Stress-reactivity of a Drosophila melanogaster strain with impaired juvenile hormone action

Met27 is a null allele of the Methoprene-tolerant gene of D. melanogaster that shows resistance to the toxic effects of both juvenile hormone (JH) and a JH analog, methoprene. The mechanism of resistance appears to be altered JH reception. We measured fertility, JH-hydrolyzing activity, and dopamine (DA) levels in Met27 and Met+ flies under normal (25°C) and heat-stress (38°C) conditions. We show that under normal conditions Met27 females have JH-hydrolyzing activity and fertility lower than Met+, but DA content did not differ between the two strains. At 38°C Met27 flies show no impairment in JH-hydrolyzing activity in response to stress, but they do show lower DA levels and impaired reproduction. The results with Met27 are consistent with the previous hypothesis that the alteration in fertility that follows heat stress in D. melanogaster could result from alteration in the JH endocrine system.