Toxicity Efficacy of Methanolic Leaf Extracts of Neem (Azadirachta indica) and Basil (Ocimum basilicum) Against Cotton Aphid (Aphis gossypii) on Pepper Crop (Capsicum annuum)
DOI:
https://doi.org/10.64943/ajhas.2026.020165Keywords:
Aphis gossypii, Azadirachta indica, Ocimum basilicum, methanolic extract, botanical insecticide, pepper, integrated pest management, LC50Abstract
The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a significant pest affecting pepper crops worldwide, causing substantial yield losses through direct feeding damage and virus transmission. The increasing concerns over synthetic pesticide resistance and environmental contamination have intensified the search for sustainable, eco-friendly alternatives. This study evaluated the insecticidal efficacy of methanolic leaf extracts from two medicinal plants—neem (Azadirachta indica A. Juss.) and basil (Ocimum basilicum L.)—against A. gossypii under controlled laboratory conditions. Methanolic extraction was performed using the Soxhlet apparatus, and five concentrations (0.5%, 1.0%, 2.0%, 4.0%, and 8.0% w/v) of each extract were tested against adult aphids using the leaf-dip bioassay method. Mortality was recorded at 12, 24, 48, and 72 hours post-treatment, with distilled water serving as the negative control. The results demonstrated that both plant extracts exhibited significant concentration-dependent aphicidal activity. Neem extract showed superior toxicity, achieving 96.4% mortality at the highest concentration (8.0%) after 72 hours, with an LC₅₀ value of 1.82% w/v. Basil extract exhibited moderate efficacy, reaching 78.3% mortality at the same concentration, with an LC₅₀ value of 3.56% w/v. Basil extract, however, demonstrated faster initial action, with 24-hour mortality rates of 42.5% at 8.0% compared to 34.7% for neem at the same concentration and time point. Statistical analysis using one-way ANOVA followed by Tukey’s HSD test revealed significant differences among treatments (p < 0.001). These findings suggest that both neem and basil methanolic leaf extracts possess promising aphicidal properties, with neem demonstrating greater overall efficacy while basil offers more rapid initial knockdown effects. The study supports the potential integration of these botanical extracts into sustainable integrated pest management (IPM) programs for pepper cultivation, reducing reliance on synthetic chemical pesticides and promoting environmentally responsible agricultural practices.
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