[Effect of ketamine on the development of Chrysomya megacephala (Diptera : Calliphoridae)]

To research the pattern of larvae and pupae development when exposed to ketamine.

The larvae of Chrysomya megacephala were reared in artificial diet containing ketamine with concentration of 0, 25, 50 and 100 mg/kg respectively at 32 degrees C, 28 degrees C and 24 degrees C in environmental chamber with a 12-h photoperiod and 75% humidity. 10 samples were collected from each group every 12 h from the 16th h after hatching to pupation. The max body length, weight of the larvae, growth rate of body length, weight and developmental duration of each stage were observed.

The average length and weight in the treatment groups were significantly less than the control before achieving the maximum (P < 0.05), and the growth rate of 1/2LD50 group at 24 degrees C was most retarded. No dose dependence were observed among the ketamine fed groups. The effect of ketamine dose, temperature and their interaction on larval length and weight was statistically significant (P < 0.01). The effect of ketamine dose, temperature and their interaction account for, respectively, 20.9%, 60.2% and 18.9% of the total effect on growth of larval length, and they account for 8.3%, 85.6% and 6.1% of the total effect on growth of larval weight. The duration of larval stage in treatment groups was significantly delayed in comparison to the control at different temperatures (P < 0.05), and the duration of prepupal stage in treatment groups was significantly delayed (P < 0.05). However, the duration of pupal stage in treatment groups at 24 degrees C was significantly shorter than the control (P < 0.05).

The time achieving maximum length and weight was significantly delayed, which results in an increased development duration of larval and prepupal stages, indicating that ketamine inhibits the growth of the larvae of C. megacephala.