Application Of Juvenile Hormone Research Articles

Parasitism by Microplitis demolitor induces alterations in the juvenile hormone titers and juvenile hormone esterase activity of its host, Pseudoplusia includens

Microplitis demolitor is a polydnavirus-carrying parasitoid that attacks the larval stage of Pseudoplusia includens and other noctuids. Parasitism or injection of wasp components like polydnavirus and teratocytes has a juvenilizing effect on P. includens development. Here we measured hemolymph juvenile hormone (JH) titers and juvenile hormone esterase activity in P. includens larvae after parasitism or injection of wasp components. Results were compared to nonparasitized larvae. During the fifth stadium, JH titers of nonparasitized larvae fluctuated between 0.08 and 0.50 ng/ml, whereas titers in parasitized larvae never fell below 2 ng/ml. P. includens larvae injected with calyx fluid plus venom or calyx fluid plus venom and teratocytes exhibited JH titers intermediate between parasitized and nonparasitized larvae. Nonparasitized larvae exhibited two peaks of JH esterase activity. The first occurred between 12 and 48 h in association with cessation of larval feeding, while the second occurred immediately before pupation. In contrast, levels of JH metabolism remained at low levels in parasitized larvae and larvae injected with calyx fluid plus venom or calyx fluid, venom and teratocytes. Only trace amounts of JH were detected in in vitro assays of teratocytes or M. demolitor larvae suggesting neither released JH into the hemolymph of parasitized larvae. Although calyx fluid plus venom and teratocytes did not elevate JH titers to the levels measured in parasitized larvae, their effects on formation of larval-pupal intermediates by P. includens were similar to those generated by exogenous application of methoprene or JH.

Effects of Juvenile Hormone and Head Ligations on the Succession of Cryptic Larval Color Patterns in Cerura vinula (Lepidoptera: Notodontidae)

The color patterns of the different larval instars of Cerura vinula Linnaeus 1758 are described and their protective function is discussed. The cuticular melanization is stepwise reduced, in different parts of the pattern at different molts. In the wandering stage, a temporary appearance of epidermal ommochrome results in completely red animals. It is investigated whether the succession of different larval colorations is controlled by the Corpora allata through different levels of juvenile hormone (JH). Head ligation at the end of a young larval instar, eliminating the Corpora allata, causes reddening of the whole epidermis without further development. Injection or topical application of JH before a larval molt causes uniform reduction of all melanin in the new cuticle. This effect does not mimic the stepwise reduction in different cuticular areas which occurs during the normal development. It is concluded that the ommochrome formation at the wandering stage depends on the absence of JH. Head ligation inhibits, in young larvae, the distribution of JH but, at the same time, interrupts that of prothoracicotropic hormone [PTTH], so that a small ecdysone peak results in the absence of JH, similar to the situation at the wandering stage, when it evokes ommochrome formation, but not a complete molt. Excessive JH causes an unspecific melanin inhibition, which cannot, by itself, explain the normal sequence of larval melanization patterns.

Overview of the regulation of metamorphosis‐associated genes in Trichoplusia ni

A review is presented of our ongoing research program on the regulation of metamorphosis-associated proteins in Trichoplusia ni. Toward the identification of mechanisms by which juvenile hormone (JH) regulates expression of metamorphosis-associated proteins, we have identified a protein that is induced by JH (juvenile hormone esterase) and a related esterase that is not JH-inducible. We have also identified three hexamerins that are suppressible by JH, and one hexamerin that is not JH-suppressible. Expression of the hexamerins is regulated at the transcriptional, translational, and posttranslational levels in T. ni. The rate of transcription of the JH esterase gene increases at the time of the prepupal peak in JH, and exogenous application of JH can cause, within 3 h, the rate of transcription to be markedly elevated above normal. Using in vitro functional transcription assay, cell line transfection functional assay, and preliminary DNase I hypersensitive site mapping we were able to identify the functional TATA box and transcription start sites of JH-sensitive genes. These methods were also observed to be powerful in the detection of regulatory DNA motifs involved in the modulation of transcriptional activity constitutively imparted by a core promoter. The experimental systems described here will also be effective in identifying those components through which JH regulatory effects are mediated. Should JH act on the genes in a primary manner, then the transcription factor mediating that action may be the (a) JH receptor. Should the JH action be in a secondary manner, then the transcription factor(s) whose activity at the JHE gene is regulated by JH will provide the tool to track back to the location and nature of the primary JH action. © 1996 Wiley-Liss, Inc.

