LABORATORY EVALUATION OF THE NOVEL NATURALLY DERIVED COMPOUND SPINOSAD AGAINST CERATITIS-CAPITATA

Laboratory studies were conducted to determine the effect of the natur ally derived compound spinosad on Ceratitis capitata Wied. (Diptera, T ephritidae). The organophosphate fenthion was used as a standard. Dire ct dose-dependent mortality and reduced fecundity were observed in ora l treatment of adults with spinosad. The LC(50) values 14 h and seven days after treatment were 19 . 50 and 0 . 49 mg litre(-1) respectively . Fenthion was less active (the LC(50) eight days after treatment was 1 . 17 mg litre(-1)) and did not affect the fecundity of the fly. Adul ts were also very susceptible to spinosad and fenthion via residual co ntact. For spinosad, 100% mortality was recorded 48 h after treatment for a dose of 10 mg litre(-1). Spinosad was more effective than fenthi on in suppressing larval development when neonate larvae were reared o n treated diet supplemented with a range of concentrations from 0 . 02 to 0 . 83 mg kg(-1) diet. Last-instar larvae were much less susceptib le to spinosad or fenthion when exposed via dipping or when they pupat ed in treated medium and both products had similar performance. A lack of ovicidal activity was observed in direct egg-treatments with spino sad but significant reductions from 1 mg litre(-1) onwards were record ed for fenthion.