Asian Journal of Plant and Soil Sciences

Aphids (Aphis gossypii), a persistent agricultural pest, cause significant damage to crops by sucking phloem sap. This study aimed to evaluate the effect of ethanolic seaweed and guava leaf extracts on the population suppression of Aphis gossypii under laboratory conditions. Moreover, the experimental trial was conducted during the month of November, 2024 (rainy season). A Completely Randomized Block Design (CRBD) was employed, using seven treatments with three replications each, to thoroughly analyze the effectiveness of the extracts. The experiment consisted of treatments using three different concentrations (100%, 75%, and 50%) of guava leaf extract and ethanolic seaweed extract. The control treatment consisted of a chemical pesticide containing methomyl, applied at a concentration of 20–35 grams per 16 liters of water. The study quantified the percentage of aphid mortality at 24, 48, and 72-hour intervals post-treatment and compared the influence of botanical insecticides and the extraction methods on the extracts' efficacy. The results showed a significant increase in mortality rates with time, with SE100 obtaining 10 ± 0 (100%) mortality within 72 hours, suggesting the maximum efficacy and is comparable to the control group. In contrast, GLE100 had a mortality rate of 6.33 ± 0.58 (63.3%) after 72 hours. Hence, the data demonstrate that Sargassum polycystum and Psidium guajava have significant insecticidal activities, with seaweed extracts outperforming them. The study confirms the superiority of ethanol extracts and establishes botanical pesticides as an environmentally acceptable, sustainable pest management alternative to ecosystem-damaging synthetic pesticides.