Selection and inheritance of developmental variants of Propylea dissecta under thermal stress conditions

The present study aims to understand the influence of two thermal extremes (15 degrees C and 35 degrees C) as thermal stressors on the selected line of developmental variants (slow and fast developers) in Propylea dissecta and to compare it with the response at the optimal temperature (27 degrees C). The ratio of slow and fast developers within an egg batch differed with thermal extremes irrespective of Fl and F15 generations. Adult body mass got depressed after selection for control slow developers at 15 degrees C while it got enhanced for selected fast developers at 35 degrees C. More selected slow developers were found at low temperature and more selected fast developers at high temperature. Selection probably favours the enhancement of immature survival and emergence ratio which was found to be highest for selected fast developers at 35 degrees C and selected slow developers at 15 degrees C. Population level disparity on thermal confliction was observed in ladybird post selection over several generations. Therefore, we put forward that exposure thermal extremes over a long duration, causes an adaptive differentiation in thermal responses of slow and fast developers.