Responses of female orange wheat blossom midge, Sitodiplosis mosellana, to wheat panicle volatiles

Air entrainment samples of volatiles from panicles of intact wheat, Triticum aestivum, cultivar 'Lynx' were collected at the ear emergence/ early anthesis growth stage. In an olfactometer bioassay, both freshly cut panicles and an air entrainment sample were found to attract female orange wheat blossom midge adults, Sitodiplosis mosellana. Coupled gas chromatography-electroantennography (GC-EAG) analyses of panicle volatiles located six electrophysiologically active components. These were identified by coupled gas chromatography-mass spectrometry and coinjection with authentic standards, on polar and nonpolar GC columns, as acetophenone, (Z)-3-hexenyl acetate, 3-carene, 2-tridecanone, 2-ethyl-1-hexanol, and 1-octen-3-ol. Although none of these was active when presented individually at the levels present in the entrainment sample, acetophenone, (Z)-3-hexenyl acetate, and 3-carene were active in the olfactometer when presented at a higher dose of 100 ng on filter paper. However, the six-component blend and a blend of acetophenone, (Z)-3-hexenyl acetate, and 3-carene, in the same ratio and concentration as in a natural sample, was as attractive to female S. mosellana as the whole air entrainment sample.