Overview of the regulation of metamorphosis-associated genes in Trichoplusia ni.

A review is presented of our ongoing research program on the regulation of metamorphosis-associated proteins in Trichoplusia ni. Toward the identification of mechanisms by which juvenile hormone (JH) regulates expression of metamorphosis-associated proteins, we have identified a protein that is induced by JH (juvenile hormone esterase) and a related esterase that is not JH-inducible. We have also identified three hexamerins that are suppressible by JH, and one hexamerin that is not JH-suppressible. Expression of the hexamerins is regulated at the transcriptional, translational, and posttranslational levels in T. ni. The rate of transcription of the JH esterase gene increases at the time of the prepupal peak in JH, and exogenous application of JH can cause, within 3 h, the rate of transcription to be the markedly elevated above normal. Using in vitro functional transcription assay, cell line transfection functional assay, and preliminary DNase I hypersensitive site mapping we were able to identify the functional TATA box and transcription start sites of JH-sensitive genes. These methods were also observed to be powerful in the detection of regulatory DNA motifs involved in the modulation of transcriptional activity constitutively imparted by a core promoter. The experimental systems described here will also be effective in identifying those components through which JH regulatory effects are mediated. Should JH act on the genes in a primary manner, then the transcription factor mediating that action may be the (a) JH receptor. Should the JH action be in a secondary manner, then the transcription factor(s) whose activity at the JHE gene is regulated by JH will provide the tool to track back to the location and nature of the primary JH action.

Pre- and post-natal effects of precocenes on aphid morphogenesis and differential rescue

Post-natal application of Precocene II (6,7-dimethoxy-2,2-dimethylchromene, PII) to newly-born pea aphid larvae, Acyrthosiphon pisum (Harris), does not influence development and the PII promotion of winged progeny previously reported after pre-natal application appears to be exerted via a maternal control mechanism. The production of winged progeny by crowded, wingless adults can be inhibited by both pre- and post-natal application of Precocene III (6-methoxy, 7-ethoxy-2,2-dimethylchromene, PIII). Precocene III treatment also induces precocious adult development, i.e., early metamorphosis. Both wing inhibition and precocious metamorphosis were dose- and age-dependent when PIII was post-natally applied. Pre-natal application of juvenile hormone III or its agonist, pyriproxyfen, following treatment with PII or PIII, did not influence the precocene effects on wing induction or inhibition, respectively. Post-natal treatment with the juvenile hormone and pyriproxyfen, subsequent to PIII, reversed the precocious metamorphosis effect but not wing inhibition. This differential result, with an identical rescue protocol, suggests that PIII induction of precocious adult development arises as the result of the selective destruction of the corpus allatum cells and a lowered JH titre. However, the property of PIII that promotes the development of wingless forms appears unrelated to this decrease in juvenile hormone titre. © 1996 Wiley-Liss, Inc.

Hormonally-regulated differential expression of the two duplicated insecticyanin genes, ins-a and ins-b, during development of the tobacco hornworm, Manduca sexta.

The effects of juvenile hormone (JH) and 20-hydroxyecdysone (20E) on the developmental expression of the two insecticyanin genes, ins-a and ins-b, were investigated with two gene-specific probes. Removal of the corpora allata (-CA, source of JH) clearly delayed and down-regulated the epidermal expression of these genes but enhanced their expression in the fat body during the early development of the fifth instar. Application of JH I to the -CA larvae at the time of head capsule slippage completely restored the normal epidermal expression pattern of the two genes in the early fifth instar, then INS-a mRNA declined prematurely whereas INS-b mRNA remained similar to that in the intact larvae. By contrast, in the fat body of -CA larvae, the exogenous JH had little effect on the levels of INS-a mRNA, but enhanced expression of INS-b mRNA relative to intact larvae. Culture of epidermis from day 1 fifth instar larvae with 40 ng/ml 20E for up to 24 h accelerated the loss of INS-a mRNA without affecting the levels of INS-b mRNA. Both mRNAs declined in isolated larval abdomens over a 24 h period, and this decline was slowed by 1 μg methoprene (a JH analog). Together these results indicate that JH controls the levels of the two mRNAs in both the epidermis and fat body, with additional factors involved in regulating these genes in the fat body during the molt and in the epidermis during the growth phase.

