Morphometry of Mouthparts of Eri Silkworm, Samia cynthia ricini Boisduval under Different Food Regimes

Eri silkworm, Samia cynthia ricini Boisduval is polyphagous feeding on several plant species. The influence of feed on growth of an animal is evident from literature. Eri larva has biting and chewing type of mouthparts comprising of a pair of mandibles, Labrum and the labio-maxillary complex. The size of these mouthparts increases with larval age. In an experiment conducted to study the influence of host on morphometric changes in mouthparts of Eri silkworm, the local castor variety with greenish petiole found to have significant influence on the length and width of mandibles (0.0803 and 0.0675 cm, respectively), labrum (0.0543 and 0.0735 cm, respectively) and labio-maxillary complex (0.1007 and 0.1145 cm, respectively). Further, there was a sudden increase in the size of mouthparts during fourth instar (85 × 67% gain in mandibles, 95 × 73% gains in LMC and 124 × 58% gain in labrum) irrespective of the host.