Yellow Fever Mosquitoes are Inhibited by Plant Compounds

Researchers have revealed that particular plant compounds inhibit an enzyme involved in the formation of a key insect hormone in the yellow fever mosquito.

Certain natural compounds found in plants called flavonoids inhibit the development in mosquitoes that can spread yellow fever disease, according to a study published in BMC Biology.

When most people think of flavonoids, natural compounds found in plants and other organisms, their nutritional benefits probably come to mind first. But these compounds may have another health benefit.

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‘Among the flavonoids tested, desmethylglycitein (DMG) showed larvicidal activity against A. aegypti and indicated promise for DMG-based insecticides in the future.’

Mosquito-borne diseases are a major component of the worldwide burden of infectious diseases in humans. Aedes aegypti is from a group of mosquitoes that can spread many viruses that cause infectious diseases in humans, including dengue fever, yellow fever, and Zika.

In the wild, A. aegypti has begun to show resistance to insecticides, revealing a need for new types of pesticides for targeting this species.

“Flavonoids — a type of metabolic product from plants, fungi, and other organisms — can interfere with insect development and physiology, and can kill larvae of A. aegypti,” says senior author of the study, Prof. Ryusuke Niwa.

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Mosquito-borne diseases, like malaria, filaria, dengue, etc are common in places conducive of mosquito breeding. Swamps, ponds and stagnated drainage provide optimal breeding ground for mosquitoes.

To investigate how flavonoids can kill mosquito larvae, the researchers analyzed the activities of several flavonoids in A. aegypti, including daidzein, which has previously been identified as a larvicide for this species.

The team found that the flavonoids inhibit the activity of glutathione S-transferase Noppera-bo (Nobo); in A. aegypti, Nobo is an enzyme involved in the biosynthesis of the hormone ecdysone.

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Ecdysone is an insect steroid hormone, or ecdysteroid, required for the initiation of metamorphosis and regulation of molting.

Because ecdysteroids are key to the life cycle of insects, chemical inhibitors of enzymes involved in making these hormones, including Nobo, are thought to be insect growth regulators (IGRs) that disrupt development in insects without affecting other organisms.

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The high prevalence of resistance in mosquitoes to current insecticides in some areas urgently requires the development of new insecticides with different chemical structures and targeting pathways from those currently in use.

The results of this study offer a new avenue for developing new IGRs that are environmentally friendly and can be used for the control of mosquito populations by inhibiting the biosynthesis of ecdysteroids.

Source-Medindia