Physiological correlates to courtship, mating, ovarian development and maternal behaviour in the ring‐legged earwig

Abstract. The involvement of the endocrine system in courtship, mating, maternal behaviour and the gonadotrophic cycle was studied in the earwig, Euborellia annulipes, after application of JH III and, alternatively, precocene II.Topical application of 35 or 122 μg of JH III to newly eclosed females advanced the onset of courtship behaviour from 6.6 ± 1.3 days in acetone‐treated controls to 1.4 ± 2.8 and 0.5 ± 2.5 days, respectively. Application of 6 μg of JH III had no effect on the onset of courtship behaviour. Applications of Juvenile Hormone had no significant effect on the age at first mating nor on the duration of mating, though the trend is towards advanced onset. The age at first oviposition was advanced by hormone treatment; clutch size and the proportion of offspring hatching was reduced by hormone treatment. The interclutch interval, size and proportion hatching of the second clutch were not affected by hormone treatment.Topical application of 50 μg of JH III to females on the day of oviposition shortened the total duration of maternal care from 15.4 ± 0.5 to 5.3 ± 1.7 days; whereas in acetone‐treated and precocene II‐treated groups maternal care lasted 16.1 ± 1.9 and 13.8 ± 1.6 days, respectively. The duration of maternal care was positively correlated with number of offspring hatching and fledging.In a corollary experiment, topical application of JH III significantly enhanced the onset of the second gonadotrophic cycle as assessed by basal follicle length; application of 20 μg of precocene II, either singly or in repeated doses, did not delay growth of basal follicles. Finally, repeated application of as much as 80 μg of precocene II had no effect on basal follicle length, nor on ovary wet weights.These results are consistent with the hypothesis that intermediate to high titres of JH are associated with oocyte growth, mating, and the cessation of maternal care; low titres of JH appear to be associated with the period of maternal behaviour and slow ovarian follicle development.

The role of the corpora allata in the adult male cricket ( Gryllus campestris and Gryllus bimaculatus) in the development and expression of its agonistic behaviour

We examined the role played by the corpora allata, paired glands which secrete juvenile hormone, in regulating male agonistic and sexual behaviours in the field cricket species Gryllus campestris and Gryllus bimaculatus. G. bimaculatus males began to exhibit their typical agonistic behaviour approx. 10–14 days after their adult moult. Application of juvenile hormone to newly moulted males did not precociously induce agonistic behaviour. Removing the corpora allata from newly moulted males had no effect on their subsequent agonistic behaviour. Allatectomized animals of both species fought with the same success, duration and intensity as controls. Therefore, neither the corpora allata nor its product, juvenile hormone III, are critically important in regulating male agonistic behaviour. Moreover, allactectomized males of both species were capable of copulating with females and transferring normal-looking spermatophores. Allatectomized G. bimaculatus males were able to mate even when they had to compete with control males. The identity of the factors that are important for the expression of sexual and agonistic behaviours in the adult male cricket remains unknown, but it is not JH III.

Sex determination in bees. XXX. Effects of juvenile hormone on the development of tergal glands inMelipona

SUMMARYWorker larvae of Melipona rufiventris, M. quadrifasciata and M. compressipes were treated topically with juvenile hormone (JH) during the cocoon-spinning phase. Examination of the tergites of the queens obtained following JH application showed induced differentiation into adults with full female (queen) traits. Melipona workers had tergal glands only in tergite II, whereas natural and JH-induced queens had tergal glands in tergite II plus additional glands in at least one other of tergites III to VII.

