Ferns and Lycophytes with Insecticidal Activity: An Overview

Despite their economic and ecological importance, some insect species are human disease vectors. In addition, agricultural pests cause significant losses in a large number of important crops worldwide. Insect control has traditionally used synthetic insecticides, but their indiscriminate use has damaged the environment and compromised human health. Thus, the search for plant-based insecticides has prompted an increase in studies. Seedless vascular plants are included in two different lineages: ferns and lycophytes. Several biological activities, including insecticidal, are attributed to the extracts/compounds of these plant groups. The aim of the present study was to analyze the literature on the insecticidal potential of fern and lycophyte extracts. The review was conducted on the PubMed, ScienceDirect, Scielo, and Web of Science databases. No time or language restrictions were established, and the search was concluded in December 2021. A total of 43 studies were found between 1994 and 2020. Of the 80 species assessed, 47 fern and 2 lycophyte species exhibited important medical or agricultural insecticidal, repellent, or insect growth-regulating activity. The insects most widely used as experimental models were Spodoptera litura and Helicoverpa armigera (Lepidoptera) and Aedes aegypti, Aedes albopictus, and Anopheles stephensi (Diptera). Most of the insect species (71.8%) assessed exhibited holometabolous development, with the highest percentage of studies performed with insect pests (69.8%). Tests normally involved adult insects or in the larval stage, contact tests being the most frequently applied. The most widely used extracts were aqueous and ethanolic, demonstrating better insecticidal activity for the species tested. Despite the scarcity of studies, it is believed that these plants show potential as a source of substances with insecticidal and repellent activity.