EFFICACY OF OREGANO (ORIGANUM VULGARE) AND TAWA-TAWA (EUPHORBIA HIRTA) STEM EXTRACTS AS LARVICIDE AND MOSQUITO KILLER

Abstract

Herbal plants such as oregano (Origanum vulgare) and tawa-tawa (Euphorbia hirta) are widely recognized in the Philippines for their medicinal properties. While previous studies have highlighted their bioactive compounds and therapeutic benefits for common illnesses, their combined efficacy as larvicides and mosquito killers remains underexplored. This study addressed this gap by investigating the larvicidal and adult mosquito-killing effects of combined oregano and tawa-tawa stem extracts. A true experimental research design was employed to analyze variations in mortality rates and knockdown times of mosquito larvae and adult mosquitoes exposed to different extract formulations: 60% tawa-tawa and 40% oregano, 40% tawa-tawa and 60% oregano, and 70% oregano and 30% tawa-tawa. Negative (water) and positive (commercial mosquito killer) controls were included for comparative analysis. Plant extracts were obtained through maceration, and phytochemical screening was conducted using Mayer’s test to determine the presence of bioactive compounds. Phytochemical screening revealed the presence of alkaloids in both tawa-tawa and oregano stem extracts, indicating potential bioactivity. One-way ANOVA results for mosquito larvae showed a significant difference (F = 6.2 > Fcrit = 3.48, p < 0.05) between the plant extract formulations and the commercial product, leading to the rejection of the null hypothesis. In contrast, results for adult mosquitoes showed no significant difference (F = 3.46 < Fcrit = 3.48, p = 0.05), indicating insufficient evidence to reject the null hypothesis. Among the tested formulations, the combination containing 70% oregano and 30% tawa-tawa demonstrated the highest efficacy. The findings demonstrated that all three combinations of oregano and tawa-tawa stem extracts exhibited strong larvicidal activity and showed potential as mosquito-killing agents. The effectiveness of the extracts against both larvae and adult mosquitoes was comparable to that of commercially available products. These results highlighted the promising potential of oregano and tawa-tawa stem extracts as natural and environmentally friendly alternatives for mosquito and pest control.