Differential Effects of Temperature on the Biological Activity of Four Biotypes of the Pea Aphid1

Abstract

Four populations of Acyrthosiphon pisum (Harris) from 4 geographical areas in the western United States—Bakersfield, Calif, Mesa, Ariz.: Corvallis, Oreg.; and Reno, Nev.,—were segregated on the basis of biological response to 4 different temperatures. Effect of temperature on all biological activities of each aphid biotype and differences in the mean development of the 1st-nymphal stadium and combined nymphal stadia were highly significant among biotypes. Fecundity among all biotypes was different at the 0.01 level of probability. A highly significant biotype by temperature interaction was found for development of the 1st instar stage and the preparturition period. Populations from Bakersfield and Mesa had similar but a significantly reduced development of the 1st instar stage than populations from Reno and Corvallis. However, populations from Reno and Mesa bad a similar but a significantly higher fecundity than populations from Bakersfield and Corvallis.