The coitus of tsetse flies better understood, a possible key to combating them

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The cost of tsetse flies better understood, possible key to combating them

Close up of a tsetse fly (File photo)

For the first time, scientists have identified a type of sex pheromones that play a role in the reproduction of the tsetse fly, a discovery that could help combat this insect vector of devastating diseases in sub-Saharan Africa.

This could be used in more effective traps to capture tsetse flies, John Carlson, co-author of the study revealing these results, told AFP. Science. Tests are already planned in Kenya, added the professor of biology at Yale University.

The tsetse fly, which does not x27;is present only in sub-Saharan Africa, transmits trypanosomiasis, a disease affecting both humans (human African trypanosomiasis, better known as sleeping sickness) and livestock (nagana).

It poses a threat to millions of people in dozens of countries and causes the death of approximately 3 million farm animals each year, representing a direct loss of up to $1.2 billion a year, according to an independent commentary article published simultaneously in Science. It is thus a major cause of rural poverty in this region.

A source of concern: the geographical area where it operates could also be #x27;extend due to climate change, notes the study.

A trypanosomiasis screening session in the village of Paanenefla, Côte d'Ivoire (File photo)< /p>

Despite more than a century of research on this animal, chemical communication between tsetse flies remains poorly understood, and scientists have never been able to identify volatile (remotely acting) pheromones in them. . However, pheromones are already used against other insects, such as certain moths.

Pheromones are a chemical substance emitted by an animal, having an effect on the behavior of its congeners. They allow insects to recognize each other in an environment where thousands of other species potentially evolve.

For their research, the scientists bathed tsetse flies for 24 hours in a solvent. The extracts were then applied to fly-shaped lures. Only the extracts of female flies attracted the males placed in the presence of the lures.

The researchers then used an analytical technique (combining chromatography and spectrometry) to isolate several chemical compounds. After multiple tests, they determined that one of them acted as an aphrodisiac and was detected by the males' antennae, activating their olfactory neurons.

Not only is it a bait, but it also has the effect of immobilizing the fly, it stops moving, explained John Carlson. A property that would help keep them out of traps.

Traps are already one of the techniques used to regulate the population of tsetse flies, but currently they use animal odors to attract them.

We we expect pheromones to improve the effectiveness of traps, said John Carlson. In addition, the identified chemical compound is less volatile than animal odors currently used, and therefore would remain in traps longer.

The type of pheromone identified in this However, this study should not be effective against all species of tsetse flies. The study focused on a species (Glossina morsitans) that is an important vector of the disease in livestock. But the tests were less conclusive on another species (Glossina fuscipes), associated with the highest number of cases of disease in humans, according to the researchers.

However, they hope that the technique developed will allow them to identify comparable pheromones that may work for this second species.

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