Diploptera Punctata Research Articles

A Novel Peptidomimetic Insecticide: Dippu-AstR-Based Rational Design and Biological Activity of Allatostatin Analogs.

Insect neuropeptides play an essential role in regulating growth, development, reproduction, nerve conduction, metabolism, and behavior in insects; therefore, G protein-coupled receptors of neuropeptides are considered important targets for designing green insecticides. Cockroach-type allatostatins (ASTs) (FGLamides allatostatins) are important insect neuropeptides in Diploptera punctata that inhibit juvenile hormone (JH) synthesis in the corpora allata and affect growth, development, and reproduction of insects. Therefore, the pursuit of novel insecticides targeting the allatostatin receptor (AstR) holds significant importance. Previously, we identified an AST analogue, H17, as a promising candidate for pest control. Herein, we first modeled the 3D structure of AstR in D. punctata (Dippu-AstR) and predicted the binding mode of H17 with Dippu-AstR to study the critical interactions and residues favorable to its bioactivity. Based on this binding mode, we designed and synthesized a series of H17 derivatives and assessed their insecticidal activity against D. punctata. Among them, compound Q6 showed higher insecticidal activity than H17 against D. punctata by inhibiting JH biosynthesis, indicating that Q6 is a potential candidate for a novel insect growth regulator (IGR)-based insecticide. Moreover, Q6 exhibited insecticidal activity against Plutella xylostella, indicating that these AST analogs may have a wider insecticidal spectrum. The underlying mechanisms and molecular conformations mediating the interactions of Q6 with Dippu-AstR were explored to understand its effects on the bioactivity. The present work clarifies how a target-based strategy facilitates the discovery of new peptide mimics with better bioactivity, enabling improved IGR-based insecticide potency in sustainable agriculture.

Enhanced gut microbiome supplementation of essential amino acids in Diploptera punctata fed low-protein plant-based diet.

Building on our previous work, we investigate how dietary shifts affect gut microbial essential amino acid (EAA) provisioning in the lactating cockroach Diploptera punctata. To that end, we fed cockroaches three distinct diets: a plant-only Gari diet composed of starchy and granulated root tuber Yucca (Manihot esculenta), a dog food diet (DF), and a cellulose-amended dog food (CADF) diet. We anticipated that the high carbohydrate, low protein Gari would highlight increased microbial EAA supplementation to the host. By day 28, we observed distinct profiles of 14 bacterial families in the insect gut microbiomes of the three dietary groups. CADF-fed insects predominantly harbored cellulolytic and nitrogen-fixing bacteria families Streptococcaceae and Xanthomonadaceae. In contrast, Gari-fed insects were enriched in anaerobic lignocellulolytic bacteria families Paludibacteraceae andDysgonomonadaceae, while DF-fed insects had a prevalence of proteolyticanaerobes Williamwhitmaniaceae and sulfate-reducing bacteria Desulfovibrionaceae. Furthermore, we confirmed significantly higher EAA supplementation in Gari-fed insects than in non-Gari-fed insects based on δ13C-EAA offsets between insect and their diets. The δ13C-EAA offsets between DF and CADF were nearly indistinguishable, highlighting the relevance of using the plant-based Gari in this experiment to unequivocally demonstrate this function in this insect. These results were underscored by lower standard metabolic rate (SMR) relative to the DF insect in Gari-fed (intermediate SMR and dietary quality) and CADF (least SMR and dietary quality) insects. The influence of diet on EAA provisioning and SMR responses in insects underscores the need for further exploration into the role of gut microbial functions in modulating metabolic responses.

Variability in phenylalanine side chain conformations facilitates broad substrate tolerance of fatty acid binding in cockroach milk proteins.

