The effect of anabolic-androgenic steroids on the developmental rate of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), a forensically important fly in Brazil

The knowledge of the effect of drugs, on the development of necrophagous insects can be very important when the estimate of the postmortem interval (PMI) is based on insect age. The presence of these substances in tissues may interfere on the necrophagous insects developmental rate, thus potentially altering the PMI. This study aimed to assess the effect of different concentrations of nandrolone decanoate (Deca-Durabolin™) (DE) associated to testosterone esters (Durateston™) (DU) on the developmental rate of Chrysomya megacephala (Diptera: Calliphoridae). These anabolic-androgenic steroids (AAS) are commonly used by bodybuilders to produce muscle mass gain. Four experimental groups were used: 2.25 mg/kg DE+3.57 mg/kg DU; 11.25 mg/kg DE+35.7 mg/kg DU; 22.5 mg/kg DE+357 mg/kg DU, and the control group without any drugs. Individual weights were recorded for groups of 10 larvae at 12h intervals from larvae eclosion until the pupal stage. One-way ANOVA was performed to compare the effect of the treatments on larval. Duncan’s test was used to compare the means. Differences were not observed on the developmental time of larvae (120h) (p=0.7463) and on the emergence interval (peak at 264 h) in all groups. However, larval viability (F=4.8449; p=0.0330) and emergence rate (F=11.5463; p=0.0033) of C. megacephala were affected by higher concentrations of AAS. At most ages (24, 48, 60, 84, 108 and 120h), the weight gain of the groups exposed to higher concentrations of DE+DU was different from the control group. These results evidence that a possible error in PMI estimate may occur if the effect of these drugs is ignored.