Effect of citrus peel in the viability of Anastrepha fraterculus (Wied.) and Ceratitis capitata (Wied.) immature stages

RUIZ, M.J.; JUÁREZ, M.L.; ALZOGARAY, R.; ARRIGHI, F. ; ARROYO, L.; GASTAMINZA, G.; WILLINK, E.; BARDÓN, A.; VERA, M.T.

Congreso; The 9th International Symposium on Fruit Flies of Economic Importance; 2014

Background: Various compounds, present in the essential oil of citrus peel, are involved in certain important mechanisms of resistance of citrus against fruit fly infestation and determine the condition of a given fruit as a host. For the South American fruit fly, Anastrepha fraterculus it has been postulated that lemon is not a host and for the Mediterranean fruit fly, Ceratitis capitata, its status as potential non-host is well recognized. We evaluated the toxic effects of the peel ether extracts from lemon and grapefruit, as well as the effects of two pure compounds (limonene and citral) on the viability of eggs and larvae of A. fraterculus and C. capitata. Methods: Eggs and first instar larvae were exposed to different concentrations of extracts and pure compounds. The number of hatched and unhatched eggs was quantified after five days of incubation at 25°C. Larval mortality was determined after 24 h of exposure. The chemical composition of peel ether extracts was established by Gas Chromatography-Mass Spectrometry (GC-MS). Results: All products assayed produced a dose-dependent mortality on eggs and larvae of both species, being larvae more sensitive than eggs. Citral at the highest concentration tested (0.02 µl/µl carboxymethylcellulose emulsion) was more toxic to eggs of A. fraterculus than to eggs of C. capitata. Grapefruit extract displayed a higher toxicity on eggs of A. fraterculus than on C. capitata eggs. Lemon extract and limonene were equally toxic to eggs of both species. Extracts and pure compounds produced identical toxic effects on larvae of both fruit fly species. The chemical composition of grapefruit and lemon essential oils was different. Conclusions: As observed for other fruit fly species, grapefruit and lemon extracts as well as citral and limonene result toxic to A. fraterculus and C. capitata immature stages thus confirming that host resistance is related to plant chemical products. Differences observed in the toxicity on eggs of the two fruit flies tested might be due to differences in the permeability of the chorion to certain compounds.