Development of modified release systems based on zein and chitosan for botanical repellents aiming whitefly (Bemisia tabaci) control in different crops

Author(s)

Jhones Luiz de Oliveira

• Document type: Doctoral Thesis
• Press: Sorocaba. 2018-09-25.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Ciência e Tecnologia. Sorocaba
• Defense date: 2018-09-06
• Advisor: Leonardo Fernandes Fraceto

Abstract

Arthropods have been a major cause of agricultural losses worldwide. Only in Brazil can these losses reach 7.7% per year. The extensive use of synthetic pesticides has been the main form of control of this type of pest, however, the adverse effects of these compounds for both the environment and human health have motivated the search for less impactful alternatives. In this context, several mechanisms are being studied in order to minimize these damages, such as the development of modified release systems using biodegradable polymers and proteins. In addition to this, the use of botanical pesticides has also shown potential for combating these pests, due to the lower impacts caused by these products of natural origin. Therefore, the present work showed the development (preparation and characterization) of nanocarrier systems produced from chitosan and gum arabic polymers and zein protein for the botanical compounds (geraniol, citronellal, eugenol and cinnamaldehyde), as well as the potential effects and phytotoxic systems. In addition, tests of the biological activity of these systems on agricultural pests (whitefly, two-spotted spider mite and soybean looper) were also carried out. The botanical compounds showed high encapsulation efficiency in both carrier systems, and the systems were able to protect the compounds against premature degradation and also against ultraviolet radiation. The phyto and cytotoxicity results showed that encapsulation decreased the toxic effect of the active compounds. The systems also showed biological activity against the agricultural pests tested. The zein nanoparticles containing the botanicals showed a repellent effect against the brindle two-spotted spider mite (Tetranychus urticae) under laboratory and semi-field conditions, as well as a sublethal effect on soybean looper (Chrysodeixis includes). The chitosan/gum arabic nanoparticles containing geraniol showed attractive effect for whitefly, being promising for applications in trap systems. The importance of this thesis lies in the dimension that the agricultural sector represents for the Brazilian and world economy, in addition to that the market for agricultural pesticides grows annually, in special as Brazil is one of the leaders in the consumption of these products. In this way, the development of new technologies to pest control in agriculture is promising since more efficient pest control systems can be produced, less impacting the environment and consequently to human health. (AU)

• FAPESP's process: 14/20286-9 - Development of modified release systems based on zein and chitosan for botanical repellents aiming the control of whitefly (Bemisia tabaci) in different cultures
• Grantee: Jhones Luiz de Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate