The Effect of Temperature and Host Species on the Population Growth Potential of the Cowpea Aphid, Aphis Craccivora Koch (Homoptera: Aphididae).

Abstract

Age-specific life and fecundity tables were compiled to determine the effect of temperature and host plant on the population growth potential of Aphis craccivora Koch. The intrinsic rate of natural increase (r*m) increased from zero at 5� to a maximum at 30�C, and then declined rapidly to zero at 35�C for aphids reared on all the host species tested. At 25�C aphids on Vicia faba showed a greater population growth potential than those on Capsella bursa-pastoris, followed by those on two Trifolium subterraneum cultivars and finally those on Medicago minima. An increase of temperature resulted in an earlier onset of mortality, irrespective of host-plant species. At higher temperatures the reproductive period began earlier and was shorter than at lower temperatures. The rate of reproduction appeared to be the key determinant in the aphid's population growth rate. The estimated lower temperature threshold of development of the aphid was 8.1�C.