Search Results (32)

Juvenile hormone (JH) analog insecticides are widely used in pest management because of their ability to disrupt insect growth and metamorphosis; however, the molecular mechanisms linking endocrine disruption to metabolic dysregulation remain incompletely understood. In addition to their established roles in diapause and developmental regulation, JH signaling pathways have also been implicated in carbohydrate and lipid metabolism. In the present study, we investigated the effects of two JH analogs, pyriproxyfen and hydroprene, on the migratory locust, Locusta migratoria, with particular emphasis on lipid metabolic regulation and the function of midgut-enriched fatty acid-binding protein gene (Mg-FABP). Bioassays were performed to evaluate insecticidal activity, and transcriptomic analyses were conducted to identify differentially expressed genes associated with endocrine signaling and lipid metabolism. Functional characterization of Mg-FABP was further performed using RNA interference (RNAi) and Oil Red O staining assays. In addition, the tertiary structure of LmMg-FABP was predicted using AlphaFold 3, and molecular docking analyses were carried out to investigate its interactions with fatty acid ligands. Both pyriproxyfen and hydroprene caused approximately 70% mortality in locust nymphs and induced significant transcriptional changes in pathways related to hormone signaling and lipid metabolism. Transcriptomic analysis revealed pronounced downregulation of Mg-FABP following JH analog exposure. RNAi-mediated silencing of Mg-FABP significantly reduced lipid droplet accumulation in the fat body, indicating that Mg-FABP plays an essential role in lipid transport and metabolic homeostasis in L. migratoria. Structural analyses further demonstrated that LmMg-FABP possesses a conserved tertiary structure highly similar to FABP homologs from other insect species. Molecular docking identified key amino acid residues involved in fatty acid binding and suggested that hydrophobic interactions are critical for ligand stabilization within the binding cavity. Collectively, our findings demonstrate that pyriproxyfen and hydroprene disrupt insect development not only through endocrine imbalance but also through perturbation of Mg-FABP-associated lipid metabolic pathways. This study provides new mechanistic insight into the coordinated interaction between hormonal signaling and lipid metabolism during JH analog exposure and identifies FABP-mediated lipid transport as a potential molecular target for the development of more selective insect growth regulators. Full article

Lipophorin receptors play a crucial role in the reproductive development of insects. However, their regulatory function in insect reproductive diapause remains poorly understood. In this study, a lipophorin receptor gene (GdLpR) was cloned from Galeruca daurica using RT-PCR. The open reading frame (ORF) of GdLpR is 2589 bp in length, encoding 862 amino acids, and possesses typical structural characteristics of the lipophorin receptor family. RT-qPCR analysis indicated that the expression of GdLpR is up-regulated in G. daurica adults before diapause, exhibits an expression pattern of initial down-regulation, subsequent up-regulation, and then further down-regulation during diapause, and is up-regulated again after diapause termination. After RNA interference of GdLpR, the expression levels of diapause-related genes ecdysone receptor (EcR), nuclear hormone receptor (HR3), and vitellogenin (Vg) were downregulated, while the expression level of fatty acid synthase (FAS) and total lipid content were upregulated, leading to premature diapause in adult G. daurica. These results indicate that GdLpR is involved in the regulation of reproductive diapause in G. daurica. Full article

Diapause hormone (DH) is an important endocrine substance capable of influencing diapause in Lepidoptera moths that is encoded by the neuropeptide hormone DH-PBAN gene. Imidazole derivative KK-42 is a synthetic insect growth regulator that can affect diapause in Lepidoptera moths, and appears to have an opposite physiological function to DH. To test the hypothesis that KK-42 may be operating through DH to affect diapause, here, we used two Lepidoptera species Bombyx mori L. and Antheraea pernyi that enter egg and pupal diapause, respectively, through examining whether KK-42 can influence DH-PBAN and some associated mRNA expression. We found that the protein sequences of DH-PBAN in insects were highly variable, although the PRXamide C-terminus was conserved. We also found that KK-42 induced significant up-regulation and prolonged expression duration of DH-PBAN in both A. pernyi and B. mori pupae, as well as in trimolter larvae of B. mori that were induced by the application of KK-42 from the normal tetramolter larvae. In addition, KK-42 can significantly upregulate glutamic acid decarboxylase (GAD) expression in B. mori in transcriptome data. Our findings suggested that KK-42 influences diapause by upregulating GAD expression, promoting DH accumulation to prolong the secretion time of DH-PBAN. Full article