Diploptera punctata, also known as the Pacific beetle cockroach, is a viviparous cockroach that gives birth to live offspring and secretes a highly concentrated mixture of glycosylated proteins as a source of nourishment for developing embryos. These proteins are lipocalins that bind to lipids and crystallize in the gut of the embryo. A structure of milk crystals harvested from the embryos showed that the milk-derived crystals were heterogeneous and made of three proteins (called Lili-Mips). We hypothesized that the isoforms of Lili-Mip would display different affinities for fatty acids due to the ability of the pocket to bind multiple acyl chain lengths. We previously reported the structures of Lili-Mip from crystals grown in vivo and recombinantly expressed Lili-Mip2. These structures are similar, and both bind to several fatty acids. This study explores the specificity and affinity of fatty acid binding to recombinantly expressed Lili-Mip 1, 2 & 3. We show that all isoforms can bind to different fatty acids with similar affinities. We also report the thermostability of Lili-Mip is pH dependent, where stability is highest at acidic pH and declines as the pH increases to physiological levels near 7.0. We show that thermostability is an inherent property of the protein, and glycosylation and ligand binding do not change it significantly. Measuring the pH in the embryo's gut lumen and gut cells suggests that the pH in the gut is acidic and the pH inside the gut cells is closer to neutral pH. In various crystal structures (reported here and previously by us), Phe-98 and Phe-100 occupy multiple conformations in the binding pocket. In our earlier work, we had shown that the loops at the entrance could adapt various conformations to change the size of the binding pocket. Here we show Phe-98 and Phe-100 can reorient to stabilize interactions at the bottom of the cavity-and change the volume of the cavity from 510 Å3 to 337 Å3. Together they facilitate the binding of fatty acids of different acyl chain lengths.

Leidynema bestium sp. n. (Oxyuridomorpha: Thelastomatidae) an intestinal parasite of blaberid cockroaches from Yaroslavl Zoo, Russia

A new species of thelastomatid Leidynema bestium sp. n. is described from the hind gut lumen of the cockroaches Diploptera punctata (Eschscholtz, 1922) and Elliptorhina chopardi (Lefeuvre, 1966). The new species is characterized by a combination of morphological features: presence of lateral alae in both sexes with posterior margin of alae in females not ending in the shape of a spike; longitudinal striation of the anteriormost annuli in males; four male genital papillae, equatorial position of vulva. In the cladogram inferred from analysis of D2-D3 segment of LSU rDNA L. bestium sp. n. demonstrates a position independent of the Leidynema species with known sequences of this taxonomic marker near the basal node for this genus.

Genome Sequence of a Blattabacterium Strain Isolated from the Viviparous Cockroach, Diploptera punctata.

Here, we report the genome sequence and characterization for a Blattabacterium strain isolated from the viviparous cockroach, Diploptera punctata, which provides amino acids critical for intrauterine embryo development. The genome was assembled by sequencing of the cockroach fat body, which is the location of this obligate symbiont.

DNA methylation patterns respond to thermal stress in the viviparous cockroach Diploptera punctata

ABSTRACT It is increasingly recognized that epigenetic mechanisms play a key role in acclimatization and adaptation to thermal stress in invertebrates. DNA methylation and its response to temperature variation has been poorly studied in insects. Here, we investigated DNA methylation and hydroxymethylation patterns in the viviparous cockroach Diploptera punctata at a global and gene specific level in response to variation in temperature. We specifically studied methylation percentage in the heat shock protein 70 (Hsp70), whose function is linked to thermal plasticity and resistance. We found high levels of DNA methylation in several tissues but only low levels of DNA hydroxymethylation in the brain. Hsp70 methylation patterns showed significant differences in response to temperature. We further found that global DNA methylation variation was considerably lower at 28°C compared to higher or lower temperatures, which may be indicative of the optimal temperature for this species. Our results demonstrate that DNA methylation could provide a mechanism for insects to dynamically respond to changing temperature conditions in their environment.

