A Review of the Potency of Plant Extracts and Compounds from Key Families as an Alternative to Synthetic Nematicides: History, Efficacy, and Current Developments

Abstract

The global nematicides market is expected to continue growing. With an increasing demand for synthetic chemical-free organic foods, botanical nematicides are taking the lead as replacements. Consequently, in the recent years, there have been vigorous efforts towards identification of the active secondary metabolites from various plants. These include mostly glucosinolates and their hydrolysis products such as isothiocyanates; flavonoids, alkaloids, limonoids, quassinoids, saponins, and the more recently probed essential oils, among others. And despite their overwhelming potential, variabilities in quality, efficacy, potency and composition continue to persist, and commercialization of new botanical nematicides is still lagging. Herein, we have reviewed the history of botanical nematicides and regional progresses, the potency of the identified phytochemicals from the key important plant families, and deciphered some of the impediments involved in standardization of the active compounds in addition to the concerns over the safety of the purified compounds to non-target microbial communities.

Comparative Bioactivity of Emamectin Benzoate Formulations against the Pine Wood Nematode, Bursaphelenchus xylophilus

“…These include among others; physical removal of infected trees and subsequent fumigation of infected wood (e.g., with metam sodium), aerial insecticide application against the insect vector (e.g., with thiacloprid and acetamiprid); and trunk injection of nematicidal compounds against the nematodes proliferating in live pine trees ( Bi et al, 2015 ; Kong et al, 2006 ; Liu et al, 2020 ). In the recent years, there have also been attempts towards testing naturally occurring nematicidal compounds isolated from plants, and other less toxic pesticides, with efforts to limit and combat environmental impacts, including effects on non-target organisms and health-related problems associated with the use of non-selective synthetic nematicides ( Mwamula et al, 2022 ; Nunes da Silva et al, 2014 ; Park et al, 2007 ; Seo et al, 2014 ). However, among all the available and tested control approaches, aerial application of insecticides such as thiacloprid and acetamiprid, and trunk injection with synthetic pesticides such as fenitrothion, morantel tartrate, emamectin benzoate, abamectin, and abamectin + sulfoxaflor mixture have been widely used in the East Asian countries ( Bi et al, 2015 ; Jung et al, 2021 ; Kishi, 1995 ; Liu et al, 2020 ).…”

Valorization of the Hydrolate Byproduct from the Industrial Extraction of Purple Alium sativum Essential Oil as a Source of Nematicidal Products

“…Similarly, the most abundant components of the hydrolate OF were diallyl disulfide (DADS), diallyl trisulfide (DATS), p-methylpyridine and methyl allyl trisulfide. Hydrolates are normally composed of water-soluble oxygenated compounds also present in the EO [7,10,28,32]. The nematicidal activity of DADS and DATS has been demonstrated against the pine wood nematode, B. xylophilus [18], M. javanica [33], and M. incognita [21]; therefore, the nematicidal effects of garlic EO and hydrolate reported here can be explained by their content in active DADS (27.44%) and DATS (16.82%).…”

“…The global nematicides market is expected to continue growing and, with an increasing demand for synthetic chemical-free organic foods, botanical nematicides are taking the lead as replacements. Consequently, in recent years, there have been efforts towards identification of the active secondary metabolites from plants [7].…”

Microbes vs. Nematodes: Insights into Biocontrol through Antagonistic Organisms to Control Root-Knot Nematodes

“…Nematicidal plant extracts are mostly from the families Meliaceae, Fabaceae, Lamiaceae, Brassicaceae, Verbenance, Euphorbiaceae, etc. [ 127 ]. Various secondary metabolites released from plants such as alkaloids, flavonoids, glucosinolates, isothiocyanates, tannins, fatty acids, and sesquiterpenes show nematicidal potential against egg hatching, juvenile mortality, and penetration of nematodes [ 128 , 129 ].…”