Pea Aphid (Homoptera: Aphididae)-Induced Changes in Some Growth Rates of Pea Plants

Feeding by Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) on young pea plants, Pisum Sativum (L.) var. ‘Alaska,’ reduced the relative growth rate and efficiency of production of new tissue relative to the amount of leaf area by as much as 118%. These changes were proportional to the number of aphids and length of infestation period and occurred because of reductions in leaf surface area up to 83% and loss of pholosynlhate which aphids extracted. Reductions were only one-fifth to two-thirds as large when infestations were delayed for 5 days. Total leaf area of the plants relative to their weights was not decreased.