Charlotte Pasquier, a French student at ISTOM (Graduate School of International Agro-Development), completed a six-month internship with our rural development team. The internship was a requirement for the completion of her final year of a Master’s degree in agronomy. She conducted her research on the island of Anjouan as part of an exchange program between the NGO Dahari and the Coconi Agricultural High School in Mayotte.
Its primary mission was to conduct a study on pest control methods—as alternatives to synthetic plant protection products—targeting aerial pests of the tomato, a crop that is widely consumed and cultivated on Anjouan.

The tomato: a crop susceptible to pests and diseases, and a heavy user of plant protection products

Producers in Anjouan face significant pressure due to the island's tropical climate and the susceptibility of tomato crops to pests and diseases. One of the most problematic pests is the tomato fruit fly (Neoceratitis cyanescens), which can cause 100% loss. Other pests can also be problematic, for example, the Tuta absoluta ), which can cause 100% loss. Other pests can also be problematic, for example, the

To combat these pests, farmers in Anjouan use chemical products—sometimes to an excessive degree. This practice can harm the health of those who apply the products, as well as that of the consumers. It can also cause significant environmental damage (such as loss of biodiversity, and soil and water pollution).

The effectiveness of insect-proof netting and PNPPs (natural preparations for plant protection) as alternatives to the use of pharmaceutical products:

These methods were chosen for the following reasons:

• The use of insect-proof netting is a method that has been successfully tested in Mayotte, primarily within the context of studies on the control of the tomato fruit fly.
• The use of a PNPP (natural preparation for plant protection) is a method that has already been tested in Mayotte by the Coconi Agricultural High School and in Anjouan by the organization Dahari. It involves a product prepared from papaya leaves and *Ocimum gratissimum* (a type of basil)—known as *Ntchoulé* in the Shidzwani language.

We set up two trial plots with farmers who partner with Dahari. One plot used synthetic plant protection products, while the other employed insect-proof netting and natural plant-based preparations (PNPP). We then compared the yields, looking at both marketable and non-marketable fruit. Across all sites, we observed that damage caused by pests was lower under the netting. The marketable yield was up to 30% higher, making it more attractive for producers—all while requiring fewer plant protection products and entailing a lower risk of losses, thanks to the physical protection provided by the netting.

At Dahari’s experimental sites, a plot was set up using only PNPP (without netting). We observed that relying solely on the selected PNPP was not sufficient to manage pests, particularly the tomato fruit fly.

The adoption of insect-proof netting by farmers in Anjouan

To assess the potential for farmers to adopt the method, surveys were conducted in the Nganzalé, Adda, and Ouzini areas. These surveys confirmed that the pests under study were indeed a significant problem for local producers, primarily Neoceratitis cyanescens and Tuta absolutaThey also highlighted the fact that losses were greater during the rainy season.

Finally, the respondents appeared convinced by the use of netting and natural plant-based protection products (PNPPs) as alternatives to synthetic plant protection products. They were able to share their perspectives on the obstacles and benefits they associated with this approach: the primary obstacle identified was physical and financial accessibility, while the main advantage cited was the assurance of a good yield and effective protection against pests.

Charlotte’s recommendations

Together with Dahari and the Coconi agricultural high school, we have identified progress regarding alternative pest control methods. We will continue to experiment with farmers, using a combination of netting and natural plant-based preparations (PNPPs), in order to further validate these promising results.

It is important to find a supplier of nets to improve both physical and financial accessibility. Furthermore, to refine installation protocols based on lessons learned:

• To prevent the risk of the nets tearing, avoid setting them up under a coconut tree. Coconuts can damage the structure when they fall.
• Always check that the net is closed after each pass through the plot.
• The netting acts as a windbreak and prevents pollinators from reaching the crops. Consequently, a higher rate of failure is observed under the netting. To avoid this, it is advisable to shake the plant supports each time you pass by.
• It is also advisable to be extra vigilant regarding the proliferation of certain pests, particularly cutworm caterpillars (noctuids). If these are found, a "strict" prophylactic approach is recommended—namely, removing both the affected fruit and the caterpillars themselves.

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