In Africa, particularly in the Sahel Belt, insect predation on harvested crops, cereals and leguminous plants can be detrimental to the farmer and can affect the exchange rate of countries. The use of chemical pesticides as a solution to the problem is being gradually abandoned due to the many disadvantages associated with this method. A return to more traditional agricultural practices combined with the use of plant-based natural substances could prove to be equally effective.

As rumour has it, in Africa the farmer works for insects. The saying is cruel and fatalistic, but in fact there is a real problem since beyond the crops loss, food security and seed quality (gathered after harvest) are at stake due to pest attacks. Thus, in tropics, up to 30% or more cereal and leguminous plant stocks are regularly destroyed, mainly after pests’ attacks. Groundnuts and cowpeas (an average-sized type of bean) are among the plants that are the most vulnerable to infestation by insects.

Generations of farmers have been fighting against this predicament since the dawn of time. However, new factors such as global warming and repeated global food crises have only served to exacerbate the recurrent problems (agronomical, climatic, economic, political, etc.) experienced by the countries of the Sahel belt, leaving them constantly exposed to a shortage of food resources. In the main countries of this vast region, agricultural crop yields traditionally remain well below the food requirements of the population. In order to feed its populations, a country like Senegal must import 600,000 tons of rice each year costing around 140 billion CFA francs.

This state of dependency is no longer tenable. So what is the solution? Protecting crops through the use of pesticides? This has certainly been the most commonly adopted solution for several decades and it is undoubtedly an easy option: the insect dies and the foodstuffs are unharmed (as long as the product is effective and used correctly). And yet what cost does this exert on the environment and on health? In Africa, as elsewhere, cases of severe poisoning, which often result in death, are regularly denounced in the press and result in a public outcry. However, undetected chronic poisoning responsible for common cancers and neuro-degenerative diseases, are not at all subject to the same scrutiny

The fact remains that the vast majority of farmers ignore safety procedures or do not possess even the most basic means of protection. “The colour of the packet seems to be the most preferred criterion for choosing a pesticide,” says Dr Momar Talla Guèye, author of a recent doctoral thesis devoted to plant-based methods of protection, completed at Gembloux Agro-Bio Tech/University of Liege (1). Chemical pesticides also raise another problem: the growing resistance of insects to chemical products. “No group amongst organophosphorus, organo-chlorine, pyrethrinoids compounds or fumigants has escaped from this resistance factor,” states the researcher. “New products need to be constantly developed.”

(1) Integrated management of pests affecting cereals and leguminous plants in Senegal through the use of plant substances.