Diet Ph Effects on Mass Rearing of Mediterranean Fruit Fly (Diptera: Tephritidae)

The effects of dietary pH on larval development of the Mediterranean fruit fly, Ceratitis capituta (Wiedemann), were studied in laboratory and pilot scale mass-rearing operations. Laboratory scale diets were formulated at eight different initial pHs ranging from 3.2 to 8.0, and the effect on larvae were evaluated based on larval development time and pupal yield. Optimal larval development occurred at pH 5.0-5.5 and pupal yield was highest between 3.2 and 5.5. Diet pHs of 6.0 or higher were found to delay larval development and reduce pupal survival. Diet pHs of 3.2 and 4.0 also delayed larval development. Pilot-scale evaluations were subsequently conducted at pH 4.0 and 5.0 and compared with the normal Animal and Plant Health Inspection Service production diet for cumulative yield and pupal weight. Optimal diet pH for pupal size, larval yield, and rapid development was determined to be 5.0 in pilot-scale tests. Optimizing physiochemical factors such as pH can improve overall yield of mass-reared C. capitata.