Climate change: Effect of weather parameters on production of summer season crop of rangeeni strain of Indian lac insect, Kerria lacca (Kerr) at Ranchi, Jharkhand

Abstract

Lac is a natural resin secreted by tiny insects, mainly Kerria lacca (Kerr) (Hemiptera: Coccoidea: Tachardiidae). The insect is cultured on tender shoots of several plants called lac-hosts. It derives its nutrition by sucking the phloem sap of the host-plant. Rangeeni and kusmi are two strains of the lac insect; each completing two cycles in a year - the rangeeni strain produces summer season (baisakhi) and rainy season (katki) crop whereas, kusmi strain produces winter season (aghani) and summer season (jethwi) crop in a year. Jharkhand is a major lac producing state in the country and India is the major lac exporting and importing country in the world. Contribution of the rangeeni strain has showed a sharp declining (−151.5 tons/year) trend over the years whereas, converse is true for the kusmi strain that has shown the increasing ( + 214.5 tons/year) production trend during 1980-81 to 2012-13 period. Contribution of the rangeeni crops in total lac production in Jharkhand has come down to 18-20% during 2008-09 to 2012-13 from 82-88% during 1988-89 to 1997-98. Therefore, performance of the rangeeni strain of lac insect, especially in Ranchi, Jharkhand in relation to changes in weather parameters was analyzed. Analysis of weather data revealed that winter months (December and January) have become colder and pre and post winter months (November and February) warmer. These changes in climatic parameters have implication in lac cultivation as it is a critical period of lac insect development (pre-sexual maturity) during the summer season crop. Monsoon and winter rainfall spells and magnitude were also found to affect lac crop performance. Effect of abiotic factors (temperature, rainfall and relative humidity) was correlated with lac production of rangeeni crop during 2006-07 to 2012-13. It was observed that maximum temperature had a significantly negative (-0.911* and -0.837*) and RH a positive significant (0.850* and 0.800*) correlation with lac production during the critical crop period (March and April) of development in summer season (baisakhi) crop whereas, during rainy season (katki) crop, minimum temperature had a significant negative (-0.765*) correlation with lac production. The vulnerability level of lac insect is high during and prior to sexual maturity stage in summer crop, thus post-winter season is the critical period for lac insect survival and any undesired variability in weather parameters in this stage can impact adversely on lac productivity.