Host Plant and Temperature as Related to Survival and Reproduction of an Alfalfa Aphid, Macrosiphum creelii Davis 1

An alfalfa aphid, Macrosiphum creelii Davis (Homoptera: Aphididae), previously a noneconomic pest in the Pacific Northwest, became increasingly abundant beginning in 1963. Its host plant relationships were determined, as well as its developmental, survival, and reproductive rates on alfalfa in the laboratory. Anatomical differences were shown to distinguish it from the pea, Acyrthosiphum pisum (Harris), and potato, Macrosiphum euphorbiae (Thomas), aphids with which it might be confused. Its primary host plants were found to be alfalfa, lentils, Austrian pea, and broadbean. Most host plants of the pea and potato aphids were not acceptable. M. creelii reproduced well at temperatures as low as 5 to l0°C, and provided up to 70 progeny each. The only parasite found to attack M. creelii was Aphidius pulcher Baker.