Effect of Citrus Peel in the Viability of Anastrepha fraterculus (Wied.) and Ceratitis capitata (Wied.) Immature Stages

M. JOSEFINA RUIZ; LAURA JUÁREZ; RAÚL A. ALZOGARAY; FEDERICO ARRIGHI; LORENA ARROYO; GERARDO GASTAMINZA; EDUARDO WILLINK; ALICIA BARDÓN; TERESA VERA

Bangkok

Simposio; 9 th 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.