With the rising tide of insecticide resistance in mosquitoes, or more commonly known as the deadliest creature on Earth, desperation for new methods of mosquito management often leads to innovation. However, sometimes innovation comes in more… carnivorous ways than we originally set out with.

Enter Utricularia aurea, or more commonly known as bladderwort. This plant is an aquatic species that captures and feeds on everything from nematodes, snails, tiny crustaceans, fish, tadpoles, and mosquitoes. The suction trap of this plant is the fastest known of all the carnivorous plants and can reach its prey up from up to 0.01 inches away. Once captured, the prey dies from lack of oxygen, and then is digested by the plant for nutritional purposes.

Utricularia aurea is a species of bladderwort that is found in India, Japan, and Australia, where several mosquito species of concern are also found. The purpose of this study was to evaluate the effectiveness of U. aurea as a potential mosquito management strategy both in the lab and the field using three different species of mosquitoes: Aedes aeygpti, or the Yellow Fever Mosquito, Anopheles stephensi, one of the Malaria mosquitoes, and Culex quinquefasciatus, or the Southern House Mosquito.

The researchers collected wild shoots of U. aurea and brought them into the lab. They then exposed mosquito larvae from their three chosen species to the plants and monitored their survival. This study also looked at the application of this plant out in the field, by using a scenario that’s common to India, and common breeding grounds of mosquitoes. When concrete slab is laid in India, it is a common practice to inundate it with water to prevent the slab from drying too quickly. These areas are known to be filled with “curing water” and are well-known as mosquito breeding grounds. These sites provided perfect field controls for studying how bladderwort would perform in the field as a mosquito management tool. The researchers specifically looked at Aedes aegypti and Anopheles stephensi, as they were respectively the largest and the smallest of the mosquito larvae tested, and they happened to be found at the curing water locations. The researchers added in the bladderwort in this curing water scenario, and then measured the populations of mosquito larvae and pupae over the course of sixteen days.

The researchers were able to successfully demonstrate that bladderwort can eat all three species of mosquito larvae. Unsurprisingly, the larger instars of each species had the highest survival probability compared to their younger and smaller compatriots. However, after just twelve hours in the lab, the bladderwort predated 95% of the first, second and third instars of all three mosquito species.

 

 

Out in the field, the researchers were able to demonstrate similar success. In the “curing water” scenario, the researchers showed that adding bladderwort to these mesocosms reduced immature mosquito populations of both A. aegypti and A. stephensi by 76% and 71% respectively over the course of just sixteen days.

 

This study is extremely promising for several reasons. First, bladderwort is a common plant that is found all over the world, so different species could be used in different locations. Previous studies have also shown that in man-made water storage containers, bladderwort was able to selectively target mosquito species, and leave other nontarget organisms. And lastly, bladderwort is also documented as being highly resistant to insecticides, herbicides, and pesticides, so it could be used in conjunction with chemical treatments. However, further research is needed on the ecological side of things. Not only does this include evaluating bladderwort’s potential for invasive spread, but it should also include a comparison of when the plants and the mosquitoes are the most active.

Article by Laura Rosenwald, BCE

References

Mohanty AK, Govekar A, de Souza C, Mohapatra A, Janarthanam MK, Vukanti R, Montemarano JJ, Balabaskaran Nina P. Evaluating the carnivorous efficacy of Utricularia aurea (Lamiales: Lentibulariaceae) on the larval stages of Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti (Diptera: Culicidae). J Med Entomol. 2024 May 13;61(3):719-725. doi: 10.1093/jme/tjae038. PMID: 38521610 

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