You Minsheng

PHYSIOLOGICAL STRESS REACTION OF CHINESE CABBAGE,BRASSICA CHINENSIS, INFESTED BY DIAMONDBACK, PLUTELLA XYLOSTELLA

Abstract The enzymatic activities of superoxidae dismutase (SOD), hydrogen peroxidae(CAT), peroxidase (POD), polyphenol oxidase (PPO), and the content of phenol in the leaves of Chinese cabbage, Brassica chinensis, changed rapidly after the cabbage leaves were infested by the larvae of diamondback moth (DBM), Plutella xyhstetta. Variations of the SOD, CAT, POD and PPO activities and the phenol content of damaged leaves within a day are generally different from that of undamaged normal leaves, which might result from the excessive stress caused by DBM infestation. The content of phenol and the activity of PPO are negatively correlated in the normal leaves, but the change is not the same as that in the damaged leaves. It is thus evident that the physiological disorder was caused by feeding activity of DBM in the cabbage plants, and the physiological stress response of the Chinese cabbage is prone systematically to the feeding of DBM. The defensive system of the Chinese cabbage could be destroyed by the infestation of DBM larvae, and there might be other defensive mechanisms in the cabbage resistant to the damage of DBM.

Effects of cover crops on mite communities in tea plantations: Effects of cover crops on mite communities in tea plantations

摘要: 螨类是茶园生态系统中重要且复杂的类群之一。为了了解不同植物间作后对茶园螨类群落的组成结构和多 样性的影响, 2006年3月至2008年4月, 在武夷山市星村镇大坪洲茶园通过间作百喜草(Paspalum notatum)或圆叶决 明(Cassia rotundifolia)、留养杂草和除杂草4种不同处理, 对茶园茶冠层(采用盆拍法及剪枝条法)和凋落层(采用捡 取凋落物法)的螨类进行系统采样、标本鉴定和统计分析。结果表明: 与留养杂草对照相比, 间作百喜草或圆叶决 明均显著增加了茶冠层和凋落层捕食螨的物种丰富度(S)、有效多样性指数(e)、个体数(N)和绝对丰度( n )。与留 养杂草和除杂草这两种对照相比, 间作百喜草或圆叶决明均显著增加了茶冠层和凋落层优势种圆果大赤螨 (Anystis baccarum)的个体数(N)。茶冠层植食螨和腐食螨及凋落层腐食螨的所有群落指标在不同处理茶园间均无显 著差异。茶冠层和凋落层螨类群落物种丰富度(S)和个体数(N)季节性变化明显, 物种组成相似性高。间作茶园和留

CHARACTERISTICS OF ARTHROPOD COMMUNITY AND THEIR DIVERSITY RESTORATION IN LEAFY VEGETABLE FIELDS

Abstract  The effect of chemical insecticides on the structure and diversity of arthropod communities in various vegetable fields and the restoration of their biodiversity after stopping application of chemical insecticides were studied. The results showed that the effect of chemical insecticides on the arthropods in vegetable fields could be characterized the species structure, the diversity index and the evenness of species distribution. Components of arthpod species depended closely on the species number of insect pests, predatory natural enemies and spiders. Investigations showed that the numbers of species in the vegetable fields managed with chemical insecticides were obviously reduced, and their diversity indices were lower comparing with that without chemical insecticides. When the applications of chemical insecticides were stopped in vegetable fields, the index of population trend (I) of dominant insect pests decreased greatly, the control effect of natural enemies on major insect pests increased, and the diversity index of arthropod increased at the same time. Thus, limiting the application of chemical insecticides, resuming the environment of vegetable fields destroyed by using chemical insecticides, escalating the control ability of natural enemies on main insect pests will play an important role in the ecological control of insect pests in vegetable fields.