Insects Of Economic Importance Research Articles

Effects of phoxim pesticide on the immune system of silkworm midgut

Silkworm (Bombyx mori) is an important economic insect. Bombyx mori, which is exposed to sublethal doses of pesticides, has a low or no mortality rate, while it is susceptible to infections triggered by foreign pathogens. The immune regulatory mechanism of silkworms caused by trace pesticides still remains unclear. The midgut is the major organ of silkworm for digestion and nutrient absorption, and it plays a critical defensive role against pathogens. In the present study, the silkworm was susceptible to Enterobacter cloacae sp. (E. cloacae) after exposure to sublethal dose of phoxim. The body weight and survival rate of the phoxim-E. cloacae co-treatment group were significantly decreased after 120 h of treatment compared with the phoxim treatment group. The immune responses and expressions of immune-related genes were dysregulated in the midgut of silkworm following exposure to phoxim. Digital gene expression (DGE) analysis revealed that 44 immune response-related and immune defense-related genes were differentially expressed. qRT-PCR results indicated that the transcriptional levels of antimicrobial peptide genes Bmdefensin1, BmcecA, Bmglv1, Bmglv2, Bmmoricin and BmmoricinB3 were down-regulated by 0.77-, 0.37-, 0.05-, 0.19-, 0.34- and 0.54-fold, respectively. The transcriptional levels of Toll signaling pathway genes Bmcactus, Bmspatzle and Bmrel were down-regulated by 0.4-, 0.37- and 0.96-fold, respectively. Peritrophic membrane (PM) protein-related genes BmCBP-02, BmPM-41, BmPM-43 and BmCDA7 were down-regulated by 0.18-, 0.02-, 0.66- and 0.16-fold, respectively. The expressions of Toll signaling pathway genes were down-regulated at 48 h and 72 h. Immune deficiency (IMD) and Janus kinase and signal transducer and activator of transcription (JAK/STAT) signaling pathway genes were dysregulated after phoxim exposure. These results indicated that phoxim might cause damage to the PM and reduce the immune response of the silkworm, leading to susceptibility of silkworm to disease and damage from foreign pathogens.

Survival of silk worm, Bombyx mori in azaserine induced oxidative stress

Cells under stress generate reactive oxygen species (ROS) in excess, which causes mitochondrial dysfunction and stimulates the apoptotic cascade. However, mild stress or pre-conditioning lead to the evasion of apoptosis by activating mitogenic signaling, including the signaling of inhibitors of apoptosis proteins (IAPs), or by inactivating certain apoptotic molecules. The silkworm (Bombyx mori) is an important economic insect which serves as a model organism in biological research. Bombyx mori apoptotic protease inducing factor (BmApaf1), a death-related ced-3/Nedd2-like protein (BmDredd), and BmSurvivin-2 (BmSvv2) are known to play significant roles in metamorphosis. Azaserine is an analogue of glutamine and irreversibly inhibits glutamine-utilizing enzymes and cysteine-glutamate transporter genes EAAT2. In the present study, we experimentally demonstrated stress induced by azaserine along with the capacity of antioxidants to modulate apoptotic/anti-apoptotic gene expression in determining the fate of the larvae. We observed higher larval survival with higher azaserine dosages and attributed this to the quantum of ROS generated and AOEs response, which favoured the BmSvv2 expression. Meanwhile higher levels of ROS with concomitant changes in AOEs were found to be responsible for BmApaf1 and BmDredd expression, which reflected a higher mortality rate.

Precision mapping of N- and O-glycoproteins in viral resistant and susceptible strains of Bombyx mori

Protein glycosylation plays important roles in protein structure, function, and immune recognition, among many other activities. One of the major roles of glycans and glycoconjugates on the cell surface is acting as the receptor for outside pathogens such as viruses. During the initial stage of viral replication, viruses interact with cell membrane receptors, which are in many cases glycoproteins. Identifying such glycoproteins is essential to understanding the mechanisms of viral infection, as well as developing antiviral strategies. Silkworm is an important economic insect as well as a model organism for molecular biology, yet current knowledge on its glycoproteome is far from complete due to both analytical challenges and perceived lack of importance. In this study, we performed a large-scale glycoproteomic survey for two silkworm Bombyx mori strains 306 and NB, which are susceptible and resistant to the baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV), respectively. More than 400 silkworm N- and O- glycoproteins were identified with high confidence, demonstrating that this organism employs extensive glycosylation. We mapped some glycoproteins only to the BmNPV susceptible or resistant strain, underlining the potential relationship between glycosylation and viral susceptibility. We predicted O-glycoproteins and O-glycan compositions for the first time for this organism. The variations in glycan site occupancy, as well as glycan diversity between the two silkworm strains, provide an insight into role of glycosylation in viral recognition and infection processes.

