Changes in an insect-plant interaction under varying water availability: Implications for the cereal leaf beetle, Oulema melanopus, and the host plant wheat, Triticum aestivum

The cereal leaf beetle, Oulema melanopus (Coleoptera: Chrysomelidae) is an introduced, widespread pest of small grains causing economic losses to wheat, oats, and barley throughout North America. Climate models indicate environmental suitability for this insect could increase by the mid-21^st century, but these models do not consider the indirect effects of climate-related stress on the beetle through its predominant crop host plant, wheat (Triticum aestivum). A direct effect of projected rising temperatures on agricultural systems in the inland Pacific Northwest is changes in crop-plant water availability, with the potential for an increase in frequency of drought and plant water stress. Previous studies on the effects of host plant water availability on insect herbivores remain largely inconclusive, and none exist for O. melanopus. We are testing the effects of differing water availability for wheat on the performance, behavior, and phenology of O. melanopus and the growth of the host plant in a glasshouse setting. This research aims to provide improved understanding of the dynamics of this economically important insect-plant interaction in a projected warming environment, and its potential impacts on future cereal grain agriculture in the Pacific Northwest and elsewhere in North America.