Pigeonpea genotypes affect the growth, food utilization and nutritional indices of spotted pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae)

Laboratory evaluation of 11 pigeonpea genotypes for resistance to spotted pod borer, Maruca vitrata Fabricius was conducted from the beginning of third instar to the pre-pupal stage of the insect on flowers of these pigeonpea genotypes. The nutritional indices such as CI (consumption index), AD (approximate digestibility), ECI (efficiency of conversion of ingested food) and ECD (efficiency of conversion of digested food) were worked out. Larval weight gain was significantly the highest on MN 1 (67.16 mg) and the lowest on AL 1747 (20.45 mg). Total weight of food consumed per larva was significantly the highest on MN 1 (119.16 mg) and the lowest on AL 1747 (56.16 mg). The relative growth rate was the lowest on AL 1747 (118.89%) and the highest on MN 1 (373.11%). Third instar larvae reared on MN 1 showed significantly the highest ECD and AD values (71.55 and 79.65%, respectively) compared with other genotypes. Significantly the lowest value of ECD and AD was observed in AL 1747 (54.71 and 66.96%, respectively). The highest (56.77%) and the lowest (36.51%) ECI of third instar larvae were recorded in MN 1 and AL 1747, respectively. Of the 11 genotypes tested, MN 1 was the most nutritive whereas, AL 1747 was the least nutritive than the others for M. vitrata larvae.