Effect of some main and alternate food plants on growth of Eri silkworm (Samia ricini D.)

Abstract

The comparison on growth of eri silkworm was conducted under laboratory condition (25 + 2.4 oC, 63.2 + 5.4 %RH) with leaves of main-and alternate food plants: castor (Ricinus communis), cassava (Manihot esculenta) variety KU 50, ceara rubber tree (Manihot aff. glaziovii Mull.Arg.), temple tree (Plumeria acuminata), and papaya (Carica papaya). It was found that eri silkworms could complete life cycles on all tested food plants, excepted papaya. On papaya leaves, the silkworms were able to develop until only the 5th instar. The shortest life cycle was derived from castor (65.90 days). Other food plants gave life cycle periods of 70.46, 71.12 and 72.93 days from KU 50 + ceara rubber tree, KU 50 and KU 50 + temple tree, respectively. The cocoon shell yields were significantly different (P<0.05) in all treatments. From high to low values, cocoon shell weights were obtained from castor, KU 50, KU 50 + ceara rubber tree and KU 50 + temple tree, respectively. Of these, the average cocoon shell weights were 0.4207, 0.2920, 0.2407 and 0.2083 g and the average total cocoon shell weights were 4.2071, 2.9198, 2.4083 and 2.0834 g, respectively. In addition, the egg yields: the highest and the lowest was derived from KU 50 (average eggs/female, 396.07; average total hatching eggs, 1,602.00) and temple tree (average eggs/female, 184.40; average total hatching eggs, 553.00), respectively. It could also indicate that papaya leaf was not suitable for rearing purpose, because all larvae died in 5th instar. Nevertheless, KU 50 + ceara rubber tree is still appropriate as alternate food plant, based on their derived egg yield components, which similar to those obtained from castor and KU 50. However, eri silkworm fed on leaves of KU 50 + temple tree could complete its life cycle even with lowest yields and percentage of survival.