Cassava starch-based essential oil microparticles preparations: functionalities in mosquito control and selectivity against non-target organisms

Abstract

Due to the production facilities and great functionalities, the starch extracted from Cassava plants' (Manihot esculenta Crantz) roots is one of the most abundant and inexpensive raw materials used in food- and non-food industries. The utilization of starches to encapsulate plant essential oils is a relevant advance in the control of insect pests, including mosquitoes that transmit human diseases. The starch-based microencapsulation of essential oils reduces the degradation and volatilization of active components, providing more sustainable and environmentally friendly activities. Here, we investigated the potential of cassava-based starch microparticle preparations containing the essential oil of a Neotropical plant (Siparuna guianensis Aublet) to control larvae of Aedes aegypti and Culex quinquefasciatus. Moreover, the selectivity of the most efficient microparticles preparation was evaluated on zebrafish embryos (Danio rerio), an aquatic non-target organism. The characterization of encapsulated microparticles was achieved by using scanning electron microscopy (SEM), infrared spectroscopy with Fourier transform (FTIR), and thermogravimetric analysis (TGA). Our results revealed an encapsulation efficiency of 82.8 % to 95.3 %, with an average particle diameter of 8.56 μm. Cassava starch microencapsulation reduced the essential oil degradation and enhanced (up to 8 days) the persistent lethal activities (over 50 %) against both species' mosquito larvae compared to the pure essential oil. Furthermore, the exposure of aquatic non-target organisms (embryos of D. rerio) revealed these microparticles' adequate selectivity. Collectively, our findings demonstrate that cassava starch-based microparticles exhibit promising functionality as carriers for essential oils with mosquitocidal activities.