Regulation of vitellogenesis in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Studies were undertaken to investigate vitellogenesis and its regulation in female adults of the fall armyworm, Spodoptera frugiperda. A single female-specific protein, likely to be the S. frugiperda vitellogenin (Vg), appeared approximately 5 h after adult eclosion in the hemolymph of virgin females. The concentration of the protein increased with age as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed. A protein with the same relative molecular mass was also present in egg extracts, but absent from hemolymph samples from male moths. The relative molecular mass of the designated S. frugiperda Vg was determined as 164.5+/-2.5 kDa. Vitellogenic oocytes became visible 36-48 h after emergence and egg deposition began on day 3 of adult life. Vg could not be detected in the hemolymph of females decapitated directly after eclosion. When decapitated virgin females were injected with the JH-mimic methoprene (MP), the level of Vg was comparable to that in non-decapitated moths, indicating that vitellogenesis in S. frugiperda depends on juvenile hormone (JH). However, the number of vitellogenic oocytes was somewhat lower than in non-decapitated virgin females. Injection of 20-hydroxyecdysone (20E) promoted Vg production to a similar extent in decapitated female moths, but in contrast to methoprene injection, treatment with 20E never resulted in the production of vitellogenic oocytes. In vitro cultivated ovaries of adult females dissected directly after eclosion produced lower amounts of ecdysteroids than those isolated on day 1 after emergence. Our results suggest a crucial role for 20E in the induction of vitellogenesis in the noctuid S. frugiperda, while JH seems to be essential for the continued uptake of Vg by developing oocytes and may trigger 20E biosynthesis in the ovary.     

Juvenile hormone biosynthesis,oocyte growth and vitellogenin accumulation in Choristoneura fumiferana and C. rosaceana: a comparative study

We assessed the effects of age and mating status on in vitro juvenile hormone (JH) biosynthesis, oocyte growth, egg production and vitellogenin (Vg) accumulation in the tortricid moths, Choristoneura fumiferana and C. rosaceana. To determine whether vitellogenesis is dependent on the presence of JH, we also examined the effects of decapitation and JH analog treatments on egg production. In both species, the corpora allata (CA) of adult females released fmol quantities of JH, with JH II being the major homolog produced. The CA began producing detectable quantities of JH around the time of emergence. Full activation of the CA was observed a few hours sooner in C. fumiferana than in C. rosaceana. In pharate adults and young virgin females of both species, growth of the basal oocyte reflected changes in CA activity. Decapitation of newly emerged females significantly reduced egg production, but treatment of decapitated females with the JH analog methoprene resulted in egg production that was similar to (C. fumiferana) or greater than (C. rosaceana) that of controls, indicating that JH is required for oocyte maturation. Vg was first observed in the hemolymph before the presumptive time of CA activation, suggesting that the synthesis of this protein is not dependent on JH. The presence of normal quantities of Vg in the hemolymph of pupae decapitated before CA activation confirmed this hypothesis. The Vg titer underwent a transient decline following CA activation and was significantly lower in mated than in virgin females of both species 3 and 5 days after copulation. Since CA activation at emergence and mating are both expected to cause a rise in the JH titer, we suggest that the declines in the levels of Vg result from JH-enhanced Vg uptake by the developing oocytes. Mating induced a significant increase in egg production but had no measurable impact on rates of JH biosynthesis in vitro.     