Regulation of cricket phonotaxis through hormonal control of the threshold of an identified auditory neuron

1. The phonotactic threshold of 3 to 5-day-old adult female Acheta domesticus and the threshold of the L1 auditory neuron drop progressively (Fig. 1). 2. Application of juvenile hormone III (JHIII) to 1-day-old females caused both the female's threshold for phonotaxis and the threshold of the L1 auditory neuron to drop 20 or more dB over the next 12 h (Figs. 3-4). 3. JHIII's effect on phonotactic threshold could be blocked by injection with a transcription (alpha-amanitin) or a translation blocker (emetine, Fig. 3). 4. Injection of emetine also prevented the JHIII induced drop in L1's threshold (Fig. 4). 5. Application of JHIII to the surface of, or microinjection of JHIII into one prothoracic hemiganglion caused the female to circle phonotactically away from the side of hormone addition at thresholds 25 to 35 dB lower than the pre-JHIII addition threshold within 2 h (Fig. 6). 6. Application of JHIII to the surface of both prothoracic hemiganglia, accompanied by microinjection of emetine into one hemiganglion resulted in the female emetine into one hemiganglion resulted in the female circling phonotactically toward the side receiving emetine injection, with a 25 to 35 dB drop in threshold (Fig. 6).

Effects of Juvenile Hormone and its Analogs on Vitellogenin Synthesis and Ovarian Development in Ornithodoros moubata (Acari: Argasidae)

Effects of juvenile hormones (JH) and JH analogs on the release of vitellogenin (Vg) into the hemolymph and ovarian development in unfed adult female ticks, Ornithodoros moubata (Murray), were investigated. Topical application of acetone solvent and injection of acetone or oils showed some increase in Vg titer in the hemolymph. Topical application of JH (JH I, JH II, JH III) and JH analogs (methoprene, S21149, S21150, and S31183) dissolved in acetone to unengorged adult females elevated Vg titer in the hemolymph but only to the same level as the acetone controls. These effects were independent of dose. Injection of JH (JH I, JH II, JH III) and methoprene dissolved in mineral oil also did not significantly increase the Vg titer in the hemolymph compared with the controls (mineral oil injection). Electrophoretic analysis of hemolymph from females 5 d after treatment topically or by injection with JH and JH analogs showed faint Vg bands which comigrated with Vg's (Vg-1 and Vg-2) of normal, engorged female hemolymph, but Vg bands were detected more clearly in the hemolymph samples that were collected greater than 2 wk after treatment. However, the same level of Vg also was detected in the hemolymph of females treated with acetone or mineral oil. Vg synthesis in females treated with JH and JH analogs was analyzed by in vivo labeling and fluorography, which showed that Vg synthesis was not induced by application of JH to unengorged females.

Effects of methoprene and juvenile hormone on the oxidative metabolism of isolated mitochondria from flight muscle ofLocusta migratoria L.

In vitro applications of juvenile hormone III and a juvenile hormone analogue, methoprene, were made to mitochondria isolated from dorsal longitudinal flight muscles of adultLocusta migratoria L. Both compounds completely inhibited oxygen consumption at the highest concentrations used. At lower concentrations, state 3 respiration and respiratory control were reduced but the ADP/O ratio was largely unaffected.

Involvement of juvenile hormone in the induction of antifreeze protein production by the fat body of larvae of the beetle Dendroides canadensis

AbstractLarvae of the Pyrochroid beetle Dendroides canadensis produce hemolymph antifreeze proteins (AFPs) as an adaptation to subzero overwintering temperatures. The AFPs are produced in early autumn in response to various environmental cues (short photoperiod, low temperature, short thermoperiod). The study presented here reinforces and extends the initial finding (Horwath and Duman, '83b) that juvenile hormone is involved in stimulating production of AFPs. Dose response curves showed seasonal variation in the sensitivity of the larvae to topical application of Juvenile Hormone (JH), with late summer larvae being more sensitive than early summer ones. The time response curve for induction of AFP activity in late summer larvae demonstrated that ∼14 days are required after JH treatment for the appearance of a significant increase in AFP activity. The timing of this response to JH induction is similar to that seen previously when larvae were acclimated to a short photoperiod.Studies with cultured fat bodies showed that the fat body is a probable site of production of the AFP, and further emphasized a role for JH in AFP induction. However, stimulation of AFP production by fat body only occurred when the fat bodies were removed from larvae that had been pretreated with JH. The presence of JH in the culture medium did not stimulate fat bodies taken from larvae that had not been pre‐treated. This suggests that an additional hormone(s), or other factor, may be required to induce fat body production of AFPs.

