Interactions between aphid infestation and plant growth and uptake of nitrogen and phosphorus by three leguminous host plants

Abstract

The effects of cowpea aphids (Aphis craccivora Koch) and pea aphids (Acyrthosiphon pisum (Harris)), both Homptera: Aphididae, on nitrogen (N) and phosphorus (P) uptake by and 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. After 10 days of aphid infestation, all leaf areas were significantly lower in infested plants, and plant dry weight, mean relative growth rate, and unit leaf rate were significantly lower in all plant–aphid combinations except for pea – pea aphids. The mean leaf area ratio was the same for infested and control plants indicating that infested plants did not reallocate their assimilate resources in response to aphid feeding. The accumulation of N and P as a percentage of plant dry weight did not differ between control and infested plants and was specific to the species examined. However, control plants all had greater absolute amounts of N and P after 10 days. Even though the responses of the plants to aphid feeding were similar, the accumulation of N and P appears to be a plant species specific phenomenon.