Effect of configuration of calyx in cowpea flowers on infestation by spotted pod borer, Maruca vitrata (Fab.) (Lepidoptera: Crambidae)

Twenty cowpea accessions were evaluated for resistance to the spotted pod borer, Marucavitrata in the Department of Agricultural Entomology, College of Horticulture, KeralaAgricultural University, Thrissur. The calyxes of the flowers were examined and the accessionswere categorized into two groups, partially free (major portion of the sepals free, the basalportion tight) and semi tight (major portion of the sepals tight, only the tip free). Significantvariation was observed in terms of damage to cowpea flowers due to spotted pod borer. Thehighest extent of flower damage (50.39 %) was recorded in case of Bhagyalakshmy.Categorization of the different accessions on the basis of the configuration of calyx indicatedthat EC 100092, Palakkadanthandanpayar, TVX – 944, EC 300039, IC 20645 and IC 52110 hadsemi tight calyx characterized by tight sepals with tips alone being free. All these accessionshad consistently low levels of infestation ranging from zero to 3.16 per cent. The accessions C– 152, Kanakamony, PKM – 1, Anaswara, IC 20431, Sreya, Hridya, Mysore local, IC 52105,Kashikanchan, Vellayani Jyothika, Malika, Bhagyalakshmy and Lola had major portion ofsepals free with their basal portion tight. Hence, they were grouped as partially free. Freesepals would provide the first instar borer larvae some extent of concealment as well as enableit to bore into the flower more easily. Tight calyx, thus, could possibly have a deterrent effecton the first instar larvae entry