Effects of Metformin Hydrochloride on Development and Survival in the Blow Fly Chrysomya Megacephala (Fabricius)

Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), commonly known as the oriental latrine fly, is a forensically important species frequently used in estimating the minimum postmortem interval (minPMI). However, pharmaceutical substances such as metformin hydrochloride, a widely prescribed antidiabetic drug, may interfere with insect development and compromise the accuracy of minPMI estimation. This study examined the effects of metformin on the growth, morphology, and survival of C. megacephala larvae. Five groups were established: one control and four treatment groups exposed to increasing concentrations of metformin. Larval length, weight, developmental time, and survival rate were recorded. The results revealed significant dose-dependent effects, with higher concentrations causing developmental delays, reduced larval growth, and increased mortality. At the highest concentration (2,100 mg/kg), larval length and weight were reduced by 17.16% and 32.44%, respectively. Morphological abnormalities, including darkened integument and spherical subintegumental particles, were observed, with severity correlating with dose. Scanning electron microscopy confirmed these ultrastructural changes. These findings highlight the influence of drug exposure on blow fly development and underscore the importance of considering such effects in forensic investigations to enhance the reliability of minPMI estimation.