Essential oils as potential biopesticides in the control of the genus Meloidogyne: A review

Root-knot nematodes (RKN), Meloidogyne spp., are among the most economically damaging phytoparasites. The pathogenic effects of these obligate biothrophs dramatically increase under mass monoculture of horticultural and field crops, causing significant economic losses for farmers. Pest management is usually a complex task given RKN worldwide distribution and wide host range. Control of RKN infestation is performed through the application of commercial synthetic nematicides that kill or disrupt the feeding or reproductive behavior of nematodes, commonly broad-spectrum fumigants and nervous system toxins. Despite their high efficiency, synthetic nematicides can cause extremely negative environmental and public health impacts, and are feared to lead to the development of resistance and immunity. Phytochemical based strategies for RKN control have been successfully employed and many essential oils (EOs) have shown remarkable activities, in some cases even surpassing those of commercial nematicides. EOs offer the advantage of being natural, biodegradable and subjected to less strict regulatory approval mechanisms for their exploration, due to a long history of use. The present work reviews the existing bibliography on the direct biological activity of EOs against Meloidogyne spp. A total of 49 publications were found reporting on the RKN antinematodal activity of EOs, from 1995 up to 2020. Plants from Lamiaceae and Compositae families make up more than 50% of the source material for EO extraction. The highest activities were reported for EOs extracted from plants of genus Monarda, Artemisia, Filipendula and Satureja. These taxa show potential to be further explored as highly active anti-RKN phytochemicals with practical applications in sustainable pest management strategies.