Developmental rates of immatures of three Chrysomya species (Diptera: Calliphoridae) under the effect of methylphenidate hydrochloride, phenobarbital, and methylphenidate hydrochloride associated with phenobarbital.

Entomotoxicology is focused on obtaining data on necrophagous entomofauna, for criminal investigations purposes. This study aimed to evaluate the effect of different concentrations of methylphenidate hydrochloride, phenobarbital, and their association on the developmental rate, larval and pupal survivorship, and the interval of emergence of adults of Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius), and Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae). Considering the therapeutic dose (TD) of methylphenidate hydrochloride (0.29 mg/Kg), the concentrations tested were 10× TD, 50× TD, and 100× TD. For phenobarbital, the concentrations used were 1× TD (=150 mg/Kg), 3.3× TD, and 6.7× TD. For the association of the drugs, the combinations used were 10× TD-methylphenidate hydrochloride plus 1× TD-phenobarbital, 50× TD-methylphenidate hydrochloride plus 3.3× TD-phenobarbital, and 100× TD-methylphenidate hydrochloride plus 6.7× TD-phenobarbital. The control group, without addition of drug, was maintained under the same conditions of temperature (25 ± 1 °C), humidity (70 ± 10%), and photoperiod (12 h). Specimens of each group were weighed every 12 h until pupariation. The developmental rate of the three Chrysomya species immatures was monitored. For C. albiceps the developmental time was delayed in 24 h for methylphenidate hydrochloride group and in 12 h for the phenobarbital and the drugs association groups. The effect was observed only at specific ages for C. megacephala, without altering the developmental time. For C. putoria, the developmental time was delayed in 12 h for methylphenidate hydrochloride group and in 24 h for the phenobarbital and the drugs association groups. The emergence interval was similar among all experimental groups, but larval and pupal viabilities were affected in different ways.