Entente Interdépartementale de Démoustication du Littoral Méditerranéen, 165 avenue Paul-Rimbaud, F-34184 Montpellier, France.
Ecotoxicol Environ Saf. 2011 May;74(4):800-10. doi: 10.1016/j.ecoenv.2010.11.001. Epub 2011 Apr 15.
Chitobiase is involved in exoskeleton degradation and recycling during the moulting process in arthropods. In aquatic species, the moulting fluid is released into the aqueous environment, and chitobiase activity present therein can be used to follow the dynamics of arthropod populations. Here, chitobiase activity was used for monitoring the impact of mosquito candidate larvicides on Daphnia pulex and Daphnia magna under laboratory conditions. Both species were exposed to spinosad (2, 4, 8 μg L(-1)) and diflubenzuron (0.2, 0.4, 0.8 μg L(-1)) for 14 days. Bacillus thuringiensis var. israelensis (Bti; 0.25, 0.5, 1 μL L(-1)) was used as the reference larvicide. Chitobiase activity, adult survival, individual growth and fecundity, expressed as the number of neonates produced, were measured every 2 days. Average Exposure Concentrations of spinosad were ten-fold lower than the nominal concentrations, whereas only a slight deviation was observed for diflubenzuron. In contrast to Bti, spinosad and diflubenzuron significantly affected both species in terms of adult survival, and production of neonates. As compared to D. pulex, D. magna was more severely affected by diflubenzuron, at low and medium concentrations, with reduced adult growth and much lower chitobiase activity. Chitobiase activity was positively correlated with the individual body length, number of neonates produced between two consecutive observation dates, and number of females and neonates. In addition, the significant positive correlations between chitobiase activity measured on the last sampling date before the first emission of neonates and the cumulative number of neonates produced during the whole observation period strongly support the potential of the activity of this chitinolytic enzyme as a proxy for assessing the dynamics of arthropod populations exposed to larvicides used for mosquito control.
几丁质酶参与节肢动物蜕皮过程中外骨骼的降解和再循环。在水生物种中，蜕皮液被释放到水环境中，其中存在的几丁质酶活性可用于跟踪节肢动物种群的动态。在这里，几丁质酶活性被用于监测候选杀蚊幼虫剂对实验室条件下大型蚤和大型溞的影响。两种物种均暴露于多杀菌素（2、4、8μg/L）和除虫脲（0.2、0.4、0.8μg/L）中 14 天。苏云金芽孢杆菌以色列变种（Bti；0.25、0.5、1μL/L）被用作参考杀幼虫剂。每隔 2 天测量一次几丁质酶活性、成虫存活率、个体生长和繁殖力，以产生的幼体数量表示。多杀菌素的平均暴露浓度是标称浓度的十倍，而除虫脲则略有偏差。与 Bti 不同，多杀菌素和除虫脲对两种物种的成虫存活率和幼体产量均有显著影响。与大型蚤相比，低浓度和中浓度的除虫脲对大型溞的影响更为严重，其成虫生长和几丁质酶活性降低。几丁质酶活性与个体体长、两次连续观察日期之间产生的幼体数量以及雌性和幼体数量呈正相关。此外，在第一次释放幼体之前的最后一次采样日期测量的几丁质酶活性与整个观察期间产生的幼体总数之间存在显著的正相关关系，这有力地支持了这种几丁质酶活性作为评估暴露于用于控制蚊子的杀幼虫剂的节肢动物种群动态的替代指标的潜力。
