Colonizing Responses of Maruca testulalis (Geyer) (Lepidoptera: Pyralidae) to Different Cowpea Cultivars in Relation to their Resistence/Susceptibility

Abstract

A comparison of the resistance/susceptibility levels of ten cowpea cultivars to the pod borer Maruca testulalis revealed that VITA l was the most susceptible. TVU 946 most resistant and VITA 5, chola local and kamboinse local rroderately resistant. In all the cultivars which were compared, flowers and pods suffered the heaviest damage compared to the stems. Colonizing responses of M. testulalis namely oviposition, larval orientation, feeding, utilization of ingested food, larval development and adult fecundity were studied on three cultivars namely VITA 1 (susceptible), VITA 5 (moderately resistant) and TVU 946 (resistant). The adults showed ovipositional nonpreference for TvU 946 and VITA 5 when these cultivars were available to the moths as a choice against VITA l • All the cultivars were equally accepted for oviposition under no choice situation. Majority of the eggs were laid on the leaves. Settling sites for 1st instar larvae on the cowpea plant in a decreasing order of preference were: flowers> terminal shoots = flower buds. The first instar larvae were capable of reaching any part of the cowpea plant either by walking or by means of silken thread which they produced and used for swinging from one plant........(continue from the attached PDF)