TRANSMISSION OF BACTERIAL BLIGHT OF COTTON, XANTHOMONAS CAMPESTRIS PV. MALVACEARUM, BY FEEDING OF THE COTTON FLEAHOPPER: IMPLICATIONS FOR STRESS ETHYLENE-INDUCED SQUARE LOSS IN COTTON

Using a model system of cotton and the causative agent of bacterial blight, Xanthomonas campestris pv. malvacearum (Smith) Dye (XCM), microbial transmission by feeding of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (CFH), was studied. In controlled feeding tests, artificially infested CFH infected 51% of the plants they attacked. Of these infected plants, 81% exhibited symptoms of the disease, while 19% did not exhibit symptoms, but contained the bacterium. After feeding to acquire XCM, salivary glands and alimentary tracts were dissected and assayed for the presence of XCM. The bacterium was reisolated from 60% of the salivary gland pairs examined, and 95% of the alimentary tracts that were analyzed. In addition, viable bacteria were isolated from 76% of CFH fecal spots which were collected within a 24 h period after insects fed on the bacterium. XCM was present in 73% of the aliquots taken from a solution which was used to surface sterilize CFH after feeding on the bacterium. The implications of CFH as vectors of microorganisms to cotton and the resulting increase in stress ethylene production by the plant are discussed.