Juvenile hormone-controlled vitellogenin synthesis in Locusta migratoria fat body. Hormonal induction in vivo.

Biosynthetic processes related to the production of vitellogenin (yolk precursor protein) have been examined in the fat body of adult female Locusta migratoria. Vitellogenin-producing capacity was assayed by incubation of fat body with [³H]leucine, followed by precipitation from the medium with specific antiserum. In normal development, vitellogenin synthesis began at about Day 7 after emergence and became maximal at about Day 13, when this protein accounted for 60% of the total fat body protein output. The production of other proteins increased to a lesser extent, becoming maximal at about Day 6. The incorporation of uridine into fat body RNA rose to a maximum at Day 8, which coincided with a marked increase in tissue RNA content. The DNA content in adult female fat body approximately doubled between Days 3 and 8. Vitellogenin synthesis, and the increases in RNA and DNA, were prevented by removal of the corpora allata (the source of juvenile hormone). In allatectomized locusts, vitellogenin synthesis was induced by JH or an analog, ZR-515. Applied topically in acetone, these gave steep dose-response curves, half-maximal at 75 and 150 μg, respectively. After a single treatment with ZR-515, fat body vitellogenin production rose slowly during 48 hr, then steeply to a maximum at 72 hr, but after decay of this effect during 10 days, a second application of ZR-515 induced renewed synthesis with little initial lag. Hormone treatment produced a smaller increase in the output of other proteins, and an increase in incorporation into RNA which preceded the major rise in vitellogenin synthesis. Male fat body produced little or no vitellogenin. These results are consistent with action of JH at the gene level.     

Endocrine biology of the Painted Lady butterfly Vanessa cardui

Experiments dealing with the role of juvenile hormone, adipokinetic hormone and diuretic hormone in the Painted Lady butterfly Vanessa cardui are reported. The results demonstrate an important role of JH in the regulation of ovarian and colleterial gland development in females, and in the regulation of accessory gland, tubular gland and ejaculatory duct development in males. In addition, the presence of an adult reproductive diapause, characterized by decreased effective juvenile hormone haemolymph titres, is suggested. Evidence for the existence of both adipokinetic and diuretic hormones in the Painted Lady is also presented, as is data indicating that both hormones may be similar or identical to those previously described in Monarch butterflies. Owing to the above results, and the existence of an artificial diet suitable for mass rearing in the laboratory, the Painted Lady appears to be an excellent species for studies on adult lepidopteran neuroendocrinology.     

Genetic and Hormonal Regulation of Vitellogenesis in Drosophila

In Drosophila the female-specific yolk protein, or vitellogenin,is synthesized in the fat body. In D. melanogaster, vitellogenin,is first detected in the female hemolymph at the time of adulteclosion and in the ovaries 20 hours later, suggesting differentregulatory mechanisms for the processes of synthesis and uptake.Transplantations of pupal or immature adult ovaries into D.melanogaster adult males induce vitellogenin synthesis, implicatingan ovarian agent in the control of synthesis. Larval ovariesfail to stimulate synthesis. Female-sterile mutants with rudimentaryor previtellogenic ovaries synthesize and accumulate large quantitiesof vitellogenin in the hemolymph, but not in the ovaries. Transplantationof these rudimentary ovaries into males induces vitellogeninsynthesis, suggesting that the ovarian inducing agent does notoriginate from the germ cells. Treatment of the homozygous female-sterilemutants with juvenile hormone stimulates the uptake of vitellogeninby the ovary in some strains. This shows that juvenile hormoneplays a role in vitellogenin uptake. The potential importanceof Drosophila vitellogenesis for studies of gene regulationis discussed.     

Purification and properties of microvitellogenin of Manduca sexta role of juvenile hormone in appearance and uptake

Microvitellogenin, a female specific protein found in hemolymph and eggs of adult female Manduca sexta (tobacco hornworm moth) has been purified to homogeneity. It is a 31,000 dalton protein lacking covalently bound carbohydrate. It appears in the hemolymph near the time of adult eclosion. The appearance of microvitellogenin in adult hemolymph is not dependent upon the presence of juvenile hormone. Uptake of both vitellogenin and microvitellogenin are greatly reduced in the absence of juvenile hormone.     

