Identificação de constituintes voláteis das glândulas salivares de machos de Ceratitis capitata e Anastrepha obliqua (Diptera: Tephritidae) e de seu hospedeiro Averrhoa carambola L.

Abstract

Behavioural and chemical studies were conducted with Ceratitis capitata Wied. and Anastrepha obliqua Macq. and their host fruit, Averrhoa carambola L. (starfruit). The bioassays were performed to find out the age and time of day when the reproductive behaviour (calling, mating and oviposition) were more frequent as well as which maturation stage of the starfruit, females of A. obliqua and C. capitata would choose for oviposition. The results demonstrated that reproductive behaviour were more frequent among individuals which were eleven day-old for C. capitata and fifteen day-old for A. obliqua, except for oviposition that were more frequent among individuals which were seventeen day-old in this ultimate specie. For C. capitata, the onset of calling, courtship and oviposition were 6:00-9:00, 7:00-12:00 and 14:00-16:00 h, respectively, whereas for A. obliqua, these activities were highest at 5:00-9:00, 7:00-10:00 and 9:00-11:00 h, respectively. The maturation stages of starfruit in which females of C. capitata and A. obliqua would prefer to oviposit are ripe and unripe, respectively. The chemical analyses of extracts (secretions from the salivary glands and headspace) from calling males of of both species by gas chromatography coupled to mass spectrometry (GC-MS) revealed alcohols, esters, ketones, nitrogenated compounds and terpenoids. Comparative analyses of volatiles present in the salivary gland secretion of A. obliqua and C. capitata males with those which were found to be present in headspace extracts of calling males of these species, demonstrated that 50% of the compounds released by calling males are present in the secretion of salivary glands, suggesting that these glands maybe the storage site of these compounds. It worthy to note that among this mixture of compounds, there should be the sex pheromone components of both species, since the salivary gland extracts of A. obliqua males attracted co-specific females. The results also showed that unsaturated and saturated esters were the major componentes in extracts of ripe starfruits and mono- and sesquiterpenes characterized the mixture of unripe starfruits. It was also found that there is a similarity between the chemical composition of extracts from salivary glands of C. capitata and A. obliqua and the volatiles released by ripe and unripe starfruits. two compounds were common between salivary glands secretions of C. capitata calling males and ripe starfruit extracts whereas eight common compounds were found in salivary glands secretions of A. obliqua males and unripe starfruit extracts. These findings suggest that these coincident compounds may act as chemical cues which help females of both species to find starfruits in the appropriate maturation stage for oviposition.