NANOinsecticides; advanced technologies for insect pest control with low environmental impact.

STADLER, T.

Buenos Aires

Taller; Primer Taller en Medioambiente; 2014

MINCYT

The world food production experienced an exponential increase in the last 60 years, even more than the rate of population growth. This achievement, which currently allows feed a global population of 7.2 billion, has been possible thanks to the control of pests and diseases through the intensive use of synthetic pesticides. This tremendous progress is not free of side effects as conventional pesticides have a strong negative impact on human health, biodiversity and ecosystems. The available scientific evidence clearly shows that pesticides are poisonous compounds and also strongly suggest that these cause cancer in both those who use the pesticides directly and those who are exposed by applications others make. The widespread concern for environmental and human health, raise the need for new reduced-risk pest control strategies and the search for new chemical classes of pesticides. Among the recent technological advances in agricultural science, nanotechnology shows considerable promises, although its development for use in crop protection is in its initial stages. The current use of nanotechnology in a wide array of fields and products as well as the recent discovery of their potential in crop protection suggests that nanomaterials have a great potential for development of new products that will impact agriculture. Part of the research on new biorational pesticides focuses on natural products such as plant extracts, oils, and inorganic insecticides. Substances with new properties are promising tools for crop protection and food production, opening new frontiers in pest management. Recently, the discovery of nanoinsecticides brings new alternatives to expand the spectrum of applications of inorganic dusts. Nanostructured alumina has been shown to have insecticidal properties, and it possesses some of the characteristics of an ideal insecticide, given that it is a natural product, not reactive, economical, with reduced probabilities of generating resistance in insects, and it is more effective than other commercially available insecticidal dusts. Development and registry of nanomaterials is based on the idea that they are not new materials, although they have different properties than the products with the same chemical structure, given that novel properties emerge from products when they are at the nanoscale. For example, reactivity, specific area, electric charge and quantum effects may differ. These substances with new properties are promising as tools for crop protection and food production, opening new frontiers for nanoinsecticides in pest management. Nanostructured alumina (NSA) is an advanced material which has engineered properties created through synthesis technology, laying claim to biological properties as insecticide action. It enables new technologies such as low toxicity pesticides for human, livestock and agricultural use, stored product protection, treatments for wood preservation, carriers of pheromone or virus for insect pest control, etc. NSA has been shown to have strong insecticidal properties to several insect species throughout a mechanism of action different from conventional pesticides. NSA kill arthropods by absorbing the epicuticular lipid layers causing excessive water loss through the cuticle and finally insect mortality by dehydration (Stadler & col. 2010a, b).  In principle, the insecticidal activity of the nanomaterial is dependent on electrical phenomena that drive the particles to adhere to the insect body. Due their high specific surface activity, Nanoinsecticide particles "capture" (adsorb) the insects´ cuticular waxes, reducing waterproof  capacity of the cuticle, causing the insect death by dehydration. Although the mechanism of action insecticide has not yet been fully clarified, we have found that far, that the Nanoinsecticide acts on the basis of electrostatic charges of the particles, since in nanomaterial synthesis obtained from oxidation of metals, resulting particles are permanent dipoles fixed electric charges, where the dipole-dipole interaction promotes aggregate formation resistant dissociation forces. In those insects that exhibit own electric charges generated by triboelectrification, nanoparticles adhere tightly to the insects´ body surface (Fig. a and d ) and the wax layer of the cuticle can be "captured" by the Nanoinsecticide because of their high surface activity (14m2.g -1) , a phenomenon that ultimately leads to the death of the insect by dehydration.