Induction of Malathion resistance in CCE/CC128 cell line of Mediterranean fruit fly (Ceratitis capitata (Wied.))(Diptera: Tephritidae)

The CCE/CC128 cell line, derived from fertilized eggs of theMediterranean fruit fly (Ceratitis capitata), was used toinvestigate whether insect cells in culture could developresistance to Malathion. After 20 cycles of pulse-chasetreatment (28 h exposure to 90 μg/ml of Malathion and 48 hrecovery in normal medium), a Mal 90 selected population wasobtained. DNA content analysis showed that the values were distributed between levels 2C and 4C and no accumulation ofcells in a specific phase of the cell cycle was observed.Furthermore, preliminary molecular analysis showed noamplification of the esterase gene in resistant cells.Cross-resistance of Mal 90 cells towards other insecticides wasassayed and found to be absent. Our data support the idea thatthe medfly cell line and, more generally, insect cell cultures,could represent a promising system to investigate insecticideresistance mechanisms.