家蝇的卵黄发生及其激素调节

用5—15%SDS-PAGE分析表明,家蝇Musce domestica viaina卵黄蛋白由三个亚基组成,其亚基分子量分别为58KD、50KD、48KD.火箭免疫电泳的结果表明,脂肪体、血淋巴和卵巢内卵黄原蛋白的变化具有密切的相关性,卵黄原蛋白在体内最早出现在羽化后30小时左右,然后迅速增加,在羽化后48小时,脂肪体和血淋巴中卵黄原蛋白含量达到最大值,卵巢开始沉积卵黄蛋白在羽化后30小时,到产卵前达到最大值,脂肪体在离体培养条件下,通过测定³H-亮氨酸掺入卵黄原蛋白的量,对不同发育时期家蝇脂肪体合成卵黄原蛋白的能力及激素的调节作用进行了研究,结果表明,羽化12小时后,合成能力迅速上升,48小时时形成高峰,60小时后迅速下跌直至产卵,其合成能力一直维持在低水平,产卵后合成能力又迅速回升,激素处理结果表明,保幼激素可以促进卵黄发生前期和后期家蝇脂肪体的卵黄原蛋白合成,20-羟基蜕皮酮可以大幅度促进卵黄发生期家蝇脂肪体的卵黄原蛋白合成.当二种激素共同处理时,对卵黄发生前期和卵黄发生期的家蝇脂肪体有协同促进作用,而对卵黄发生后期的脂肪体没有这种作用.本文还对家蝇卵黄发生过程中脂肪体、血淋巴和卵巢三者之间的关系及家蝇卵黄发生的激素调节进行了讨论.     

Juvenile hormone regulation of longevity in the migratory monarch butterfly.

Monarch butterflies (Danaus plexippus) of eastern North America are well known for their long-range migration to overwintering roosts in south-central Mexico. An essential feature of this migration involves the exceptional longevity of the migrant adults; individuals persist from August/September to March while their summer counterparts are likely to live less than two months as adults. Migrant adults persist during a state of reproductive diapause in which both male and female reproductive development is arrested as a consequence of suppressed synthesis of juvenile hormone. Here, we describe survival in monarch butterflies as a function of the migrant syndrome. We show that migrant adults are longer lived than summer adults when each are maintained under standard laboratory conditions, that the longevity of migrant adults is curtailed by treatment with juvenile hormone and that the longevity of summer adults is increased by 100% when juvenile hormone synthesis is prevented by surgical removal of its source, the corpora allatum. Thus, monarch butterfly persistence through a long winter season is ensured in part by reduced ageing that is under endocrine regulation, as well as by the unique environmental properties of their winter roost sites. Phenotypic plasticity for ageing is an integral component of the monarch butterflies' migration-diapause syndrome.     

Maturation of locust corpora allata during the reproductive cycle: Effect of reserpine on allatotropic activity,juvenile hormone-III biosynthesis,and oocyte development

Reserpine, at doses of 20–175 μg per g body weight, severely retards oogenesis in newly emerged adult female migratory locusts (Locusta migratoria migratorioides) but does not increase mortality during the first 9 days and only slightly delays somatic growth. Total protein, and hemolymph vitellogenin content particularly, are significantly reduced in reserpine-treated locusts. The synthesis of juvenile hormone III (JH-III) following adult emergence, essential for induction of vitellogenesis and subsequent oogenesis, is dependent on the maturation and activation of the corpora allata (CA). CA of 7- to 8-day-old female locusts, treated with reserpine at day 1 after adult emergence, are only marginally active in vitro and are only slightly stimulated by an allatotropic factor. The basal activity and response of CA from the reserpine-treated locusts resembles that of newly emerged locusts, suggesting that reserpine specifically retards the initial maturation of the locust CA. Recovery of basal CA activity is evident on days 12–13 in reserpine-treated locusts, but responsiveness to the allatotropic factor is not recovered. Starvation of newly emerged females for 3 days and subsequent feeding did not effect ooctye development or CA activity. Cerebral content of the allatotropic factor, assayed on days 7–8, is not reduced by the reserpine treatment.     

Activation of vitellogenin synthesis in the mosquito Aedes aegypti by ecdysone

Injected β-ecdysone was found to induce the synthesis of yolk protein (vitellogenin) in adult female Aedes aegypti without a blood meal. After injection of 5 μg ecdysone per mosquito, vitellogenin constituted 80 per cent of the total protein secreted by explanted fat body, a proportion comparable to that produced by fat body from blood-fed females. Moreover, the time course of induction of vitellogenin synthesis in ecdysone-injected mosquitoes was similar to that triggered by a blood meal. Response to ecdysone is dosedependent: 0·5 μg per female was required to stimulate synthesis to 50 per cent of the level found 18 hr after a blood meal. Ecdysone was effective in decapitated or ovariectomized mosquitoes, and also when applied directly to fat body preparations in vitro. Thus it appears that ecdysone acts directly on the fat body to induce specific protein synthesis, as does the vitellogenin stimulating hormone (VSH) from the ovary of blood-fed mosquitoes. These results suggest that ecdysone can replace VSH in inducing vitellogenin synthesis in the unfed mosquito.     

