Using agronomic traits and semiochemical production in winter wheat cultivars to identify suitable trap crops for the wheat stem sawfly

Trap crops are a plausible control strategy for the wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), especially in alternate wheat fallow cropping systems. Identifying the most suitable winter wheat (Triticum aestivum L., Poaceae) cultivars is necessary to further improve the effectiveness of winter wheat trap crops. We compared cultivars suitable for cultivation in Montana to identify those that exhibit the greatest potential as trap crops. To accomplish this we used nine winter wheat cultivars to analyze plant characteristics that influence the oviposition behavior of the WSS: stem height, stem diameter, rate of plant development, and emission of the WSS attractant (Z)-3-hexenyl acetate. Data on sawfly-induced stem cutting collected from these cultivars in field nurseries were analyzed to evaluate the potential of each cultivar to attract sawflies. Based on these criteria, five cultivars with good potential as trap crops are 'Norstar', 'Neeley', 'Morgan', 'Rampart', and 'BigSky'. More data from laboratory preference tests and detailed measurement of semiochemical production from these cultivars are required for selecting optimal cultivars for trap-cropping.