The effect of pod growth stages in cowpea on aphid reproduction and damage by the cowpea aphid, Aphis craccivora (Homoptera: Aphididae).
In screenhouse studies in Nigeria, cowpea (Vigna unguiculata) seedlings (variety Ife Brown) were planted in pasteurised soil in plastic cups and infested at the young (4-6 days after flower opening), mid-fill (7-10 days after flower opening) and mature (12-16 days after flower opening) pod growth stages with 1, 2 and 3 pre-reproductive adult apterae of the aphid Aphis craccivora to determine the effects on aphid damage and reproduction. Infestation at the young pod stage caused significantly more pod shrivelling compared with uninfested pods. At the mid-fill pod stage, infestation with 2 or 3 pre-reproductive apterae also produced more pod shrivelling compared with uninfested pods. None of the aphid infestation levels produced pod shrivelling at the mature pod stage. The fecundity of A. craccivora was greater on young and mid-fill pods than mature pods irrespective of the initial level of infestation. All levels of infestation caused a significant reduction in seed yield irrespective of the age of the pod.