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

Met(27) is a null allele of the Methoprene-tolerant gene of D. melanogaster that shows resistance to the toxic effects of both juvenile hormone (JH) a nd a JH analog, methoprene. The mechanism of resistance appears to be alter ed JH reception. We measured fertility, JH-hydrolyzing activity, and dopami ne (DA) levels in Met(27) and Met(+) flies under normal (25 degrees C) and heat-stress (38 degrees C) conditions. We show that under normal conditions Met(27) females have JH-hydrolyzing activity and fertility lower than Met( +), but DA content did not differ between the two strains. At 38 degrees C Met(27) flies show no impairment in JH-hydrolyzing activity in response to stress, but they do show lower DA levels and impaired reproduction. The res ults with Met(27) are consistent with the previous hypothesis that the alte ration in fertility that follows heat stress in D, melanogaster could resul t from alteration in the JH endocrine system. (C) 2000 Elsevier Science Ltd . All rights reserved.