: IDENTIFICATION OF A SEX-SPECIFIC COMPOUND PRODUCED BY Xyleborus sp., A BEETLE ASSOCIATED WITH COCOA TREE

Abstract

Beetles of the genus Xyleborus Eichhoff, 1864 (Coleoptera: Curculionidae) have been recorded since the 19th century in cocoa crops in the state of Bahia, Brazil. They are considered vectors of Ceratocystis cacaofunesta, the etiologic agent of Ceratocystis wilt disease. The purpose of the present study was to identify sex-specific compounds of Xyleborus sp. For this, cocoa tree trunks infested with Xyleborus sp. were collected in the municipalities of Ilhéus and Mutuípe, both located in Bahia State. The trunks were transported to the Biological Control and Semiochemical Laboratory (LaCoBSe) at the State University of Santa Cruz (UESC). The insects were removed from the galleries formed in the trunks and subsequently separated by sex. For the extraction of volatiles, aeration was performed in glass chambers, using a vacuum pump, operating with air flow of 1.0 L/min. The volatiles released by the insects and carried by air were adsorbed on polymer in a period of 72 hours, on triplicates for each sex. The elution of the adsorbed compounds in the polymers was performed with 200 µL of hexane per repetition and stored in a freezer at -20 °C, and then analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Based on the interpretation of the chromatograms obtained from the analyzes, it was possible to verify the presence of a sex-specific compound produced by females of Xyleborus sp. Through the mass spectrum analysis, the retention index calculation and comparison of the data with the literature, this compound was identified as an unsaturated ester. It is a compound of great interest for presenting sex-specificity, and these data serve as a basis for research on techniques for the management of this insect in the field.