Molecular mechanisms underlying milk production and viviparity in the cockroach, Diploptera punctata

Viviparous reproduction is characterized by maternal retention of developing offspring within the reproductive tract during gestation, culminating in live birth. In some cases, a mother will provide nutrition beyond that present in the yolk; this is known as matrotrophic viviparity. While this phenomenon is best associated with mammals, it is observed in insects such as the viviparous cockroach, Diploptera punctata. Female D. punctata carry developing embryos in the brood sac, a reproductive organ that acts as both a uterus and a placenta by protecting and providing a nutritive secretion to the intrauterine developing progeny. While the basic physiology of D. punctata pregnancy has been characterized, little is known about the molecular mechanisms underlying this phenomenon. This study combined RNA-seq analysis, RNA interference, and other assays to characterize molecular and physiological changes associated with D. punctata reproduction. A comparison of four stages of the female reproductive cycle and males revealed unique gene expression profiles corresponding to each stage and between sexes. Differentially regulated transcripts of interest include the previously identified family of milk proteins and transcripts associated with juvenile hormone metabolism. RNA interference and methoprene application experiments established the potential impacts of bothbreakdown and synthesis reduction of juvenile hormone in maintaining pregnancy in D. punctata. These studies provide the comprehensive molecular mechanisms associated with cockroach viviparity, which will be a critical resource for comparative purposes among viviparity in insect systems.

Role of the gut microbiome in mediating standard metabolic rate after dietary shifts in the viviparous cockroach, Diploptera punctata.

Diet may be a significant determinant of insect gut microbiome composition. However, the extent to which dietary shifts shape both the composition and relevant functions of insect gut microbiomes, and ultimately impact host energy balance (i.e. metabolic phenotype), is not well understood. We investigated the impacts of diet switching on Diploptera punctata females maintained on a dog food (DF) diet relative to those fed a comparatively sub-optimal cellulose-amended dog food (CADF) diet for 4weeks. After this period, dietary shift resulted in a significantly higher average mass-specific standard metabolic rate (SMR) in CADF-fed females compared with DF-fed females. We also uncovered significant 13C-enrichment in DF-fed insect samples relative to CADF-fed insect samples and lowered bacterial essential amino acid (EAA) provisioning in CADF-fed samples. Differences in SMR and EAA provisioning were not accompanied by significant differences in overall microbiome composition between the two groups. However, cellulolytic and nitrogen-fixing bacterial families dominant in wild omnivorous cockroaches and wood-feeding termites were significantly enriched in CADF-fed females than in DF-fed females, at the end of the study. We propose that these changes in microbiome composition after dietary shifts are associated with changes in EAA provisioning and possibly SMR. Further studies are needed to comprehensively understand the relative importance of gut microbial functions among the complexity of factors known to underscore SMR responses in insects under varying dietary conditions.

Matrotrophic viviparity constrains microbiome acquisition during gestation in a live-bearing cockroach, Diploptera punctata.

The vertical transmission of microbes from mother to offspring is critical to the survival, development, and health of animals. Invertebrate systems offer unique opportunities to conduct studies on microbiome‐development‐reproduction dynamics since reproductive modes ranging from oviparity to multiple types of viviparity are found in these animals. One such invertebrate is the live‐bearing cockroach, Diploptera punctata. Females carry embryos in their brood sac, which acts as the functional equivalent of the uterus and placenta. In our study, 16S rRNA sequencing was used to characterize maternal and embryonic microbiomes as well as the development of the whole‐body microbiome across nymphal development. We identified 50 phyla and 121 classes overall and found that mothers and their developing embryos had significantly different microbial communities. Of particular interest is the notable lack of diversity in the embryonic microbiome, which is comprised exclusively of Blattabacteria, indicating microbial transmission of only this symbiont during gestation. Our analysis of postnatal development reveals that significant amounts of non‐Blattabacteria species are not able to colonize newborn D. punctata until melanization, after which the microbial community rapidly and dynamically diversifies. While the role of these microbes during development has not been characterized, Blattabacteria must serve a critical role providing specific micronutrients lacking in milk secretions to the embryos during gestation. This research provides insight into the microbiome development, specifically with relation to viviparity, provisioning of milk‐like secretions, and mother–offspring interactions during pregnancy.

