Hydrogels Containing Botanical Repellents Encapsulated in Zein Nanoparticles for Crop Protection

Abstract

Essential oils and their derivatives are ecofriendly biopesticides that can contribute to reducing the use of synthetic pesticides in agricultural pest control, offering advantages including less harm to humans and the environment. This work concerns hydrogel-based repellent systems containing botanical compounds that were emulsified or encapsulated in zein nanoparticles. The hydrogels were prepared according to a two-step process involving molding and cross-linking. They presented good rheological properties, even at elevated temperature (40 °C), a swelling degree of ∼30 ± 1.2%, and were able to modulate the release of active compounds. The hydrogels containing botanical compounds presented high repellency (>80%) against two important agricultural pests: whitefly (Bemisia tabaci) and two-spotted spider mite (Tetranychus urticae). These repellent systems are promising for use in sustainable agriculture, since they are based on the use of natural substances for both the matrices and the active agents. It is noteworthy that the systems can be used without direct contact with plants, which minimizes any problems related to phytotoxicity.

Enzyme Stimuli–Responsive Nanoparticles for Bioinsecticides: An Emerging Approach for Uses in Crop Protection

“…The release profile of the bioinsecticides was performed by a dialysis technique . The presence of the enzyme strongly influenced the release of GRL when compared to the control without enzymes, resulting in the release of 56% and 36% of GRL for assays with enzyme addition and only 15% release in the absence of enzyme after 48 h. The CND release was not influenced by the addition of enzyme, reaching a maximum release of 36% with and without trypsin.…”

Gel Carriers for Plant Extracts and Synthetic Pesticides in Rodent and Arthropod Pest Control: An Overview

“…Mechanisms of improving essential oil stability include various encapsulation techniques of natural substances by formulating them as nano- and microemulsions [ 131 ], microspheres [ 132 ], and nanoparticles [ 133 ]. The use of highly sorptive hydrogels may also provide higher and longer activity of essential oils applied as pesticides and repellents [ 46 , 98 , 134 ].…”

A Review of Design and Fabrication Methods for Nanoparticle Network Hydrogels for Biomedical, Environmental, and Industrial Applications

“…For example, NNHs consisting of gum ghatti (Gg), N,N-dimethylacrylamide (DMA) and silver NPs have been used to deliver the herbicide 2,4-dichlorophenoxyacetic acid (900 mg L −1 solubility) [46] while NNHs based on carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), and zein nanoparticles successfully delivered the botanical essential oils eugenol and geraniol (650 mg L −1 and less); in the latter case, the phytotoxicity, release kinetics, and organism stress loading (>80% repellency) were all improved due to the botanical compounds being entrapped and stabilized inside hydrophobic regions in the zein NPs within the plum pudding architecture effectively slowing release and protecting the compounds from external environmental (Figure 9). [192] While most NNHs (including all those discussed to this point) are used for systemic delivery either through foliar or root routes of administration, localized pesticide action can also be achieved using NNH patches, analogous to the use of wound dressings in medicine (Section 3.8). For example, Laromaine et al…”