Control efficacy of <i>Bidens pilosa</i> L. extract against immature stages of <i>Musca domestica</i> L. (Diptera: Muscidae): laboratory and semi-field evaluations

The development of environmentally friendly insecticides is crucial for managing house fly ( Musca domestica ) populations in urban and agricultural settings. This study evaluated the insecticidal potential of Bidens pilosa extracts against the immature stages of house flies. In the laboratory, extracts using solvents of varying polarity were tested against eggs, larvae, and pupae. The insecticidal activity of B. pilosa extracts varied by solvent and life stage. Hexane and ethyl acetate extracts were the most effective ovicides and showed high larvicidal toxicity upon ingestion. In contrast, acetone and ethanol extracts acted as potent contact larvicides, while the hexane extract was also significantly pupicidal. Notably, extracts with lower lethal effects still demonstrated significant sub-lethal impacts by affecting the insect growth. The ethyl acetate extract, identified as the most effective, was evaluated for its impact on detoxifying enzyme activities. This extract was found to significantly inhibit glutathione-S-transferase (GSTs) activity in treated larvae but did not affect carboxylesterase (CarE). A subsequent field trial on a poultry farm using the ethyl acetate extract resulted in a 75.71% reduction in the house fly population within three days. Gas chromatography-mass spectrometry (GC-MS) analysis identified linolenic acid as a major compound. These findings demonstrate that B. pilosa extract, particularly the ethyl acetate fraction, is a promising botanical insecticide for effective house fly control.