Inhibitory Effects of Bidens pilosa Plant Extracts on the Growth of the Bloom-Forming Alga Microcystis aeruginosa

Algal blooms are one of the greatest aquatic environmental concerns, and the control of algal blooms has become a great challenge in recent years. In this study, we evaluated the effects of Bidens pilosa plant extracts in comparison to those of several widespread plants, including rice ( Oryza sativa ), Pistia stratiotes , Eichhornia crassipes , and Pteris vittata , on the growth of the bloom-forming blue-green alga Microcystis aeruginosa . Both ethanolic and methanolic extracts of B. pilosa , in contrast to the other plant extracts, exhibited high inhibitory effects on M. aeruginosa growth at a concentration of 500 mg/L (dry weight equivalent, DWE). The inhibition efficiency in terms of the cell density and chlorophyll a concentration significantly reached 84–88% ( p