Embrapa Meio Ambiente (SP) has developed a more effective and sustainable insecticide with the Chemistry Institute of the State University of Campinas (Unicamp).
The work resulted in a controlled release system for the insecticide molecule thiamethoxam. The encapsulation was conducted in polymeric nanomicelles, structures smaller than one billionth of a meter, or more than 80,000 times smaller than the thickness of a strand of hair. Studies show that the application of nanopesticides can be much more effective than existing conventional pesticides and may completely replace them in the near future. Nanomaterials have unique physical, chemical and biological properties, different from the characteristics of the same materials on a larger scale, due to the increase in the surface-to-volume ratio and quantum effects.
Nanopesticides refer to formulations that use nanomaterials in their composition and that present high application efficiency and less toxic effects on the environment compared to conventional formulations of the same active ingredient. In this study, the formulation method used was the nanoencapsulation of the active ingredient studied, resulting in a sustained release by the nanoparticles, high stability and specificity. ″The results indicated that the nanostructures were effective with a dose approximately two times lower compared to commercial formulations,″ explained Embrapa analyst Marcia Assalin, coordinator of the study, which the São Paulo Research Foundation (Fapesp) supported.
The effectiveness of the nanoinsecticide was assessed by controlling, in greenhouses, the insect (Diaphorina citri) responsible for the spread of greening, also known as huanglongbing and HLB, caused by the bacterium Candidatus liberibacter spp. The disease affects all citrus plants and has no cure. Once contaminated, it is impossible to eliminate the bacteria from the plant, which continues to act as a source of inoculum for contaminating other plants.
In addition to increasing efficiency, the new product can reduce the number of applications, attenuate the development of pest resistance to the insecticide, and a reduction in environmental impact and associated costs.
According to Ljubica Tasic, a professor at Unicamp, the nanoinsecticide showed reduced toxicity to aquatic organisms used in ecotoxicity assessment studies (Raphidocelis subcapitata and Artemia salina). Therefore, she believes that the product obtained represents how nanotechnology can promote more sustainable agricultural practices. To be considered sustainable, agriculture must guarantee future generations the ability to meet the planet’s production needs and quality of life. To ensure that, it must increase agricultural yields with fewer resources while reducing its environmental impact and ensuring the health of supporting ecosystems to guarantee the continuity and quality of the natural resources necessary for food production.
Citrus greening is one of the most important diseases affecting citrus today. Its severity is mainly due to the rapid and efficient spread of the bacteria by the insect Diaphorina citri and the lack of genetic resistance in citrus. Thiamethoxam, one of the active ingredients used to control the disease, belongs to a relatively new class of insecticides, neonicotinoids, which have been on the market since the early 1990s and are among the best-selling pesticides. This chemical has high solubility in water, leaching potential, and rapid degradation by photolysis, which is the process of degradation of organic molecules by using light.
Assalin states that, when applying conventional insecticides, numerous losses can occur due to several factors, such as application techniques used, environmental conditions, degradation by photolysis and leaching. This leads to repeated applications, using insecticides in larger quantities than necessary to control the vector insect. Thus, it causes various problems, such as increased treatment costs, contamination of surface and underground water bodies, and risk of psyllid resistance to the insecticide, in addition to representing a risk to human health and aquatic invertebrates. ″In addition, it is extremely important to emphasize that neonicotinoid insecticides are highly toxic to pollinating insects such as bees and have been banned from fields in the European Union for this reason,″ he emphasized.
Nanoencapsulated pesticide formulations allow for controlled release of the active ingredient and protection against premature degradation, making conventional insecticides more efficient and sustainable. Therefore, evaluating the effectiveness of encapsulated pesticide formulations is essential to allow their use in agriculture. Studies on the possible impacts on humans and the environment should be carried out, according to Assalin.
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