Diapause is a vital overwintering strategy for many insects, yet its comprehensive molecular architecture remains elusive. In the polyphagous pest Helicoverpa armigera, facultative pupal diapause is key to its ecological success. To elucidate the complex diapause regulatory network, we conducted a transcriptomic analysis of diapause (DP) versus non-diapause (NP) pupal brains across early pupal development (days 2, 5, and 10). Integrated analyses, including differential expression, persistent gene identification, weighted gene co-expression network analysis (WGCNA), and multiscale embedded network analysis (MEGENA), were employed to define core regulatory modules and hubs. The number of differentially expressed genes (DEGs) increased over time, with 1781 genes persistently regulated across all time points, enriched in mitochondrial metabolism, hormone signaling, and chromatin remodeling. WGCNA revealed a diapause-associated module (red) linked to RNA processing/transcription and a development-associated module (blue) enriched for translation and mitochondrial metabolism. Network analyses pinpointed three central hub genes: DDX5 and PLK4 (downregulated in diapause, upregulated upon 20E treatment) and TAF5L (upregulated in diapause, downregulated after 20E). This study provides a systems-level view of the transcriptional landscape governing pupal diapause in H. armigera and identifies novel candidate regulators for future functional studies. Full article

Diapause enables insect survival in unfavorable environments. The parasitic wasp A. japonicus, a natural enemy of several fruit-tree pests, undergoes larval diapause. Previous work has shown that larval diapause in A. japonicus can be induced by medium temperatures in combination with short-day photoperiods; however, the molecular functions associated with this response remain poorly understood. Here, integrated transcriptomic and proteomic approaches were employed to investigate the molecular signatures associated with larval diapause in A. japonicus. The identification of 3399 differentially expressed genes and 3112 differentially expressed proteins was carried out between diapause and non-diapause larvae. Among these, five gene–protein pairs showed consistent differential expression, including farnesol dehydrogenase, crystallin (associated with longevity-related pathways), forkhead-associated (FHA) domain-containing proteins, and the detoxification enzyme cytochrome P450. These findings show that larval diapause in A. japonicus is accompanied by extensive physiological and biochemical remodeling, and juvenile hormone-related signaling is likely involved in this process. In summary, these results provide insights into future gene function research, especially with regard to the mechanism of larval diapause in A. japonicus. Full article

The circadian clock is a conserved timekeeping mechanism that enables organisms to anicipate and adapt to daily environmental cycles. While its role in photoperiodic diapause has been documented, its fundamental function in maintaining reproductive and metabolic homeostasis under favorable conditions remains less explored, especially in biological control agents. This study investigates the functional roles of the core circadian clock genes Cycle (AcCyc) and Clock (AcClk) in the predatory bug Arma chinensis, focusing on their regulation of reproduction and metabolism under non-diapause conditions. We characterized these genes and analyzed their spatiotemporal expression under diapause and non-diapause conditions. Using RNA interference, we knocked down AcCyc and AcClk in non-diapausing females and evaluated phenotypic impacts on ovarian development, fecundity, and energy reserves. qPCR analyses delineated downstream effects on juvenile hormone (JH) signaling. Results showed that diapause altered AcCyc and AcClk expression rhythms. Their knockdown severely impaired reproduction, reducing ovarian size, vitellogenin expression, and egg production, while concurrently decreasing triglyceride levels indicating disrupted energy homeostasis. Mechanistically, gene silencing downregulated key JH pathway components, Methoprene-tolerant (Met) and Krueppel homolog 1 (Kr-h1). We conclude that AcCyc and AcClk are essential maintainers of reproductive–metabolic homeostasis, not merely diapause regulators. This reframes the clock’s role from a seasonal timekeeper to a central hub for daily physiological coordination, offering new insights for improving biocontrol agent production. Full article

