Department of Biological Sciences, University of Rhode Island, Woodward Hall, 9 East Alumni Ave, Kingston, USA.
U.S. Geological Survey Patuxent Wildlife Coastal Field Station, Kingston, USA.
Parasit Vectors. 2020 Apr 21;13(1):208. doi: 10.1186/s13071-020-04084-4.
Biological controls with predators of larval mosquito vectors have historically focused almost exclusively on insectivorous animals, with few studies examining predatory plants as potential larvacidal agents. In this study, we experimentally evaluate a generalist plant predator of North America, Utricularia macrorhiza, the common bladderwort, and evaluate its larvacidal efficiency for the mosquito vectors Aedes aegypti and Aedes albopictus in no-choice, laboratory experiments. We sought to determine first, whether U. macrorhiza is a competent predator of container-breeding mosquitoes, and secondly, its predation efficiency for early and late instar larvae of each mosquito species.
Newly hatched, first-instar Ae. albopictus and Ae. aegypti larvae were separately exposed in cohorts of 10 to field-collected U. macrorhiza cuttings. Data on development time and larval survival were collected on a daily basis to ascertain the effectiveness of U. macrorhiza as a larval predator. Survival models were used to assess differences in larval survival between cohorts that were exposed to U. macrorhiza and those that were not. A permutation analysis was used to investigate whether storing U. macrorhiza in laboratory conditions for extended periods of time (1 month vs 6 months) affected its predation efficiency.
Our results indicated a 100% and 95% reduction of survival of Ae. aegypti and Ae. albopictus larvae, respectively, in the presence of U. macrorhiza relative to controls within five days, with peak larvacidal efficiency in plant cuttings from ponds collected in August. Utricularia macrorhiza cuttings, which were prey-deprived, and maintained in laboratory conditions for 6 months were more effective larval predators than cuttings, which were maintained prey-free for 1 month.
Due to the combination of high predation efficiency and the unique biological feature of facultative predation, we suggest that U. macrorhiza warrants further development as a method for larval mosquito control.
以幼虫蚊媒的捕食者为生物控制手段，历史上几乎完全集中在食虫动物上，很少有研究检查作为潜在幼虫杀伤剂的食虫植物。在这项研究中，我们实验评估了北美广食性植物捕食者，Utricularia macrorhiza，普通的囊泡草，并在无选择的实验室实验中评估其对蚊子媒介 Aedes aegypti 和 Aedes albopictus 的幼虫杀伤效率。我们首先试图确定 U. macrorhiza 是否是容器繁殖蚊子的有能力捕食者，其次，它对每种蚊子的早期和晚期幼虫的捕食效率。
新孵化的第一龄 Aedes albopictus 和 Aedes aegypti 幼虫分别暴露于 10 个在野外收集的 U. macrorhiza 扦插中。每天收集发育时间和幼虫存活率的数据，以确定 U. macrorhiza 作为幼虫捕食者的有效性。使用生存模型评估暴露于 U. macrorhiza 的群体和未暴露于 U. macrorhiza 的群体之间幼虫存活率的差异。通过随机排列分析来研究在实验室条件下长时间（1 个月与 6 个月）储存 U. macrorhiza 是否会影响其捕食效率。
我们的结果表明，与对照相比，在存在 U. macrorhiza 的情况下，Aedes aegypti 和 Aedes albopictus 幼虫的存活率分别降低了 100%和 95%，在 8 月收集的池塘植物扦插中达到峰值幼虫杀伤效率。与维持 1 个月的无猎物的 U. macrorhiza 扦插相比，在实验室条件下饲养 6 个月的 U. macrorhiza 扦插是更有效的幼虫捕食者。
由于高捕食效率和兼性捕食的独特生物学特征的结合，我们建议进一步开发 U. macrorhiza 作为控制幼虫蚊子的方法。
