Quantitative Evidence on the Use of Medicinal Plant By-Products as Sustainable Biopesticides: A Systematic Review and Meta-Analysis of Pest Mortality, Disease Suppression, and Crop Yield

The concerns regarding the toxicity and environmental impact of synthetic pesticides are rising. Alternatively, eco-friendly sources of bioactive compounds with potential as integrated pest management are presented by plant-based bioactive compounds. In accordance with the preferred reporting Items for systematic reviews and meta-analyses (PRISMA) principles, four databases, including Scopus, Web of Science, PubMed, and the Cochrane Library, were searched systematically, and the records were analyzed in Central Access Database for the Impact Management and Assessment of Genetic Improvement Technologies (CADIMA). Ten studies were included according to the criteria, and 9 out of them had to be included in the meta-analysis. The comparisons showed a strong, statistically significant insect mortality and behavioral control (g = 7.10, 95% CI: 5.30 - 8.90) and plant health promotion (g = 12.95, 95% CI: 0.48 - 25.42). There was a high level of efficacy in nematode management at the individual study level, though there was high heterogeneity that inhibited pooled interpretation. The results of pathogen suppression were rather inconsistent, and they were mostly explained by the variability of methods and the difficulties in directionality coding. Sublethal effects, such as effects on insect growth and feeding behavior, were always major in regard to the physiological parameters. The studies were all rated as low risk of bias. To allow the practical use of these circular-economy biopesticides, future studies should also aim to standardize methods, conduct field-level validation, and determine ecological safety.