Toxicity of Ethanolic Plant Extracts to Aphis gossypii, Bemisia tabaci, and Frankliniella occidentalis and Selectivity to Coccinella septempunctata and Menochilus sexmaculatus.

Abstract

The excessive use of synthetic chemical pesticides in agriculture has led to the emergence of resistant insect populations, posing significant threats to both ecosystems and human health. As part of sustainable pest management, Integrated Pest Management (IPM) strategies have increasingly incorporated eco-friendly alternatives, such as plant ethanolic extracts, to reduce chemical pesticide dependency. This study aimed to evaluate the effectiveness of ethanolic extracts from Cannabis sativa L., Citrullus colocynthis L. Schrad., and Laurus nobilis L. in controlling tomato crop pests. Repellency essays, olfactometer responses, and field trials were conducted to compare the efficacy of these extracts with natural enemies (ladybird beetle Coccinella septempunctata L. and zigzag beetle Menochilus sexmaculatus Fabricius) and a synthetic pesticide (Acetamiprid 20% SP). Results show that L. nobilis exhibited the highest repellency against whiteflies and thrips, significantly reducing pest population, followed by C. colocynthis and C. sativa. Olfactometer bioassays revealed that C. septempunctata and M. sexmaculatus were strongly attracted to L. nobilis and C. sativa. Greenhouse trials demonstrated that the combination of natural enemies and botanical extracts resulted in a significantly lower pest population compared to synthetic pesticides alone. These findings support the potential of botanical extracts, particularly L. nobilis, as integral components of IPM systems, offering an environmentally sustainable approach to pest management by reducing reliance on chemical pesticides while promoting crop health and productivity.