Insinga, J.K., A. Alyokhin, J. Hao, T. Ge, N. F. Marangoni, A. Baron. 2021. Dickeya dianthicola is not vectored by two common insect pests of potato. PhytoFrontiers 1: 160-172.

Dickeya dianthicola (Samson) is an important pathogen causing blackleg disease of potato. Previous work suggested that insects might vector species of Pectobacteriaceae between plants but no conclusive work has confirmed this. Green peach aphids (Myzus persicae Sulzer) and Colorado potato beetles (Leptinotarsa decemlineata Say) are aggressive potato pests and related to known vectors of several species of bacteria other than D. dianthicola. This study sought to determine whether these insects vector D. dianthicola for potato infection. Neither insect species showed olfactory discrimination based on the presence of infection in laboratory tests but beetles were repelled by uninfected foliage treated with 2,3-butanediol, a primary Dickeya metabolite. Beetle recruitment to plants was not affected by their infection status; however, aphids preferred uninfected foliage when conspecifics were present. In the laboratory, neither insect acquired or transmitted D. dianthicola through feeding. In the field, neither insect’s abundance was significantly correlated with disease spread. Overall, this study did not find indications that D. dianthicola is vectored by the tested insect species. Therefore, efforts to limit Dickeya spread should focus on sanitation, water management, and seed screening—not on the control of these insect species. [Full Text]