Effect of intercropped herbage in jujube plantation on the community dynamics of natural predators and pests

作者 SHI GuangLu; LIU SuQi; ZHAO LiLin; MIAO ZhenWang; CAO Hui; LI DengKe

期刊 Acta Ecologica Sinica , 2006,5:26

摘要 To understand the ecological impact of intercropped herbages in jujube plantation on natural enemies and pests, during March 10 to September 30 in 2004 a systematic survey was conducted under four treatments toward the jujube trees that were all in lO-years old and in full fruit production in a jujube plantation that is located 2.5 km west of Taigu （111°32＇E, 37°26＇N, 781.9 m elevation） in Shanxi Province, China. Among the four different treatments, three of them applied intercropped herbage treatment （Lotus comiculotus）, and one without herbage treatment. In each treatment, five trees chosen by the chessboard sampling method were used to monitor and record the population dynamics of natural predators and pests in every 10 days. Each treatment was performed in triplicate. The natural enemies and pests were distinguished based on their trophic relationships and taxonomy. Abundance and dominance of species, diversity indices of community, and breadth and overlap of two-dimensional temporal-spatial niches were used to analyze and compare the successions of natural enemies and pests in the four different treatments. Our result showed that the natural predators in the jujube plantations intercropped with herbage were significantly larger than those in the plantations without intercropped herbage （p 〈 0.05）. Also in the plantation with the herbage treatment, the natural predators under the integrated pest management were significantly larger than those under the conventional management （p 〈 0.05）. During the periods of the jujube development, the treatment with intercropped herbage has significantly weakened the pests＇ development in terms of its number of species, indices of diversity and evenness than its counterpart （p 〈 0.05）. On the contrary, larger dominant degree is found in the plantations without herbage treatment than those with intercropped herbage treatment （p 〈 0.05）. In addition, the ratio of numbers of natural enemies to pests was significantly larger in the plantations with intercropped herbage, and significantly larger under the integrated pest management than their respective counterparts （p 〈 0.05）. In different developing stages of the jujube trees, no significant differences were found between the pests＇ breadths of two- dimensional temporal-spatial niches. However, the average breadth of two-dimensional temporal-spatial niches of the natural predators was significantly larger in the plantations intercropped with herbage than in those without herbage （p 〈 0.05 ）. Similarly, the average overlap value of two-dimensional temporal-spatial niches between the natural enemies and pests were significantly larger in the plantations intercropped with herbage （p 〈 0.05） than in those without herbage （p 〈 0.05）. Loadings of the first two principal components of major natural enemies were significantly larger （ p 〈 0.05） at the plantations intercropped with herbage than those without herbage. On the contrary, loadings of the first two principal components of major insect pests were significantly larger （p 〈 0.05） at the plantations without herbage than those with herbage. Further statistical analysis revealed a close correlation of the dynamic changes between the natural enemies and pests in the investigated jujube plantation under different treatments. The results suggested that it was practicable to investigate the dynamic community of natural enemies and pests on the basis of their functional groups rather than species in different developing stages of jujube trees. In general, the increased population of natural predators in the jujube plantation treated with intercropped herbage has improved the stability and sustainability of controlling jujube pests.