Juvenile hormone and reproduction in crickets, Gryllus bimaculatus De Geer: corpus allatum activity (in vitro) in females during adult life cycle

Abstract

Incubation conditions were established for a short-term radiochemical assay of spontaneous juvenile hormone (JH) biosynthesis in vitro by corpora allata from adult female Gryflus bimucufutus. The only J H synthesized was shown by HPLC to be JH 111. A further incubation product, predominantly extracted from the corpora allata, was thought to be the JH I11 precursor, methyl farnesoate. In adult females reared at a constant temperature of 27°C the synthetic activities of the corpora allata-corpora cardiaca complexes in v i m increase from almost zero to a high peak value 4 days after the imaginal moult.Thereafter the activity decreases to varying intermediate levels, but always lower than the first maximum. Two days after the first peak in corpus allatum activity, ovarian fresh weight increases dramatically and the first oviposition occurs 2 days later.Topical application of JH I11 to females reared at 20°C, which usually have a low fecundity, causes a dose-dependent stimulation of egg production and oviposition.

Effects of the NMDA receptor antagonist MK-801 on female reproduction and juvenile hormone biosynthesis in the cricketGryllus bimaculatusand the butterflyBicyclus anynana

“…For G. bimaculatus it was necessary to use DMSO as solvent because of the much higher concentrations of MK-801 employed. Concomitantly, lifetime fecundity was generally lower than in other studies (Koch and Hoffmann, 1985;Lorenz, 2007;Meyering-Vos et al, 2006), but again, there was no detectable effect on mortality rates, although data were restricted to the egg laying period in this case.…”

“…In the experiments of Chiang et al (Chiang et al, 2002a) CA glands were incubated with NMDA to compensate for the missing glutamate stimulus from the severed nerves, with much lower concentrations of MK-801 needed for this degree of inhibition. The rise of JH III titres in the haemolymph between days·3 and 4 was expected, as in G. bimaculatus JH III titres reach their maximum shortly before the onset of egg laying (Koch and Hoffmann, 1985). Taken together, the available evidence leaves little doubt that MK-801 affects JH biosynthesis, and concomitantly JH titres, in both species.…”

“…Furthermore, Steigenga et al (Steigenga et al, 2006) demonstrated that applications of the JH mimic pyriproxifen significantly increased fecundity but decreased longevity, supporting the notion that in B. anynana JH has pleiotropic effects on key life-history traits, as has been found for other insects (Flatt et al, 2005;Ramaswamy et al, 1997;Zera et al, 1998). For G. bimaculatus much more detailed information on JH biosynthesis and the hormonal control of reproduction, especially egg maturation, is available (Hoffmann et al, 1996;Koch and Hoffmann, 1985;Lorenz et al, 1997). However, we propose that the overall similar reduction in reproductive output found in both species is causally related to the inhibitory effects of MK-801 on JH biosynthesis (Chiang et al, 2002a).…”

“…These findings may suggest some differences in the effects of JH on egg maturation across species. In G. bimaculatus JH biosynthesis and fecundity can be manipulated throughout the entire oviposition period by allatostatins and JH (mimic) injections administered early in life (Koch and Hoffmann, 1985;Lorenz, 2001). Therefore, egg maturation seems to depend on a constant input of JH-mediated signals in G. bimaculatus.…”

Age-correlated changes and juvenile hormone III regulation of the syllable period specific responses of the L3 auditory interneurons in the cricket, Acheta domesticus

“…This lack of selectivity continues throughout the duration of the cricket's life (Walikonis et al 1991). The rate of juvenile hormone III (JHIII) biosynthesis also changes in adults at these ages (Renucci and Strambi 1983;Koch and Hoffmann 1985;Loher et al 1987;Wennauer et al 1989). JHIII peaks on day 4 following the imaginal molt of female A. domesticus, which parallels the onset of phonotaxis (Walikonis et al 1991).…”