Using aquatic predators (including fish, amphibians or other insects) feeding on mosquito larvae as a form of biological control is not new. But now, mosquitoes may have a new enemy. And it is not an animal, but a plant. We are talking about the common bladderwort (Utricularia macrorhiza), a carnivorous plant of lakes and ponds of North America.
The bladderwort feeds on a variety of aquatic protozoa and small invertebrates. To do so, it uses its submerged bladder-like structures which have a pore surrounded by hairs. When an organism swimming by touches the hairs, it triggers a reaction causing the pore to open inward so that the prey is sucked inside the bladder and trapped. The unfortunate creature is then slowly digested by the plant enzymes.
A team of researchers tested whether the bladderwort could be used to control container-breeding mosquitoes such as Aedes aegypti and Aedes albopictus, the vectors of important arboviruses such as Dengue, yellow fever and Zika. The experiments confirmed that the plant can feed on mosquito larvae (up to the third instar), and that it can survive for a few months when introduced in artificial containers. More importantly, the survival of mosquito larvae in the presence of the plant was significantly reduced over time compared to those grown without it.
Mosquitoes breeding in man-made containers are notoriously difficult to control, also because these environments do not usually support animal predators. As pointed out by the researchers, the bladderwort could be introduced in these containers instead. Its flowers could also provide resources for bees and other pollinators, making it a environmentally friendly approach for integrated vector management (IVM).
In the future, the efficacy of bladderwort for controlling Aedes vectors and the scalability of this approach should be evaluated in carefully designed controlled trials. This carnivorous plant is nevertheless an interesting and promising addition to the list of potential novel vector control tools, which we desperately need.
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Couret J, Notarangelo M, Veera S, LeClaire-Conway N, Ginsberg HS, LeBrun RL. Biological control of Aedes mosquito larvae with carnivorous aquatic plant, Utricularia macrorhiza. Parasit Vectors. 2020;13(1):208. Published 2020 Apr 21. doi:10.1186/s13071-020-04084-4