Temporal profiles of juvenile hormone titers and egg production in virgin and mated females of Heliothis virescens (Noctuidae)

Juvenile hormones (JH) I, II, and III were monitored in hemolymph of virgin and mated females of various ages in Heliothis virescens. JH I was the predominant homologue followed by JH II, but JH II was present at a higher level in young virgin females. JH III was detectable only at a low level. In virgin females, hemolymph JH titers were low at emergence (2.2ng/ml-total amount of JH I and JH II), but increased thereafter and reached a maximum at 24h of age (53.5ng/ml). At 30h and 36h of age, JH titers dropped to a low level, but increased again in older virgin females. After mating, JH titers increased significantly. JH titers at 0h after uncoupling (137.4ng/ml) were nearly 3 times as high as those in 24-h-old virgin females. Within 6h after uncoupling, JH titers decreased slightly, but titers increased with age of mated females and reached a level of 320.2ng/ml hemolymph at 72h after uncoupling. The titer of JH I and JH II was correlated highly with total number of eggs produced (r(2)=0.70, P<0.001). Mating stimulated JH production, resulting in an increase in egg production.     

Juvenile hormone III produced in male accessory glands of the longhorned beetle,Apriona germari,is transferred to female ovaries during copulation

We report on juvenile hormone (JH) biosynthesis in vitro by male accessory glands (MAGs) in the longhorned beetle, Aprionona germari, accompanied by the transfer of JH from males to females during copulation. JH was extracted from the MAGs and separated by reversed‐phase high‐performance liquid chromatography. JH III was identified as the major JH by gas chromatography–mass spectrometry. A radiochemical assay and a non‐radioactive method were used to measure the in vitro rate of JH biosynthesis by the MAGs. After 4 h of incubation with ³H‐methionine in the medium, the radioactivity in the MAGs substantially increased. In a separate assay, incubation of the MAGs with non‐radioactive methionine for 4 h resulted in a 39% increase in JH III. Seven‐day‐old males were injected with medium 199 containing ³H–methionine and 24 h later they were mated with virgin females. Hemolymph and the MAGs were collected from the mated males and hemolymph, ovaries and eggs were collected from the mated females for assaying radioactive JH. The radioactivity incorporated into JH in the MAGs was transferred to the females during copulation and later transferred into their eggs. Assayed 1 h after copulation, JH III level in the MAGs decreased 42% and the content of JH III in the male hemolymph did not change, whereas the content of JH III in the female hemolymph and ovaries both increased. © 2010 Wiley Periodicals, Inc.     

Mating in Heliothis virescens: Transfer of juvenile hormone during copulation by male to female and stimulation of biosynthesis of endogenous juvenile hormone

Studies were undertaken to determine whether adult males of Heliothis virescens transfer juvenile hormone (JH) to females during copulation, and an in vitro radiochemical assay was used to determine whether mating causes an allatotropic effect, i.e., stimulation of JH biosynthesis by corpora allata (CA). In vitro, CA from 3-day-old mated females synthesized and released approximately 2.5 times total JH as that of CA from comparably aged virgin females. Of the homologues, JH II exhibited significant increase in mated females; JH I also increased but not significantly. JH III remained similar to that of virgin females. This is the first demonstration of an allatotropic effect of mating in moths. In contrast to the female, CA of virgin males did not produce any JH, but accessory sex glands (ASG) in 3-day-old males synthesized small amounts of JH. Immediately after adult emergence, male ASG contained approximately 1.5 ng JH I and II, which increased by 12 h after emergence and remained at this high level up to 54 h after emergence. JH III was barely detected in ASG. JH in ASG of mated male immediately after uncoupling was depleted almost completely, and 24 h later recovered to levels comparable to that of 54-h-old virgin male. Virgin female bursa copulatrix did not contain any JH, but mated female bursa, immediately after uncoupling, had JH at levels comparable to that observed in virgin male ASG. By 6 h after uncoupling, JH levels decreased dramatically in mated female bursa. These data suggest the transfer of JH to females by the male. Arch. Insect Biochem. Physiol. 38:100–107, 1998. © 1998 Wiley-Liss, Inc.     

