Integration of ABC curve, three dimensions of alpha diversity indices, and spatial patterns of fish assemblages into the health assessment of the Chishui River basin, China.

Index of biotic integrity (IBI) based on fish has been applied globally. However, few have considered that fish assemblages change among different aggregate ecoregions when conducted their health assessment. Indeed, some comprehensive indices, such as functional and phylogenetic diversity indices and ABC curve, can be used to identify aspects that are not captured by traditional metrics. Consequently, we try to integrate comprehensive indices and spatial patterns of fish assemblages to develop IBI systems and then verified their effectiveness and accuracy for assessing the environmental health of the Chishui River basin. The comprehensive disturbance index (CDI), based on 11 water quality parameters and 4 human land use, was set to distinguish reference sites and impaired sites. According to the spatial patterns of fish assemblages, the 40 sites were finally divided into 2 aggregate ecoregions, include wadeable streams and nonwadeable rivers. 97 candidate metrics were selected to develop our IBI systems based on the systematic screening method. The result also showed that our IBI systems performed well in discriminating anthropogenic disturbances at both aggregate ecoregions, which suggests that our systems could provide a reliable evaluation. The mean IBI score of the Chishui River basin was 72.09 ± 16.58, and was classified as good status. However, S1 (Chishuiyuan Town), Baisha River, Tongzi River, and Xishui River were disturbed by various human activities. We conclude that the spatial patterns of fish assemblages should be combined with more comprehensive indices to assess river health. On the other hand, we do believe that the process of developing and verifying our IBI systems could be regarded as a reference for biomonitoring in more mountain river systems.

Main predators of insect pests: screening and evaluation through comprehensive indices.

BACKGROUND: Predatory natural enemies play key functional roles in integrated pest management. However, the screening and evaluation of the main predators of insect pests has seldom been reported in the field. Here, we employed comprehensive indices for evaluating the predation of a common pest (Ectropis obliqua) by nine common spider species in Chinese tea plantations. RESULTS: We established the relative dominance of the spider species and their phenological overlap with the pest species, and analyzed DNA from the nine spider species using targeted real-time quantitative polymerase chain reaction to identify the residual DNA of E. obliqua. The predation rates and predation numbers per predator were estimated by the positive rates of target fragments and the residual minimum number of E. obliqua in predators' guts, respectively. The results showed that only four spider species preyed on E. obliqua, and the order of potential of the spiders to control E. obliqua from greatest to smallest was Neoscona mellotteei, Xysticus ephippiatus, Evarcha albaria and Coleosoma octomaculatum by the Z-score method. CONCLUSION: The orb-weaving spider N. mellotteei has the maximum potential as a biological control agent of E. obliqua in an integrated pest management strategy. An approach of screening and evaluating main predators of insect pests through comprehensive indices was preliminarily established. © 2017 Society of Chemical Industry.