Molecular Identification and Pathogencity of Bacillus thuringensis SW2 on Silkworm (Bombyx mori L.)

The silkworm is an important economic insect due to production of silk. It is the larva or caterpillar of the domesticated silk moth, (Bombyxmori L.) . In the rearing of silkworm bacterial flacherie considered the most important disease effect in silk production. Flacherie is a Syndrome associated with bacterial disease. In the present study the isolation of pathogenic bacteria from infected larvae . The infected larvae samples were serially diluted from which 10-5,10-6 and cultivated onto nutrient agar plate. The dominant colonies were selected identification by colony morphology, Gram staining property and biochemical test and confirmed the identification by 16SrRNA which proved the name of bacteria as Bacillus thuringensis SW2 with accession number (MK327364.1). The genus of Bacillus thuringensisSW2 was responsible of mortality in 4th and 5th instars of the larval stages of B. mori L. after 3 days recorded 4.66a and 2.66b in 4th, 5th instars respectively post infection and highest mortality rate was obtained at 5 days recorded 12a, 12.66a in 4th and 5thinstars receptively and the total injury reach to 31a,32a in 4th and 5thinstars receptively after 5days.

Proteomic Identification of Immune-Related Silkworm Proteins Involved in the Response to Bacterial Infection

Bombyx mori (Lepidoptera: Bombycidae) is an important economic insect and a classic Lepidopteran model system. Although immune-related genes have been identified at a genome-wide scale in the silkworm, proteins involved in immune defense of the silkworm have not been comprehensively characterized. In this study, two types of bacteria were injected into the silkworm larvae, Gram-negative Escherichia coli (Enterobacteriales: Enterobacteriaceae), or Gram-positive Staphylococcus aureus (Bacillales: Staphylococcaceae). After injection, proteomic analyses of hemolymph were performed by liquid chromatography—tandem mass spectrometry. In total, 514 proteins were identified in the uninduced control group, 540 were identified in the E. coli-induced group, and 537 were identified in the S. aureus-induced group. Based on Uniprot annotations, 32 immunological recognition proteins, 28 immunological signaling proteins, and 21 immunological effector proteins were identified. We found that 127 proteins showed significant upregulation, including 10 immunological recognition proteins, 4 immunological signaling proteins, 11 immunological effector proteins, and 102 other proteins. Using real-time quantitative polymerase chain reaction in the fat body, we verified that immunological recognition proteins, signaling proteins, and effector proteins also showed significant increases at the transcriptional level after infection with E. coli and S. aureus. Five newly identified proteins showed upregulation at both protein and transcription levels after infection, including 30K protein, yellow-d protein, chemosensory protein, and two uncharacterized proteins. This study identified many new immune-related proteins, deepening our understanding of the immune defense system in B. mori. The data have been deposited to the iProX with identifier IPX0001337000.

An Assessment of the Seychelles Scale Icerya seychellarum (Westwood) as a Potential Insect of Economic Importance in South Africa

An Assessment of the Seychelles Scale Icerya seychellarum (Westwood) as a Potential Insect of Economic Importance in South Africa

Characterization of the 12S rRNA Gene Sequences of the Harvester Termite Anacanthotermes ochraceus (Blattodea: Hodotermitidae) and Its Role as A Bioindicator of Heavy Metal Accumulation Risks in Saudi Arabia.