Control of follicular epithelium development and vitelline envelope formation in the mosquito; role of juvenile hormone and 20-hydroxyecdysone

Using microsurgical manipulations, hormone applications, and transmission electron microscopy we have investigated the regulation of differentiation of the follicular epithelium and formation of the vitelline envelope (VE) in primary follicles in the ovary of the mosquito, Aedes aegypti. During the first 3 days after eclosion, the primary follicle grows, and cells of the follicular epithelium differentiate, their content of mitochondria, rough endoplasmic reticulum, and Golgi complexes increases significantly. Growth and differentiation of the follicular epithelium appear to be under the control of juvenile hormone (JH), because they are blocked by removal of corpora allata in newly closed adult females and can be restored by either implantation of corpora allata or application of JH III. In insects, including mosquitoes, VE is the first layer of the eggshell to be deposited. It is formed from the secretory products of the follicle cells and its deposition coincides with yolk accumulation by developing oocytes. Only follicle cells adjacent to the oocyte deposit VE. In decapitated females, given a blood meal by enema and injected with picogram doses of 20-hydroxyecdysone (20-HE), follicle cells synthesize the VE precursors and deposit morphologically normal VE, in contrast to saline injected controls which deposit no VE. We conclude that 20-HE, as well as factors originating from the blood meal and the oocyte, are required for the normal formation of VE in the mosquito follicles.

Effects of azadirachtin on the dietary utilization and development of the variegated cutworm Peridroma saucia

The phytochemical azadirachtin from the neem tree Azadirachta indica was administered to different larval instars of the variegated cutworm, Peridroma saucia orally in artificial diet, topically, or by injection. Nutritional analyses revealed that insect growth inhibitory and antifeedant effects were independent of each other and relative to the level of treatment. Injection of a 2 μg/g body weight dose of azadirachtin to sixth-instar larvae does not lead to starvation. However, substantial developmental anomalies result upon pupation. Ligature experiments demonstrated that head ligation in last-instar larvae, counteracted the azadirachtin-induced interference with pupation, pointing to an “aza-sensitive head factor”. Exogenous application of juvenile hormones I or II or juvenile hormone esterase inhibitor, BEPAT (in order to elevate hormone levels in the larvae) did not counteract any of the effects of azadirachtin treatment. The significance of these results in terms of hormonal events in P. saucia is discussed.

Juvenile Hormone and host‐plant colonization by the black bean aphid, Aphis fabae

Abstract Host‐plant colonization by winged, summer forms of Aphis fabae Scop, involves the resumption of embryogenesis and larviposition, leading eventually to flight muscle degeneration. Topical application of Juvenile Hormone I to young adults which (a) had access to the host plant, (b) were starved, (c) were starved and treated with precocene III, or (d) were decapitated shortly after the final ecdysis suggests that embryogenesis and flight muscle histolysis may be stimulated by an increase in Juvenile Hormone titres after settling. The duration of the pre‐reproductive period and the initial reproductive rate were not significantly affected, possibly because other neuroendocrine factors are involved in parturition.

Photoperiodic diapause in Drosophila melanogaster involves a block to the juvenile hormone regulation of ovarian maturation

