Arable: Yellow Wheat Blossom Midge - an emergent threat to UK wheat production

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Yellow Wheat Blossom Midge (Contarinia tritici; YWBM) is a poorly understood pest of wheat, with no reported host resistance. Its larvae feed on wheat anthers and stigmas, leading to significant yield losses. The complex control of both adult midge emergence and wheat flowering time means that YWBM outbreaks can be sporadic and difficult to predict. We aim to further our knowledge of this pest and its impact.

Previously, some NIAB experimental wheat pre-breeding lines have shown consistently little YWBM damage, in contrast to nearby varieties at matching developmental stages. Partners will grow promising NIAB lines alongside susceptible commercial varieties at several field locations and monitor YWBM levels. Samples of unripe ears containing live larvae and soil containing dormant pupae from these trials will be used as a source of midges.

At NIAB East Malling, midges will be reared individually until they emerge as adults, with sex determined through differences in genital and antennal morphology. Volatiles will be collected from groups of virgin adult males and females through headspace entrainment onto Porapak.

At NRI, potential pheromone components will be determined through GC coupled to electroantennographic recording (GC-EAG), and their possible structure determined by gas chromatography - mass spectrometry. Identification will be informed by differences in volatiles produced by males and females, and by our experience with related species (e.g., the newly discovered oilseed rape pest Contarinia brassicola). We will begin synthesis of potential pheromone components, and if supply of midges allows, confirm their detection by males through GC-EAG.

Future possible work includes investigations into the genetic control of host resistance, the optimisation of synthetic pheromone lure traps, and the feasibility of maintaining laboratory colonies of YWBM to further understand its life cycle and host interactions.