The determination and validation of degree day requirements for Bactericera cockerelli (Sulc) (Hemiptera: Triozidae)

The potato psyllid (Bactericera cockerelli Sulc) is a major pest of potato that vectors ‘Candidatus Liberibacter solanacearum,’ the bacterium that putatively causes zebra chip disease in potato. With few other options available, zebra chip is controlled almost exclusively by managing potato psyllid populations with multiple calendar timed insecticide applications. In addition, there is mounting evidence of insecticide resistance in some populations of potato psyllids. To address these concerns, a degree day model was developed in an effort to better time insecticide applications around seasonal population peaks of the potato psyllid and thus, reduce the use of insecticides to control the potato psyllid. Constant temperature studies and non-linear and linear modeling was used to estimate the developmental parameters used in degree day modeling. The developmental parameters were validated using greenhouse and field data. Results and their implications are discussed.