Termites are social insects of economic importance that have a worldwide distribution. Identifying termite species has traditionally relied on morphometric characters. Recently, several mitochondrial genes have been used as genetic markers to determine the correlation between different species. Heavy metal accumulation causes serious health problems in humans and animals. Being involved in the food chain, insects are used as bioindicators of heavy metals. In the present study, 100 termite individuals of Anacanthotermes ochraceus were collected from two Saudi Arabian localities with different geoclimatic conditions (Riyadh and Taif). These individuals were subjected to morphological identification followed by molecular analysis using mitochondrial 12S rRNA gene sequence, thus confirming the morphological identification of A. ochraceus. Furthermore, a phylogenetic analysis was conducted to determine the genetic relationship between the acquired species and other termite species with sequences previously submitted in the GenBank database. Several heavy metals including Ca, Al, Mg, Zn, Fe, Cu, Mn, Ba, Cr, Co, Be, Ni, V, Pb, Cd, and Mo were measured in both collected termites and soil samples from both study sites. All examined samples (termite and soil) showed high concentrations of metals with different concentrations and ratios. Generally, most measured metals had a significantly high concentration in soil and termites at Taif, except for Ca, Cd, Co, Cr, Cu, Mg, and Ni showing significantly high concentrations at Riyadh. Furthermore, termites accumulated higher amounts of heavy metals than the soil at both locations. The mean concentrations of the measured metals in soil samples were found to be in the descending order Ca ˃ Al ˃ Mg ˃ Zn ˃ Fe ˃ Cu ˃ Mn ˃ Ba ˃ Cr ˃ Co ˃ Be ˃ Ni ˃ V ˃ Pb ˃ Cd ˃ Mo, while it was Ca ˃ Mg ˃ Al ˃ Fe ˃ Zn ˃ Cu ˃ Mn ˃ Be ˃ Ba ˃ Pb ˃ Cr ˃ V ˃ Ni ˃ Cd ˃ Mo ˃ Co in termite specimens. The mean concentrations of the studied metals were determined in the soil and termite specimens at both locations. In addition, the contamination factor, pollution load index (PLI) and degree of contamination were calculated for all studied metals in different samples, indicating that both studied sites were polluted. However, Taif showed a significantly higher degree of pollution. Thus, the accurate identification of economically important insects, such as termites, is of crucial importance to plan for appropriate control strategies. In addition, termites are a good bioindicator to study land pollution.

Host plants for mealybugs (Hemiptera: Pseudococcidae) in grapevine crops

ABSTRACT Mealybugs (Hemiptera: Pseudococcidae) are considered pest insects of economic importance in grapevine crops. They are highly polyphagous, feeding on host plants of about 250 families. This study aimed to identify host plants for mealybugs in grapevine crops, in the São Francisco Valley region, Brazil. The samples included weeds, ornamentals, windbreaks, fruit trees and native plants of the Caatinga biome. A total of 37 species of host plants for mealybugs were identified, distributed in 18 families. The Malvaceae family was the most frequent one, with eigth host species identified, followed by Fabaceae with four and Euphorbiaceae with three. Most of these host plants are being recorded here for the first time in association with mealybugs species. From the identified plant species, 24 are hosts for Maconelicoccus hirsutus, 16 for Phenacoccus solenopsis, one for Ferrisia virgata, one for Dysmicoccus brevipes and one for Planococcus citri. The obtained results are important to better understand the host plant diversity for mealybugs, in order to implement integrated pest management programs.

Entomopathogenic nematode Steinernema carpocapsae surpasses the cellular immune responses of the hispid beetle, Octodonta nipae (Coleoptera: Chrysomelidae)

The Nipa palm hispid, Octodonta nipae (Maulik) is an important invasive pest of palm trees particularly in Southern China. How this beetle interacts with invading pathogens via its immune system remains to be dissected. Steinernema carpocapsae is a pathogenic nematode that attacks a number of insects of economic importance. The present study systematically investigates the cellular immune responses of O. nipae against S. carpocapsae infection using combined immunological, biochemical and transcriptomics approaches. Our data reveal that S. carpocapsae efficiently resists being encapsulated and melanized within the host's hemolymph and most of the nematodes were observed moving freely in the hemolymph even at 24 h post incubation. Consistently, isolated cuticles from the parasite also withstand encapsulation by the O. nipae hemocytes at all-time points. However, significant encapsulation and melanization of the isolated cuticles were recorded following heat treatment of the cuticles. The host's phenoloxidase activity was found to be slightly suppressed due to S. carpocapsae infection. Furthermore, the expression levels of some antimicrobial peptide (AMP) genes were significantly up-regulated in the S. carpocapsae-challenged O. nipae. Taken together, our data suggest that S. carpocapsae modulates and surpasses the O. nipae immune responses and hence can serve as an excellent biological control agent of the pest.

