Insecticidal activity and physiological property of Annona squamosa (L.) seed extracts against the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

Abstract

Insecticidal activity and biological properties of A. squamosa seed extracts against C. capitata were evaluated in the laboratory. Extracts were effective against the medfly from egg to adult stages. Extract bioassays with respect to medflies clearly demonstrated that A. squamosa contained a factor toxic to insect. Assays successfully guided extract fractionation to yield 1 or 2 active insecticidal compounds. Insect active fraction was 2.5 x 10^-3 and 2.07 x 10^-3 as toxic as malathion to male and female flies, respectively. Topical application of sublethal doses of ~ squamosa seed extracts caused no abnormal behavior among the flies. Insects were able to feed, undergo courtship behavior, mate and oviposit eggs. The extract did not affect adult longevity but exhibited a chemosterilant effect by reducing egg hatchability. Significantly, less eggs hatched when dipped in > 0.313% of extract. Measurement of ovarian length of treated flies revealed that extract affected oocyte development. Ovarian growth was significantly reduced which suggests interference with vitellogenesis. The extract was a repellent and an oviposition deterrent. Significantly, fewer flies were attracted to treated papaya tissues. Chronic exposure to A. squamosa seed extract treated diets affected insect growth and development. Larval period was significantly prolonged and pupation was reduced. Delays in development occurred only during larval period with no treatment effect on length of pupal period.