Influence of a bacterial pathogen on vector behavior and exposure dynamics in the Cucurbita pathosystem.
Our recent studies have shown that Erwinia tracheiphila, which is vectored by cucumber beetles and causes wilt disease, can be transmitted to wild Cucurbita via the floral nectaries as well as via foliar feeding. Here, we examine the attraction of beetles to healthy and diseased plants and we examine the role of volatile organic compounds in mediating the attraction of beetles to leaves and flowers. Using GC/Mass spectrometry, we show that healthy and diseased plants differ in the total volatiles that are produced. We also show that cucumber beetles are more attracted to diseased plants under both field and laboratory conditions than to healthy plants and that the beetles prefer to eat diseased plants when provided a choice. The flowers of healthy plants, however, produce more total volatiles than the flowers from wilt diseased plants and the beetles prefer to aggregate in the flowers of healthy plants. The combination of attraction to the foliage of diseased plants and heavy feeding on diseased plants leads to high rates of pathogen acquisition by the beetles. Healthy plants are exposed to the pathogen when these beetles disperse to flowers of healthy plants and their infested frass accumulates in the vicinity of the nectaries.
Contact
Ash Pathak
akp13@psu.edu
814-867-2941