆虫个体数多,出现科数也多,互花米草群落中主要是啮虫目的种类和杆蝇科,两者占了互花米草群落昆虫总个体数的86.83％,而在芦苇群落中,以杆蝇科、蚁形甲科、瓢虫科3科为主,占芦苇群落昆虫总个体数的79％;在江亚南沙,藨草(海三棱藨草)群落中的昆虫主要是管蓟马科、叶蝉科、杆蝇科、茧蜂科和摇蚊科等5个科的昆虫,个体总数占了该类群落昆虫总个体数的96.82％,而菰群落中同样的5个科的昆虫个体数仅占菰群落昆虫总个体数的31.53％;(4)多样性指数以中生化群落最高,其次为芦苇和互花米草群落,最小为菰群落,物种丰富度则芦苇群落最高,其次为互花米草和中生化,最小为菰群落;(5)排序分析表明,植物群落中昆虫科的组成相似性反映了植物群落的演替方向,即菰群落、藨草/海三棱藨草群落的昆虫组成较相似,其次是互花米草与芦苇群落的,与中生化群落类型中的差异最大.%Investigations were made on insect diversity on order and family levels in five dominant plant communities on four shoals and different gradient tidal creeks in Jiuduansha Nature Reserve. A total of 35444 specimens were collected, belonging to 64 families and 13 orders. According to species number, the dominant families ranked as Chloropidae (42) ,Eulophidae (29) , Pteromalidae (24) ,Braconidae (22) , Ichneumonidae (15) ,Scelionidae (12) ,and the dominant orders as Hymenoptera (137) , Diptera (85) .Coleoptera (32) ,Hemiptera (10). Our analyses showed: (1) The insect species richness in summer was higher than those in other three seasons; (2) In Phragmites australis community on low tidal flat in summer,the species richness of insects was the highest,that on high tidal flat ranked the second,then that on middle tidal flat. On the low tidal flat,the individual number of Blissidae, Chloropidae, Coccinellidae and Anthicidae was much higher than those on the middle and high tidal flats. The individual number of Blissidae and Delphacidae increased from Lower to High tidal flat. Compared with that on the low tidal flat, the insect composition on the middle tidal flat was closer to that on the high tidal flat. (3) The family and individual numbers of insects in Spartina alterniflora community were higher than those in Phragmite australis community on Middle shoal in summer. Psocoptera and Chloropidae were two dominant families in Spartina altemiflora community, their individuals accounting for 86. 83% of the total. While in Phragmite australis community, Chloropidae, Anthicidae and Coccinellidae were three dominant families , their individuals accounting for 79% of the total. In the Scirpus mariqueter-S. Triqueter community on Jiangyanansha, the dominant insect families were Phlaeothripidae,Cicadellidae,Chloropidae,Chironomidae and Braconidae,their individual accounting for 96.82% of the total,those in Zizania latifolia community only accounting for 31. 52% of the total. (4) The shannon-weiner biodiversity index of the insects in mesophytic communities was highest, following those in Phragmite australis community and Spartina altemiflora community, and lowest in Zizania latifolia community, the highest species richness was seen in Phragmite australis community,following those in Spartina altemiflora community and mesophytic communities,lowest in Zizania latifolia community ; (5) According to PC-ORD analysis, the family similarity of the insects in the five plant communities revealed the gradual changes from Zizania latiflora community and S. Mariqueter-S. Triqueter community, to Spartina alterniflora community and Phrag-
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