A popular sandwich filler has been shown to be an effective defense mechanism against the world’s deadliest animal: mosquitoes.
This discovery paves the way for natural insecticides to control mosquito populations without using synthetic chemicals.
The sandwich filling in question is garden cress, a small leafy plant in the mustard family that is usually paired with egg mayonnaise and two slices of bread. In a recent study, published in the journal Nature Science Reportsscientists from the Illinois Agricultural Research Service have demonstrated how the seed meal of this plant and others in the mustard family can be used to kill mosquito larvae.
Mosquitoes kill more people than any other animal in the world by spreading diseases like malaria, dengue fever, West Nile virus, yellow fever, Zika and chikungunya, to name a few. Controlling mosquito populations is therefore essential for public health.
However, many of today’s insecticidal solutions use strong synthetic chemicals. These can seep into the surrounding environment and affect other non-target insects and animals. Mosquitoes can also develop resistance to these compounds after prolonged use, rendering the insecticide ineffective.
The researchers then turned to biological solutions, in particular those made by plants. The study authors say that plant-based insecticides are generally safe for the environment because they are biodegradable and low in toxicity to non-target organisms. Plants also produce a diverse range of different compounds to target different aspects of the mosquito life cycle and biology.
During their larval stage, mosquitoes are largely confined to concentrated areas of standing water where they feed on bits of organic matter and microbes present on the surface of the water. This makes them an easier target than mature adults who constantly move through the air over long distances.
When the seeds of plants in the mustard family are soaked in water, they release a special group of plant defense chemicals called isothiocyanates. These products have already been shown to kill harmful insects and parasites present in the soil.
To investigate whether these plants showed similar promise against mosquitoes, the research team, led by Lina Flor-Weiler of the United States Department of Agriculture (USDA) Agricultural Research Unit, prepared seed flour from four different mustard plants: brown mustard, garden cress, garden mustard. watercress and white mustard. The researchers then added each of these elements to small beakers filled with water containing larvae of Aedes aegypti the mosquito, a species that can transmit dengue fever, yellow fever and Zika.
Of all the plants tested, garden cress was found to be the deadliest, killing 100 percent of mosquito larvae within 48 hours.
Further research is needed to determine whether combinations of different plants might enhance the effect of these insecticides. However, the researchers say this study is an exciting demonstration of the potential of mustard seed cakes in controlling plant-based mosquito populations.
USA News Gb2