Hormonal control of pheromone responsiveness in the male black cutwormAgrotis ipsilon

In Lepidoptera, reproduction is linked to chemical communication between conspecific partners. When exposed to the female sex pheromone, males respond by exhibiting typical sexual behaviour which leads to mating. Here we show that presence of the juvenile hormone producing gland (corpora allata) of the male black cutworm,Agrotis ipsilon, is necessary for pheromone responsiveness. Allatectomized males do not show any sexual behaviour, although their antennal olfactory system is functional. Allatectomized males implanted with active corpora allata recover full pheromone receptivity. It is suggested that reproductive processes are synchronized in males and females through endocrine control; timing of the mating activity could serve as an adaptive strategy linked to the migratory behaviour of this species.     

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.     

Influence of corpora allata and brain extract on the lipid release from the fat body of termite queen Odontotermes assmuthi

Summary Short term in vitro experiments on the influence of the extracts of corpora allata and brain from the termite queenOdontotermes assmuthi on the lipid release from the fat body into the haemolymph indicated that the extract of corpora allata does not influence the lipid mobilization, whereas the brain extract increases the free fatty acid level in the haemolymph. It is believed that the brain extract stimulates triglyceride hydrolysis in the fat body.     

Endocrine regulation of the bursa copulatrix and receptacle gland ofDanaus plexippus L. (Lepidoptera: Danaidae)

Summary Significant growth occurs in the bursa copulatrix and receptacle glands of female Monarch butterflies held in summer conditions after adult emergence. Removal of the corpora allata prevents this growth, but normal development occurs if juvenile hormone is injected into females lacking corpora allata.     

Effect of the photoperiod on corpus allatum activity in vitro in the beetle,Pterostichus nigrita F

Summary In the carabid beetlePterostichus nigrita reproduction is controlled by photoperiods and the corpus allatum hormone. Corpora allata were incubated in vitro and the release of juvenile hormone was quantified. Short-day conditions induced low activity of the corpora allata; long days, after short-day treatment, stimulate high corpus allatum activity, while long days alone have no effect.     

Octopaminergic control of corpora allata activity in an insect

Summary Octopamine enhanced the release of JH3 from isolated corpora allata of locusts in short-term cultures. This effect was suppressed when phentolamine (inhibitor of the octopamine receptors) was added to the culture medium. Moreover an octopamine-sensitive adenylate cyclase was found in the corpora allata. The results suggest a positive octopaminergic control on the activity of the corpora allata.     

Juvenilizing effect of ecdysone mimic RH 5849 inGalleria mellonella larvae

The response of the final instar larvae ofG. mellonella to topical application of the non-steroidal ecdysone mimic, RH 5849, was age-related as well as dose-dependent. In young final instar larvae, moderate doses of RH 5849 induced perfect supernumerary larval moults, but doses equal to and higher than 8.5 μg per larva caused premature formation of larval cuticle and were lethal. Application of RH 5849 significantly increased allatotropic activity of the brain, and also activated synthesis of juvenile hormone (JH) by the corpora cardiaca/corpora allata complex. Simultaneous application of RH 5849 and FMev, a potent inhibitor of JH synthesis, to young final instar larvae lowered the incidence of perfect supernumerary larval moults. We conclude that the effect of RH 5849 on the developmental programme inG. mellonella is mediated by the corpora allata.     

Ecdysteroid receptors in the neuroendocrine-endocrine axis of a moth

With a combination of thaw-mount autoradiography using a tritiated 20-hydroxyecdysone agonist, ponasterone A, and immunocytochemistry with a monoclonal antibody to 29 K-prothoracicotropic hormone, high affinity binding sites for ecdysteroids were identified in the tissues of the neuroendocrine-endocrine axis inManduca sexta larvae. At specific times during larval-pupal development in fifth stadium larvae, nuclear ecdysteroid binding sites were present in the cerebral prothoracicotropes, the corpora allata and prothoracic glands, the main axis for the regulation and production of ecdysteroids. A stage-specific appearance of ecdysteroid receptors also occurred in cells of fat body, midgut and Malpighian tubules, tissues which convert ecdysone into 20-hydroxyecdysone. Our data identify new target tissues for ecdysteroids and suggest that ecdysteroids could affect their own production at the genomic level via long and short feedback loops.     

Allatotropic activity of the median neurosecretory cells ofGalleria mellonella (lepidoptera) larval brain

Summary The brain allatotropic hormone (ATTH) is released inGalleria mellonella from the Median neurosecretory cells located in the pars intercerebralis. These cells show the ability to elicit supernumerary larval molts upon implantation into sensitive host larvae, and the ability to in vitro stimulate the juvenile hormone synthesis in corpora cardiaca-corpora allata glands ofG. mellonella.11 November 1986Acknowledgments. I am greatly indebted to Wesleyan University (Connecticut, USA) for supporting this study.     

