Field studies on preferential feeding sites of spotted pod borer, Maruca vitrata (Lepidoptera: Crambidae) on different legumes

Abstract

A field study was carried out to know the preferential feeding sites of spotted pod borer, Maruca vitrata (Geyer) within its host plant at crop fields of Department of Pulses, TNAU, Coimbatore during 2012-13. Five different host plants viz., pigeonpea (var: CO RG 7), greengram (var: CO GG 7), blackgram (var: CO BG 6), cowpea (var: CO 7) and lablab or field bean (var: Rohini) were maintained under pesticide free environment for the study. Among three different plant parts of legumes, the maximum preferential feeding was towards top portions irrespective of host crop. Among different host plants, on lablab, the highest population of 6.3 larvae/ plant was recorded followed by 5.7 larvae/ plant on redgram and 2.1 larvae/ plant on cowpea when compared to 1.1 larva/ plant on black gram (Table 1). However least and non significant difference was recorded with respect to population on middle and bottom portions irrespective of host plants. On bottom portion the population was very meager (less than 0.2 larvae/ plant). Only slight microclimate variation recorded within each host plant and there were no significant variations recorded in maximum and minimum temperatures as well as maximum and minimum relative humidity among top middle and bottom portions.