Application Of Juvenile Hormone Analogue Research Articles

Effect of Juvenile Hormone on Worker Behavioral Transition in the Red Imported Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae).

The division of labor among workers is a defining characteristic of social insects and plays a pivotal role in enhancing the competitive advantage of their colony. Juvenile hormone (JH) has long been hypothesized to be the essential driver in regulating the division of labor due to its ability to accelerate behavioral transitions in social insects, such as honeybees. The regulation of behavioral transitions by JH in the red imported fire ant (RIFA), Solenopsis invicta, a typical social pest, is unclear. Through video capture and analysis, we investigated the effects of the juvenile hormone analogue (JHA) methoprene on brood care, phototaxis behavior, and threat responsiveness of RIFA nurse workers. Our results showed that the JHA application significantly reduced the time and frequency of brood care behavior by nurse workers while increasing their walking distance and activity time in the light area. Additionally, the application of JHA made ants become excited, indicating a significant improvement in their activity level (movement distance, time, and speed). Furthermore, it was observed that the application of JHA did not affect the threat responsiveness of nurse workers towards stimuli (nestmates or non-nestmates). Our study demonstrates that the application of JHA reduced brood care behavior and enhanced phototaxis in nurse workers, which may reveal the role of JH in facilitating behavioral transitions in RIFA from intranidal tasks to extranidal activity. This study provides an experimental basis for further elucidating the mechanism underlying the division of labor in social insects.

113. Application of juvenile hormone analogue, pyriproxyfen, increases protein and reduces fat proportion in yellow mealworms

113. Application of juvenile hormone analogue, pyriproxyfen, increases protein and reduces fat proportion in yellow mealworms

Toxicity and insect growth regulatory effects of root extract from the medicinal plant, Withania somnifera (Linnaeus) against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

The insect growth regulatory effects of the medicinal plant, Withania somnifera (Family: Solanaceae) on the moulting and metamorphosis of economically important stored grain pest, Tribolium castaneum (Coleoptera: Tenebrionidae) were assessed under laboratory conditions. Seventh instar larvae of the red flour beetle, T. castaneum were topically treated with different doses of root extract of W. somnifera. Treatment with root extract of W. somnifera disrupted growth, development, moulting and metamorphosis in T. castaneum. The results included mortality, prolongation of larval-pupal and pupal-adult ecdysis, ecdysial stasis, development of larval-pupal and pupal-adult intermediates and adultoids, eclosion inhibition, reduced pupation and adult emergence. The LC50 value in topical application of root extract of W. somnifera was 0.5850 µg·µL−1 against last instar larvae of T. castaneum. These results are similar to those observed by the application of juvenile hormone analogues and may be due to interference with the normal hormonal mechanism of moulting and metamorphosis.

Juvenile hormone regulates the shift from migrants to residents in adult oriental armyworm, Mythimna separata

In migratory insects, increasing evidence has demonstrated juvenile hormone (JH) is involved in regulating adult reproduction and flight. Our previous study demonstrated that the switch from migrants to residents in Mythimna separata could be induced by adverse environmental conditions during a sensitive period in adulthood (the first day post-emergence), but the role of JH in this switch is not clear. Here, we found a significantly different pattern of JH titers between migrants and residents, with migrants showing a slower release of JH during adulthood than residents. Application of JH analogue (JHA) in the 1-day-old adults, significantly accelerated adult reproduction and suppressed flight capacity. The pre-oviposition period and period of first oviposition of migrants treated with JHA were significantly shorter, while the total lifetime fecundity and mating percentage increased. The flight capacity and dorso-longitudinal muscle size of the migrants were decreased significantly when treated with JHA. The effect of JHA on reproduction and flight capacity indicate that JH titers during the sensitive period (first day post-emergence) regulates the shift from migrants to residents in M. separata.

Diapause hormone directly stimulates the prothoracic glands of diapause larvae under juvenile hormone regulation in the bamboo borer, Omphisa fuscidentalis Hampson.

