Sublethal effect and molecular responses of Musca domestica to cinnamon extracts

The house fly, Musca domestica L., plays a crucial role as a mechanical vector for a variety of pathogens that impact both humans and animals, highlighting the need for effective control measures. Conventional approaches, including sanitation and waste management, exhibit certain constraints, resulting in a dependence on synthetic insecticides that carry potential risks of toxicity and the development of resistance. This research examined the lethal and behavioral effects of Cinnamomum verum (cinnamon) extracts on house flies, employing an age-stage two-sex life table methodology to evaluate life table parameters. The analysis utilizing gas chromatography-mass spectrometry (GC-MS) revealed significant phytochemicals present in cinnamon bark, such as cinnamaldehyde and eugenol, which are recognized for their insecticidal and behavioral effects in insects. Acute toxicity assessments demonstrated lethal concentrations (LC₅, LC₂₅, and control) of cinnamon extracts, significantly affecting developmental and reproductive parameters. Interestingly, lower concentrations (LC₅) promoted fecundity and intrinsic growth rates compared to higher concentrations (LC₂₅), suggesting a biphasic response that aligns with the concept of pesticide-induced hormesis. Furthermore, oviposition preference trials confirmed a concentration-dependent deterrent effect of cinnamon extracts, with higher doses significantly reducing egg-laying behavior in gravid females. This research has included traditional GC-MS-based phytochemical screening by incorporating comprehensive biological and molecular assessments, offering a more integrated approach for biopesticide identification. The identification of phytochemicals like cinnamaldehyde and α-muurolene establishes a robust basis for the screening of additional bioactive compounds and exploring novel insecticidal agents.