A quantitative assessment of larval infestation level required for intensive screening of cowpea for resistance to the black cowpea moth, Cydia ptychora (Meyrick) (Lepidoptera: Tortricidae)

Abstract

Assessment of the damage potential of Cydia ptychora (Meyrick) was carried out in Ife Brown cowpea at different levels of larval infestation and different pod growth phases. The results showed that C. ptychora caused significant shrivelling in pods of Ife Brown cowpea when infested with either one, two or three first-instar larvae per pod at either the young or mid-fill growth phases, relative to the corresponding controls. A significant reduction in seed yield was also recorded in plants subjected to an infestation level of either one, two or three first-instar larvae per pod at both mid-fill and mature pod growth phases. Thus, an infestation level of one first-instar larva per pod at either the mid-fill or mature pod growth phases would be adequate for intensive screening of cowpea varieties for resistance to C. ptychora, using Ife Brown as a standard for comparison.