A strong relationship exists between the livestock and blowfly, Chrysomya megacephala (Order: Diptera, Family: Calliphoridae), because it plays a major role in causing the veterinary condition known as myiasis, which involves the fly larvae invading the living animal tissues. Animal health and welfare gets severely impacted by this condition which also leads to major economic losses. The adult C. megacephala plays active role in transferring different types of pathogens, primarily bacteria, protozoans and helminthic parasites. The common practice followed for the management of insect population including blowflies in Central Punjab involves the use of insecticides. But their repeated exposure has resulted into emergence of resistances in various insect species against these insecticides. This study assessed the resistance levels of blowfly populations against several insecticides, including deltamethrin, fipronil, chlorpyrifos, imidacloprid, and pyriproxyfen. Insecticide bioassays involving both adult and larval stages of C. megacephala were followed to assess the resistance profiles. The studied populations displayed different levels of resistance at different concentrations. Overall results showed moderate resistance to deltamethrin (8.57-15.84) fold, whereas the resistance to fipronil, chlorpyrifos, imidacloprid and pyriproxyfen was found to be very low with resistance values ranging from (3.34-8.38) fold. The enzyme assays demonstrated significant upregulation of certain enzymes including monooxygenase, glutathione-S-transferase, and non-specific (α and β) esterase activities in response to insecticide exposure. This suggests a functional role for these enzymes in the development of resistance, potentially through the detoxification of insecticides or the modification of target site sensitivity. Our findings provide insights into the biochemical basis of insecticide resistance in this species, with implications for the development of novel control strategies in veterinary medicine. This research aims to inform evidence-based approaches for managing blowfly populations and mitigating their impact on animal health.

To Cite This Article: Javaid S, Mukhtar MK, Amjad N, Khan SY and Khan HAA 2025. Enzymatic detoxification of insecticides in blowfly (Chrysomya megacephala): a threat to ectoparasite control in livestock from Central Punjab, Pakistan. Pak Vet J, 45(2): 825-833. http://dx.doi.org/10.29261/pakvetj/2025.192