Positive effects of biological control of Pistia stratiotes
Pistia stratiotes (Araceae: EPPO A2 List) is a free-floating perennial freshwater macrophyte native to South America. The species is invasive in many regions of the world including Africa, Asia, Central America and the Caribbean, North America, and Oceania. In the EPPO region, the species is established in thermally abnormal waters in Slovenia and Germany and is invasive in the south of France. Management of P. stratiotes, in the form of biological control has been implemented by several countries (e.g. Australia, South Africa, USA) using Neohydronomus affinis (Coleoptera: Curculionidae). Using large outdoor mesocosms, the effect of P. stratiotes invasion on benthic macroinvertebrate biodiversity and its recovery after the introduction of N. affinis was evaluated. Three treatments were set-up and replicated and included (1) with P. stratiotes, (2) with P. stratiotes and the biocontrol agent and (3) no P. stratiotes (control). Each treatment was measured for benthic macroinvertebrate biodiversity over a 36-week period. Mats of P. stratiotes altered the community composition and reduced the benthic macroinvertebrate diversity compared to the control. The biocontrol agent reduced the percentage cover of P. stratiotes which resulted in a significant increase in dissolved oxygen and the benthic macroinvertebrate community recovered to a level similar to the control.
Coetzee JA, Langa SDF, Motitsoe SN, Hill MP (2020) Biological control of water lettuce, Pistia stratiotes L., facilitates macroinvertebrate biodiversity recovery: a mesocosm study. Hydrobiologia. DOI: 10.1007/s10750-020-04369-w