Duckweeds produce strong oviposition avoidance and high larval mortality in invasive Aedes mosquitoes

Abstract Background We examined how two invasive mosquito species, Asian tiger mosquitoes, Aedes albopictus , and Asian rock pool mosquitoes, A. japonicus , responded to the presence of duckweeds when ovipositing and how these plants affected Aedes larval survivorship found. Since duckweeds have been shown to increase egg-laying but kill mosquito larvae in some species, they could be used as a natural form of biocontrol. A total of four experiments were conducted in 2019 and 2022 that quantified the number of Aedes eggs laid and the percent survival of their larvae in sites with and without the duckweeds Spirodela polyrhiza and Wolffia arrhizal . Results Females of both species laid significantly fewer eggs in sites with duckweeds, and these plants significantly increased larval mortality. In A. japonicus , larval survivorship was 0% with duckweeds. Conclusions Unfortunately, our results suggest that biological control of Aedes mosquitoes using duckweeds appears less promising given the ability of females to detect and avoid these plants.