Females of Drosophila melanogaster held under short-day photoperiods at a moderately low temperature (12°) enter a state of ovarian diapause in which yolk deposition in the oocytes is suspended (D. S. Saunders, V. C. Henrich, and L. I. Gilbert, Proc. Natl. Acad. Sci. USA 86, 3748–3752, 1989). An enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies raised against D. melanogaster yolk polypeptides (YPs) showed that diapausing flies synthesize and accumulate YPs in the hemolymph, but very little in the ovary. Nondiapausing females at the same temperature but at long days, and short-day flies in which diapause was broken by an upshift in temperature or topical application of juvenile hormone (JH), showed enhanced titers of YPs in the ovaries, suggesting stimulated uptake. Determinations of juvenile hormone bisepoxide (JHB 3) and JH III synthesis in vitro by single excised corpora allata showed that glands from nondiapausing flies or corpora allata from flies in which diapause had been broken synthesized JH at a rate about four times higher than glands from diapausing flies. Corpora allata incubated in medium supplemented with farnesoic acid showed an increase in the rate of JH synthesis, but the increase was relatively greater with corpora allata from nondiapausing flies. Glands from diapausing flies presented the appearance of newly emerged or “immature” glands. Ovarian diapause is terminated at 12° LD 10:14 in 7 days following topical application of either JH III or JHB 3 at a concentration of about 0.5 μg per fly, diapause termination being expressed by an increased rate of vitellogenesis and by an increase in the number of fully developed eggs per vitellogenic female. It is concluded that the short-day-elicited diapause in D. melanogaster results from a “block” to the JH-stimulated uptake of yolk proteins from the hemolymph, caused by a reduced rate of JH synthesis by the corpus allatum. Photoperiodic regulation of the corpus allatum may be mediated via the brain.

Juvenile hormone controls previtellogenic proliferation of ribosomal RNA in the mosquito fat body

During the previtellogenic development of mosquito fat body cells, the nucleolus, the organelle responsible for producing ribosomes, enlarges threefold, reaching maximal size between 2 and 3 days after eclosion. The granular component of the nucleolus containing ribosomal precursors increases considerably as well. These signs of nucleolar activation correlate with the synthetic rate and accumulation of poly(A) − RNA (predominantly ribosomal RNA) in the fat body cells. The amount of poly(A) − RNA in fat body cells increases during the first 2 days after eclosion and then declines gradually. The rate of RNA synthesis exhibits similar kinetics, but both the rise and the decline are sharper than for the accumulation of RNA. All the characteristics of nucleolar activation, its enlargement, accumulation of poly(A) − RNA, and the increased rate of RNA synthesis, are blocked by removal of the corpora allata (CA) in newly eclosed adult females but could be restored by either implantation of CA or topical application of juvenile hormone III or its analog, 7- S-methoprene, to allatectomized females. Thus, previtellogenic activation of fat body nucleoli for ribosomal RNA production is controlled by juvenile hormone from the corpora allata.

Induction of vitellogenin synthesis and maturation of transplanted previtellogenic eggs by juvenile hormone III in males of the sawfly, Athalia rosae

Both haploid and diploid adult males of the hymenoptera, Athalia rosae (Symphyta, Tenthredinidae), produced the two vitellogenins, L and S, in their haemolymph following topical application of juvenile hormone III. Previtellogenic ovaries transplanted into the abdoment of haploid adult males which were then given juvenile hormone III topically, maturated and the eggs upon in vitro activation successfully completed embryonic development.

Effects of ecdysone, juvenile hormone and haemolymph transfer on cryoprotectant metabolism in diapausing and non-diapausing pupae of Pieris brassicae

Hormone applications and haemolymph transfer were used to study the control of cryoprotectant synthesis in diapause and non-diapause Pieris brassicae. Diapause pupae are 24% heavier than non-diapause pupae 5 days after pupation and have 10 times more sorbitol and 8 times more mannitol in the absence of low temperature exposure. In diapause pupae, sorbitol increases 8-fold from 5 to 55 days at 20°C. Other carbohydrates such as glucose, mannose, glycerol, mannitol and inositol also increase during this time. Injection of ecdysone (500 ng) terminates diapause at all stages investigated but does not affect development or carbohydrate levels in non-diapause pupae. Diapause pupae show significant decreases in glucose, mannose, sorbitol and mannitol after ecdysone injection, whilst glycerol increases. Juvenile hormone application (500 ng) has no effect on the development of diapause or non-diapause pupae but the latter show significant increases in glucose and glycerol whilst sorbitol levels are unchanged. In contrast, diapause pupae show significant increases in sorbitol whilst glycerol decreases. Haemolymph transfer did not influence carbohydrate levels. Implications for the relationship between cryoprotectant synthesis and diapause are discussed and a model is proposed.