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 the Mediterranean fruit fly (Ceratitis capitata), was used to investigate whether insect cell s in culture could develop resistance to Malathion. After 20 cycles of puls e-chase treatment (28 h exposure to 90 mu g/ml of Malathion and 48 h recove ry in normal medium), a Mal 90 selected population was obtained. DNA conten t analysis showed that the values were distributed between levels 2C and 4C and no accumulation of cells in a specific phase of the cell cycle was obs erved. Furthermore, preliminary molecular analysis showed no amplification of the esterase gene in resistant cells. Cross-resistance of Mal 90 cells t owards other insecticides was assayed and found to be absent. Our data supp ort the idea that the medfly cell line and, more generally, insect cell cul tures, could represent a promising system to investigate insecticide resist ance mechanisms.