Potential of alternative control of leaf-cutting ants using essential oils: A systematic review

Leaf-cutting ants (LCAs) are abundant and cause considerable damage to agricultural and forest crops in the Neotropical region, and are commonly controlled using sulfluramid-based ant baits. However, this active ingredient is a precursor of perfluorooctane sulfonic acid (PFOS), a persistent, human-made pollutant that poses serious environmental and health risks. Several studies have highlighted more natural alternatives to conventional pesticides as a strategic approach for safer management.

In this context, the aim of the present study was to conduct a review through scientific, technological, and molecular mapping of the main plant species and their major compounds used in the alternative control of LCAs using plant essential oils (PEOs).

Seven plant families used for the extraction of PEOs were identified: Aristolochiaceae, Euphorbiaceae, Lamiaceae, Myrtaceae, Piperaceae, Verbenaceae, and Winteraceae. Additionally, 28 patents related to the use of PEOs against pest insects, including LCAs, were identified. Although Brazil has the highest number of scientific publications on this topic, the number of registered patents does not follow the same trend.

This review emphasizes the need to translate scientific knowledge into technological solutions to make alternative products available for the control of LCAs. This is essential to uphold the commitment made under the Stockholm Convention, which seeks to eliminate or restrict the use of Persistent Organic Pollutants.

Methods
Literature Review

The process used for the systematic literature review and subsequent systematic review followed the guidelines of the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA), which involved the stages of identification, screening/elimination, eligibility, and inclusion of articles (Figure 1).

Scientific Mapping

The review was conducted in March 2024 using the indexing platforms Scopus (https://www.scopus.com/) and Web of Science (https://webofknowledge.com/), based on the Boolean search (Atta OR Acromyrmex OR “leaf-cutting ants” OR “leaf-cutting ant”) AND (“essential oils” OR “essential oil” OR “major compounds”). The search included titles, abstracts, and keywords. Articles published in English were considered, without any specific time frame imposed. The metadata of the scientific publications obtained for each search term in both databases were exported in BibTex format. The datasets were combined into a single set, and duplicate entries were removed. The screening of articles was conducted using the inclusion criterion of PEOs associated with activity on LCAs; the exclusion criterion was articles unrelated to the subject. The systematic review was performed using the Bibliometrix package in R software (Aria & Cuccurullo, 2017). The full text of the articles selected after screening was evaluated.

The molecular structures of the major compounds identified in the evaluated studies were accessed in the PubChem database (https://pubchem.ncbi.nlm.nih.gov/). Subsequently, the structures were drawn using ChemDraw software (https://www.acdlabs.com/).

Technological Mapping

The potential technological use of PEOs on LCAs was evaluated through patents obtained and surveyed from the World Intellectual Property Organization – WIPO (https://www.wipo.int/portal/en/index.html), the European Patent Office – EPO (https://www.epo.org/en), the database platform The Lens (https://www.lens.org/), the Spanish and Portuguese Patent Database – LATIPAT (https://lp.espacenet.com/), and the National Institute of Industrial Property – INPI (https://busca.inpi.gov.br/) in April 2024. Duplicate documents and those irrelevant to the research were reviewed and excluded. The data were analyzed for plant species used for essential oil extraction, the countries where the patents were filed, the international patent classification code, and the assignees. The documents were processed using The Lens database platform.

The methodological scope of the research included the following keywords: (Atta OR Acromyrmex OR “leaf-cutting ants” OR “leaf-cutting ant”) AND (“essential oils” OR “essential oil” OR “major compounds”) through advanced search. This information was searched in the titles and abstracts of the patent documents, without a time limitation.

Molecular Data Mapping

The Genetic Sequence Database - GenBank (https://www.ncbi.nlm.nih.gov/genbank/) from the National Center for Biotechnology Information (NCBI) was used for the search of genes, proteins, or complete genome sequences. In this phase, the genes of the four major compounds with the highest number of published articles were investigated. After identifying the major compounds in the articles selected for the systematic review, a new search for published articles on these compounds in other pest insects was conducted. The methodological scope of the research included the following keywords: (“name of the major compound”) AND (“insecticidal property” OR “insecticidal activity” OR “insecticidal activities” OR “insecticides”).

To observe the functional association between the query genes through the construction of gene interaction networks, the GeneMANIA tool (https://genemania.org/) was used. Correlations between the genes were evaluated through the networks of physical interaction, co-expression, predicted, genetic interactions, co-localization, and shared protein domain, and based on the results, the functions of the genes were predicted. The species Arabidopsis thaliana was used as the source organism.