In general, the silkworm, Bombyx mori, has a diapause trait in its eggs. Therefore, transgenic silkworm can be produced by embryonic microinjection using eggs laid by a non-diapause strain in B. mori. In this study, we performed microinjection using eggs of diapause strains which have good characteristics for industrial use, such as a big cocoon, thin and smooth silk, and tolerance against disease due to the growing industrial use of transgenic silkworms. For the conversion of egg diapause traits from diapause to non-diapause types, we used anti-serum against the diapause hormone of B. mori (BmDH), which was injected into maternal pupae, producing non-diapause eggs at a high rate. Finally, we attempted microinjection using three diapause strains with different voltinism (i.e., number of generations of an organism in a year) and were able to successfully produce transgenic silkworms in all three of them, demonstrating that our method is applicable to a wide range of silkworm strains with a diapause trait. Full article

In insects, the number of life cycles varies inter- and intra-specifically, and it is widely accepted that the variation in the number of life cycles is an adaptive response to diverse environmental conditions. However, the molecular mechanism that underlies the variety and plasticity in the number of life cycles is largely unknown. In the silkworm, Bombyx mori, the Voltinism (V) locus has three alleles, V¹(univoltine; dominant), V² (bivoltine; standard), and V³ (polyvoltine; recessive), which are known to generate variation in the number of life cycles in a year under natural conditions, with obligatory diapause for the V¹ allele, facultative diapause for V², and non-diapause for V³. Here, we further confirm that the γ-aminobutyric acid (GABA)ergic neuron signal pathway modulates progeny diapause via controlling diapause hormone release. A population genetic analysis (Fst) revealed that the synaptic vesicle glycoprotein 2A and 2B (BmSV2A and BmSV2B) genes, tightly related to the transport of neurotransmitters, are located in the V locus. Importantly, using the CRISPR/Cas9 editing technique, we have discovered that the BmSV2A and BmSV2B genes increased or modified the expression of GABAergic neuron signal pathway genes, respectively. These results demonstrate that BmSV2A and BmSV2B, positioned within the V locus, could be involved in voltinism control via the GABAergic neuron signal pathway. Full article

20-hydroxyecdysone (20E) signaling plays an important role in regulating insect growth, development, and reproduction. However, the effect of 20E on reproductive diapause and its regulatory mechanisms have not been fully understood. Galeruca daurica is a new pest in the Inner Mongolia grasslands, and it aestivates in an obligatory reproductive diapause form. In this study, the complete open reading frame (ORF) sequence of the ecdysone receptor (EcR) was cloned from G. daurica. Application of 20E promoted the expression of EcR, nuclear hormone receptor (HR3), and vitellogenin (Vg), whereas it reduced the expression of fatty acid synthase (FAS) and lipid content, leading to delayed diapause entry in female adults. Silencing EcR or HR3 by RNAi increased the expression of FAS and lipid content, whereas it reduced the expression of Vg, inducing reproductive diapause. These results indicate that 20E may mediate reproductive diapause via a conserved EcR/HR3 cascade in G. daurica. Full article