Contamination of Cockroaches (Insecta: Blattaria) by Medically Important Bacteriae: A Systematic Review and Meta-analysis

Cockroaches have the potential to disseminate bacteria in their environments and therefore a systematic review and meta-analysis was conducted to assess the state-of-the-art of our knowledge regarding bacterial contaminants of cockroaches. At least 78 bacterial species and 42 genera from 24 families and 11 orders of bacteria were reported to have contaminated cockroaches. At least 61, 42, 12, 13, 7, and 16 bacterial species have contaminated Blattella germanica (L.) (Blattaria: Ectobiidae), Periplaneta americana (L.) (Blattaria: Blattidae), Blatta orientalis (L.) (Blattaria: Blattidae), Diploptera punctata (Eschscholtz) (Blattaria: Blaberidae), Periplaneta fuliginosa (Serville) (Blattaria: Blattidae), and Supella longipalpa (F.) (Blattaria: Ectobiidae), respectively. Blattella germanica is the most commonly contaminated cockroach species, with the widest bacterial species diversity that threatens human health, followed by P. americana. Cockroach bacterial contaminants may result in the dissemination of opportunistic or pathogenic infections, particularly nosocomial and foodborne infections. One-way analysis of variance (ANOVA) revealed significant differences between bacterial contaminant species of cockroaches, species of cockroaches with bacterial contaminants, cockroach body part surfaces from the point of view bacterial contaminants and countries of cockroach infested with bacterial contaminants (P < 0.05). This statistical analysis indicates that the bacterial contaminants of the external cockroach body parts are potentially more harmful than from internal surfaces, and secondly, the bacterial contaminants of cockroaches in hospital environments are potentially more harmful than from other human environments. The survey indicated that the bacterial contaminant species of cockroaches appear to be mostly multiple drug resistant. The challenges of cockroaches as being potential vectors of pathogenic or opportunistic agents of human infections are discussed.

Old method not old-fashioned: parallelism between wing venation and wing-pad tracheation of cockroaches and a revision of terminology

The Comstock–Needham system, the foundation of main vein homology of insects, is grounded in the comparison between wing venation and wing-pad tracheation, particularly that of Plecoptera and Blattodea. However, the trachea-based approach has come into great dispute in recent years. Meanwhile, the terminology used to describe the wing venation of cockroaches requires a revision according to homology and the practical need. These motivated us to examine the wings of cockroaches, comparing the tracheation of nymphs with the tracheation and venation of adults. We find a correspondence between the tracheation and the main vein venation; therefore the trachea-based approach is effective in cockroaches. It is supported that Neopteran insects have six homologous main veins, namely, Sc, R, M, Cu, Pcu and V. We interpret the wing morphology of cockroaches in detail, including veins, furrows, folds and apical folding. RA and RP in hindwing, ScP, CuA and CuP in tegmen and hindwing, are recognized. Hindwing R + M is the only normal venal fusion in cockroaches. In addition, we propose several descriptive terms: cmv, V[1], V[s], pseudostem and characteristic posterior branch. The venation of 41 species (representing 41 genera), and the wing-pad tracheation of four of them including Diploptera punctata, which has unique apical folding, are illustrated.

Female clustering in cockroach aggregations—A case of social niche construction?

AbstractIndividuals in groups can suffer costs through interactions with adversarial or unknown conspecifics. Social niche construction allows individuals to buffer such potential costs by only engaging in preferred associations. This may be particularly beneficial in insect aggregations, which are often large and highly fluid. However, little is known regarding the structuring of such aggregations. Here we use social network analyses to test for fine‐scale social structure in resting aggregations of the sub‐social cockroach Diploptera punctata and to explore the social pressures that contribute towards such structure. We showed that females were significantly more gregarious than males and formed the core of the proximity network, thus demonstrating a higher level of social integration. This fine‐scale structure is likely to result from females displacing males; females initiated most displacements whilst males received the majority. We explain this behaviour in terms of social niche construction by showing that females received significantly fewer approaches and investigations at more female‐biased local sex ratios. We therefore suggest that female social clustering occurs in this, and presumably other, species to reduce potential costs associated with male harassment. This demonstrates how social niche construction can lead to higher level social structure; we suggest this approach could be used across a range of species in order to improve our understanding of the evolution of sociality.

