Identification and origin of host-associated volatiles attractive to Prorops nasuta, a parasitoid of the coffee berry borer

Previous studies have shown that prepupae/pupae and dust/frass from Hypothenemus hampei (Ferrari) reared on coffee berries were attractive to its parasitoid Prorops nasuta Waterston, while the same biological materials obtained from an artificial diet were not. In this study, we identified the volatiles from prepupae/pupae and dust/frass from H. hampei reared on Coffea canephora Pierre ex Froehner berries and artificial diet by gas chromatography coupled with mass spectrometry (GC–MS), evaluated their behavioural activity, and investigated the possible origin of the kairomones in the H. hampei dust/frass attractive to P. nasuta. The GC–MS analysis indicated that 24 peaks were consistently present in the headspace volatiles of dust/frass from H. hampei reared on coffee berries, 18 of these peaks were identified. Nineteen compounds were found in the dust/frass from H. hampei reared on an artificial diet. The compounds 1-octen-3-ol, limonene, n-tridecane, n-tetradecane, longifolene, n-pentadecane and n-heptadecane were common in dust/frass from H. hampei reared on coffee berries and artificial diet. Parasitoids were more attracted to 3-octanone, limonene, longifolene and n-dodecane compared to clean air. In contrast, P. nasuta preferred clean air to n-tetradecane. The rest of the compounds did not influence the behaviour of parasitoids. Two compounds were released by prepupae/pupae from H. hampei obtained from coffee berries, whereas six compounds were emitted by prepupae/pupae from the artificial diet. The compounds n-hexadecane and n-heptadecane were found in both types of prepupae/pupae. Parasitoids were more attracted to n-hexadecane than to clean air. In contrast, females did not show any preference for n-heptadecane or clean air. Among the compounds identified from dust/frass from H. hampei attractive to P. nasuta, only longifolene was found in the healthy C. canephora berry volatiles. Four species of fungi were isolated from the dust/frass of H. hampei, including Fusarium solani (Mart.) Sacc., Penicillium crustosum Thom, Aspergillus aculeatus lizuka and Mucor sp. Among the compounds identified in the dust/frass from H. hampei attractive to P. nasuta females, only 3-octanone was detected in the volatiles from F. solani and P. crustosum.