Utilization of plant secondary metabolites for plant protection

In the past two decades, the need for a new concept in agriculture has emerged. The new "Greener revolution" should rely on the implementation of sustainable practices in crop production and the achievement of increased yields under the conditions of reduction of water, fertilizer, and pesticide use. The utilization of plant secondary metabolites is viewed by many authors as a possible alternative to synthetic chemicals. Bioactive botanical compounds can be obtained from plants in the form of extracts, essential oils (EO), or both. There are four main groups of plant secondary metabolites depending on their chemical structure: terpenes, phenolics, nitrogen-, and sulfur-containing compounds. A growing body of publications is devoted to the pesticidal properties of various secondary metabolites obtained from plants. The botanical families Meliaceae, Rutaceae, Asteraceae, Annonaceae, Labiatae, and Canellaceae include the most valuable species that are rich in secondary metabolites. The strong fumigant properties of the EOs from many plant species make them attractive in different Integrated Post-Harvest Pest Management systems. Suitable carriers for EOs delivery can be designed using nanoencapsulation. On a worldwide scale, the main botanical insecticides that are commercially available at present are Pyrethrum, Azadirachtin from Neem, and EOs from various plant species. Among the botanicals with considerable antimicrobial activity, there are some successfully authorized and developed commercial phenolics, terpenes, and alkaloids. Among the proven active substances are cinnamaldehyde, l-glutamic acid and gamma-aminobutyric acid, Jojoba oil, essential oils, and others.