Aphids Associated with Lettuce (Lactuca sativa L.) in the Matanuska Valley, Alaska

ABSTRACT Commercial lettuce fields in Alaska were surveyed for aphid infestations and species composition. Sixteen species were collected in green tile trap pans. The majority were Lipaphis erysimi (Kaltenbach), Macrosiphum euphorbiae (Thomas), and Pemphigus spp. Pemphigus populitransversus Riley, Subacyrthosiphon, and Cryptobium Hille Ris Lambers were added to Alaska collection records. Macrosiphum euphorbiae complex were the only aphids to colonize lettuce during the 1994 season. Seedlings were infested with aphids within four days of transplanting and more alates landed on 1–3 week old seedlings than on older plants. During the 1–3 week seedling period, more alates were recorded on head lettuce than leaf lettuce. Percent infested plants averaged 9.2 and 19.3 for leaf and head lettuce, respectively, during that period. Green tile trap pans were not effective indicators of aphid activity in lettuce fields under these test conditions.