Differential responses of biotypes of the pea aphid, Acyrthosiphon pisum (Harris), to a chemically defined diet

Abstract

Four clones of the pea aphid, Acyrthosiphon pisum (Harris), collected from different regions in North America (St-Jean and Ile-aux-Coudres, Quebec, in Canada, and New Mexico and Kansas in the United States) were reared on an aseptic chemically defined diet and characterized into biotypes. The clones from St-Jean and Kansas appeared similar and represent one biotype, whereas those from New Mexico and Ile-aux-Coudres were different from each other, as well as from St-Jean and Kansas. Third-generation larvae were produced only by biotypes St-Jean and New Mexico; however, none of them reached the adult stage.The amount of diet ingested and its utilization by different clones also varied. In 24 h, the total diet ingested by flrst-instar larvae from St-Jean, Kansas, New Mexico, and Ile-aux-Coudres was 164,140, 112, and 65 μg per aphid respectively. During the same period the larvae increased their weights by 28, 13, 10, and 10% respectively. Total, or percent increase in weight, was however not proportional to the amount of diet ingested, thus reflecting on the relative efficiency of diet utilization by different clones.