Larval diapause in many lepidopteran insects is induced and maintained by high juvenile hormone (JH). In the case of the bamboo borer, Omphisa fuscidentalis, the effect of JH is the opposite: The application of juvenile hormone analog (JHA: S-methoprene) terminates larval diapause, unlike in other insect species. Here, we analyzed the expression of JH-receptor Met, DH-PBAN, and Kr-h1 in the subesophageal ganglion (SG) from October to April using semi-quantitative polymerase chain reaction (PCR). The results show that OfMet and OfDH-PBAN messenger RNA in the SG are mainly expressed during the larval diapause stage, while OfKr-h1 increases during the pupal stage. Using tissue culture techniques and an enzyme-linked immunosorbent assay (ELISA), diapause hormone (DH) was found to induce ecdysteroidogenesis in the culture medium of the prothoracic gland (PG) after incubation for 30 min with 25 ng and 50 ng of DH. Thus, DH is a novel stimulator for the PG. We identified a DHR homolog in the bamboo borer and confirmed that it is expressed in the PG. In addition, for in vitro experiments, DH increased the expression levels of OfDHR, OfEcR-A, and ecdysone-inducible genes in the PG. These results demonstrate that DH can function as a prothoracicotropic factor, and this function of DH might be through of DHR expressed on PG cells. Consequently, DH is one of the key factors in larval diapause break which is triggered by JH in the bamboo borer, O. fuscidentalis.

Effects of larval diapause and the juvenile hormone analog, fenoxycarb, on testis development and spermatogenesis in the wax moth, Galleria mellonella (Lepidoptera: Pyralidae)

Facultative diapause in the wax moth, Galleria mellonella, occurs in the final larval instar. Application of juvenile hormone analogs (JHAs) to the larvae of this species has similar effects to diapause, in terms of prolonged development of the larval stages and the arrest in the metamorphosis of internal organs. Here, we focus on testes development and spermatogenesis at the end of larval development in G. mellonella, how they are affected by diapause induced by an environmental decrease in temperature to 18°C and the application of a JHA (fenoxycarb) to larvae. Because neither testis development nor spermatogenesis are described in detail for this species, we examined them in individuals not in diapause during the period from the last larval instar to the newly emerged adult and present a timetable of changes that occur in the development of testes in this species. These observations have increased the very limited data on the course of spermatogenesis in pyralid insects. We then used these data for comparative analysis of testes in larvae from two experimental groups: individuals in diapause and those treated with fenoxycarb. The results on the general morphology testes revealed obvious degenerative changes caused by fenoxycarb (but not by diapause), including testicular wall hypertrophy and disarrangement of testicular follicles. Moreover, treatment with fenoxycarb finally resulted in the disintegration of nearly all testicular cyst-containing germ cells at different stages of spermatogenesis, a situation never previously described in the literature. In contrast, the main effect of diapause on testes was merely the degeneration of spermatocytes in the proximal regions of the testicular follicles. Finally, the TUNEL analyses, revealed that the degenerative changes in germ cells were apoptotic in character in the testes of both individuals in diapause and fenoxycarb-treated males.

Methoprene and Temperature Stimulation of Emergence and Longevity in Adults of Osmia Rufa L. (Megachilidae; Apoidea) During Wintering Period

Abstract In this study methoprene, a juvenile hormone analogues, was tested as a factor that stimulates the end of diapause, bee activation and emergence. In addition, the survival of bees was checked when combined with an application of methoprene. The experimental activation of wintering bees was carried out once a month between December and March, Three groups of bee cocoons were selected for each activation term: treated with either methoprene or acetone as vehicle control and untreated as controls. After the applications were finished the cocoons were incubated at temperature 26°C. The emerged adult males and females were then kept in the laboratory and fed sucrose solution to evaluate the longevity of bees. The application of juvenile hormone analogue reduced the emergence time of adult bees in December, February and March. The rate of emergence presented in the form of cumulative percentage of emerged adult bees indicated that the bees treated with methoprene started to emerge 1-2 days earlier than bees from acetone and control groups and finished emergence 2-5 days earlier too. Methopren application did not reduce the longevity of the bees after emergence. Moreover, the median longevity of these females was higher than untreated in December and February.