The biosynthesis of Juvenile Hormone, its degradation and titres in females of the true armyworm: a comparison of migratory and non-migratory populations

In a previous study [ McNeil et al. (1996) Archives of Insect Biochemistry and Physiology, 32, 575–584], patterns of sexual maturation and Juvenile Hormone (JH) biosynthesis were compared in virgin females from migratory (North American) and non‐migratory (Azorean) populations of the true armyworm moth, Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae). Sexual maturation occurred at a significantly earlier age after emergence in the non‐migrant population, and the rates of biosynthesis of JH in vitro suggested that lower titres of JH may be required to initiate the onset of calling behaviour (pheromone emission) and ovarian development in Azorean females. To examine the physiological differences in the reproductive biology of migratory and non‐migratory populations in greater detail, the haemolymph titres of JH and JH esterase activity were compared in virgin females as a function of age. In addition, the effects of mating on JH biosynthesis in vitro, JH titres, JH esterase activity and egg production were measured in the two populations. As expected, JH titres rose more rapidly after emergence in Azorean females than in their North American counterparts but, contrary to our prediction, the maximum levels were also higher in the non‐migrant population. Activity of JH esterase was much higher in Azorean females on the day of emergence. However, by the second day both populations had similar activity levels (about 17 nmol JH/min/ml) and exhibited a similar age‐related decline in subsequent days. Mating did not affect the rate of JH biosynthesis in vitro but resulted in a significant increase in the titres of JH in the haemolymph of both populations. The maximum titre (a five‐fold increase) occurred within 24 h of mating in Azorean females. In North American individuals the increase was greater (seven‐fold) but did not occur until 48 h after mating. No difference in the activity of JH esterase was observed between mated and virgin North American females. By contrast, while there was an age‐related decline in the activity of JH esterase in mated Azorean females, as seen in both North American groups, activity levels in virgin females remained constant with age. In all females, mating resulted in a significant increase in egg production within 24 h. The Azores is a volcanic archipelago, so these non‐migratory populations were probably founded by immigrants originating from migratory continental populations. It is clear from our results that the change from a life history that includes migration to a non‐migratory one involved more than just a temporal shift in the timing of the production of JH. Furthermore, the interpopulation differences in titres of JH and mating‐induced changes reported here cannot be fully explained by the observed differences in the patterns of activity of JH esterase and JH biosynthesis in vitro.     

Influence of the ovaries on JH titer in Teleogryllus commodus

Mating and availability of substrate were found to have a dramatic effect on the level of egg production and juvenile hormone III (JH III) titer in Teleogryllus commodus. Mated females with egg laying opportunity produced twice as many eggs, and exhibited an 8-fold increase in JH titer, as compared with virgin females or mated females forced to retain most of their eggs due to the absence of substrate for egg deposition. Denervation of the ovaries, or nerve cord transection, also caused accumulation of eggs and lowered the JH level, suggesting a feedback mechanism in which the state of egg depletion of the ovaries determines the level of JH secretion by the corpora allata (CA). Results from ovariectomy of mated or virgin animals suggest that the feedback mechanism includes inhibitory humoral factors secreted by the ovary.     

Role of juvenile hormone-esterase in mating-stimulated egg development in the moth Heliothis virescens

Juvenile hormone (JH) titer in virgin females of Heliothis virescens is significantly lower than that in mated females of the same age. The JH titer in virgin females follows a diel pattern in which it begins to increase towards the end of photophase, remains high around the onset of scotophase, and declines during scotophase. The titer reaches its lowest levels at the onset of photophase, and remains low during the first half of photophase. In mated females, the diel pattern of JH titers is not as pronounced. JH-esterase (JHE) activity in mated females is significantly lower than that of virgin females during photophase; JHE levels in the former are similar to levels seen in newly emerged females. JHE activity in mated females also exhibits a diel pattern, in which activity is low during photophase and high at the onset of scotophase. Evidence for the indirect involvement of JHE in the mating-stimulated egg development is provided by the effect of selected JHE inhibitors in inhibiting JHE activity and stimulating egg production in virgin females.     

