Kreutzweiser David P, Back Richard C, Sutton Trent M, Thompson Dean G, Scarr Taylor A
Canadian Forest Service, Great Lakes Forestry Centre, Sault Sainte Marie, Ont., Canada.
Aquat Toxicol. 2002 Mar;56(4):257-73. doi: 10.1016/s0166-445x(01)00216-8.
A natural, plant-derived insecticide, neem, is being evaluated as an alternative insect pest control product for forestry in Canada. As part of the process to investigate the environmental safety of neem-based insecticides, a mesocosm experiment was conducted to assess the effects of neem on natural zooplankton communities. Replicate (n=5), shallow (<1 m) forest pond enclosures were treated with Neemix 4.5, at concentrations of 0.035 (the expected environmental concentration), 0.18, 0.70, and 1.75 mg/l active ingredient, azadirachtin. Zooplankton communities were quantitatively sampled over a 4-month experimental period in treated and control enclosures, and water samples were collected to track azadirachtin concentrations. Concentrations in water declined linearly with estimated DT(50) values of 25-29 days. Trends in abundance over time among populations of cladocerans, copepods, and rotifers were found to differ significantly among treatments. At the two highest test concentrations, adverse effects were obvious with significant reductions in several cladoceran species, and near elimination of the three major copepod species present. More subtle effects at the two lowest test concentrations were determined by comparing the community structure of enclosures across treatment levels and over time through an analytical process based on the multivariate statistical software, PRIMER. Significant effects on community structure were detected at both of these lower concentrations, including the expected environmental concentration of 0.035 mg/l azadirachtin. Differential responses among species (some increases, some decreases) caused detectable disruptions in community structure among zooplankton of treated enclosures. Perturbations to zooplankton communities were sufficient to cause measurable differences in system-level metabolism (midday dissolved oxygen concentrations) at all but the lowest test concentration.
一种天然的、源自植物的杀虫剂——印楝，正在加拿大被评估为一种用于林业的替代害虫防治产品。作为调查印楝基杀虫剂环境安全性过程的一部分，进行了一项中宇宙实验，以评估印楝对天然浮游动物群落的影响。使用Neemix 4.5对重复的（n = 5）、浅（<1米）的森林池塘围隔进行处理，活性成分印楝素的浓度分别为0.035（预期环境浓度）、0.18、0.70和1.75毫克/升。在4个月的实验期内，对处理过的和对照围隔中的浮游动物群落进行定量采样，并采集水样以追踪印楝素浓度。水中的浓度呈线性下降，估计的DT(50)值为25 - 29天。发现不同处理之间，枝角类、桡足类和轮虫种群数量随时间的变化趋势存在显著差异。在两个最高测试浓度下，出现了明显的不利影响，几种枝角类物种数量显著减少，三种主要桡足类物种近乎灭绝。通过基于多变量统计软件PRIMER的分析过程，比较不同处理水平和不同时间围隔的群落结构，确定了两个最低测试浓度下更细微的影响。在这两个较低浓度下，包括预期环境浓度0.035毫克/升印楝素，均检测到对群落结构有显著影响。物种之间的不同反应（一些增加，一些减少）导致处理过的围隔中浮游动物群落结构出现可检测到的破坏。除了最低测试浓度外，对浮游动物群落的扰动足以导致系统水平代谢（中午溶解氧浓度）出现可测量的差异。
