Integrated control of wheat blossom midge - HGCA

Fig. 15 Ratio of females on yellow sticky: males on pheromone trap1.210.80.60.4LittleBonesSummerdells/ClaGt KnottHoosfield/Xi0.2001-Jun 08/06/200 14/06/200 21/06/2003.2 RESULTS : PART 2 – PLANT VOLATILESInitial laboratory experiments were carried out in 2002 and are reported in Birkett et al. (2004). Airentrainment samples of volatiles from panicles of intact wheat, Triticum aestivum, cultivar ‘Lynx’ werecollected at the ear emergence/early anthesis growth stage. In the olfactometer bioassay, both freshly cutpanicles and an air entrainment sample were found to attract female orange wheat blossom midge adults.Coupled gas chromatography electroantennography (GC-EAG) analyses of panicle volatiles located sixelectrophysiologically active components. These were identified by coupled gas chromatography-massspectrometry and co-injection with authentic standards, on polar and non-polar GC columns, asacetophenone, (Z)-3-hexenyl acetate, 3-carene, 2-tridecanone, 2-ethyl-1-hexanol and 1-octen-3-ol. Althoughnone of these were 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 higherdose of 100ng 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 tofemale S. mosellana as the whole air entrainment sample.In 2003 further analyses and bioassays were carried out to investigate electrophysiological andbehavioural effects of volatiles from the susceptible wheat variety ECO22 (Advanta seeds). This variety wasidentified by plant breeders as particularly susceptible to S. mosellana. Active volatiles in air entrainmentsamples were located by GC-EAG and identified by GC-MS as α-pinene, 6-methyl-5-hepten-2-one, 3-carene, acetophenone and 2-dodecanone. The natural sample (ECO22-1) was significantly attractive inolfactometer studies (P = 0.034, n = 8). A five-component blend comprising α-pinene, 6-methyl-5-hepten-2-one, 3-carene, acetophenone and 2-dodecanone in the same ratio as the natural sample (ECO22-1) was62