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

Abstract

The present study aims to understand the influence of two thermal extremes (15°C and 35°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°C). The ratio of slow and fast developers within an egg batch differed with thermal extremes irrespective of F1 and F15 generations. Adult body mass got depressed after selection for control slow developers at 15°C while it got enhanced for selected fast developers at 35°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°C and selected slow developers at 15°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.