Abstract
The environmental dilemma facing researchers is how to control pests without damaging the environment. In light of the search for solutions to this dilemma, the current research was conducted to combat a serious pest, the red palm weevil, Rhynchophorus ferrugineus which threatens the palms of date and oil all over the world. Hematoporphyrin dihydrochloride (HPD) photosensitizer has the ability to target the tissues of the pest. After feeding and exposure to light, HPD stimulates the production of free radicals that destroy the intestinal cells and inhibit the antioxidants. The present work investigates the insecticidal effects of HPD and sheds light on its mode of action against some key antioxidant enzymes in adults, males and females of R. ferrugineus. The adults were exposed to serial concentrations of HPD, 67, 670 and 6720 ppm then exposed to direct sunlight (355 w/m(2)) for different periods, 0.5, 1, 1,5, or 2 hours. The results showed that the recorded mortality ratios were depending on both HPD concentration and sunlight exposure period. The biochemical effects of HPD on the adults resulted in significant inhibition of catalase (CAT), superoxide dismutase (SOD) and glutathione 5-transferase (GST) in insects exposed to sunlight for one hour as post-treatment period. However, the content of malondialdehyde (MDA) increased as HPD concentration increased.