Aphid-induced changes in growth indices of three leguminous plants: unrestricted infestation

Abstract
The effects of various densities of cowpea aphids (Aphis craccivora Koch) and pea aphids (Acyrthosiphon pisum Harris), both Homoptera: Aphididae, on the growth of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona), broad bean (Vicia faba L. cv. Aquadulce), and garden pea (Pisum sativum L. cv. Victory Freezer) seedlings were investigated. Within 10 days of infestation, aphid feeding significantly reduced plant dry weights and mean relative growth rates for the six plant–aphid combinations. In all cases except one, the mean unit leaf or net assimilation rate was also significantly reduced within 10 days. The mean leaf area ratio was the same for infested and control plants. The aphid-induced changes in host plants appear to be due to changes in photosynthesis, respiration, and translocate removal from the phloem over the 10-day period. Changes in the growth patterns of the host plant within this period are similar, but the underlying physiological effects could vary among particular plant–aphid combinations.