Vitellogenin synthesis,processing and hormonal regulation in the tick,Ornithodoros parkeri (Acari:Argasidae)

This study was undertaken to determine the processing of vitellogenin (Vg) and the role of juvenile hormone (JH) in the regulation of vitellogenesis in the tick Ornithodoros parkeri. Ticks usually require a blood meal to induce vitellogenesis. However, we have shown that a pyrethroid, cypermethrin (CyM), can stimulate Vg synthesis in unfed Ornithodoros moubata females. Vg concentration and synthesis were analyzed by SDS-PAGE spotting-scanning and fluorography using [³⁵S]-methionine. Although unfed females show high titers of Vg in the hemolymph, this is not due to new synthesis. Vg synthesis stimulated by engorgement increases beginning on day 2 after engorgement and reaches a maximum level on day 8. Vg is synthesized in the fat body, secreted into the hemolymph and then processed and incorporated into the ovaries as vitellin. JH I, II and III, methoprene (JHA), and CyM were topically applied to unfed females and Vg synthesis analyzed on day 5 by fluorography. JH and JHA did not stimulate Vg synthesis. CyM stimulated Vg synthesis but not ovarian development. These preliminary results indicate that JH does not function in the regulation of vitellogenin synthesis in this species.     

Control of pheromone biosynthesis in mated redbanded leafroller moths

Mating in the redbanded leafroller moth, Argyrotaenia velutinana, causes a permanent decline in pheromone titers. Three hours following the termination of mating, phermone titers were significantly decreased from premating levels, and titers remained low for at least four days after mating. Pheromone titers were similar in females that had been decapitated or mated for twenty-four hours. In the redbanded leafroller moth, two peptides control pheromone production. The pheromone biosynthesis activating neuropeptide is produced in the brain and the pheromonotropic bursa peptide is produced in the corpus bursae. Both peptides stimulated pheromone biosynthesis in mated females and extracts prepared from brains and bursae of mated females contained pheromonotropic activity. However, severing the ventral nerve cord before mating prevented the decline in pheromone titer that occurred in mated females. Hemolymph collected during scotophase from mated females did not have pheromonotropic activity, whereas hemolymph collected during scotophase from virgin females contained activity. These results indicate that mating produces a signal sent by the ventral nerve cord to the brain to stop the release of pheromone biosynthesis activating neuropeptide. © 1993 Wiley-Liss, Inc.     

The effect of ovariectomy on reproductive behaviour and physiology of adult female ring-legged earwigs, Euborellia annulipes

The effect of ovariectomy on feeding, mating, Juvenile Hormone (JH) production, and maternal behaviour was assessed in female ring-legged earwigs, Euborellia annulipes (Lucas) (Dermaptera: Carcinophoridae), during the first 16 days of adult life (the first gonadotrophic cycle and early brooding). Ovariectomy of 2-day-old adults did not affect weight gain, nor did it alter mating behaviour on day 7. Similarly, ovariectomy did not prevent the increase in JH biosynthesis that accompanies vitellogenesis in this species, which suggests a cycle of JH production that is not dependent on the presence of the ovaries. Both ovariectomy and mating status affected feeding behaviour. Most introduced eggs were consumed (i.e. disappeared) within 24 h, and younger (7-day-old) females consumed more eggs than did older ones. However, 12-day-old intact virgins and 16-day-old ovariectomized, mated females consumed fewest eggs, and allowed some hatching. Thus, ovariectomy did not abolish changes in feeding behaviour that normally accompany reproduction but, instead, appeared to delay the reduction in feeding that normally accompanies the completion of the cycle of egg development. By contrast, mating enhanced the reduction in feeding late in the reproductive cycle. Mating significantly enhanced maternal behaviour in both ovariectomized and sham-operated females. Hatching success from egg clutches introduced to day 16 virgin or mated females that had been ovariectomized or sham-operated on day 2, was significantly greater in the mated groups.     