Endocrine influence upon the development of vitellogenic competency in Oncopeltus fasciatus

Immunoelectrophoretic analysis of the blood of precocious adult females of Oncopeltus demonstrated the presence of the A form of vitellogenin but no detectable AB form, the form present in mature adult-female haemolymph. Although the appearance of the AB form could be induced by topical treatment of precocious adult females with juvenile hormone, no yolk deposition was induced in these females. Histological examination revealed that the ovaries of precocious adult females reached only a previtellogenic stage of development with or without treatment with juvenile hormone. Topical treatment of normal larvae and adults with the hormone demonstrated that vitellogenin synthesis could not be induced with juvenile hormone treatment alone until after adult emergence. Since the precocious adult females are chronologically younger than normal last-stage larval instars, we suggest that a transition period during which juvenile hormone is absent (i.e. the precocious moult in treated animals; the final moult in control animals) must occur before some tissue of the precocious or normal adult females, presumably the fat body, becomes competent to respond to further exposure to the hormone by making the AB form of vitellogenin. The ovary requires a similar transition period prior to becoming capable of depositing vitellogenin; however, the times when the fat body and the ovary become competent to respond to the transition period differ.     

The roles of juvenile hormone and 20-hydroxy-ecdysone during vitellogenesis in isolated abdomens of Drosophila melanogaster

Both juvenile hormone and 20-hydroxy-ecdysone seem to be involved in the regulation of vitellogenesis in Drosophila melanogaster. It is the purpose of this paper to begin to define the functions of these two hormones. Although vitellogenin synthesis does not occur at a high rate in 1-day-old female abdomens isolated from the head and thorax before 0.75 hr after eclosion, both ZR515 (a juvenile hormone analogue) and 20-hydroxy-ecdysone can cause in these preparations vitellogenin synthesis and secretion into the haemolymph. The synthesis and secretion into the haemolymph of all three vitellogenins which are detectable by electrophoresis in sodium dodecyl sulphate-containing gels of polyacrylamide is promoted by both hormones. That result excludes the hypothesis that these two hormones regulate the synthesis of different vitellogenins. A dose-response curve showed that an injection of 0.2 μl of a 10^?6 M 20-hydroxy-ecdysone solution was sufficient to promote vitellogenin synthesis and secretion in isolated abdomens. Ovaries from isolated female abdomens treated with juvenile hormone analogue showed nearly normal amounts of all three vitellogenins and morphologically normal advanced vitellogenic follicles, whereas ovaries from isolated abdomens treated with 20-hydroxy-ecdysone contained little vitellogenin and no vitellogenic follicles. We conclude that under the conditions used, juvenile hormone permits vitellogenin uptake into the oöcyte much more readily than does 20-hydroxy-ecdysone.     

Expression and regulation of vitellogenin messenger RNA in the mosquito,Aedes aegypti

Vitellogenin (yolk protein) gene expression in the mosquito was investigated at the level of mRNA using a subcloned fragment (403-1c) of the vitellogenin DNA derived from an Aedes aegypti genomic library. Message appeared 1–3 hr after a blood meal, peaked at 36 hr and was rapidly degraded thereafter. Fluctuations in levels of 20-hydroxyecdysone after a blood meal coincided with accumulation of vitellogenin message. Blood-fed, decapitated females injected with 5 μg of 20-hydroxyecdysone accumulated up to 75% of the message found in blood-fed controls. Fat bodies from non-blood-fed females incubated with physiological levels of 20-hydroxyecdysone and the juvenile hormone analog methoprene contained twice as much vitellogenin message as those incubated with 20-hydroxyecdysone alone. Methoprene alone had no effect.     

