Carvacrol and linalool co-loaded in \u03b2-cyclodextrin-grafted chitosan nanoparticles as sustainable biopesticide aiming pest control

Estefânia V R Campos,Renata Lima,Daniel J Andrade,Jaqueline F Della Vechia,Tatiane Pasquoto-Stigliani,Kelly C Gonçalves,Fabrício O Fernandes,Cirano C Melville,Leonardo F Fraceto,Anderson E S Pereira,Lígia Nunes De Morais Ribeiro,Jhones L Oliveira,Patrícia L F Proença,Ricardo A Polanczyk

doi:10.1038/s41598-018-26043-x

Abstract

Pesticides are the main tactics for pest control because they reduce the pest population very fast and their efficiency does not depend on abiotic factors. However, the indiscriminate use of these substances can speed up the development of resistant populations and causing environmental contamination. Therefore, alternative methods of pest control are sought, such as the use of botanical compounds. Nanoencapsulation of volatile compounds has been shown to be an important tool that can be used to overcome the lack of stability of these compounds. In this work, we describe the preparation and characterization of chitosan nanoparticles functionalized with β-cyclodextrin containing carvacrol and linalool. The toxicity and biological activity were evaluated. Decreases of toxicity were observed when the compounds were nanoencapsulated. The nanoparticles presented insecticidal activity against the species Helicoverpa armigera (corn earworm) and Tetranychus urticae (spider mite). In addition, repellent activity and reduction in oviposition were observed for the mites.

Highlights

67,000 species of organisms are known to attack crops, among which insects and mites are among the most virulent invasive species and are responsible for reducing global agricultural production by about 10 to 16%
A carrier system based on chitosan nanoparticles functionalized with β-cyclodextrin was developed to carry two botanical insecticides together, in order to create an effective and environmentally safe system for the control of agricultural pests
For the development of the modified chitosan with β-CD used in this study we have been used a chitosan with high aqueous solubility since the functionalization of cyclodextrin occurs in the amino groups, which are essential for the solubilization of this polymer and nanoparticle formation

Summary

Introduction

67,000 species of organisms are known to attack crops, among which insects and mites are among the most virulent invasive species and are responsible for reducing global agricultural production by about 10 to 16%. The success of H. armigera as a pest is due to its high reproduction rate and facultative diapause, which favor increased spatial distribution among hosts[8], as well as the capacity to adapt to adverse conditions of humidity and temperature[9], resistance to the routinely used insecticides[10,11] and resistance to plants expressing the Bt protein[7,12,13] Another agriculturally important species, due to the extent of the damage caused and its wide range of hosts, is the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae)[14,15]. One option is the use of botanical insecticides that can provide pest control, while reducing environmental damage and effects on nontarget organisms[22,23,24,25]

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