Genetics of esterases in Drosophila. VII. Genetic control of the activity level of juvenile hormone (JH)-esterase and heat resistance in D. virilis at high temperatures.

The heat-resistant subline 147S was obtained in Drosophila virilis by selecting for viability individuals of heat-sensitive stock 147. It was shown that in the heat-treated 147S pupae the activity of juvenile hormone (JH)-esterase is decreased and, consequently, the titer of juvenile hormone is increased compared with those in the control pupae. These changes are consistent with those observed earlier for resistant stock 101. Heat-resistant stocks 101 and 147S were crossed with heat-sensitive stock 147, whose heat-treated larvae show earlier activation and higher activity of JH-esterase than control larvae. The viability and electrophoretic esterase patterns were analyzed in the F1 and F2 hybrids at different temperatures. It was found that the F1 hybrid is resistant to the effect of high temperature and its activity level of JH-esterase is lower compared with controls. In the F2 hybrid, there was a 3:1 segregation of viability and a 1:2:1 segregation of the activity level of JH-esterase at high temperatures. It is concluded that the activity level of JH-esterase and heat resistance in D. virilis are monogenically controlled at high temperatures.