Negative regulation of juvenile hormone analog for ecdysteroidogenic enzymes

Disruption of the appropriate balance between juvenile hormone (JH) and ecdysteroids causes abnormal insect development. The application of a JH analog (JHA) during the early days of the final (fifth) instar induces dauer larvae with low ecdysteroid titers in insects, but the mechanism that underlies the action of JHA remains unclear. In this study, we clarified the negative effects of JHA on ecdysteroidogenic enzymes. JHA application to Bombyx mori larvae during the early stage of the fifth instar suppressed the expression of four enzymes, i.e., neverland (nvd), spook, phantom, and disembodied but not non-molting glossy and shadow. Furthermore, JHA application reduced the amount of 7-dehydrocholesterol, a metabolite produced by Nvd, in both the prothoracic glands and hemolymph, indicating JHA can disrupt ecdysteroidogenic pathway from the first step. Neck ligation resulted in increased nvd expression, whereas JHA application reversed this increase. These results suggest that the endogenous JH represses ecdysteroidogenesis during the early days in final instar larvae. Neck ligation and JHA application had no substantial effects on the expression of a transcription factor, ftz-f1, or a prothoracicotropic hormone receptor, torso; therefore, the inhibitory regulation of JHA may not involve these factors. Further analysis is required to clarify the regulation of JHA in ecdysteroidogenesis, but this study showed that JHA, and probably endogenous JH, can suppress the transcription of four of six ecdysteroidogenic enzymes. This regulation may be essential for maintaining the appropriate balance between JH and ecdysone during insect development.

Reproductive Soldier-like Individuals Induced by Juvenile Hormone Analog Treatment in Zootermopsis nevadensis (Isoptera, Archotermopsidae).

Eusocial insects have highly sophisticated societies, showing a conspicuous division of labor associated with different phenotypes. These castes show specific morphologies adapted to discrete tasks. Termite castes are divided into reproductives, workers, and soldiers. Individuals with soldier-like heads as well as developed gonads have been recorded in several primitive families, and are called reproductive soldiers. In some termite species, however, a trade-off-like developmental relationship has been shown between soldier and imaginal characteristics. Thus, while the mechanism that regulates the development of both characteristics in the same individual is interesting, the details are still unclear. We focused on juvenile hormone (JH), which is involved not only in termite caste differentiation, but also in the gonad development of many insects, and we aimed to clarify the effects of JH on the differentiation of reproductive soldiers in Zootermopsis nevadensis. We succeeded in the induction of individuals with reproductive soldier-like gross morphologies by JH analog (JHA) application to several developmental stages. We also observed that gonad development was significantly promoted by JHA application after molts in the induced reproductive soldier-like individuals, but not in natural soldiers. Finally, we confirmed that the gene expression level of vitellogenin was extremely high in the induced reproductive soldier-like individuals following JHA treatment after the molt. These results suggested that soldiers do not have regulatory mechanisms for gonad development involving JH, and the regulation of reproductive soldiers development is different from that of soldiers. Reproductive soldiers may have evolved independently from the soldier caste rather than from an intermediate stage of soldier evolution.

Cloning and expression of a JHA-inducible glutathione S-transferase gene in the common cutworm Spodoptera litura (Lepidoptera: Noctuidae)

The juvenile hormone titer during the last instar is a crucial determining switch for metamorphosis in lepidopterans. We previously observed that the induction of glutathione S-transferase (GST) activity by a juvenile hormone analog (JHA) is reversely proportional to the occurrence of JHA-induced supernumerary instars following topical application of JHA to Spodoptera litura during the last instar period. In this paper, at least five JHA-induced GSTs were purified by glutathione-affinity chromatography, and one was further isolated for determination of the N-terminal sequence. The corresponding cDNA was cloned and named SlGST1 (GenBank accession no. AY506545). SlGST1 was classified into the epsilon class of GSTs by phylogenetic analysis. Northern blot analyses further showed that the SlGST1 in fat bodies can be induced by JHA, particularly in 0-day-old sixth-instar larvae, in which induction was much higher than that in 1- and 2-day-old sixth-instar larvae. To our knowledge, this is the first JHA-inducible GST to have been identified, and we believe that it will provide new insight into the role of GST in insect development, particularly during metamorphosis.

Microarray Analysis of the Juvenile Hormone Response in Larval Integument of the Silkworm, Bombyx mori.

Juvenile hormone (JH) coordinates with 20-hydroxyecdysone (20E) to regulate larval growth and molting in insects. However, little is known about how this cooperative control is achieved during larval stages. Here, we induced silkworm superlarvae by applying the JH analogue (JHA) methoprene and used a microarray approach to survey the mRNA expression changes in response to JHA in the silkworm integument. We found that JHA application significantly increased the expression levels of most genes involved in basic metabolic processes and protein processing and decreased the expression of genes associated with oxidative phosphorylation in the integument. Several key genes involved in the pathways of insulin/insulin-like growth factor signaling (IIS) and 20E signaling were also upregulated after JHA application. Taken together, we suggest that JH may mediate the nutrient-dependent IIS pathway by regulating various metabolic pathways and further modulate 20E signaling.