In vivo role of 20-hydroxyecdysone in the regulation of the vitellogenin mRNA and egg development in the American dog tick, Dermacentor variabilis (Say)

Injection of the hormone 20-hydroxyecdysone (20-E) into partially fed (virgin) female adults of the American dog tick, Dermacentor variabilis, while they are attached and feeding on the rabbit host, initiated the expression of the vitellogenin (Vg) gene, and Vg protein secretion and uptake by the ovary. The induction of egg production by 20-E in this bioassay was dose dependent in the range of 1-50 times the concentration normally found in a replete, vitellogenic female. Ticks examined 4 d after the 50 x treatment were still attached to the host, had numerous enlarged vitellin-filled (brown) oocytes in their ovaries, but had not engorged to repletion. The ovaries reached weights similar to those found in untreated, replete (mated) females (pre-oviposition) while solvent-injected controls demonstrated no increase in oocyte size or increase in ovary weight. An increase in the levels of a putative Vg protein was observed in hemolymph samples collected 1, 2 and 3d post-20-E injection but was not observed in the corresponding solvent controls as determined by native PAGE. Analysis of the ecdysteroid-induced protein by tryptic digestion-mass fingerprinting and BLASTP found that the putative Vg had the strongest match to GP80 (U49934), the partial sequence for the vitellogenin protein from Boophilus microplus. A partial Vg cDNA was cloned and sequenced from replete females of D. variabilis with a high similarity to GP80. Using this message as a probe, Northern blots conducted with RNA collected from partially fed, virgin females 1, 2 and 3d post-20-E injection showed upregulation of the Vg mRNA on all 3 days. Controls injected with solvent only showed no Vg mRNA. Injections with juvenile hormone III did not stimulate Vg expression, oocyte growth or full engorgement. These studies indicate that ecdysteroids and not JH can initiate expression of the Vg gene, Vg protein synthesis and release into hemolymph, and Vg uptake into developing oocytes under bioassay conditions mimicking normal feeding on the host.     

Juvenile hormone analog and injection effects on locust hemolymph protein synthesis

In adult female Locusta migratoria, at about day 8 after eclosion, when vitellogenin (Vg) is first produced as a result of induction by juvenile hormone (JH), the intensity of hemolymph protein electrophoretic bands at about 75 kDa and 20 kDa increases sharply, suggesting that JH may induce additional proteins. A major component of the elevated protein is persistent storage protein (PSP; subunit 74 kDa). Administration of the JH analog, methoprene, to precocene-treated adult locusts was followed by a rise in hemolymph levels of PSP but not in apolipophorin III (19 kDa), identified immunochemically and electrophoretically. The synthesis of PSP in adult fat body was confirmed by incorporation of [³H]leucine. At 48 h after treatment with methoprene, Vg synthesis was induced in females (as previously observed) and synthesis of PSP in both sexes was elevated above controls, while synthesis of apolipophorin III was not stimulated. We conclude that in adult locust fat body the synthesis of several proteins responds in different ways to the JH analog: Vg (and a 21 kDa protein described elsewhere) is induced de novo solely in females; PSP (and a 19 kDa protein described elsewhere) is stimulated in both sexes but is not fully JH-dependent; apolipophorin III is not stimulated. In these experiments, methoprene was administered both by injection in mineral oil and topically in acetone. After injection of mineral oil as a vector control, incorporation into secreted proteins was stimulated at 24 h, presumably due to a wound effect; topical application of acetone avoids this effect and is a preferred route for administration of JH analog. © 1992 Wiley-Liss, Inc.     

