Differences in the stimulation by calcium ionophore of juvenile hormone III release from corpora allata of solitarious and gregariousLocusta migratoria

Summary Incubation of the calcium ionophore A23187 resulted in an increase in the median rate of juvenile hormone III release by corpora allata (CA) of both gregarious and solitarious adultLocusta migratoria females at 3, 5 and 8 days after fledging. At all 3 datapoints, the enhancement of release rates was highly significant for CA from gregarious females but not significant for CA from solitarious females.     

Juvenile hormone degradation in brain and corpora cardiaca-corpora allata complex during the last larval instar ofGalleria mellonela (Lepidoptera,Pyralidae)

Summary Time course analysis of juvenile hormone degradation in the brain and the corpora cardiaca-corpora allata complex shows that during the first two days of the last larval instar the juvenile hormone degradation is very low. Starting from the third day up to the seventh day a continuous increase of esterase activity is observed.     

In vitro biosynthesis of juvenile hormone III by the corpora allata ofCalliphora vomitoria and its role in ovarian maturation and sexual receptivity

Summary JH III is the only JH detected by GLC-MS in medium from in vitro incubations of corpora allata of adult females ofCalliphora vomitoria. When corpora allata were removed from females at various times during the reproductive cycle and the JH III produced by the glands in vitro measured by a JH III radioimmunoassay, an increase in the level of synthesis was found to occur before previtellogenesis (0–24 h). A second increase appeared at the onset of vitellogenesis (72–83 h) and continued until the end of vitellogenesis (96 h) and the occurrence of chorionation (120 h). Since sexual receptivity develops with vitellogenesis, the significantly higher levels of JH III biosynthesis in vitro at this time supports a possible role for JH in the acquisitive of receptivity.     

Phosphoramidon enhances allatostatin-mediated inhibition of juvenile hormone biosynthesis in the corpora allta of the cockroach,Diploptera punctata

Use of the enkephalinase inhibitor phosphoramidon in the in vitro radiochemical assay for juvenile hormone biosynthesis enhanced allatostatin-mediated inhibition of hormone production by corpora allata of the cockroach,Diploptera punctata. Significant increases in inhibition in day 2 virgin female CA by AST 1 (at 10^–7 M) and AST 4 (10^–8–10^–7 M) were observed in the presence of phosphoramidon (10^–5M or greater). No significant increases in inhibition were seen in CA from day 6 mated females with AST 4 (10^–9–10^–7M) and phosphoramidon combined. Phosphoramidon alone had no effect on JH biosynthesis. Analysis of allatostatin content of the CA, as determined by ELISA, revealed that addition of phosphoramidon to the medium increased the endogenous allatostatin conten in CA of virgin and mated females. The similarity in primary structure between allatostatins and enkephalin-like peptides and their similar distribution makes it probable that phosphoramidon acts by preventing breakdown of allatostatins within the CA.     

Effects of corpora cardiaca extract,furosemide and ion substitution on sodium and chloride flux in perfused Malpighian tubules ofLocusta

Treatment with the co-transport inhibitor, furosemide decreased³⁶Cl^– flux across perfused Malpighian tubules ofLocusta. However, exclusion of³⁶Cl^– from the bathing medium had not effect on²²Na⁺ flux whereas substitution of bathing medium Na⁺ by K⁺ increased³⁶Cl^– flux. Diuretic extract of corpora cardiaca increased²²Na⁺ (by 106%) and³⁶Cl^– (by 335%) fluxes differentially.     

Photoperiodic regulation of mating behaviour in the linden bug,Pyrrhocoris apterus,is mediated by a brain inhibitory factor

Active inhibition of mating behaviour in a male insect is reported here for the first time. InPyrrhocoris apterus L. (Heteroptera), the most important inhibitory pathway runs from the pars intercerebralis (PI) of the brain and does not pass through the corpora allata. The inhibitory activity of the PI is promoted by short day conditions and suppressed by long days. As the effect of photoperiod is delayed, transfer procedures enabled us to record daily rhythms in mating behaviour during short days. While the extirpation of the PI results in a discrete phase shift of the long day rhythm, there is a much less significant phase shift after this operation during short days. Thus the PI has been shown to mediate the effect of photoperiod on both the inhibition and the rhythm of mating behaviour.     

