the photoactive compounds phloxine B and menadione are relatively safe food additives and possess efficient insecticidal properties against certain insect species. The two compounds were tested for toxicity to the peach fruit fly, Bactrocera Zonata (Saunders) under both dark and sunlight conditions. Both compounds had no significant toxic effect in dark and concentration-dependent toxicity when insect exposed to sunlight for 2 hrs. Phloxine B was approximately 1000 time more toxic to B. zonata than menadione with LC25 in the water of 0.0007 g% and 0.854 g% (w/v), respectively. Adding menadione to phloxine resulted in significant antagonistic effects on insect mortality, which could be due to menadione alteration of the pH of the feeding media and/or menadione induction of the ROS-detoxifying enzymes, particularly peroxidase. It is concluded that phloxine B and menadione are incompatible and their mixture is not likely to pose any significant addition to their control potential against B. zonata.