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Studies on methods of combating aerial pests of tomatoes

Charlotte Pasquier, a French student at ISTOM (Higher School of International Agro-Development), completed a six-month internship with our rural development team. The objective of the internship was to be able to complete his final Master year in agronomy. It was within the framework of the exchange program between the NGO Dahari and the Lycée Agricole de Coconi in Mayotte that she was able to carry out her research on the island of Anjouan.
Its main mission was to carry out a study on alternative control methods to synthetic phytosanitary products against aerial pests of tomatoes, a widely consumed crop grown in Anjouan.

The tomato: a crop sensitive to pests and a consumer of phytopharmaceutical products

Anjouanese producers face significant pressure due to the island's tropical climate and the sensitivity of tomato cultivation to pests. One of the most problematic pests is the tomato maggot (Neoceratitis cyanescens), which can cause 100% loss. Other pests can be problematic, for example the Absolutely all and noctuid caterpillars, also called moths.

To fight against these pests, Anjouanese producers use pharmaceutical products, sometimes excessively. This practice can cause damage to the health of users of the products and that of consumers. It is also a practice that can cause considerable damage to the environment (loss of biodiversity, soil and water pollution, etc.).

The effectiveness of the anti-insect net and PNPP against the use of pharmaceutical products:

The choice of these methods was made for the following reasons:

  • The use of anti-insect netting is a method successfully tested in Mayotte, mainly as part of studies on the fight against the tomato fly.
  • The use of a PNPP which has already been a method tested in Mayotte by the Lycée agricole de Coconi and in Anjouan by Dahari. This is a product prepared from papaya leaves and false basil, called Ntchoulé in Shidzwani.

We have installed two plots with Dahari partner farmers. One plot with the use of synthetic phytosanitary products and another with the use of anti-insect net and PNPP. We then compared the yields obtained in marketable fruits, but also in non-marketable fruits. Across all sites, we found that pest damage was less significant under the netting. The marketable yield was then up to 30% higher and therefore more attractive for producers. And this with fewer plant protection products and less risk of loss due to the physical protection of the net.

On the experimental sites of Dahari, a plot was installed with the use of PNPP only (without net). We noticed that the sole use of the chosen PNPP was not sufficient to deal with pests, in particular the tomato fly.

The adoption of the anti-insect net by Anjouanese farmers

To verify the possibility of adoption of the method by farmers, surveys were carried out in the areas of Nganzalé, Adda, and Ouzini. These surveys made it possible to confirm that the pests studied were really problematic for local producers, mainly Neoceratitis cyanescens et Absolutely all. They also highlighted the fact that losses were greater during the rainy season.

Finally, the respondents seemed convinced by the use of the net and PNPP instead of synthetic phytosanitary products. They were able to express themselves on the obstacles and advantages that this inspired in them: The main obstacle stated was physical and financial accessibility and the main lever was the guarantee of good yield and good protection against pests. .

Charlotte's recommendations

With Dahari and the Coconi agricultural high school, we were able to identify advances in alternative control methods. We will continue to experiment with the net method in combination with PNPPs with farmers in order to further validate these promising results.

It is important to find a net supplier to improve physical and financial accessibility. Thus, to improve installation protocols based on lessons learned:

  • To avoid the risk of tearing the nets, you should avoid carrying out installations under a coconut tree. Coconuts damage the structure when falling.
  • Always check that the net is closed after each pass through the plot.
  • The net has a windproof effect and blocks access to the crop for pollinators. Thus, we notice a greater number of failures under the net. To avoid this, it is advisable to shake the stakes each time.
  • It is also recommended to pay increased attention to the multiplication of certain pests, particularly moth caterpillars. If the latter are present, it is recommended to carry out “severe” prophylaxis, that is to say, remove the affected fruits as well as the individuals.

I was delighted to work with Dahari, a dynamic organization very committed to agroecological agriculture in the Comoros.