Embryonic diapause is a common evolutionary adaptation observed across a wide range of organisms. Artemia is one of the classic animal models for diapause research. The current studies of Artemia diapause mainly focus on the induction and maintenance of the embryonic diapause, with little research on the molecular regulatory mechanism of Artemia embryonic reactivation. The first 5 h after embryonic diapause breaking has been proved to be most important for embryonic reactivation in Artemia. In this work, two high-throughput sequencing methods, ATAC-seq and RNA-seq, were integrated to study the signal regulation process in embryonic reactivation of Artemia at 5 h after diapause breaking. Through the GO and KEGG enrichment analysis of the high-throughput datasets, it was showed that after 5 h of diapause breaking, the metabolism and regulation of Artemia cyst were quite active. Several signal transduction pathways were identified in the embryonic reactivation process, such as G-protein-coupled receptor (GPCR) signaling pathway, cell surface receptor signaling pathway, hormone-mediated signaling pathway, Wnt, Notch, mTOR signaling pathways, etc. It indicates that embryonic reactivation is a complex process regulated by multiple signaling pathways. With the further protein structure analysis and RT-qPCR verification, 11 GPCR genes were identified, in which 5 genes function in the embryonic reactivation stage and the other 6 genes contribute to the diapause stage. The results of this work reveal the signal transduction pathways and GPCRs involved in the embryonic reactivation process of Artemia cysts. These findings offer significant clues for in-depth research on the signal regulatory mechanisms of the embryonic reactivation process and valuable insights into the mechanism of animal embryonic diapause. Full article

Artemia is a widely distributed small aquatic crustacean, renowned for its ability to enter a state of embryonic diapause. The embryonic diapause termination (EDT) is closely linked to environmental cues, but the precise underlying mechanisms remain elusive. In this study, ATAC-seq and RNA-seq sequencing techniques were employed to explore the gene expression profiles in Artemia cysts 30 min after EDT. These profiles were compared with those during diapause and 5 h after EDT. The regulatory mechanisms governing the EDT process were analyzed through Gene Ontology (GO) enrichment analysis of differentially expressed genes. Furthermore, the active G-protein-coupled receptors (GPCRs) were identified through structural analysis. The results unveiled that the signaling transduction during EDT primarily hinges on GPCRs and the cell surface receptor signaling pathway, but distinct genes are involved across different stages. Hormone-mediated signaling pathways and the tachykinin receptor signaling pathway exhibited heightened activity in the ‘0–30 min’ group, whereas the Wnt signaling pathway manifested its function solely in the ‘30 min–5 h’ group. These results imply a complete divergence in the mechanisms of signal regulation during these two stages. Moreover, through structural analysis, five GPCRs operating at different stages of EDT were identified. These findings provide valuable insights into the signal regulation mechanisms governing Artemia diapause. Full article

Chrysoperla nipponensis (Okamoto) displays typical adult reproductive diapause under short photoperiods; however, our understanding of the molecular mechanism underlying photoperiod-sensitive reproduction remains limited. In this study, we performed transcriptome profiling of four treatments (the diapause-sensitive stage and pre-diapause phase under long and short photoperiods) of C. nipponensis using RNA sequencing (RNA-seq). A total of 71,654 unigenes were obtained from the samples. Enrichment analysis showed that fatty acid metabolism-related pathways were altered under a short photoperiod. Moreover, β-oxidation-related gene expression was active during the diapause-sensitive period under a short photoperiod. The knockdown of juvenile hormone acid methyltransferase 1 (Jhamt1) prolonged the pre-oviposition period but did not affect the reproductive ability of female individuals in C. nipponensis. These findings provided us with a more comprehensive understanding of the molecular mechanisms of photoperiod-sensitive diapause and show that groundwork is crucial for bolstering the long-term storage and biocontrol potential of C. nipponensis. Full article

