Effects of DifferentSemiochemicalFound in the Sex Pheromone of the Males onthe Response of Anastrepha fraterculus Females.

BřÍZOVÁ; JUÁREZ; RUIZ; KALINOVÁ, ; BACHMANN; SEGURA; FERNÁNDEZ; TEAL ; VERA

Bangok

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

Background: Anastrepha fraterculus (Wiedemann) has a lek mating system. At the lek, males emit a sexual pheromone to attract females. Once in the lek, females choose with whom to mate and strong sexual selection operates over several traits. Pheromone composition has been shown to be variable among the several morphotypes of this cryptic species. The morphotype present in Argentina has at least 30 compounds that are emitted by males. Females displayed strong electroantennographic (EAG) responses to five of them. Here we tested if some of these compounds (presented alone or in a blend) elicit a behavioral response in A. fraterculus females. Methods: To determine female behavioral response, we performed laboratory trials in which 10 virgin females were released in a testing cage that contained two landing stations: one with the test stimulus and one with the blank. The stimuli consisted of: farnesene (in a mixed of Z,Z-α-farnesene and Z,E-α-farnesene at a 4:1 ratio) at 4 different concentrations; nonenol [(3Z)-non-3-en-1-ol]; a three component blend of farnesene, nonenol and nonadienol [(3E,6Z)-nona-3,6-1-ol] at a 1:1:1 ratio; extracts from the collection of pheromone volatiles; and five live males confined in a container (artificial lek). The hexane solution of the respective individual compounds, the blend and the male pheromone extract were loaded on a piece of white filter paper (5 cm2). After solvent evaporation, the paper was hung from the top of the cage; the males were confined in a perforated container that allowed pheromone dispersion and also hung from the top of the cage. In the case of the single components, the blend or the extract, the blank was hexane; for the calling males, the blank was the same container without males. The cage was virtually divided in two halves and the number of females in each side was scored every 10 minutes for two hours. Observations took place early in the morning (time at which flies are sexually active) under ambient temperature in a room that had natural light. Results: Females were significantly attracted to the artificial leks. Female response to farnesene was concentration dependent. Low concentrations elicited attraction, while higher concentrations were repellent. At the concentration tested, nonenol was significantly attractive as well as the three component blend. Surprisingly, the pheromone collection extract did not elicit any attraction. Only a single concentration was tested, so the pheromone collection needs further evaluation.Conclusions: At least two compounds emitted by A. fraterculus males have been shown to be EAG active to females and attract females when they are offered individually. It would be interesting to see now if these compounds elicit a higher attraction when they are together (synergisms) and if they are involved in species recognition within the complex.