Insecticidal fungal metabolites fabricated chitosan nanocomposite (IM-CNC) preparation for the enhanced larvicidal activity - An effective strategy for green pesticide against economic important insect pests

In the present study, enhanced pesticidal activity and biocompatibility of chitosan nanocomposite prepared with biocompatible polymer chitosan - insecticidal metabolites derived from potential fungal biopesticidal agent Nomuraea rileyi were studied. Insecticidal metabolites were isolated from the culture filtrate of fungal strain grown in sabouraud maltose yeast extract broth (SMYB) and the collected filtrate was extracted with ethyl acetate followed by purification using G-60 silica gel column. Chitosan nanocomposite was prepared with metabolites thus acquired by ionic gelation method. Synthesized nanocomposite was found to have high stability, uniformly dispersed particles with high loading and entrapment efficiency. Insecticidal activity was studied by determination of cumulative mortality against larval instars of Spodoptera litura and changes in biochemical composition of midgut, hemolymph macromolecules which revealed that the nanocomposite was effective against all the larval stages in terms of high mortality, drastic reduction of midgut and hemolymph macromolecules biochemical composition. Biocompatibility of nanocomposite was carried out by evaluation of developmental toxicity against zebrafish and in vitro hemolysis with peripheral blood cells. Chitosan nanocomposite treatment was not induced any toxic effect on the developmental stages of zebra fish. Hemolysis was also not recorded in the nanocomposite treatment. The observed results imply that insecticidal metabolites fabricated chitosan nanocomposite prepared in our present system is a promising candidates for pest control against economically important insect pests without affecting non-target organisms.

Aluminum toxicity related to SOD and expression of presenilin and CREB in Bombyx mori.

Aluminum (Al) is an important environmental metal factor that can be potentially associated with pathological changes leading to neurotoxicity. The silkworm, Bombyx mori, is an important economic insect and has also been used as a model organism in various research areas. However, the toxicity of Al on silkworm physiology has not been reported. Here, we comprehensively investigate the toxic effects of Al on the silkworm, focusing on its effects on viability and development, superoxide dismutase (SOD) activity, and the expression of presenilin and cAMP response element-binding protein (CREB) in BmE cells and silkworm larvae. BmE cell viability decreased after treatment with aluminum chloride (AlCl3 ) in both dose- and time-dependent manners. When AlCl3 solution was injected into newly hatched fifth instar larvae, both larval weight gain and survival rate were significantly decreased in a manner correlating with AlCl3 dose and developmental stage. Furthermore, when BmE cells and silkworm larvae were exposed to AlCl3 , SOD activity decreased significantly relative to the control group, whereas presenilin expression increased more than twofold. Additionally, CREB and phosphorylated CREB (p-CREB) expression in the heads of fifth instar larvae decreased by 28.0% and 50.0%, respectively. These results indicate that Al inhibits the growth and development of silkworms in vitro and in vivo, altering SOD activity and the expressions of presenilin, CREB, and p-CREB. Our data suggest that B. mori can serve as a model animal for studying Al-induced neurotoxicity or neurodegeneration.

Insecticide Susceptibility in Tuta absoluta (Lepidoptera: Gelechiidae) and Metabolic Characterization of Resistance to Diazinon.

The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a globally important economic insect pest of tomatoes that has rapidly expanded in range. The pest is generally controlled by insecticides; however, reduced susceptibility of T. absoluta to many recommended insecticides has been reported. The aims of this study were to determine the efficacy of diazinon, spinosad, abamectin, and Bt on second instar larvae of Iranian greenhouse populations of T. absoluta from Soufian (SF) and Qom (QM) and a susceptible (SS) population originally from Bonab, and assess the possibility of resistance in the populations. The results showed that spinosad was the most effective insecticide, whereas in contrast, Bt was ineffective against the populations. Abamectin was effective, but susceptibility in SF population was lower than in QM and SS. Susceptibility to diazinon was low in SF and QM populations. Mediation of diazinon resistance by metabolic mechanisms and activity of detoxifying enzymes and acetylcholinesterase on resistance were assessed. The results showed that enhanced activity of monooxygenases and esterases may have played a role in resistance of T. absoluta to diazinon. Our results will be useful in resistance management in this injurious pest and reduce the negative impacts of high rates of insecticide use on the environment.

