Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, Oslo, Norway.
Department of Animal Biology, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
Ecotoxicology. 2023 Dec;32(10):1209-1220. doi: 10.1007/s10646-023-02715-x. Epub 2023 Nov 21.
Standard toxicity tests expose springtails (Collembola) through soil, while dietary exposure tests with animals visible on a surface are less commonly applied. We refined a method for dietary chemical exposure for two widely distributed and abundant Collembola species: Folsomia quadrioculata and Hypogastrura viatica as existing methods were sub-optimal. Newly hatched Collembola were offered bark with a natural layer of Cyanobacteria that was either moistened with a solution of the neonicotinoid insecticide imidacloprid using a micropipette or soaked in the solution overnight. The first method was superior in producing a measured concentration close to the nominal (0.21 and 0.13 mg/kg dry bark, respectively), and resulting in sub-lethal effects as expected. The adult body size was reduced by 8% for both species, but egg production only in H. viatica. Contrastingly, soaked bark resulted in a measured concentration of 8 mg/kg dry bark, causing high mortality and no egg production in either species. Next, we identified the sub-lethal concentration-range by moistening the bark to expose H. viatica to 0, 0.01, 0.04, 0.13, 0.43 and 1.2 mg imidacloprid/kg dry bark. Only the highest concentration affected survival, causing a mortality of 77%. Imidacloprid reduced moulting rate and the body size at first reproduction. The age at first reproduction appeared delayed as some replicates did not reproduce within the experiment duration. The method of moistened bark for dietary exposure proved optimal to continuously study life history traits, such as growth and reproductive outcomes, which are important to understand effects on key events crucial for population viability and growth.
标准毒性测试通过土壤暴露跳虫（弹尾目），而动物可见表面的饮食暴露测试则应用较少。我们改进了一种用于两种广泛分布且丰富的弹尾目物种（Folsomia quadrioculata 和 Hypogastrura viatica）饮食化学暴露的方法，因为现有的方法并不理想。用移液器将新孵化的跳虫提供的带有天然蓝藻层的树皮润湿，或者将树皮浸泡在溶液中过夜，提供含有自然蓝藻层的树皮，蓝藻层要么用新烟碱类杀虫剂吡虫啉的溶液润湿，要么浸泡在溶液中过夜。第一种方法在产生接近标称值（分别为 0.21 和 0.13mg/kg 干树皮）的测量浓度方面表现更优，并且产生预期的亚致死效应。两种物种的成虫体型均缩小 8%，但只有 H. viatica 的产卵量减少。相比之下，浸泡的树皮导致测量浓度为 8mg/kg 干树皮，导致两种物种均出现高死亡率和无产卵。接下来，我们通过润湿树皮使 H. viatica 暴露于 0、0.01、0.04、0.13、0.43 和 1.2mg/kg 干树皮的吡虫啉，来确定亚致死浓度范围。只有最高浓度会影响生存，导致死亡率为 77%。吡虫啉降低蜕皮率和第一次繁殖时的体型。首次繁殖的年龄似乎延迟了，因为一些重复在实验期间没有繁殖。湿润树皮的饮食暴露方法被证明是优化的，可以持续研究生活史特征，如生长和繁殖结果，这对于理解对种群生存和增长至关重要的关键事件的影响很重要。