Vitellogenin mRNA in locust fat body: coordinate induction of two genes by a juvenile hormone analog

Levels of vitellogenin (Vg) mRNA in Locusta migratoria fat body were determined as indicators of gene expression induced by the juvenile hormone analog methoprene. After injection of methoprene into juvenile hormone-deprived locusts, excised fat bodies were cultured with [3H]leucine for immunochemical assay of Vg synthesis, and RNA was assayed for Vg mRNA content by hybridization with probes from the previously cloned locust Vg genes A and B. In general, the rise in Vg mRNA paralleled the rise in Vg synthesis. During the primary response to methoprene (in female locusts in which the corpora allata had been destroyed immediately after emergence), Vg mRNA was first detected after 18-24 hr and accumulated rapidly between 36 and 48 hr. The secondary response (in locusts allatectomized during vitellogenesis and kept until Vg disappeared) was accelerated, as Vg mRNA was detectable at 12 hr and titers rose steeply after 18 hr. When Vg synthesis was prematurely induced by injection of methoprene into fifth-stage female larvae, the kinetics of mRNA accumulation were similar to those of primary stimulation in the adult. After allatectomy of vitellogenic females, fat body Vg mRNA decayed with a half-life of about 24 hr, roughly paralleling the decline in Vg synthesis. Assays with the two Vg probes showed coordinate accumulation of gene A and gene B messages under all conditions tested: during primary and secondary stimulation in adult females and in the low-level response obtained by treating male larvae with methoprene.     

Protein synthesis in the fat body of Leucophaea maderae during vitellogenesis

During the early stages of vitellogenesis in Leucophaea, vitellogenin accounted for most if not all of the secreted protein synthesized by the fat body. Synthesis began about 5 days after mating and continued until 24 hr or so before the formation of the oötheca. Ligation resulted in the degeneration of the oöcytes, the first evidence of which was seen within 24 hr. Ligation also curtailed the synthesis of vitellogenin at about the same time. Isolated abdomens treated with an analog of juvenile hormone commenced vitellogenesis within 12 to 24 hr and measureable oöcyte growth occurred after 5 days. Despite continued synthesis of vitellogenin, the oöcytes in isolated abdomens always degenerated.     

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.     

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.     

Genetic variations in the pre-feeding and pre-oviposition periods among four pure lines in the brown planthopper, <Emphasis Type="Italic">Nilaparvata lugens</Emphasis> (Hemiptera: Auchenorrhyncha:Delphacidae)

In the brown planthopper, Nilaparvata lugens Stål, traits related to ovarian development were compared among four pure lines predominantly expressing the designated characteristics: blackish short-winged (BS), yellowish brown short-winged (YS), blackish long-winged (BL), and yellowish brown long-winged (YL). The pre-oviposition period was longer in the following order: BS < YS < BL = YL line. The pre-feeding period, namely, the time of non-feeding after adult emergence, which was estimated from dry weight loss during starvation, was also longer in the same order: BS < YS < BL = YL. Vitellogenin, the precursor of yolk protein, first appeared in the hemolymph about 1½ days later after the initiation of feeding in respective lines. One-day’s starvation did not have any effect on the timing of vitellogenin’s appearance in the long-winged lines (BL, YL), but delayed it by 1 day in the short-winged lines (BS, YS). Further, we showed that the synthesis of vitellogenin mRNA was induced in the adults even before feeding by being topically applied with juvenile hormone III (JH III). These results suggest that feeding first triggers the increase of JH III titer, which activates vitellogenin synthesis, and enhances ovarian development. Thus, genetic differences in the pre-feeding periods cause the differences in the timings of physiological events relating to ovarian development among the four lines.     

Release of egg development neurosecretory hormone in Aedes aegypti and Aedes taeniorhynchus induced by an ovarian factor

Ovariectomized Aedes aegypti do not synthesize vitellogenin after a blood meal, unless an ovary from a blood-fed donor is implanted. Decapitation, however, prior to implantation inhibits vitellogenin synthesis. A female ovariectomized and decapitated 6 hr after a blood meal, synthesizes vitellogenin if an ovary from a blood-fed donor is implanted. On the other hand, females that are fed on blood and immediately decapitated can not be stimulated to synthesize vitellogenin with implanted ovaries removed from blood-fed donors. These experiments led to the hypothesis that the blood meal stimulates the ovary to secrete a corpus cardiacum stimulating factor, that in turn promotes release of egg development neurosecretory hormone stored in the corpus cardiacum.Injection of 20-hydroxy-ecdysone or ovarian extract prepared from ovaries removed from unfed females does not release egg development neurosecretory hormone. Thus corpus cardiacum stimulating factor is not 20-hydroxy-ecdysone, and ovaries removed from unfed females do not store it.The rate of inactivation of egg development neurosecretory hormone released from the corpus cardiacum after a blood meal was investigated by implanting an ovary into females that were blood fed for various intervals than decapitated and ovariectomized. Seventy per cent of implants grow when the operation is done 18 hr after feeding, and 30% when the operation is done between 18 and 24 hr after feeding, indicating that egg development neurosecretory hormone is stable for the first 18 hr after a blood meal.Aedes taeniorhynchus females ovariectomized 24 hr after adult emergence do not synthesize vitellogenin. When such a female is implanted with an ovary removed from a sugar-fed or blood-fed Aedes aegypti donor vitellogenin synthesis is initiated, and the implant grows. Decapitation prior to implantation inhibit vitellogenin synthesis and implants do not grow. These results indicate that corpus cardiacum stimulating factor is not species specific.     

