Light quantity and quality strongly influence plant growth. Solar radiation is one of the main environmental factors driving vegetation carbon assimilation. As one of the natural climatic variables, clouds change the fraction of diffuse radiation arriving on the land surface and can influence carbon dioxide exchange between vegetation and the atmosphere. In this study, CO 2 flux was continuously measured during the vegetative growing season (June鄄August) from 2006 to 2008 by the eddy covariance systems in a mixed plantation in the Xiaolangdi area, Henan province. The clearness index (k t) was used to describe the effects of cloudiness on solar radiation. Clear mornings and afternoons were identified based on the change of k t with solar elevation (茁) at a half鄄day scale. The impacts of cloudiness on the net ecosystem exchange of carbon dioxide (NEE) were investigated to reveal the mechanism of changes in coordinate of solar radiation and other

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Spiders are among the most abundant predators of insects and other invertebrates in agro鄄 and forest ecosystems, playing an important ecological role by regulating invertebrate populations. Biological control using spiders may represent a sustainable method of controlling agricultural pest species and reducing the amount of pest damage on crops. However, pesticide application on agricultural crops may directly or indirectly impact spider foraging in the crop. In particular, pesticides may have mutagenic effects on spiders, negatively affecting the spider population abundance and transferring these effects to the next generation. Recent studies have reported that low鄄dose pesticides kill pests, but promote the predation of natural enemies. Therefore, revealing the mechanism behind low鄄dose pesticides on natural enemies is critical to improving predator ability, exploring the potential control of insect predators and coordinating bio鄄 and chemical control.Our aim was to investigate the effect of low鄄dose pesticides on spider predation behavior and reveal the underlying mechanisms. Pardosa astrigera was treated with a low鄄dose of imidacloprid using the drug鄄film method. We determined the sensitivity of P. astrigera, the predation effect of P. astrigera on B. brassicae and the activity of acetylcholinesterase ( AChE) , glutathione S鄄transferase ( GSTs) , superoxide dismutase ( SOD) , catalase ( CAT) and midgut proteinase. The