Myotropic activity of allatostatins in tenebrionid beetles

Neuropeptides control the functioning of the nervous system of insects, and they are the most diverse signalling molecules in terms of structure and function. Allatostatins are pleiotropic neuropeptides that are considered potent myoinhibitors of muscle contractions in insects. We investigated the effects caused by three distinct allatostatins, Dippu-AST1 (LYDFGL-NH2 from Diploptera punctata), Grybi-MIP1 (GWQDLNGGW-NH2 from Gryllus bimaculatus) and Trica-ASTC (pESRYRQCYFNPISCF-OH from Tribolium castaneum) on contractile activity of the myocardium, oviduct and hindgut of two tenebrionid beetles, Tenebrio molitor and Zophobas atratus. Studies showed that all three peptides exerted myostimulatory effects on the oviduct and hindgut of the beetles, however they did not cause any effect on myocardium. The effects of Dippu-AST1, Grybi-MIP1 and Trica-ASTC were dose-dependent and tissue and species specific. The highest stimulatory effect was caused by Trica-ASTC, showing stimulation of approximately 82% at a 10−12 M concentration and 76% at a 10−11 M concentration for T. molitor and Z. atratus, respectively. The oviduct of T. molitor was more susceptible to allatostatins than that of Z. atratus. Dippu-AST1 showed the maximum stimulating effect at 10−11 M (57%), whereas Grybi-MIP 1 at 10−10 M caused a 41% stimulation. Trica-ASTC, in both species, showed a myostimulatory effect over the whole range of tested concentrations but was most potent at a 10−12 M concentration and caused a 54% and 31.9% increase in the frequency of contractions in the oviduct of T. molitor and Z. atratus, respectively. The results suggest that allatostatins may affect the regulation of egg movement within the oviducts and movement of food in the digestive tract of beetles and do not regulate directly the activity of heart, thus being good candidate compounds in neuropeptides based pest control agents in future research.

Exploring the N-terminus region: Synthesis, bioactivity and 3D-QSAR of allatostatin analogs as novel insect growth regulators

Allatostatins (ASTs), a family of insect neuropeptide, can inhibit juvenile hormone (JH) biosynthesis by the corpora allata (CA) in Diploptera punctata, and therefore be regarded as potential leads for the discovery of new insect growth regulators (IGRs). But several shortcomings, such as their sensitivity to peptidases and high cost, impeded their practical application in pest management. In order to discover new IGRs, one AST analog B1 possessing non-peptide group was discovered with high ability to inhibit JH biosynthesis in vitro (IC50: 0.09μmol/L) in our previous studies. In the present work, two series of B1 analogs with different substituents on the N-terminus region were designed and synthesized. The result suggested that benzene showed better activity than other heterocycles, and the para-substitution on the benzene was beneficial for activity. Moreover, analogs with logP value over 2.0 exhibited good activity, which indicated the hydrophobicity is important to the bioactivity. Three dimension quantitative structure-activity relationship (3D-QSAR) studies were performed to highlight the structural requirements of AST analogs, which demonstrated introduction of bulkier substituents on the N-terminus would increase the activity. Analog II12 (IC50: 0.08μmol/L) exhibited similar inhibitory activity to the lead B1, but its synthetic route was simpler than B1. Therefore, II12 could be used as a new lead compound for the discovery eco-friendly IGRs.

Personality in the cockroach Diploptera punctata: Evidence for stability across developmental stages despite age effects on boldness.

Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes.

Compositional differences among female-associated and embryo-associated microbiota of the viviparous Pacific Beetle cockroach, Diploptera punctata.

