The use of nanoencapsulated neem oil to counter agricultural pests

Researchers at the Brazil Science and Technology Institute for the Biorational Control of Pest Insects have developed a method for the preservation of neem's main active ingredient.

By Mônica Pileggi

Agência FAPESP – Neem (Azadirachta indica), a plant native to southeastern Asia, is considered a promising resource for the production of organic insecticides. In agriculture, plants of the Meliaceae family, such as neem, are used in diverse regions to control plagues, acting on roughly 400 species of insects.

With rapid growth and a dense crown, neem can grow up to 15 meters and can be cultivated in hot climates and well-drained soil. In Brazil, the plant was first officially introduced by the Paraná Agronomy Foundation Institute in 1986 with seeds from the Philippines and in 1989 using seeds from India, Nicaragua and the Dominican Republic. In the following decade, the plant’s properties became more widely recognized, spurring commercial planting in several states.

Specialists noted that oil extraction techniques in Brazil could benefit from some adjustments. The main ingredient in the oil extracted here (Azadirachtine), for example, degrades when exposed to sunlight. One research project conducted at São Carlos, however, has managed to optimize the extraction process through the nanoencapsulation of the oil to preserve the neem plant’s insecticidal properties.

“The instability of Azadirachtine under the Sun’s radiation is costly in farming because farmers have to apply the oil several times,” explains Maria Fátima das Graças Fernandes da Silva, professor at the Center for Exact Sciences and Technology at Universidade Federal de São Carlos (UFSCar), in an interview with Agência FAPESP.

She coordinates the National Science and Technology Institute (INCT) Biorational Control of Pest Insects, which is financed by FAPESP and the National Council for Scientific and Technological Development (CNPq). Her organization has the objective of studying non-toxic compounds that can control diseases and the behavior of pests in agriculture.

Among the INCT’s research is the study “Nano and micro particles from Meliaceae extracts for pest control using lignin from sugarcane” by Eveline Soares Costa and coordinated by Moacir Rossi Forim, both of the Center of Exact Sciences and Technology at UFSCar.

Silva explains that the study identified mechanical errors in the conventional extraction process for neem oil. According to Silva, during the procedure – which involves collecting the fruit and removing its seeds – almost 60% of the plant’s active ingredient is lost.

“Extraction is done through a process known as compression, which forms something like a ‘pie.’ Nevertheless, this pie – where the majority of the Azadirachtine is found – is discarded.”

Costa’s study consisted of the development of a methodology for enriching the oil. In addition to adjustments in the extraction process, which resulted in a patent request at the National Industrial Property Institute (INPI), the researchers developed a natural polymer of sugarcane bagasse to encapsulate the neem oil at the nanometric scale.

“This nanoencapsulation allows for greater protection of the main ingredient in relation to solar radiation. After being applied, the oil is effective for an extended time on the soil, which represents an important savings for the farmer, who does not have to apply it several times,” stresses Silva.

The nanoencapsulation study – which also resulted in a patent request – sparked the interest of Germany-based DVA, whose Brazilian representative office is responsible for selling neem oil from India in Brazil.
According to Silva, the partnership formed with DVA should accelerate the arrival of the encapsulated oil in the market. “As it commercializes the Indian oil in the country, DVA already has toxicity tests and authorization from the National Health Surveillance Agency (Anvisa). All it needs is a toxicity test on nanoencapsulation,” she said.