Osmia bicornis syn. O. rufa is a univoltine bee species in which adults fly in spring and the offspring overwinter as cocooned imagoes. The flight period of solitary bees is short, so methods of control for development and emergence time are needed to synchronize the activity of managed pollinators with blooming. In our study, we tested the effectiveness of a juvenile hormone analog for the prevention of winter diapause. Bees developed in settled nests outdoors or in the laboratory (22 °C) until the end of the pre-pupa stage, then cocoons were removed from the nest cells and treated with a JH analog—methoprene—during the pupa and young imago stages. Then, bees were activated at 25 °C until the adults left the cocoons. Topical application of methoprene to the cocoon at the pupa or imago stage induced the emergence of some adult bees in the pre-diapause period, while no adults emerged when the bees were not treated with methoprene. Most adults emerged (about 50%) when treated with methoprene on 3-week-old cocooned imagoes. Bees treated in the pupal stage had a lower emergence rate (20–30%), but adult bees emerged earlier. The emergence time of adults for the laboratory group was, on average, from 70 to 91 days, and that for outdoor groups was from 57 to 72 days. Full article

It has been found that 5-hydroxytryptamine (5-HT) modulates the feeding of some insects, and this phenomenon was found in Harmonia axyridis (Pallas) by our previous study. An understanding of the 5-HT system in this beetle is helpful for utilizing 5-HT to modulate its predation to improve biological control efficiency, especially in greenhouses in winter in north China. This is because 5-HT influences diapause in insects by modulating the synthesis and release of prothoracic hormone (PTTH) and, therefore, influences feeding. To elucidate the molecular basis of the H. axyridis 5-HT system, reverse-transcription polymerase chain reaction (RT-PCR), multiple sequence alignment, and phylogenetic tree construction were used to identify the 5-HT receptor in H. axyridis, and quantitative real-time PCR (qRT-PCR) was used to analyze the expression pattern of these receptor genes in different developmental stages and in the nervous system (brain + ventral nerve cord), digestive tract, pectoral muscles, and gonads of the adult ladybird. The results showed that four 5-HT receptors were identified in H. axyridis, named 5-HT_1AHar, 5-HT_1BHar, 5-HT₂Har, and 5-HT₇Har. The four receptors were expressed at high levels in the adult stage, especially in 2-day-old adults, with expression levels of 18.72-fold (male) and 14.21-fold (female) of that in eggs for 5-HT_1A, 32.27-fold (male) and 83.58-fold (female) of that in eggs for 5-HT_1B, 36.82-fold (male) and 119.35-fold (female) of that in eggs for 5-HT₂, and 165.47-fold (male) and 115.59-fold (female) of that in eggs for 5-HT₇. The level of expression decreased with the advance of day-age in adults. The levels of expression of 5-HT_1BHar, 5-HT₂Har, and 5-HT₇Har were low at the egg, larval, and pupal stages, and 5-HT_1AHar was not expressed in the larval stage. The four receptors were expressed in the nervous system, digestive tract, pectoral muscles, and male and female gonads. The 5-HT_1AHar was expressed at a high level in the pectoral muscle (6.75-fold of that in the nervous system), 5-HT_1BHar in male gonads (1.02-fold of that in the nervous system) and the nervous system, 5-HT₂Har in male gonads (5.74-fold of that in the nervous system), and 5-HT₇Har in the digestive tract (1.81-fold of that in the nervous system). The results of this study will lay a foundation for research on the function of the 5-HT receptor by RNA interference in the regulation of predation by H. axyridis. Full article

This review addresses the physiology and behavioral events involved in the reproduction of soft ticks (family Argasidae), with special attention to the events of their adult life: mating, sperm transfer and egg-laying. Many of these aspects are held in common with hard ticks, but the repeated short duration of feeding bouts in soft ticks, in contrast to the extended single engorgements of hard ticks, has consequences peculiar to soft tick reproduction. Reviewed are the dramatic external mechanism of sperm transfer, the unusual maturation and unique morphology and motility of the spermatozoa, the mechanism of oogenesis and its hormonal control, the mystery of fertilization, the involvement of pheromones in mating, the control of reproductive arrests and the vertical transmission of symbiotes in reproduction. Jumping-off points for further investigation are discussed throughout. Full article