~ 1961 ~ Journal of Entomology and Zoology Studies 2020; 8(3): 1961-1966 E-ISSN: 2320-7078 P-ISSN: 2349-6800 www.entomoljournal.com JEZS 2020; 8(3): 1961-1966 © 2020 JEZS Received: 29-03-2020 Accepted: 30-04-2020 SR Manjunatha Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India Manjunath Gowda Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India Nataraja Karaba Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India KC Narayanaswamy Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India KS Jagadish Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India Corresponding Author: SR Manjunatha Department of Sericulture, Department of Crop Physiology and @ Department of Agril. Entomology, UAS, GKVK, Bangalore, Karnataka, India Performance of silkworm hybrid PM x CSR2 on drought tolerant transgenic mulberry lines SR Manjunatha, Manjunath Gowda, Nataraja Karaba, KC Narayanaswamy and KS Jagadish Abstract Crop plants adaptable for water stress conditions are gaining importance due to scarcity of water resource, so as mulberry in sericulture potential areas. In this context newly evolved drought tolerant mulberry lines namely, VR, ST, BT, MT and RD have been developed and silkworm bioassay was conducted on these lines utilizing V instar silkworms of hybrid PM X CSR2 with V1 as a check (wild type), at the Department of Crop Physiology, UAS, GKVK, Bangalore, during June 2016. Fifth instar silkworms were reared on these mulberry lines and their influence on silkworm growth and few economic traits were assessed. The results revealed that these lines had no deleterious effects on silkworm growth and cocoon yield. The food consumption and food digestion of the silkworms were normal on all the transgenic mulberry lines and no significant differences were observed though wild type (V1) registered better values. Similarly, Effective rearing rate (ERR) calculated based on the V instar initial number and V instar larval weight were on par in all the lines tested. However, wild type fared better than the transgenic line (100% ERR and 39.19 g/10 larvae). Among the cocoon characters, cocoon yield by number, single cocoon weight and pupal weight were on par in all the lines, while cocoon yield by weight, single shell weight, shell ratio and silk productivity were significantly different and the wild type recorded higher values of 1817.25 g / 1000 worms, 0.36g, 19.26% and 5.21 cg/day, respectively. These findings suggest that drought tolerant transgenic mulberry lines have no adverse effect on silkworms and line ST performed better than other transgenic lines evaluated, being next only to wild type (V1). Keywords: transgenic mulberry, PM X CSR2, rearing parameters and cocoon parameters Introduction Silk is the most elegant textile in the world with unparalleled grandeur, natural sheen, and inherent affinity for dyes, high absorbance, light weight, soft touch and high durability and known as the “Queen of Textiles” the world over. On the other hand, it stands for livelihood opportunity for millions owing to high employment oriented, low capital intensive and remunerative nature of its production. The very nature of this industry with its rural based on- farm and off-farm activities and enormous employment generation potential has attracted the attention of the planners and policy makers to recognize the industry among one of the most appropriate avenues for socio-economic development of a largely agrarian economy like India. Mulberry (Morus indica L.) is the sole food plant of the silkworm (Bombyx mori L.) which has been exploited commercially in the sericulture industry. A major determining factor for enhancing the production of silk is to produce quality mulberry foliage under extreme agro- climatic conditions by developing plants that are able to adapt to different climatic conditions. It has been estimated that various abiotic stress conditions, such as moisture, salinity and alkalinity can cause yield losses in mulberry in the range of 50 to 60 per cent (Rao, 2002) [1] . Development of mulberry varieties for tolerance to water stress under semi-arid conditions holds tremendous potential as nearly 48 percent of the Indian cultivars of mulberry fall under rain-fed, water stressed conditions. Yield losses under stressful conditions are always associated with reduction in leaf quality. There is an urgent need to evolve mulberry types having stress tolerance traits that can grow and produce sufficient foliage under environmental stresses. There are transgenic approaches attempted in mulberry with varied degrees of success (Das et al., 2011; Checker et al., 2012; Sajeevan et al., 2017) [4, 3, 2] . Recently, mulberry transgenic plants expressing Arabidopsis gene, AtSHN1 to improve post-harvest water loss and impart