Possible roles of Juvenile Hormone and Juvenile Hormone binding protein on changes in the integument during termination of larval diapause in the bamboo borer Omphisa fuscidentalis

AbstractTo understand the role of Juvenile Hormone (JH) on changes in the integument of Omphisa fuscidentalis Hampson (Lepidoptera: Pyralidae) during larval–pupal development, the expression patterns of transcripts of the O. fuscidentalis JH binding protein gene (OfJHBP) are determined in the integument of diapausing larvae. Quantitative real‐time polymerase chain reaction (qRT‐PCR) studies show that the relative levels OfJHBP mRNA in the integument do not differ significantly in different segments of the body. Application of the JH analogue (JHA) methoprene to diapausing larvae results in a relatively low expression of OfJHBP mRNA from days 0 to 8 after JHA application and reaches maximal levels in the pupal stage. Changes in OfJHBP expression after 20‐hydroxyecdysone (20E) injection also show low levels of OfJHBP mRNA from days 0 to 8 and show a peak of expression in the pupal stage. Incubation of the integument in vitro in the presence of JHA (3.22 µm) induces high levels of OfJHBP expression within 120 min, whereas incubation with 20E (2.08 µm) induces gene expression at 150 min. To study the cooperative effect on OfJHBP expression of these two hormones, dose–response experiments are performed. Larval integument is maintained in the presence of 0.32 µm JHA or 2.08 µm 20E or a combination of both hormones in vitro for 120 min. Induction of OfJHBP expression by JHA and 20E in combination is significantly higher than that of either hormone alone. The results impact not only on our understanding of how methoprene (and hence JH) terminates larval diapause through an increase in ecdysteroid titre in the haemolymph, but also on how JH acts directly on the integument to stimulate the expression of a JH binding protein gene.

Programmed cell death of larval tissues induced by juvenile hormone in the bamboo borer, Omphisa fuscidentalis

Programmed cell death (PCD) plays a critical role during animal development through the destruction of unneeded cells and tissues. In some insects, the prothoracic glands (PGs) and anterior silk glands (ASGs) are larval-specific tissues that are normally eliminated by PCD after pupation. Previous studies report that juvenile hormone analog (JHA) terminates the larval diapause of Omphisa fuscidentalis by increasing the hemolymph ecdysteroids that trigger PCD. Because JHA may indirectly induce the PCD of the PGs and ASGs of Omphisa diapausing larvae, the effects of JHA on the induction of PCD were determined. The application of 1μg JHA induced PCD in the PGs and ASGs of larvae identified as stage G0 (prior to pupation). The injection of 1μg 20E triggered the PCD of the ASGs when the larvae expressed a G0–G1 morphology, whereas PCD occurred in the PGs on day 1 post-injection. Histological studies revealed similar patterns of morphological changes during the PG and ASG PCD in the JHA- and 20E-treated larvae. Furthermore, to confirm that PCD was induced by a high ecdysteroid level that increases after JHA application, the expression profiles of EcR-A and EcR-B1 in the PGs and ASGs from the JHA-treated larvae were examined, and the results showed that the expression levels of EcR-A and EcR-B1 mRNA increased during the G0 stage. These results suggest that JHA may be involved in PCD by increasing the ecdysteroid titer, leading to termination of the larval diapause period in Omphisa fuscidentalis.

20-hydroxyecdysone and juvenile hormone analog prevent precocious metamorphosis in recessive trimolter mutants of Bombyx mori