All cockroach species, except one, harbor the endosymbiont Blattabacterium, transmitted from females to embryos. Adult cockroaches acquire non-Blattabacterium bacteria as part of their gut microbiota over time, but our knowledge of the possible transmission of these non-Blattabacterium bacteria from females to embryos is rudimentary. We characterized the gut microbiota of gravid viviparous Diploptera punctata females and the non-Blattabacterium microbiota of associated developing embryos, as well as the gut microbiota of non-gravid females, and the microbiota of orphan embryos (females not included), following high-throughput sequencing of the 16S rRNA gene to assess bacterial transference. We determined significant differences in community composition between gravid females and associated embryos and overall greater similarity in community composition among embryos than adult females. Results suggest various routes of transference of bacteria from females or the environment to embryos. The bacterial families Halomonadaceae and Shewanellaceae were more abundant in embryos than in gravid females. The functional relevance of these families remains to be elucidated, but provisioning of amino acids deficient in the brood sac secretion is a possibility. Overall, our results highlight the need for further studies investigating the uptake and selective screening of microbes by D. punctata embryos, as well as their functions.

New species of Hammerschmidtiella Chitwood, 1932, and Blattophila Cobb, 1920, and new geographical records for Severianoia annamensis Van Luc & Spiridonov, 1993 (Nematoda: Oxyurida: Thelastomatoidea) from Cockroaches (Insecta: Blattaria) in Ohio and Florida, U.S.A.

Two new species of thelastomatid nematodes parasitic in the hindgut of cockroaches are described. Hammerschmidtiella keeneyi n. sp. is described from a laboratory colony of Diploptera punctata (Eschscholtz, 1822) from a facility in Ohio, U. S. A. This species is characterized by having females with a short tail and males smaller than those described from other species. The new species also differs from others in the genus by a number of differing measurements that indicate a distinct identity, including esophageal, tail, and egg lengths as well as the relative position of the excretory pore. Blattophila peregrinata n. sp. is described from Periplaneta australasiae (Fabricius, 1775) and Pycnoscelus surinamensis (Linnaeus, 1758) in a greenhouse from Ohio, U.S.A. and from wild P. surinamensis in southern Florida, U.S.A. This species differs from others in the genus by having a posteriorly directed vagina, vulva in the anterior third of the body, no lateral alae in females, and eggs with an operculum. In P. surinamensis from southern Florida, an additional species, Severianoia annamensis Van Luc & Spiridonov, 1993 was found and did not co-parasitize the host with B. peregrinata n. sp. Blattophila peregrinata n. sp. and S. annamensis also occur in the Galápagos Islands, Ecuador, indicating that these have a widespread global range.

柠檬酸转运载体在蟑螂保幼激素合成中的研究进展

目的：研究太平洋折翅蠊(Diploptera punctata)中一种柠檬酸转运载体(Citrate carrier, CiC)在保幼激素(juvenile hormone, JH)合成通路中的功能，探讨该CiC与JH合成的关系，为针对保幼激素途径进行的新型害虫防治提供理论依据。方法：以太平洋折翅蠊为研究对象，利用荧光定量PCR技术对CiC在不同器官及咽侧体不同发育时期的表达量进行分析。结果：柠檬酸转运载体在合成保幼激素的主要场所咽侧体(Corpora allata, CA)中表达量最高，其次是脂肪体(Fat body, Fb)。在雌性蟑螂交配后0~7天内，咽侧体中CiC表达量与JH释放量成正相关。利用RNA干扰(RNA interference, RNAi)技术对JH合成关键酶3-羟基- 3-甲基戊二酸单酰辅酶A还原酶和保幼激素酸甲基转移酶基因进行干扰后，CiC表达量明显下调。结论：CiC与JH合成通路密切相关，其可能是通过介导乙酰辅酶A由线粒体到细胞质的跨膜运输，影响JH的从头合成。 Purpose: To determine the function of Citrate carrier (CiC) in the biosynthesis of Juvenile hormone in cockroach, D. punctata, and build a basic theory for pest control. Methods: The expression profile and tissue distribution of CiC were determined by qRT-PCR. Furthermore, the relationship between JH biosynthesis and CiC were investigated by knocking down the essential genes in JH biosynthesis pathway using RNAi. Results: CiC has the highest expression level in CA, which is the biosynthetic site of JH, and followed by Fb. CiC expression pattern in CA corresponds with JH biosynthesis in the CA of 0 - 7d after mated female. There is a down regulation in CiC expression after knocking down the 3-hydroxy-3-methylglutaryl coenzyme-A reductase and Juvenile hormone acid methyl transferase, two key genes that play essential roles in JH biosynthesis. Conclusion: Our result suggested CiC was involved in JH biosynthesis pathway, probably by mediating the transmembrane transport of Acetyl-CoA. Further investigate was needed to determine the accurate function of CiC.

