Studies show that the application of nanopesticides can be more effective compared to conventional pesticides
A more effective and sustainable insecticide was developed by Embrapa Meio Ambiente (SP) in partnership with the Chemistry Institute of Unicamp (State University of Campinas). The work resulted in a controlled release system for the insecticide thiamethoxam. The encapsulation was carried out 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 more effective than existing conventional pesticides and may, in the near future, completely replace them. Nanomaterials have unique physical, chemical and biological properties, different from the characteristics of the same materials at larger scales, 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 work, 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 at a dose approximately two times lower compared to commercial formulations”says Embrapa analyst Marcia Assalin, coordinator of the study, which had the support of Fapesp (São Paulo State Research Support Foundation).
The efficiency of the nanoinsecticide was evaluated by controlling the insect (Diaphorina citri) responsible for the spread of greening, also known as huanglongbing and HLB, caused by the bacteria Candidatus Liberibacter spp. The disease affects all citrus plants and has no cure: once contaminated, it is not possible to eliminate the bacteria from the plant, which acts as a source of inoculum for the contamination of other plants.
In addition to increasing efficiency, the new product can lead to a reduction in the number of applications, attenuation in 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 It is Artemia salina). Therefore, she believes that the product obtained represents one of the ways in which nanotechnology can promote more sustainable agricultural practices.
Agriculture, to be considered sustainable, must guarantee future generations the ability to meet the production and quality of life needs of the planet. To do this, it must be able to increase agricultural yields, using fewer resources, while reducing its environmental impact and ensuring the health of supporting ecosystems, in order to guarantee the continuity and quality of the natural resources needed for food production.
Thiamethoxam and greening
Greening is one of the most important citrus diseases today. Its severity is mainly due to the rapid and efficient spread of bacteria by the insect. Diaphorina citri and the absence 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, that is, the process of degradation of organic molecules by means of 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, resulting in the use of insecticides in greater quantities than necessary to control the insect vector.
Thus, it causes a series of problems, such as increased treatment costs, contamination of surface and underground water bodies, 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 highlight that neonicotinoid insecticides are highly toxic to pollinating insects such as bees, and have been banned from EU fields for this reason.”he says.
Nanoencapsulated pesticide formulations allow controlled release of the active ingredient, as well as protection against premature degradation, enabling the use of conventional insecticides in a more efficient and sustainable manner.
Therefore, evaluating the effectiveness of encapsulated pesticide formulations is essential to enable their use in agriculture. Studies on the possible impacts on humans and the environment must be carried out, according to Assalin.
With information from Embrapa Agency.