Plant Essential Oils as Biopesticides: Applications, Mechanisms, Innovations, and Constraints

The advent of the “Green Revolution” was a great success in significantly increasing
crop productivity. However, it involved high ecological costs in terms of excessive use of synthetic
agrochemicals, raising concerns about agricultural sustainability. Indiscriminate use of synthetic
pesticides resulted in environmental degradation, the development of pest resistance, and possible
dangers to a variety of nontarget species (including plants, animals, and humans). Thus, a sustainable
approach necessitates the exploration of viable ecofriendly alternatives. Plant-based biopesticides
are attracting considerable attention in this context due to their target specificity, ecofriendliness,
biodegradability, and safety for humans and other life forms. Among all the relevant biopesticides,
plant essential oils (PEOs) or their active components are being widely explored against weeds,
pests, and microorganisms. This review aims to collate the information related to the expansion and
advancement in research and technology on the applications of PEOs as biopesticides. An insight
into the mechanism of action of PEO-based bioherbicides, bioinsecticides, and biofungicides is also
provided. With the aid of bibliometric analysis, it was found that ~75% of the documents on PEOs
having biopesticidal potential were published in the last five years, with an annual growth rate of
20.51% and a citation per document of 20.91. Research on the biopesticidal properties of PEOs is
receiving adequate attention from European (Italy and Spain), Asian (China, India, Iran, and Saudi
Arabia), and American (Argentina, Brazil, and the United States of America) nations. Despite the
increasing biopesticidal applications of PEOs and their widespread acceptance by governments, they
face many challenges due to their inherent nature (lipophilicity and high volatility), production costs,
and manufacturing constraints. To overcome these limitations, the incorporation of emerging innovations like the nanoencapsulation of PEOs, bioinformatics, and RNA-Seq in biopesticide development
has been proposed. With these novel technological interventions, PEO-based biopesticides have the
potential to be used for sustainable pest management in the future