利用18S rDNA分析冬水田蜘蛛对弹尾虫的捕食作用

为明确冬水田蜘蛛对弹尾虫的捕食作用,在分析弹尾纲18S r DNA通用引物特异性的基础上,利用18S r DNA标记法检测了冬水田中蜘蛛取食弹尾虫后其体内猎物的残留情况,并分析了拟水狼蛛Pirata subpiraticus取食单头纵纹刺齿?Homidia socia后的阳性检出率与消化时间的关系。结果表明,弹尾纲18S r DNA通用引物Col4F/Col5R可作为冬水田蜘蛛捕食弹尾虫后检测该猎物的有效特异性引物;蜘蛛目6科11种蜘蛛均捕食弹尾虫,阳性检出率均大于69.0%,其中丰富度最高的几个优势种食虫沟瘤蛛Ummeliata insecticeps、草间小黑蛛Erigonidium graminicolum、纵条蝇狮Marpissa magister、棕管巢蛛Clubiona japonicola和拟水狼蛛的阳性检出率依次是81.8%、75.0%、71.4%、70.0%和69.1%。试验条件下,拟水狼蛛取食纵纹刺齿?后的阳性检出率随消化时间的延长而下降,该下降曲线可用指数方程拟合,并计算得到该蜘蛛体内弹尾虫DNA检测成功率50%时的消化时间DS50为19.3 h;根据拟合曲线,阳性检出率在0~40 h下降最快,之后减缓,64 h为最长的阳性检出率时间。研究表明弹尾虫是冬水田蜘蛛的重要捕食猎物。

Analysis of predation of the spiders on collembolans using the gene of 18S rDNA in fallow waterlogged paddy fields in Chongqing

To study the predation of spiders on collembolans in fallow waterlogged paddy fields (FWPF) during postharvest seasons in Chongqing, China, the gene of 18S rDNA was used to identify the collembolans consumed by the spiders. The universal primers of Collembola Col4F/Col5R of 18S rDNA was used to detect the remains of collembolans in the gut of spiders collected in FWPF and reared in the laboratory. The specificity tests performed with the universal primers showed that the band existed only in two species of Collembola, i.e., Homidia tiantaiensis and H. socia. The detection indicated that the field-collected spiders from 11 species of six families in Araneae consumed collembolans, and all of the percentages of positive responses of collembolan DNA in these predators were over 69.0%. The detection rates of collembolans in five dominant species Ummeliata insecticeps, Erigonidium graminicolum, Marpissa magister, Clubiona japonicola and Pirata subpiraticus were 81.8%, 75.0%, 71.4%, 70.0% and 69.1%, respectively. Under experimental conditions, the percentage of positive responses in P. subpiraticus feeding single collembolan of H. socia declined as digestion time extended, and such declining patterns could be described by exponential equation, with prey DNA detectability success over time (DS₅₀) as 19.3 h.According to the fitted curves, there was a rapid decline during 0-40 h.Thereafter, the decline slowed down, and no H. socia DNA could be detected at 64 h after digestion. The results indicated that Collembola were an important prey group for ground spiders in FWPF.