Effectiveness of different control measures against western corn rootworm larvae Diabrotica virgifera virgifera LeConte, 1868

<p>The Western Corn Rootworm (WCR), <em>Diabrotica virgifera virgifera</em> LeConte, 1868, [Coleoptera, Chrysomelidae], whose larvae cause damage to maize roots, is an important economic insect pest in America and Europe. Its larvae are usually controlled by granular soil insecticides or insecticide-treated seeds. Biological control options, such as entomopathogenic nematodes (EPN) have played an important role as an alternative for synthetic chemical insecticides. Therefore, for the WCR larvae control we compared the effectiveness of inundative biological control on the basis of EPN <em>Heterorhabditis bacteriophora</em> Poinar, 1976 (Rhabditida: Heterorhabditidae); (commercial product Dianem<sup>®</sup>) and the conventional insecticides Force 1.5 g (active substance tefluthrin) from the group of synthetic pyrethriods and Sonido (active substance thiacloprid) from the group of neonicotinoids. Field experiments were carried out at geographically different locations under different population pressure of the insect pest in a), Bučečovci (Prlekija; Eastern Slovenia) and b), Šmartno (Gorenjska: northern Slovenia). The differences between the treatments were very similar at both locations; although the population of WCR in Gorenjska was approximately 5-fold lower than in Prlekija. The highest number of WCR beetles was caught in the negative control, followed by the product Sonido, Force and Dianem<sup>®</sup>, in decreasing order. Statistical analysis showed that only in the treatment where EPN were used, significantly less WCR was caught than in the control. The results of the WCR larvae control in maize using <em>Heterorhabditis bacteriophora</em> are comparable to published literature. However, the weather conditions in the 2016 trial were very favorable for the development and survival of EPN in the soil.</p>

Research progress on the immune mechanism of the silkworm Bombyx mori

AbstractThe silkworm Bombyx mori L., representing an important economic insect and one of the best models for studying insect immunity, possesses an efficient and sophisticated innate immune system against invasive microorganisms. The innate immune system basically includes humoural immunity and cellular immunity. The humoural immunity, which functions via molecules including humoural factors, lysozymes, phenoloxidase, hemolin, lectins and, in particular, antimicrobial peptides, plays a central role in eliminating the invading pathogens. The cellular immunity is primarily carried out and mediated by plasmatocytes and granular cells of haemocytes in the haemolymph, usually followed by melanization. Additionally, apoptosis, a primary viral defence for insects lacking adaptive immunity, comprises an important part of the silkworm immune system. Currently, there is still the lack of a comprehensive and systematic understanding of the molecular mechanisms of silkworm immunity. We review the latest research progress on silkworm immune mechanisms, including phenoloxidase‐dependent melanization and apoptosis, which is conducive to improving our understanding of the silkworm immune mechanism, clarifying the relationship of various immune mechanisms, and also providing a theoretical basis and reference for the future research of insect immunity.

Hippo pathway regulates somatic development and cell proliferation of silkworm

Hippo signaling pathway (signaling pathway Hippo, hereinafter referred to as the Hippo pathway) was the earliest found in Drosophila (Schneck [1]), which can regulate the development of tissues and organs, even some components of the pathway were identified as tumor suppressor [2]. The pathway was more concerned in fruit flies and mice (Schneck [1]), but little attention has been given in silkworm, an important economic and lepidopteran model insect. In this manuscript, we identified major Hippo pathway related genes (Hippo, Salvador, Warts, Mats, Yorkie) in silkworm and named BmHpo, BmSav, BmWts, BmMats, BmYki. The domain organization of these genes was highly conserved in silkworm and other organisms suggesting that they could use similar protein-protein interactions to construct the Hippo kinase cascades. The expression profiles of these genes in silkworm during embryonic, larval, wandering, pupal and adult stages were analyzed, 14 tissues/organs of the day 3, 5th instar larvae (L5D3) as well. Experimental results showed that the expression of Hippo pathway had some influence on the development of silkworm. In order to find out the mechanism of Hippo pathway affecting silkworm development, BmHpo and BmYki were up-regulated and de-regulated in the cell line of Bombyx mori-BmN-SWU1(NS), and the changes of cell proliferation activity and cell cycle were detected. The distribution of BmYki was detected by immunofluorescence technique. This study provides insights into the genes of Hippo pathway which have a certain effect on somatic development and cell proliferation in silkworm.

