Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2017
Publication Date: N/A
Citation: N/A Interpretive Summary: Psyllid and leafhopper insects are well-known to transmit pathogens to many crops, including solanaceous plants like potatoes, tomatoes, and peppers; negatively affecting production in the United States and around the world. Researchers at USDA-ARS Wapato in Washington, in collaboration with scientists at INIFAP in Mexico, assessed symptomatic pepper plants collected from central Mexico for the presence of several common pathogens transmitted by psyllids and leafhoppers that affect these solanaceous crops. Interestingly, several pathogens were detected within each field, and more surprisingly, several pathogens were detected in individual plants within a field. Similarly, the psyllid and leafhopper insect vectors also contained mixed-infections. These results suggest that mixed-infections are more common than previously thought, and further suggest those who growers in Central and North America will need to effectively monitor and control the psyllids and leafhoppers to prevent the decline of their crops and any economic losses that may result from these pathogens.
Technical Abstract: In the fall of 2014, five to seventy-five percent of chili and bell peppers (Capsicum annuum L.) in commercial fields located in the Mexican states of Durango, Zacatecas, and Michoacán, had various symptoms of deformed, small, mosaic, curled, and chlorotic leaves, shortened internodes and plant dwarfing, and/or phyllody and rosetting leaf tips. At the same time, leafhoppers and psyllids were observed in the fields, and over 50 beet leafhoppers (Circulifer tenellus Baker) and nearly 300 potato psyllids (Bactericera cockerelli Sulc) were collected from the pepper plants and adjacent weeds. Based on the insect pressure and observed symptoms, nearly 400 pepper samples were collected across this region of Mexico and tested for the presence of leafhopper- and psyllid-associated pathogens. Seventy six percent of the pepper samples were found to be infected with ‘Candidatus Liberibacter solanacearum’ (Lso), beet leafhopper transmitted virescence agent (BLTVA) phytoplasma, a strain of curtovirus, or a combination of any two or three of these pathogens. Additionally, 77% of the collected leafhoppers and 40% of the psyllids were infected with one or more of these pathogens, in addition to Spiroplasma citri. Specifically, the leafhoppers were infected with BLTVA phytoplasma, S. citri, and/or a strain of curtovirus. Of particular interest, potato psyllids were not only infected with Lso, but also with phytoplasmas that belong to the groups 16SrVI subgroup A and 16SrI subgroup A. The presence of mixed infections in pepper plants and the insect vectors highlights the need for growers to effectively control both leafhoppers and potato psyllids from solanaceous crops in this region of Mexico in order to prevent the spread of these bacterial and viral pathogens.