There was garlic has been considered a natural mosquito repellent for centuries. In popular culture, its potent smell is believed to repel insects that, in addition to causing sleepless nights, transmit diseases such as dengue fever and malaria. Now this belief has a scientific explanation.
A group of scientists from Yale University conducted phytochemical analysis of 43 fruits and vegetables to identify natural compounds that could interfere with the reproductive behavior of flying pests. For this purpose, the team used fruit flies, a species often associated with food, as a model organism.
Based on this behavior, researchers hypothesized that some fruits and vegetables may contain substances capable of altering the reproductive processes of these insects. After exposing various samples to the purees involved in the experiment, they observed that none of the products had a significant aphrodisiac effect. However, they found that garlic completely blocked mating and egg laying.
After this initial discovery, scientists sought to determine the source of the effect and focused their attention on the effect of garlic on the flies’ sense of taste and smell. For this purpose, they conducted two experiments. In the first one, they placed garlic puree in such a way that the insects could only smell it; in the second they also let them try. The results showed that taste was a factor that actually inhibited reproductive behavior.
The team then performed a chemical analysis of the garlic to identify the compound responsible for this effect. They determined that the element causing the inhibition was diallyl disulfide. In practice, this substance acts on a sensory receptor located in the fly’s taste organs, known as TrpA1.
The TrpA1 receptor acts as a sensor that triggers an immediate rejection response when it detects a potentially harmful taste. According to the article published in the journal Cell, garlic specifically activates a group of bitter taste-sensitive neurons containing this receptor. This activation not only triggers the physical avoidance response, but also changes at the molecular level, modifying the expression of various genes.
Among the identified changes, a gene closely related to the feeling of satiety stands out, which suggests that contact with garlic compounds directly disrupts biological processes that regulate appetite and feeding in these insects. The authors posit that increased satiety appears to drive mating- and reproductive-limiting behavior, primarily in females.
A natural repellent for many species
In addition to fruit flies, the experiments were repeated on other flying insects, including two species of mosquitoes that transmit diseases such as yellow fever, dengue and Zika, as well as tsetse flies. In all cases, tests showed that garlic could act as an effective reproductive deterrent.
Scientists’ discoveries suggest that this plant, Allium sativum can be used as a tool to combat various insect pests harmful to both human health and agriculture.
“It is inexpensive and grown all over the world.” he said John Carlson, a Yale professor and co-author of the study. “The idea of using it to repel blood-forming creatures was proposed in 1897 by Bram Stoker in his novel DraculaAnd maybe he was right.”
This story originally appeared on WIRED in Spanish and was translated from Spanish.