DIFFERENTIAL LARVAL AGE SUSCEPTIBILITY OF THE MEDFLY, CERATITIS-CAPITATA WIED (DIPT, TEPHRITIDAE) TO CYROMAZINE

Ceratitis capitata Wied. larvae reared on an artificial diet supplemen ted with a range of concentrations of the IGI cyromazine, suffered sev ere developmental disruption depending on larval age. 100% mortality w as recorded when young larvae (1- and 2-day-old) were exposed to a 10 mg/kg cyromazine-treated diet, whereas later-stage larvae (6- to 9-day old larvae; L6 to L9) were able to pupate with 25 to 100 mg/kg concen trations. Moreover the adult emergence rate was severely affected in t hese cases (less than 7 % for L6 to LS, and just 36% for L9). Larval m obility (measured as popped pupae) was drastically reduced except for L9. A significant larval growth inhibition at 3 days was observed in L 2, L4 and L6, in a dependent dose manner: the median inhibitory concen tration being near 1 mg/kg for young larvae, but reaching 100 mg/kg fo r the older ones.