Control of corpus allatum activity inDiploptera punctata: roles of the pars intercerebralis and pars lateralis

Summary Control of the corpora allata (CA) ofDiploptera punctata is maintained by at least 2 factors. The glands are directly inhibited by an allatostatin arriving at the CA via the nervi corporis cardiaci I (NCC I). Destruction of the putative source (median neurosecretory cells, MNC) of the allatostatin by radio-frequency (RF) cautery relieved the inhibition imposed on the CA of virgin females, and the glands became active. Similarly, destruction of the lateral neurosecretory cells (LNC) also relieved the inhibition. We propose that the LNC stimulated the MNC to release allatostatin. RF-cautery did not result in the activation of CA of pregnant or ovariectomized females. Activation of the CA may therefore require not only absence of the inhibitory factor but also the presence of a stimulatory one (perhaps from the ovary).     

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.     

Effect of some insecticides on cellular lipids of the neurosecretory complex of the red cotton bug,Dysdercus koenigii

Summary In normal specimens of the bug,Dysdercus koenigii, the cells of the pars intercerebralis stain highly positively with Sudan black B and acid haematein, while the corpora cardiaca and allata stain lightly. After the administration of parathion, carbamate and endrin the situation is reversed. The increased level of lipids in the corpora cardiaca and allata coincides with the degree of loss of lipids from the cells of the pars intercerebralis.The authors are thankful to Professor G.P. Sharma for the encouragement and to Dr H. S. Vasisht, for providing them the laboratory facilities. Financial assistance provided to Dr Suman Taneja by C.S.I.R., New Delhi is gratefully acknowledged.     

Endocrine basis of wing casting and flight muscle histolysis in the fire antSolenopsis invicta

Summary In the imported fire antSolenopsis invicta, wing casting and flight muscle histolysis are blocked by allatectomy. Treatment of alate allatectomized females with a synthetic mixture with high juvenile hormone activity induced wing casting and flight muscle histolysis. Apparently, wing casting and flight muscle histolysis in the fire ant are part of postemergence developmental program regulated, directly or indirectly, by the corpora allata.The author thanks the Entomology Department of the University of Georgia for postdoctoral support and Dr A.O. Lea for the use of his facilities.     

Endocrine organs of different larval instars of Spodoptera (Prodenia) litura Fabricius (Lepidoptera: Noctuidae)

Summary A₁ and A₂ cells of the median neurosecretory group are filled with PF stained neurosecretory material between the first 24 to 48 h of the earlier moult in each instar followed by immediate release before the next moult at 72 h, while loaded posterior and lateral neurosecretory cells also appear from the 3rd and 5th instars onwards. Corpora cardiaca, corpora allata and prothoracic glands increase in size in each instar.     

Reactivation of juvenile hormone synthesis in adult drones of the honey bee,Apis mellifera carnica

Juvenile hormone synthesis was measured by the corpora allata radiochemical assay in vitro. No hormone was produced during pupal stages, but soon after adult eclosion the corpora allata were reactived. The rate of juvenile hormone III synthesis increased until day 10 after emergence. Possible functions of juvenile hormone in adult drones are discussed.     

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.     

Autoinhibition of juvenile hormone production. The case of the cockroachBlattella germanica (L.)

In 6-day-old females ofBlattella germanica, the activity of corpora allata (CA) was inhibited in vitro by juvenile hormone III (JH III). Effective doses (281.5 and 375.4 M in the medium) were somewhat higher than (although of the same order of magnitude as) the estimated intraglandular concentration of JH III at this age, and they induced about 45% inhibition of hormonal release and a significant intraglandular accumulation of JH III and methyl farnesoate. The results suggest that autoinhibitory mechanisms operate in the CA to constrain the upper limit of JH III production at the end of the gonadotrophic cycle.     

Occurrence of a pheromone-producing gland in female tobacco beetles

Summary A pheromone-producing gland was discovered in the second abdominal segment of virgin female tobacco beetles,Lasioderma serricorne (Fabricius). The gland duct extends to an orifice below the genital pore and is supported by a rigid invagination of the integument. Hexane extracts of intact pheromone glands were found attractive to male tobacco beetles and also induced high receptor potentials in the olfactory sensilla of the antennae of maleL. serricorne. A surface extract of virgin females proved to be significantly more attractive than an extract of pheromone glands.     

In vitro inhibition of tRNA methyltransferases by queen substance, a pheromone of queen honeybees]

The Queen Substance 1, a pheromone of the queen Honeybee Apis mellifica is an in vitro inhibitor of E. coli B tRNA methylations. This activity is not specific of the methylase source, as inhibitions have been observed with preparations from queen honeybee ovaries, Rat liver or a Mouse plasmocytoma 1-adenine methylase. These results, together with preceding ones concerning t, t-farnesyl-acetone 3, are discussed.     

Identification of in vitro release products of corpora allata in female and male loreyi leafworms,Leucania loreyi

The in vitro release of juvenile hormones (JH) by female, and of JH acids (JHA) by male corpora allata (CA) ofLeucania loreyi was identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Separation and quantification were accomplished by HPLC and GC, respectively. JH II and JH III were the major components released by CA of females. Four JHA analogues were identified as the release products of male CA, i.e. JHA III, Iso-JHA II, JHA II and JHA I. JHA III and Iso-JHA II were reported for the first time as the major release products of CA of adult male Lepidoptera. Iso-JHA II is a new member of the insect juvenile hormone analogue family.