What do mosquitoes and vampires have in common? Leaving aside their blood-sucking tendencies, the pair share a strong aversion to garlic.
Researchers tested insects’ response to a selection of different fruit and vegetables, and discovered that the pungent allium may prevent mosquitoes (and various other winged insects) from mating. By blocking the mating process, the team hopes garlic can offer an eco-friendly and affordable form of pest control.
“The notion of using garlic to deter blood-feeding creatures was proposed in 1897 by Bram Stoker in his novel [Dracula],” John Carlson, professor of Molecular, Cellular, and Developmental Biology at Yale University, said in a statement. “Maybe he was onto something.”
The paper has been published in the journal Cell.
How Garlic Stops the Mating Process
The researchers did not set out to find birth control. Rather, the opposite. Shimaa Ebrahim, an associate research scientist at Yale, wanted to find out if fruits or vegetables functioned as an aphrodisiac for fruit flies (Drosophila melanogaster).
To do so, Ebrahim laid out a “fruit fly buffet,” said Carlson. Purées from 43 types of fruits and vegetables were placed in individual Petri dishes along with a female and male fly, who were monitored for an hour.
While the researchers couldn’t identify an aphrodisiac, they did notice something odd. In the petri dish that contained the garlic purée, mating was “completely abolished”. The same effects were observed when the experiment was re-run with other species of fruit fly — six out of seven showed a sharp drop in mating behavior when exposed to garlic.
Additional observations revealed that the presence of the vegetable did not just prevent the flies from mating. It stopped females from laying eggs.
To find out if smell or taste was responsible for the aversion, the researchers placed flies in one of two setups. In the first, flies could smell the garlic but were unable to touch or taste the vegetable thanks to the addition of a mesh barrier. In the second, flies could both smell and taste the garlic.
The results suggest taste is the key factor. Around 80 percent of flies mated when they were unable to taste the garlic. In stark contrast, none of the flies mated when they could.
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Finding the Compound and Receptor Responsible
To dig a little deeper and find out what specific compound or compounds were responsible for the insects’ repulsion, the researchers separated the chemical compounds within the garlic purée. The answer was diallyl disulfide, a chemical compound responsible for garlic’s distinctive odor.
The findings suggest diallyl disulfide triggers a sensory receptor called TrpA1, found in the insect’s taste organs, and deters both mating and egg-laying behaviors. While other receptors appeared to be associated with reduced mating activity, TrpA1 alone was associated with egg-laying inhibition. By investigating mating behavior in mutant flies, the researchers discovered the effect appeared to impact female flies more.
An Eco-Friendly Pest Control
Fruit flies are not the only flying insect that has this receptor. Garlic also appears to be repulsive to tsetse flies and Aedes vector mosquitoes — two insects responsible for spreading disease to people and animals. This suggests the plant could be used as a deterrent and a natural form of pest control that is inexpensive, safe, and easily accessible, according to researchers.
Saying this, garlic’s potential as an insect deterrent might not come as a complete surprise. It’s already found in many commercial garden products.
“You can already buy some products that have garlic in them, consistent with our findings that insects don’t like garlic. But what we’ve discovered is the ‘why,’” said Carlson. “And now that we know how to look easily for natural compounds that act as insect deterrents, the door has been opened to all kinds of possibilities.”
While TrpA1 and diallyl disulfide appear to play a key role in the mating activity of fruit flies and mosquitoes, the study’s authors note there may be additional receptors and compounds that also influence the insects’ behavior.
This article is not offering medical advice and should be used for informational purposes only.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references a study published in Cell: A phytoscreen identifies a garlic compound as a deterrent of mating and egg laying in Drosophila and mosquitoes
