Lepidoptera, hormones

Yamanaka A., Imai H., Adachi M., Komatsu M., and Islam A. T. M. F. (2004). Hormonal control of orange coloration of diapause pupae in the swallowtail butterfly, Papilio xuthus L. (Lepidoptera Papilionidae). Zool Sci 21 1049-1055. 

Arima R., Takahara K., Kadoshima T., Numazaki F., Ando T., Uchiyama M., Nagasawa H., KitamuraA. and Suzuki A. (1991) Hormonal regulation of pheromone biosynthesis in the silkworm moth, Bombyx mori (Lepidoptera Bombycidae). Appl. Entomol. Zool. 26, 137-147. 

Phvtoluvenolds. Wigglesworth (JL) demonstrated that a hormone secreted by the insect corpora allata was responsible for the control of differentiation in immature insects and reproduction in adult female insects. Williams (3) prepared an active extract of this hormone from adult male cecropia moths and called it "juvenile hormone". We were able to derive sufficient knowledge of the chemistry of the juvenile hormone from the study of the active cecropia extract to synthesize JH III Q). Seven years later its presence as a natural hormone in the tobacco hornworm was confirmed Ci). Three other analogous juvenile hormones (JH 0, I, II) have been found to occur only in lepidoptera (5, ., 2.) (Figure 1). Juvenile hormone III is the principal juvenile hormone of insects and has been demonstrated in all of the insect taxa investigated. 

A number of inhibitors of methyl farnesoate epoxidase of Blaberus glganteus corpora allata have been described (18). They include typical cytochrome P-450 monooxygenase inhibitors such as methylenedloxyphenyl compounds and substituted imidazoles. In assays of JH III biosynthesis by Perlplaneta amerlcana CA in vitro some methylenedloxyphenyl compounds were shown to inhibit hormone production at moderate to high concentrations (19). Both methylenedloxyphenyl compounds and terpenoid imidazoles have also some anti-juvenile hormone activity in Lepidoptera (7, 20). 

The prothoracicotropic hormones that activate the synthesis of ecdysone in Lepidoptera are highly species-specific, unlike other insect neuropeptides. If something can... 

In the Lepidoptera, four other homologs have been isolated in addition to JH III. The ethyl branched homologs, juvenile hormone I (JH I), methyl-10/ , 1 l-epoxy-7-ethyl-3,l 1-dimethyl-2,6-tridecadienoate, and juvenile hormone II, methyl-10/ , 1 l-epoxy-3,7,11-trimethyl-2,6-tridecadienoate, and their corresponding acids predominate in this order [14, 15, 16]. Two additional homologs, juvenile hormone 0 (JH 0), 10/ , 11-epoxy-3,7-diethyl-1 l-methyl-2,6-tridecadienoate, and 4-methyl JH I have been isolated from embryos of the tobacco homworm, Manduca sexta JH 0 has also been isolated from males of the silkworm, Hylophora cecropia [17, 18, 19]. In higher Diptera (flies), a unique JH bisepoxide, methyl-6,7,10,1 l-bisepoxy-3,7,11-trimethyl 2 -dodecenoate, has been isolated and appears to be the principle JH of some species in this order [20]. 

Plant secondary metabolites which mimic JH activity appear to be active on a narrow range of host species. What account(s) for this effect The majority of bioassays used last larval instars of P. apterus, O. fasciatus and pupae of T. molitor to test for activity of the juvenoids. Are these the most sensitive insects Six JHs have been identified to date different homologs have been isolated from specific insect orders. Juvenile hormone III appears to be ubiquitous [12, 13] and, in most species, is the only JH present. Juvenile hormone I and II are important in the regulation of metamorphosis and ovarian maturation in Lepidoptera [5] and the bis-epoxide appears to be the principle JH in higher Diptera [20]. Therefore, the nature of the JH in the test insect and the role that it plays in development must be considered in the selection of the bioassay a compound which mimics the action of JH in P. apterus (Hemiptera) is unlikely to be active in a Lepidopteran insect. 

In a few Lepidoptera, like the silkworm moth Bombyx mori), hehothide species as the corn earworm (Helicoverpa zea) and the cabbage moth (Mamestra brassicae) it has been demonstrated that a neuronal hormone (PBAN, pheromone biosynthesis activating neuropeptide) is synthesised by a cephalic organ in their brain, dependent on the day/night rhythm. This mediator controls the sex pheromone production in these moths. [161, 170]... 

The corpora allata of most orders of insects (excepting the Lepidoptera) are, in addition to being the site of the production of the juvenile hormone, necessary for the development of the eggs in the ovary and primarily for the deposition of the yolk substance47.4 . For a long time the view prevailed that it was the juvenile hormone itself which had this function in the adult animal, but more recent investigations - make it probable that a second hormone is responsible for these actions. 

Kramer, K.J. et al. Purification and characterization of the carrier protein for juvenile hormone from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera Sphingidae), /. Biol. Chem., 251,4979,1976. 

An important hormone in insects is the so-called juvenile hormone, produced in the corpora allata, a part of the brain. It acquired that name because it is required at each moult between immature stages (see Figure 1.4). When JH is absent, the insect moults to the adult form. But the hormone is also produced in adult insects and has other functions there. Pheromone release in Lepidoptera and Coleoptera is often under the control of JH. 

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