|Buchman, Jeremy -|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 11, 2011
Publication Date: December 30, 2011
Citation: Buchman, J., Markley, B.E., Munyaneza, J.E. 2011. Effects of liberibacter-infective Bactericera cockerelli (Hemiptera: Triozidae) density on zebra chip potato disease incidence, potato yield, and tuber processing quality. Journal of Economic Entomology. 104(6):1783-1792. Interpretive Summary: Zebra chip, an important disease of potato, is caused by a new bacterial pathogen that is vectored by the potato psyllid. Researchers at USDA-ARS Wapato, WA determined how many insects per plant are required to cause the disease. It was discovered that a single potato psyllid was as damaging as 25 psyllids per plant, causing substantial potato yield loss and reduction in tuber processing quality. This information will help potato producers minimize damage caused by this disease by developing effective psyllid monitoring strategies and controlling this insect pest with insecticide sprays, even when its numbers in the field are very low.
Technical Abstract: In plant pathosystems with insect vectors, disease spread, incidence, and severity are often dependent on the density of the vector population and its rate of infectivity with the disease pathogen. The potato psyllid, Bactericera cockerelli (Šulc), has recently been associated with zebra chip (ZC), an emerging and economically important disease of potato in the United States, Mexico, Central America, and New Zealand. “Candidatus Liberibacter solanacearum”, a previously undescribed species of liberibacter has been linked to the disease and is transmitted to potato by B. cockerelli. Experiments were conducted under laboratory and field conditions to determine the impact of B. cockerelli density on ZC incidence, potato yield, and tuber processing quality. Insect densities ranging from one to 25 liberibacter-infective psyllids per plant were used during the experiments. Results showed that a single adult potato psyllid was capable of inoculating liberibacter to potato and causing ZC disease after a 72-h inoculation access period and was as damaging as 25 psyllids per plant. In addition, ZC-diseased plants showed a sharp reduction in tuber yield but the disease response was independent of the density of psyllids. Furthermore, both glucose and sucrose were found to have highly elevated concentrations in ZC-diseased potato tubers compared with non-infected ones and psyllid density did not vary the response. The high reducing sugar concentrations found in ZC-infected potato tubers are believed to be responsible for browning and reduced quality in processed ZC-infected tubers. This information could help ZC-affected potato producers in making effective management decisions for this serious disease.