**4. Conclusion**

The increasing worldwide demand for foods requires modern techniques of agricultural production minimizing losses in the crops, transportation and storage. Among the main causes of agricultural losses there are the plague insects. Insecticides are an important con‐ trol tool. However, some collateral effects may be credited to their indiscriminate use such as environmental contamination, human poisoning, reduction in the number of natural ene‐ mies, insecticide resistance by plague insects, etc.

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In this scenario, nano- and microparticles have been reaching a prominent position. Formu‐ lations containing insecticides have been prepared in colloidal suspensions or powder, in nano or micro scale, where they present several advantages such as increasing stability of the active organic compound (UV, thermal, hydrolysis, etc.), foliar settling, reduction in fo‐ liar leaching, systemic action, synergism, specificity, etc. As consequence, the amount of in‐ secticide necessary (dosage), the number of applications, human exposure to insecticides and environmental impact are reduced. The nano- and microformulations have been em‐ ployed not only for synthetic insecticides but also in alternative products to control plague insects such as natural products (herbal extracts) and entomopathogenic microorganisms.

In order to prepare nano- and microformulations, several chemical and physical techniques have been developed. In general, they should be prepared by using polymeric materials which are biocompatible and biodegradable. This practice has the aim to avoid the emer‐ gence of new environmental and toxicological problems. The biopolymers are produced by microorganisms, synthesis or even petroleum derivate products. In common, when exposed to the environment they are easily destroyed by UV radiation and/or microorganism en‐ zymes generating CO2 and H2O as final product. The degradation processes of biopolymers may lead, or not, to the release mechanisms of active organic compounds of a nano- or mi‐ croparticles. Processes such as swelling, hydrolysis, diffusion, erosion, etc., must be manipu‐ lated in a controlled way in order to obtain the desired characteristics of application and biological activity for the formulated products.

As a result of the application of these new nano- and micro- technologies, which have been quickly developed due to new sensitive analytical technologies of characterization, new ways to control plague insects are emerging, thinking not only in lethal action on the target insect, but also in all ecosystems, which include fishes, natural enemies, vegetation, microor‐ ganisms, animals, the man himself, etc.
