Regulation of reproductive function in Drosophila females due to hormonal interaction under stress is genetically determined

The effect of heat stress (38 degreesC) on the content of octopamine (OA) a nd 20-hydroxyecdysone (20HE) was studied under normal and stressful conditi ons in adult flies of Drosophila virilis lines contrasting in the level of the juvenile hormone (JH). The wild-type flies (line 101) exhibited a prono unced sex dimorphism for the content of both OA and 20HE, which was substan tially lower in this line than in flies of the mutant line 147. The level o f both hormones increased in flies of line 101 exposed to heat stress, wher eas it remained unchanged in flies of line 147 under the same conditions. T he effect of heat stress on the level of JH metabolism and fertility was al so studied in D. melanogaster wild-type lines and lines carrying mutations in genes responsible for OA and DA syntheses. In octopamineless females of the T betah(nM18) line and in females of the Ste line characterized by a do ubled content of DA, JH degradation differed from normal: it was increased in both young and mature T betah(nM18) females, while decreased in young an d increased in mature Ste flies. Fertility was substantially lower in the S te than in the wild-type line. Flies of all of the D. melanogaster lines pr oduced a stress response; however, in mutant lines, both fertility and stre ss reactivity of the systems controlling JH metabolism differed significant ly from that of the wild-type lines. The role of JH, 20HE, OA, and DA inter action in regulation of Drosophila reproduction under stressful conditions is discussed.