Effect of rearing season, host plants and their interaction on economical traits of tropical tasar silkworm, Antheraea mylitta Drury- an overview

Abstract

Tropical tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) is a polyphagous silk producing forest silkworm of commercial importance in India. Forest dependent people rear its larvae on different forestry host plants twice or thrice in a year for small household income. Larvae of A. mylitta feeds on many forest tree species, but always show a great degree of selectivity as a function of its behavioural responses to physical structure and chemical features of the host plants. Cocoon crop of A. mylitta is influenced by heterogeneity of tasar food plants and climatic conditions of the habitat. The role of host plants, temperature, humidity, rainfall, photoperiod and climatic variables on the growth and development of insects have clearly been demonstrated. This article entails an in-depth analysis on ecological and nutritional aspects of A. mylitta, which may provide selective information to researcher and forest managers, who are particularly associated with livelihood improvement of the poor people in forested area through location specific forest insect industry. In nature, A. mylitta has opted forty-five forest tree species as primary, secondary and tertiary food plants (Srivastav and Thangavelu, 2005) and have built up sixty-four different forms of ecological populations called ecoraces (Rao et al., 2003). The polyphagous nature of the tasar silkworm is a boon for many rural tribal in central The knowledge regarding insect-host plant relationship has highlighted the food preference by insects with regard to its nutritional value. Long back, Hiratsuka (1920) carried out a comprehensive quantitative study on digestion and utilization of Bombyx mori on mulberry leaf. Thereafter, Evans and Goodliffe (1939) worked on utilization of food by insects. Earlier studies on utilization of food by insects were not clearly described because several indices were used to report more or less the same measurement in different names (Hopkins, 1912;Evans and Goodliffe, 1939; Crowell, 1941;Smith, 1959;Mathur, 1967;Saxena, 1969). Study of the effects of host plants on the biology of insects is important in understanding the host suitability under different environmental condition (Xue et al., 2009). First, Thangavelu (1992 emphasised the need for conservation of wild sericigenous insects in Himalayan states of India. He highlighted the importance of systematic research on various aspects of non-mulberry silks, because studies on the host plant interaction of sericigenous insects are necessary for better management and development of the sericulture industry (Sinha et al., 2000). Siddiqui et al. (2006) stressed that conservation of A. mylitta in different pockets of forest under different geographical and climatic area is necessary and some of the commercial ecoraces of A. mylitta viz., Raily, Modal, Bhandara, Sukinda, Daba and Andhra local are being maintained in different forest areas of central India; but it is lacking in Uttarakhand. As suggested by many sericulturists, the specific climatic and geographical pockets...