| Summary: | In the current study, to combat insecticide resistance, we explored larvicidal, ovicidal, synergistic, and repellent activities of <i>Sophora alopecuroides</i> extract and its dominant constituents against <i>Aedes albopictus</i>. The results of the toxicity bioassays demonstrated that the extract of <i>S. alopecuroides</i> exerted significant larvicidal activity (16.66–86.66%) against the third-instar larvae of <i>Ae. albopictus</i> at different concentrations (5–50 ug/mL) and low hatchability of eggs (2.32–75%) at 5–50 ug/mL. The constituents of <i>S. alopecuroides</i> showed a synergistic effect when applied as a mixture (LC<sub>30</sub> + LC<sub>30</sub>) against larvae, while no synergistic effect was observed against the eggs of <i>Ae. albopictus</i>. <i>S. alopecuroides</i> extract provided 93.11% repellency in the first 90 min and gradually decreased to 53.14% after 240 min, while the positive control DEET (N,N-diethyl-3-methylbenzamide) showed 94.18% in the first 90 min and 55.33% after 240 min. All of the results exhibited a concentration-dependent effect. To the best of our knowledge, this is the first time that a study has identified a highly effective extract of <i>S. alopecuroides</i>, which could be used as an alternative agent to control larvae and eggs and to repel adults of <i>Ae. albopictus</i>.
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