The effect of clubroot disease infection on oviposition preference of bertha armyworm, Mamestra configurata Walker (Lepidoptera: Noctuidae)

Infection of plants with plant pathogens can result in the upregulation of induced response reactions and change the volatile organic compound profile of the infected plant.  This may alter the appearance and suitability of the plant to foraging herbivores in the system.  Here we test if canola infected with club root disease, caused by a soil-borne protist, Plasmodiophora brassicae, influences oviposition preference and performance of the generalist herbivore, the Bertha armyworm, Mamestra configurata. Canola is an economically important crop in the Prairie Provinces of Canada.  Both club root infection and Bertha armyworm infestation are major problems in Alberta canola fields, thus it is important to study the potential interaction between clubroot diseased plants and Bertha armyworm to properly manage both threats. Two hybrid canola cultivars (Pioneer 45H26 (susceptible to clubroot) and Pioneer 45H29 (resistant)) were used in a no-choice oviposition experiment to assess the effect of clubroot infection on oviposition of Bertha armyworm. Plant growth parameters, disease severity and total number of eggs laid by female Bertha army worm moths were assessed. Following infection with clubroot, there were no clubroot symptoms or reduced plant growth in the resistant canola hybrid.  There were more eggs on infected resistant canola as compared to uninfected resistant canola plants. Fewer eggs were laid, however, on infected susceptible plants as compared to uninfected susceptible plants. Further experiments are ongoing to investigate the mechanism driving the difference in oviposition.