Nutrigenic Efficiency Change and Cocoon Crop Loss due to Assimilation of Leaf Spot Diseased Mulberry Leaf in Silkworm, Bombyx mori L.

Abstract

Healthy growth and development of silkworm largely depending on the quality of mulberry leaves. The activity of sericulture is declining due the reduction of mulberry production area in sericulture practicing countries, which lead to adverse effects on silkworm rearing and cocoon production. Screening for nutritional trait change by feeding leaf spot diseased of mulberry leaf to silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) is an essential prerequisite for better understanding of reduced food consumption, nutritional efficiency loss and low efficiency conversion. The aim of this study was to identify efficiency and cocoon crop loss due to the consumption of leaf spot diseased mulberry leaves to bivoltine silkworm breeds using the hybrid races as SH6 and NB₄D₂. The 1stday of 5th stage silkworm larvae of bivoltine strains were subjected to standard gravimetric analysis until spinning for two to three consecutive generations covering two different seasons on 11 nutrigenic traits. Highly significant (p ≤ 0.01) differences were found among all nutrigenic traits of bivoltine silkworm strains in the treated worms compared to the control worms, where healthy leaves were given. Higher nutritional efficiency conversions were found in the bivoltine silkworm strains on efficiency of conversion of ingesta to cocoon and shell than leaf spot diseased leaf fed worms of the same races. Comparatively smaller consumption index, respiration, metabolic rate with superior relative growth rate, and quantum of food ingesta and digesta requisite per gram of cocoon and shell were found; the highest amount was in healthy leaf fed worms than in the diseased leaf fed worms. The significant weight loss in both the races ranged from the 3.38% to 34.28% in the diseased leaf fed larva as compared to the healthy leaf fed larva Furthermore, based on the overall loss in nutrigenic traits utilized as index or ‘biomarkers’, the two bivoltine silkworm strains (SH6 and NB₄D₂) were identified as having the high potential for nutrition efficiency conversion, when healthy leaves were provided to the silkworms. The data from the present study advances our knowledge to study the loss of nutritional efficiency conversion due to the leaf spot disease fed mulberry leaves and their effective commercial consequences in the sericulture industry progress and management.