氰戊菊酯和锐劲特对原生动物群落的联合毒性试验研究

氰戊菊酯和锐劲特两种农药被广泛用于茶树、果树、水稻、蔬菜等的病虫害防治,它们同时出现在同一环境中的机会非常多,但有关两种农药对生态系统的复合毒性效应却未见有研究报道.与单种生物毒性试验相比,群落级生物毒性试验对毒物胁迫的反映更具环境真实性.以PFU在天然淡水中采集到的原生动物群落为靶生物,研究了氰戊菊酯和锐劲特2种农药对淡水原生动物群落的毒性效应,对于水生生态环境的保护有特殊的意义.研究结果表明,2种农药单独存在时对原生动物群落的48h半数致死浓度分别为15 93mg·L-1和35 83mg·L-1;2种物质以等毒性比(单一LC50的比值)混和,进行联合毒性试验研究,用Marking相加指数法进行评价,其AI值为0 9,表现为协同作用.氰戊菊酯和锐劲特进入水环境后,将使水环境中原生动物群落的结构和组成发生变化,原生动物种类数减少,群落结构变得简单.在所有种类中,纤毛虫受损最大,水生生态系统的物质循环和能量流动将会受到一定程度的影响.

Study on the joint toxicity experiment of fenvalerate and fipronil to protozoan community

Fenvalerate and fipronil are two pesticides that are widely used in Preventing the tea, fruit, rice and vegetable from the damage of the pest. The widespread use of these pesticides consequently leads to increasing chance of concurrence. Thus, it is very important to study the joint toxicity of these two pesticides. Compared with the species toxicity tests, the toxicity tests at the community level stimulate the natural environment more really, and protozoa community collected by the PFU(Polyurethane Foam Unit)plays an important role in aquatic ecosystem. So the study about the effects of fenvalerate and fipronil on freshwater protozoan community had special significance. Experimental results showed that the 48h-LC₅₀ of the single pesticide of fenvalerate and fipronil were 15.93mg·L^-1 and 35.83mg·L^-1 respectively. If two pesticides were mixed at the ratio of equal toxicity (the ratio of concentration is1:2.25), the Marking Additive Index was evaluated as 0.9, which meant that the joint toxicity of both pesticides on freshwater protozoan community appeared as synergism. With the addition of the pesticides into the aquatic environment, the structure and component of the protozoan communities were changed, and the abundance of the protozoan species reduced and the structure of the community became simple. All functional groups were affected to different extent. Bactivoresdetrivorse(B) was still in existence at high concentration as tolerant group,while Saprotrophs(S) and Photosynthetic autotrophs(P)were so sensitive that nearly disappeared. Among the entire protozoan community, the ciliate was damaged most seriously, and the damage on the ciliate protozoan mightbe affect the energy flow and the material cycle of ecosystem.