JH III production, titers and degradation in relation to reproduction in male and female Anthonomus grandis

Juvenile hormone (JH) is necessary for the production of vitellogenin (Vg) in the boll weevil, Anthonomus grandis. Occurrence of Vg in this species is typically restricted to reproductively competent females, and is not detected in untreated males. However, the JH analog, methoprene stimulates Vg production in intact males and in the isolated abdomens of both male and female boll weevils (where in each case no Vg is detected without treatment), suggesting that males are competent to produce Vg but are normally not stimulated to do so. Preliminary work indicating that male boll weevil corpora allata (CA) produced little or no JH in vitro suggested that failure of males to produce Vg might be due to very low JH levels compared to females. This study re-examines the question of JH in male boll weevils by determining in vitro production of JH III by male CA during the first 10 days after adult emergence, determining hemolymph JH esterase activity during this same time period and hemolymph JH III titers in adults of both sexes. We also re-examine the ability of isolated male abdomens to produce Vg in response to hormonal stimulation, analyzing the effect of a wide range of methoprene and JH III dosages. Results indicate that male A. grandis have circulating JH titers and JH production similar to females. JH esterase activity is slightly but significantly higher in males than females. Vg production by isolated abdomens of both sexes after stimulation with methoprene or JH III was confirmed. Dose response studies indicated that high levels of methoprene were less effective than intermediate doses in stimulating Vg synthesis in both sexes. We conclude that the sexually dimorphic effect of JH on Vg synthesis is not due to differences in JH production or differences in JH titer between the sexes.     

Influence of juvenile hormone and mating on oogenesis and oviposition in the codling moth,Cydia pomonella

Oogenesis in the codling moth, Cydia pomonella, and the role of juvenile hormones (JHs) were addressed. Rudimentary ovarian structures were recognisable in day 3–4 pupae, when haemolymph JH was still undetectable by coupled gas chromatography‐mass spectrometry in the selected ion mode (GC‐MS/SIM). The presence of developing oocytes was observed by light microscopy on day 8, coincident with very low JH titres (0.74 ± 0.05 ng/ml JH II). Chorionation was only evident upon emergence, following an increase in JH in the pharate adult (0h old: 4.71 ± 0.34 ng/ml JH II). Analysis of haemolymph from virgin and mated females indicated that JH II was predominant, with approximately equal and lower quantities of JHs I and III (3.3‐ to 5.0‐fold less). When pupae or newly emerged adults were treated with JH homologues, no alteration in ovarian protein content was apparent, but the JH mimetic, fenoxycarb, depressed the number of oocytes filling ≥ 50% follicular volume. Chorion deposition was stimulated by JHs I, II, or III (10 μg), but not by fenoxycarb (0.05 μg, 10 μg). Mating provided correct stimuli for enhanced choriogenesis and egg laying, and, since haemolymph JH titres were concomitantly elevated (approximately 2‐fold), it was postulated that the rise in JH elicited both these events. Application of JHs to virgin females, however, could not mimic mating; only increases in choriogenesis were induced: JH‐treatment of virgins (or mated insects) significantly decreased oviposition rates over 24 and 48 h and markedly reduced the life‐time total number of eggs. Arch. Insect Biochem. Physiol. 41:186–200, 1999. © 1999 Wiley‐Liss, Inc.     

Differential response of Trichogramma wasps to extreme sex pheromone types of the noctuid moth Heliothis virescens

1. Chemical espionage in nature may occur when predators or parasitoids home in on animal or plant communication signals. Parasitoid wasps are known to use pheromones emitted by adults hosts to locate host eggs, larvae or pupae. The response of Trichogramma egg parasitoids to a synthetic sex pheromone blend of moths has been shown in a number of studies over the past 40 years. 2. Trichogramma pretiosum (Hymenoptera, Trichogrammatidae) is a tiny parasitic wasp, attacking the eggs of the noctuid moth Heliothis virescens (Lepidoptera, Noctuidae). This study investigated whether T. pretiosum homes in on the sex pheromone of H. virescens at close range. The arrestment response of the wasps to sex pheromone gland extracts of two types of female moths, so‐called high and low females, was also tested, referring to two selected extreme pheromone types of H. virescens. The study also investigated whether the wasps would mount females, possibly to hitchhike with them. 3. The wasps were arrested by the common, ‘low’ pheromone, but not by the rare, ‘high’ pheromone or by extracts from male hairpencils. The wasps did not show a preference for separate sex pheromone compounds, but when pre‐exposed to the major sex pheromone component of H. virescens before the tests together with H. virescens eggs, they did show a preference, indicating learning behaviour. In the mounting experiments, mated females were mounted significantly more than virgin females or males, suggesting that hitchhiking is a strategy used by these wasps to locate moth eggs. 4. This represents the first study to show a differential response of parasitoid wasps to two different sex pheromone types in a single host species. The results warrant further investigations into the potential role of parasitic wasps in the evolution of sexual communication in moths.     

