Sex pheromone of the iris gelechiid moth Monochroa divisella

The iris gelechiid moth, Monochroa divisella (Douglas) (Lepidoptera: Gelechiidae), is a serious pest in iris horticulture. The overuse of pesticides for conventional control has a great risk of water pollution because irises are often planted in damp areas. To minimize pesticide applications, it is essential to monitor moth emergence by using pheromone traps. The female pheromone of M. divisella was analyzed by means of gas chromatography‐electroantennographic detection (GC‐EAD) and GC‐mass spectrometry. Two male EAD‐active compounds were detected and identified as (Z)‐3‐dodecenyl acetate (Z3‐12:Ac) and (Z)‐5‐tetradecenyl acetate (Z5‐14:Ac), the amounts of which were ca. 40 and 6 ng per female (100:15), respectively. Synthetic Z3‐12:Ac alone attracted only a few males in field trap experiments, but the attractiveness was significantly enhanced when 15% (wt/wt) Z5‐14:Ac was added; traps baited with their binary mixtures captured 21.3‐106.4 males/trap/day, as compared with 2.3 males/trap/day attracted by a crude extract of 10 virgin females. We conclude that Z3‐12:Ac and Z5‐14:Ac are M. divisella pheromone components, which can be offered as an attractant in monitoring traps. Although dodecenyl acetates are a major class of lepidopteran pheromone components, those with the double bond at the 3 position are rare and appear to be unique to gelechiids.