The trimolter mutants of Bombyx mori have four instead of five larval instars of normal tetramolters. Here, we show that the tetramolter was induced in the recessive trimolter European No.7 mutant (rt-E7) by application of either the juvenile hormone analog (JHA) or 20-hydroxyecdysone (20E). However, treatments with JHA or 20E did not change the number of larval instars of the dominant trimolter Si Chuan mutant (DT-SC). Krüppel-homolog 1 (Kr-h1) is an early JH-response gene that mediates the anti-metamorphic action of JH. In the wing disc of tetramolter B. mori, Kr-h1 RNAs decreased shortly after ecdysis to the fifth instar, while pupal specifier gene, Broad Complex Z1 (BR-Z1) RNAs slightly increased and coincided with the onset of metamorphic competence of wing discs. Analysis of the developmental profile of Kr-h1 in the wing disc of rt-E7 showed that its transcript slightly increased from 12 to 24 h and gradually decreased between 24 and 72 h in the fourth (last) larval instar, while Kr-h1 mRNA decreased rapidly between 12 and 72 h in DT-SC. In addition, the expression of BR-Z1 in DT-SC during the early fourth (last) larval instar is relatively higher than that in rt-E7. These results indicated that the occurrence of pupal commitment of the wing disc in DT-SC was much earlier than that in rt-E7. In the early fourth larval instar of rt-E7, feeding on 20E or treatments with exogenous JHA caused up-regulation of Kr-h1, suppressed premature induction of BR-Z1, and then induced an additional larval instar. By contrast, in DT-SC mutant, since pupal commitment immediately occurred after third ecdysis, precocious metamorphosis was not successfully rescued. The results suggest that Kr-h1 and BR-Z1 involved in the prevention of precocious metamorphosis in recessive trimolter mutants by application of 20E and JHA. The result indicated that Kr-h1 and BR-Z1 expression reflected larval–pupal transition of the recessive trimolter of B. mori.

Photoperiodic diapause under the control of circadian clock genes in an insect

BackgroundMost organisms have evolved a circadian clock in order to anticipate daily environmental changes and many of these organisms are also capable of sophisticated measurement of daylength (photoperiodism) that is used to regulate seasonal events such as diapause, migration and polymorphism. It has been generally accepted that the same elements are involved in both circadian (daily) and seasonal (annual) rhythms because both rely upon daily light-dark cycles. However, as reasonable as this sounds, there remains no conclusive evidence of such a molecular machinery in insects. We have approached this issue by using RNA interference (RNAi) in Riptortus pedestris.ResultsThe cuticle deposition rhythm exhibited the major properties of circadian rhythms, indicating that the rhythm is regulated by a circadian clock. RNAi directed against the circadian clock genes of period and cycle, which are negative and positive regulators in the circadian clock, respectively, disrupted the cuticle deposition rhythm and distinct cuticle layers were produced by these RNAi. Simultaneously, period RNAi caused the insect to avert diapause under a diapause-inducing photoperiod whereas cycle RNAi induced diapause under a diapause-averting photoperiod. The expression patterns of juvenile hormone-regulated genes and the application of juvenile hormone analogue suggested that neither ovarian development itself nor a downstream cascade of juvenile hormone secretion, were disturbed by period and cycle RNAi.ConclusionsThis study revealed that the circadian clock genes are crucial not only for daily rhythms but also for photoperiodic diapause. RNAi directed against period and cycle had opposite effects not only in the circadian cuticle deposition rhythm but also in the photoperiodic diapause. These RNAi also had opposite effects on juvenile hormone-regulated gene expression. It is still possible that the circadian clock genes pleiotropically affect ovarian development but, based on these results, we suggest that the circadian clock operated by the circadian clock genes, period and cycle, governs seasonal timing as well as the daily rhythms.See Commentary: http://www.biomedcentral.com/1741-7007/8/115

Impact of a juvenile hormone analogue on the anatomy and the frontal gland secretion of Prorhinotermes simplex (Isoptera: Rhinotermitidae)

In termites, juvenile hormone plays a key role in soldier differentiation. To better understand the evolutionary origin of the soldiers, we studied the external and inner morphology of pseudergate–soldier intercastes and neotenic–soldier intercastes formed artificially by the application of juvenile hormone analogue in Prorhinotermes simplex. A majority of these intercastes had a soldier phenotype, whereas the inner anatomy had an intermediary form between two castes or a form specific to intercastes. Our experiments showed that traits of neotenics and soldiers can be shared by the same individuals, although such individuals do not exist naturally in P. simplex, and they have not been reported in other species but in some Termopsidae. Our results reinforce the hypothesis that soldiers may have emerged from soldier neotenics during the evolution of termites.

Is juvenile hormone involved in the maternal regulation of egg size and progeny characteristics in the desert locust?