A potential insect growth regulator forcockroach control: design, synthesis andbioactivity of N-terminal-modified allatostatin analogues.

The FGLa-allatostatins (ASTs) are a family of neuropeptides that can inhibit juvenile hormone biosynthesis by the corpora allata (CA) in vitro, and therefore they are regarded as insect growth regulator (IGR) candidates for pest control. In our previous studies, an AST mimic, H17, was found to have a significant effect on JH biosynthesis by cockroach CA, both invitro and in vivo. To discover new potential mimics and explore the substituent effect on the inhibition of JH biosynthesis, 30 analogues, modified with various substituents on the benzene ring at the N-terminus of lead compound H17, were designed and synthesised. Their bioactivity in inhibiting JH biosynthesis by the CA of Diploptera punctata and the potency of M9, M10 and M11 in activation of Dippu-AstR were evaluated. All the analogues showed an effect on JH biosynthesis by CA in vitro. M9, M10 and M11 can activate the Dippu-AstR, albeit with much lower potency than that of AST 1. M11 also exhibited improved in vitro activity (IC50 6.98 nm) in comparison with the lead compound H17 (IC50 29.5 nm). In particular, M11 displayed good in vivo activity in inhibiting JH biosynthesis and basal oocyte growth. The structure-activity relationship studies suggest that different positions of substituents on the benzene ring of the cinnamic acid can lead to different activities. The para-substitution on the benzene ring plays an important role in inhibiting JH biosynthesis in vitro. Moreover, M11 is considered to be a potential IGR for cockroach control. © 2016 Society of Chemical Industry.

Identification of allatostatins in the brown-winged green bug Plautia stali

Juvenile hormone (JH) biosynthesis is inhibited under short-day conditions in the brown-winged green bug Plautia stali. We investigated allatostatic molecules in the brain of P. stali. Methanol brain extracts strongly inhibited JH biosynthesis. The allatostatic activities of the brain extracts were heat stable but gently suppressed by trypsin treatment, indicating that the allatostatic molecules were peptides. Grybi-MIP1, found in Gryllus bimaculatus as an allatostatic molecule, inhibited JH biosynthesis in P. stali. In contrast, peptides such as Dippu-AST2, 8, and 9, found in Diploptera punctata, did not affect JH biosynthesis in P. stali. We found a cDNA sequence encoding a peptide precursor of myoinhibitory peptides (MIPs), which we named Plast-MIP. Three synthetic peptides, AWKDLSKAW-NH2 (Plast-MIP1), GWSDLQSAGW-NH2 (Plast-MIP5), and AADWGSFRGSW-NH2 (Plast-MIP8), deduced from the precursor sequence, showed clear inhibition of JH biosynthesis in P. stali. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and tandem mass spectrometry showed that Plast-MIP8 resides in the brain. Expression of the Plast-MIP mRNA precursor was detected in the brain of insects reared under short- and long-day conditions. These results suggest that Plast-MIP is an allatostatic molecule and that MIPs are synthesized irrespective of photoperiod. To our knowledge, this is the first study to identify Plast-MIP as a functional allatostatin in hemipteran insects.