Traditional knowledge of biopesticidal plants in Northwestern Algeria: An ethnobotanical inventory and assessment of intergenerational knowledge erosion

Abstract

Background: Traditional knowledge of pesticidal plants is part of local agro-ecological heritage undergoing rapid intergenerational erosion across the Mediterranean Basin, yet no quantitative ethnobotanical inventory of this domain had previously been conducted in Algeria. This study documents traditional biopesticidal plant knowledge in the Province of Sidi Bel Abbes (Northwestern Algeria) and its erosion across generations.

Methods: A purposive survey of 205 informants (February–May 2023) used semi-structured interviews, analysed through five ethnobotanical indices — Use Value (UV), Relative Frequency of Citation (RFC), Cultural Importance Index (CI), Fidelity Level (FL) and Family Use Value (FUV) — alongside chi-square, ANOVA, Shannon diversity and Kendall concordance tests. As a secondary step, the resulting species ranking was also compared against previously published bioactivity reports (2000–2024).

Results: A total of forty species from 20 families were recorded; the Lamiaceae family was both the most species-rich (22.50%; χ²=35, p=0.014) and the most important by Family Use Value (FUV=0.243). The three priority species included Urtica urens L., Allium sativum L. and Capsicum annuum L. (UV=0.131-0.097). Aphids represented the most targeted group of organisms (25%), and the leaves were the most used plant organ (57%). Individuals that were over the age of 50 knew of more species than those that were of the age of 30 or younger (F(3,201)=47.3, p<0.001). Additionally, the rank of the plants with published scientific studies of their bioactivities correlated with the efficacy of the plants as medicinal species (r=0.81, p<0.001; n=15/40).

Conclusions: The inventory has shown the loss of knowledge of plants with biopesticidal potential that is occurring in Algeria as a result of the passing of generations. The inventory allows for the determination of which plant and transmission knowledge should be preserved, indicating the value of the knowledge and the need for its preservation. Furthermore, the convergence of these two types of literature can help to initiate future collaborations between authors of such research.

Keywords: Ethnobotany; Traditional ecological knowledge; Knowledge erosion; Biopesticidal Plants; Semi-arid; Algeria