The role of juvenile hormone (JH) in the maternal regulation of progeny characteristics was examined in the desert locust, Schistocerca gregaria. Female adults of this species are known to produce smaller but more eggs when reared in isolation than do those reared in a group. Eggs laid by isolated females develop green hatchlings typical of solitarious forms, whereas those laid by the latter produce black hatchlings typical of gregarious forms. Topical application of a juvenile hormone analog (JHA), fenoxycarb, or implantation of corpora allata (CA) taken from the migratory locust, Locusta migratoria, caused crowded S. gregaria females to deposit smaller eggs, but did not have a significant effect on the number of eggs per egg pod except at high doses of JHA. The production of smaller eggs by treated and untreated crowded females was closely associated with earlier deposition of the egg pods and shorter oviposition intervals. However, neither JHA application nor CA implantation influenced the progeny characteristics in actively reproducing aged females under crowded conditions, while untreated control females started producing smaller and more eggs upon transfer to isolated conditions. These results may suggest that JH is not directly involved in the maternal regulation of phase-dependent progeny characteristics.

Influence of methoprene and dietary protein on male Anastrepha suspensa (Diptera:Tephritidae) mating aggregations

The Caribbean fruit fly, Anastrepha suspensa (Loew), like many polyphagous tephritids, exhibits a lek polygyny mating system, and juvenile hormone levels and adult diet are known to have important positive effects on male sexual success. Among the potential components of this success are male lek tenure and female response to the sexual signals of lekking males. Male A. suspensa where submitted to four different treatments: (M +P +) application of juvenile hormone analog, methoprene (M) and sugar and hydrolyzed yeast as adult food; (M +P −) application of M and sugar as adult food; (M −P +) no application of M and sugar and hydrolyzed yeast as adult food; and (M −P −) no application of M and sugar as adult food. M +P + males initiated and participated more in aggregations, mated more frequently, and occupied the lek centers more often. They also had fewer unsuccessful mounting attempts than males in all the other treatments. M +P + males also emitted pheromones and acoustically signaled more often and attracted more females than males in other treatments. Male sexual performance was improved due to methoprene, protein supply, and the interaction of methoprene and protein for most of the parameters. Since the success of the sterile insect technique (SIT), a commonly employed technique to control pest tephritids, requires the release of males that can form leks, engage in agonistic sexual interactions, and attract females, these positive effects of protein and methoprene may substantially improve SIT programs.

Molecular analysis of juvenile hormone analog action in controlling the metamorphosis of the red flour beetle, Tribolium castaneum

The juvenile hormone analogs (JHA) are known to disrupt insect development but the molecular mechanisms of their action have been studied only in a few model insects belonging to orders Diptera and Lepidoptera. Here, we investigated the mechanisms of JHA action in red flour beetle, Tribolium castaneum, belonging to the order Coleoptera. Application of JHA during penultimate and final instar larval stages blocked larval-pupal metamorphosis and induced supernumerary larval molts. When compared to the control insects undergoing larval-pupal molt, down-regulation of expression of transcription factor, Broad, and up-regulation of other genes involved in 20-hydroxyecdysone (20E) action (FTZ-F1, E74) were observed in JHA-treated larvae undergoing supernumerary larval molts. The presence of JHA during the final instar larval stage blocked the midgut remodeling wherein programmed cell death (PCD) of larval cells and proliferation and differentiation of imaginal cells to pupal gut epithelium were impaired. The comparative analysis of 20E-induced gene expression in the midguts of JHA-treated and control insects revealed that JHA suppressed the expression of EcRA, EcRB, Broad, E74, E75A, and E75B, resulting in a block in PCD as well as proliferation and differentiation of imaginal cells.

Juvenile hormone acid O-methyltransferase in Drosophila melanogaster

Juvenile hormone (JH) acid O-methyltransferase (JHAMT) is the enzyme that transfers a methyl group from S-adenosyl- l-methionine (SAM) to the carboxyl group of JH acids to produce active JHs in the corpora allata. While the JHAMT gene was originally identified and characterized in the silkworm Bombyx mori, no orthologs from other insects have been studied until now. Here we report on the functional characterization of the CG17330/DmJHAMT gene in the fruit fly Drosophila melanogaster. Recombinant DmJHAMT protein expressed in Escherichia coli catalyzes the conversion of farnesoic acid and JH III acid to their cognate methyl esters in the presence of SAM. DmJHAMT is predominantly expressed in corpora allata, and its developmental expression profile correlates with changes in the JH titer. While a transgenic RNA interference against DmJHAMT has no visible effect, overexpression of DmJHAMT results in a pharate adult lethal phenotype, similar to that obtained with application of JH analogs, suggesting that the temporal regulation of DmJHAMT is critical for Drosophila development.