Insecticidal effects of methanolic extracts of tephrosia vogelii, tithonia diversifolia, azadirachta indica, and ocimum americanum on fleas

Abstract

Background: Fleas are important ectoparasites of veterinary and public health significance. Currently, there is growing interest in plant-based alternatives to synthetic insecticides for their control. This study aimed to experimentally assess the insecticidal effects of extracts from plants traditionally used in Tanzania to manage ectoparasites. Methods: An experimental study was conducted over four months in the Morogoro Region. Plant collection and processing were carried out in June and July 2025, while extract preparation and testing were conducted between January and April 2026. Different concentrations of leaf extracts from Tephrosia vogelii, Tithonia diversifolia, Azadirachta indica, and Ocimum americanum were evaluated for their insecticidal activity against fleas. The extracts (100mg/ml) were tested at concentrations of 25%, 50%, 75%, and 100% following a single exposure to determine their effectiveness. Flea mortality was monitored over time, and survival rates were analyzed using the Kaplan–Meier test. Results: All four plant species demonstrated insecticidal activity, causing complete flea mortality at varying concentrations and post-exposure times. T. vogelii exhibited rapid activity, with 100% mortality achieved within 2 hours at 100% concentration and within 3 hours at 50% and 75% concentrations. T. diversifolia showed high efficacy, with 25%, 50%, and 75% concentrations causing 100% mortality within 2 hours, while the 100% concentration achieved complete mortality after 4 hours. A. indica produced 100% mortality within 4 hours at 25%, 50%, and 100% concentrations, whereas the 75% concentration required 6 hours. O. americanum caused complete mortality after 3 hours at 75% concentration, after 4 hours at 25%, and after 12 hours at both 50% and 100% concentrations. Conclusion: Overall, all plant extracts were highly effective against fleas and performed comparably to the positive control, indicating their potential as environmentally friendly botanical insecticides for flea management.