Impact of abiotic stresses on summer preservation of ecorace bhandara of Antheraea mylitta D
Tushar R Khare
Of the 44 ecoraces of tropical tasar silkworm Antheraea mylitta, Drury across the India, Bhandara ecorace is one of population available in Vidarbha region of Maharashtra. Its natural population has decreased down due to it’s over exploitation by tribals and traders, deforestation and change in atmospheric conditions. To save the natural population efforts are made to collect third generation wild cocoons from its natural habitats and kept under summer preservation for its further multiplication. The third generation harvested cocoons kept under summer preservation exposes to various abiotic stresses results in great difficulty in its further multiplication. This three year (2016 to 2018) study was under taken to understand and form a database on impact of abiotic stresses on summer preservation loss of ecorace Bhandara. Based on the results of three years of study it was revealed that abiotic stresses (mainly temperature, humidity and rainfall) leads to total cocoon preservation loss of 25.80, 47.04 and 41.91% during the year of 2016, 2017 and 2018 respectively. Of which loss due to pupal mortality and unseasonal emergence stands at 7.14, 37.26, 27.41% and 18.66, 9.78, 14.5% during 2016, 2017 and 2018 respectively. Pupal mortality and unseasonal moth emergence is the major factors for loss of seed cocoons resulted from fluctuation in temperature and relative humidity. The maximum loss of cocoons due to unseasonal moth emergence was found in the month of June followed by May while the maximum loss due to pupal mortality was found in the month of May followed by June. Cocoon loss under preservation was found minimum from February to April (2.22 -12.36%) while maximum from May to June (23.58-45.05%). Result indicated that May and June month is the most critical period for ecorace as during this period cocoons adversely exposed to prevailing abiotic stresses. Hence, there is urgent need of developing technology to protect exposure of summer preserved cocoons to fluctuation in temperature and relative humidity so that loss of valuable genetic material could be avoided.