Dispersal of Bactericera cockerelli (Hemiptera: Triozidae) in relation to phenology of Lycium barbarum (Solanaceae)

Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) is a key pest of potato ( Solanum tuberosum ) and tomato ( S. lycopersicum ) in western North America.  Native Lycium (Solanales: Solanaceae) in the southwestern U.S. have been known since the early 1900s to support populations of B. cockerelli .  These shrubs are adapted to survive arid habitats by entering a summer dormancy characterized by partial or complete defoliation.  Summer leaf fall by native Lycium in the southwestern U.S. triggers the dispersal of B. cockerelli to new seasonally available hosts including potato.  Recently, B. cockerelli in the Pacific Northwest (Washington, Oregon, and Idaho) was found to occur on a non-native Lycium known as matrimony vine.  Monitoring of matrimony vine at several locations in previous years suggested qualitatively that this non-native shrub in the Pacific Northwest also entered a summer dormancy with effects on psyllids populations.  Our study had three principal objectives: 1) examine the genetic and morphological diversity of matrimony vine in potato growing regions of the Pacific Northwest, 2) document when and under what conditions matrimony vine enters summer dormancy, and 3) determine whether summer leaf fall is associated with dispersal of B. cockerelli from these plants.  We report that “matrimony vine” in Washington State includes at least two morphologically distinct varieties of a single non-native species, L. barbarum .  Like the native Lycium species in the desert southwestern U.S., matrimony vine in Washington entered a period of summer dormancy in response to low soil moisture, and the onset of summer dormancy was associated with dispersal of B. cockerelli from the matrimony vine host, with potato being a potential destination for some of those dispersing psyllids.