New Use For Cashew Nut Byproduct Could Help Trap Tsetse Fly

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Written by Dana Sanchez

A new chemical method applied to a byproduct of cashew nuts could make it easier to lure tsetse flies to traps and create new revenue for nut producers in sub-Saharan Africa, according to a report in AllAfrica.

The tsetse fly kills 3 million livestock each year in Africa, according to U.N. reports. Fatal if untreated in humans, it infects up to 75,000 people with trypanosomiasis and causes more than $4 billion USD in agriculture income losses.

Cashew nut production is widespread in sub-Saharan Africa including Côte d’Ivoire, Nigeria and Tanzania. Guinea Bissau, the second largest producer in Africa, produces 90,000 tonnes, and almost all the production is exported to India for processing.

A new method produces a chemical that attracts flies from cashew nut oil starting material, which could mean African countries could produce the chemicals locally, according to a report in Green Chemistry. Cashew nut producers generate more than 300,000 tonnes of this waste product every year.

Tsetse flies carry sleeping sickness, or African trypanosomiasis. The technology could offer a sustainable and cheaper way to make two tsetse fly-attractant chemicals —  3-ethylphenol and 3-propylphenol — according to a paper published in November in Green Chemistry.

Many odor attractants on the market such as buffalo urine are prohibitively expensive and not widely available in large quantities, AllAfrica reports.

The cashew nut liquid byproduct contains the chemical cardanol, which can be used to make 3-propylphenol and 3-ethylphenol using chemical processes developed by Lukas Goossen, a chemist at the University of Kaiserslautern in Germany who jointly led the research, AllAfrica reports.

The resulting attractant can be coated on a plastic sheet along with an ordinary insecticide, said David Cole-Hamilton, a chemist at the University of St Andrews, U.K., who also led the research. “The attractant lures the insects to the sheet where they are poisoned,” he told SciDev.Net.

The work is commendable, said Andrew Jonathan Nok, a biochemist at Ahmadu Bello University, Nigeria, one of the country’s leading sleeping sickness researchers.

But advances in trapping flies are unlikely to lead to the elimination of sleeping sickness
because tsetse flies may learn to ignore the attractants, he said. Drug and vaccine development are still the best ways to tackle the disease, according to Nok.