Precocious induction of vitellogenin with JH III in the twospotted stink bug, Perillus bioculatus (Heteroptera: Pentatomidae)

The effect of juvenile hormone (JH) III on the hemolymph composition of vitellogenin was examined in Perillus bioculatus. Adult females were treated topically with JH III, and the premature presence of vitellogenin in the hemolymph was then detected using electrophoresis and Western blot analyses. JH III treatment resulted in a dose-dependent early production of vitellogenin that was detectable 48 h before vitellogenin was present in non-treated insects. Vitellogenin was not observed in the hemolymph of JH III-treated adult males. The techniques reported here may be useful for the detection, isolation and characterization of compounds with JH-like activity in P. bioculatus and other species of Heteroptera (which are thought to have JH-like substances other than the JHs with known chemical identity). These same techniques may also provide a method for researchers to investigate the interactions of JH-like compounds and other substances, such as ecdysteroid, in the regulation of vitellogenesis in Heteroptera.     

Ovarian maturation in Leucophaea maderae: Juvenile hormone regulation of thymidine uptake into follicle cell DNA

Our research demonstrates that juvenile hormone (JH I) stimulates thymidine incorporation into ovarian follicle cell DNA in the ovoviviparous cockroach, Leucophaea maderae.A rapid, quantitative method for monitoring ³H-thymidine incorporation into ovarian DNA, in vitro, is described. Cultured ovarian tissue from L. maderae incorporates ³H-thymidine into DNA at a linear rate between 16 and 120 min; analysis of the incorporated label revealed at least 98% of it to be in DNA.Using L. maderae females that had been mated 7 days after adult emergence, we monitored the following biochemical phenomena during the 18–22 day period of terminal oöcyte growth: (1) ³H-thymidine incorporation into ovarian DNA: (2) general protein synthesis in fat body; and (3) specific fat body vitellogenin synthesis.Decapitation of mated females with maturing oöcytes arrested both ovarian DNA synthesis and fat body vitellogenin synthesis. Substantial restoration of both types of synthesis was induced by injection of JH I. The resumption of thymidine incorporation into DNA was localized in the follicular epithelium of the terminal oöcyte.In decapitated virgin females, injection of JH I stimulated oöcyte growth and ³H-thymidine incorporation into ovarian DNA. Dose and time response curves indicate that peak stimulation of ovarian DNA synthesis occurred between 72 and 96 hr after administration of a single optimal dose of 25 μg JH I. The concurrent manifestation of ³H-thymidine uptake into ovarian DNA and activity within the fat body indicates that a similar hormonal mode of action may be operative with respect to both tissue types in virgin females.     

Purification and characterization of biliverdin-binding vitellogenin from the hemolymph of the common cutworm,Spodoptera litura

Biliverdin-binding vitellogenin (Vg) was purified from adult female hemolymph of the common cutworm, Spodoptera litura, by using gel filtration and ion exchange chromatographies. The molecular mass of the protein was 490 kDa and it was composed of two 188-kDa subunits. Three internal amino acid sequences obtained by digestion of the protein with lysylendopeptidase showed high similarity to those of Bombyx mori Vg, supporting the purified blue protein to be vitellogenin. latroscan analyses demonstrated the presence of biliverdin in Vg that occupied 2.4% of total lipid components. Among the lipids of Vg (9.5 micrograms total lipids per 100 micrograms protein), diacylglycerol was the most predominant, followed by phospholipid, hydrocarbons, and then triacylglycerol, while in biliverdin-binding proteins (BPs) purified from larval hemolymph (3.1 micrograms total lipids per 100 micrograms protein), phospholipid was the most abundant lipid followed by diacylglycerol; hydrocarbons and triacylglycerol were minor components. Vg was first detected in the hemolymph of female pupae one day before eclosion, but injection of 5 micrograms of methoprene into a 3-day-old pupa induced Vg in the hemolymph 4 days earlier than in the control. Methoprene also induced a faster decline in BP-A and BP-B titers in the hemolymph with a corresponding increase of the Vg titer. These results suggest that juvenile hormone (JH) induces not only vitellogenesis but also the uptake of these proteins by stimulating the metamorphosis of fat body during the pupal stage.