Recombinant juvenile hormone esterase as a biochemical anti-juvenile hormone agent: Effects on ovarian development in Acheta domesticus

By investigating the effects of recombinant juvenile hormone esterase (JHE) on the stimulation of ovarian development and egg laying in the house cricket Acheta domesticus L., we have tested the hypothesis that recombinant JHE (derived from the tobacco budworm Heliothis virescens) can be used as a biochemical anti-juvenile hormone (JH) agent. Recombinant JHE, produced by a genetically engineered baculovirus, was affinity-purified and injected into females of A. domesticus. JHE was cleared rapidly from the hemolymph of the crickets. However, upon repeated injection, significant reductions were seen in the extent of development of the ovaries and in the numbers of eggs laid. The effects of JHE could be rescued by topical application of the JHE inhibitor, OTFP. Thus, we have demonstrated an anti-JH effect on reproduction and that the recombinant JHE derived from a lepidopteran is active in an orthopteran insect. Arch. Insect Biochem. Physiol. 34:359–368, 1997. © 1997 Wiley-Liss, Inc.     

Activity of the corpora allata of adult female Aedes aegypti: effects of mating and feeding

The synthesis of juvenile hormone III (JH III) by the isolated corpora allata (CA) of Aedes aegypti adult female was studied using an in vitro radiochemical assay. We dissected the corpora allata-corpora cardiaca (CA-CC) complex attached to a piece of aorta. The complex was left connected to the intact head capsule to facilitate the visualization and transfer of the glands. A linear increase in the cumulative amount of biosynthesized JH III was found for at least the first 6 h of incubation; approximately 45% of the synthesized JH III was present in the medium. There was a dependence of JH III synthesis on exogenous methionine supply. Using reversed phase high performance liquid chromatography two major labeled products biosynthesized by the CA were separated. They co-migrated with JH III and methyl farnesoate (MF). The identity of the biosynthesized JH III was confirmed by gas chromatography-mass spectrometry. JH III synthesis was only 2.0 fmol/pair gland/h immediately after adult emergence, but increased to 32.6 fmol/ pair gland/h 18 h later in sugar-fed females. Two days after emergence, the CA biosynthetic activity slowly started to decrease, and reached values of around 5.3 fmol/pair gland/h by one week after emergence. Synthesis of JH was similar from either sugar-fed females mated or unmated. A blood meal resulted in a decrease of JH III synthesis in CA from mated females by 12 h after feeding and from virgin females by 24 h after feeding. JH III biosynthesis remained low for at least 96 h in mated females, but was back to higher levels 72 h after feeding in virgin females. Rates of JH III biosynthesis closely reflected the hemolymph levels of JH III both after emergence and after a blood meal described by Shapiro et al. (1986). The activity of the CA in Aedes aegypti females seems to be regulated by developmental changes and nutritional signals, and to be independent of mating stimulus.     

The effect of C18 juvenile hormone and Altosid on the efficiency of egg production in Rhodnius prolixus

The product (R) of the weight of the blood meal and the initial weight of the insect is shown to be a reliable predictor of egg production. The egg production efficiency (E), defined as the number of eggs produced per R, has a value characteristic of virgin females, and another, higher, value characteristic of mated females. Topical applications of C18 JH or Altosid to virgin females increase the value of E to the mated level in a fashion which suggests that these compounds act via a trigger mechanism. These compounds do not affect the rate at which oviposition occurs.