The male pheromone of the old house borerHylotrupes bajulus (L.) (Coleoptera: Cerambycidae): Identification and female response

We report here the identification of the long-range, male-produced sex pheromone of the Old house borerHylotrupes bajulus. Chemical analysis of hexane extracts obtained by surface extraction from dissected prothoracic glands and from headspace samples of the two sexes, revealed male-specific compounds: (3R)-3-hydroxy-2-hexanone, 2-hydroxy-3-hexanone, the diastereomeric diols (2R, 3R)-2,3-hexanediol and (2S, 3R)-2,3-hexanediol, 2,3-hexanedione, as well as 1-butanol.In wind tunnel bioassays we tested the influence of these male-specific compounds from the prothoracal glands on the behaviour of unmated and mated females. Specific behavioural sequences of the tested females (activity, running behaviour, searching, cleaning, flying, extension of ovipositor) were recorded. Unmated females were attracted by male beetles, headspace extracts of males, synthetic blends of the major pheromone compounds as well as by the components (3R)-3-hydroxy-2-hexanone, and the diastereomeric diols. Hexane, female beetles and 2,3-hexanedione did not attract unmated females. The reactions of mated females to male beetles and headspace samples did not differ significantly from those of the controls.The results of the bioassays show that the two-stage premating behaviour is initiated by emission of a long-range sex pheromone from the male prothoracal glands, which functions as an activator, attractant, and possibly aphrodisiac for unmated females.     

Identification and biological significance of 4-methyl-3Z,5-hexadienoic acid produced by males of the gall-forming tephritidsUrophora cardui (L.) andUrophora stylata (Fab.) (Diptera: Tephritidae)

Summary A new natural substance has been identified in the rectal ampullae of gall-forming fruit flies. The substance was found to be the only volatile compound in the rectal ampulla of maleUrophora cardui andUrophora stylata. GC-MS methods were used to characterize its structure as 4-methyl-3Z,5-hexadienoic acid. Physiological parameters such as the amount of the acid at different ages and under different conditions were investigated. The biological significance of the new volatile as an arresting pheromone was tested in several bioassays. The arrestant function could not be established, but the results gave hints of a territorial function between conspecific males. The results are discussed with respect to gland morphology and predictions of communication models among fruit flies.     

Sexual dimorphism in the lipid fraction of the defensive secretion ofGastrophysa viridula (Coleoptera: Chrysomelidae)

The lipid fraction of the defensive secretion of adultGastrophysa viridula was analyzed by gas-liquid chromatography and gas chromatography-mass spectrometry. Three long chain acetates and two methyl-branched hydrocarbons were identified and their amounts in the secretion of single field-collected and laboratory-reared beetles determined. The composition of the secretion was affected by the sex, reproductive status, and age of the beetle. The ratio of (Z)-11-eicosenyl acetate to (Z)-13-docosenyl acetate ranged from 0.30 to 0.78 in male beetles and from 1.05 to 2.06 in female beetles. The biological significance of this sexual dimorphism is discussed.     

Confirmation of sex pheromone biosynthesis from (16-D3)palmitic acid in the turnip moth using capillary gas chromatography

Summary (16-D₃)palmitic acid was applied topically to pheromone glands of the turnip moth. After incubation omega labeled analogues of fatty acid methyl esters and acetates were identified by gas chromatography with flame ionization detection and selected ion monitoring. The pheromone components (Z)-5-decenyl, (Z)-7-dodecenyl- and (Z)-9-tetradecenyl acetate were all biosynthesized from palmitic acid along a common pathway.     

Oviposition-deterring pheromone inRhagoletis cerasi L.: Purification and determination of the chemical constitution

Summary An oviposition-deterring pheromone (ODP) of the European cherry fruit flyRhagoletis cerasi L. was isolated from faeces using cellulose and several reverse phase TLC and HPLC procedures. The biological activity was evaluated by means of behavior tests and by electrophysiological recordings from tarsal contact chemoreceptors. The compound was structurally characterized as a N[15(-glucopyranosyl)oxy-8-hydroxypalmitoyl]-taurine by spectroscopic means. The configurations of C-8 and C-15 of the fatty acid constituent remain to be established by synthetic work.     

Occurrence of 3-epi-22-deoxy-20-hydroxyecdysone and its phosphoric ester in diapause eggs of the silkworm,Bombyx mori

Ecdysteroids in diapause eggs of the silkworm,Bombyx mori, were analyzed using high-performance liquid chromatography (HPLC) combined with radioimmunoassay (RIA). A relatively large amount of an unidentified free ecdysteroid and its phosphoric ester (conjugated form) were detected. These two compounds were isolated by a combination of column chromatography on silicic acid, thin-layer chromatography (TLC), and HPLC using a reverse-phase (RP) column. The purified compounds were identified as 3-epi-22-deoxy-20-hydroxyecdysone (22d20E) and 3-epi-22-deoxy-20-hydroxyecdysone 2-phosphate (22d20E2P) by means of mass spectrometry and nuclear magnetic resonance spectroscopy. to our knowledge, this is the first report of 22d20E and 22d20E2P.