A New Problem and Old Questions: Potato Psyllid in the Pacific Northwest

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) is a small phloem-feeding insect that develops almost exclusively on plants within the Solanaceae (Fig. 1A). The psyllid was described in 1909 by Karel Sulc from specimens collected in Boulder, Colorado, and is found in Mexico, Central America, the western U.S., and southern Canada, and as an introduction in New Zealand (Wallis 1955, Teulon et al. 2009, Munyaneza 2012). Outbreaks of potato psyllid in North America occurred at regular intervals in potatoes, tomatoes, and peppers beginning in the late 1800s and extending into the mid-1900s, largely along a corridor on both sides of the Rocky Mountains. The outbreaks failed to extend into the Pacific Northwest. That pattern changed dramatically in 2011, when an outbreak of potato psyllid caused massive economic losses to potato growers in Washington, Oregon, and Idaho. Losses were due to a new tuber disorder (“zebra chip”; Fig. 1 B-C), now known to be associated with a bacterium that is vectored by potato psyllid. Fig. 1. (A) Adult potato psyllid. (B, C) Discoloration of infected fresh tubers and of tuber slices after frying. The historical absence of psyllid problems in the Pacific Northwest means that our understanding of psyllid biology under Pacific Northwest conditions is woefully lacking. The outbreak in 2011, coupled with our limited …