De novo transcriptome assembly and analysis of differential gene expression following peptidoglycan (PGN) challenge in Antheraea pernyi

Antheraea pernyi is not only an important economic insect, it is increasingly employed as a model organism due to a variety of advantages, including ease of rearing and experimental manipulation compared with other Lepidoptera. Peptidoglycan (PGN) is a major component of the bacterial cell wall, and interactions between PGN and A. pernyi cause a series of physiological changes in the insect. In the present study, we constructed cDNA libraries from a A. pernyi PGN-infected group and a control group stimulated with phosphate-buffered saline (PBS). The transcriptome was de novo assembled using the Trinity platform, and 1698 differentially expressed genes (DEGs) were identified, comprising 894 up-regulated and 804 down-regulated genes. To further investigate immune-related DEGs, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were performed. GO analysis identified major immune-related GO terms and KEGG enrichment indicated gene responses to three pathways related to the insect immune system. Several homologous genes related to the immune response of the A. pernyi fat body post-PGN infection were identified and categorised. Taken together, the results provide insight into the complex molecular mechanisms of the responses to bacterial infection at the transcriptional level.

The effect of acclimation on heat tolerance of Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae)

Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae) is an important economic insect of various stored products worldwide. With the restricted use of methyl bromide and the increasing negative effects of repeated use of phosphine fumigation, heat treatment becomes the main approach to control stored-product insects. We investigated effect of the acclimation to sublethal high temperature of 36°C and 42°C for different times on heat tolerance of L. serricorne adults, pupae, larvae, and eggs to lethal high temperature of 50°C in laboratory. The acclimation of L. serricorne pupae, larvae, and eggs, but not adults, to 36°C improved their survival when exposed to lethal high temperature of 50°C. The acclimation of all life stages of L. serricorne to 42°C significantly improved their survival when exposed to 50°C. For eggs, larvae, and adults, the protective effectiveness of acclimation to 42°C was much more profound than that of to 36°C. LT50 and LT90 of all life stages increased with increasing acclimation time to 42°C in general. The LT50 of L. serricorne adults, pupae, larvae, and eggs acclimation to 42°C for 20h were 2.2, 2.2, 3.4, and 4.8 times higher than that of insects without acclimation, respectively. The results suggest that acclimation to sublethal high temperatures can significantly improve the heat tolerance of L. serricorne by the means of increasing their survival when confronting lethal high temperatures. In the face of global warming, the protective effects induced by acclimation to sublethal high temperatures should be fully considered when design or apply heat treatment to control L. serricorne.

Tissue-specific genome editing of laminA/C in the posterior silk glands of Bombyx mori

The RNA-guided CRISPR/Cas9 system has been shown to be a powerful tool for genome editing in various organisms. A comprehensive toolbox for multiplex genome editing has been developed for the silkworm, Bombyx mori, a lepidopteran model insect of economic importance. However, as previous methods mainly relied on delivery of transient Cas9/guide RNA (gRNA), they could not be used in loss-of-function studies of essential genes. Here, we report a simple and versatile tissue-specific genome editing strategy. We perform a proof-of-principle demonstration by establishing and crossing two transgenic B. mori lines, one expressing Cas9 protein in the posterior silk glands (PSGs) and the other constitutively expressing BmlaminA/C (BmLMN) gRNA. All BmLMN alleles in the PSG cells were edited precisely at the target genome region, resulting in diverse mutations. mRNA expression of BmLMN was reduced by up to 75%, and only very low levels of BmLaminA/C protein were detected. Knockout of BmLMN produced obvious defects in gland cell development and cocoon production. In this study, we developed an efficient strategy for spatially controlled genome editing, providing unprecedented opportunities for investigating the function of essential/lethal genes in B. mori, with potential application for other insects.

Silkworm: A Promising Model Organism in Life Science.

As an important economic insect, silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) has numerous advantages in life science, such as low breeding cost, large progeny size, short generation time, and clear genetic background. Additionally, there are rich genetic resources associated with silkworms. The completion of the silkworm genome has further accelerated it to be a modern model organism in life science. Genomic studies showed that some silkworm genes are highly homologous to certain genes related to human hereditary disease and, therefore, are a candidate model for studying human disease. In this article, we provided a review of silkworm as an important model in various research areas, including human disease, screening of antimicrobial agents, environmental safety monitoring, and antitumor studies. In addition, the application potentiality of silkworm model in life sciences was discussed.

Genome-Wide Identification and Characterization of Carboxypeptidase Genes in Silkworm (Bombyx mori).

The silkworm (Bombyx mori) is an economically-important insect that can secrete silk. Carboxypeptidases have been found in various metazoan species and play important roles in physiological and biochemical reactions. Here, we analyzed the silkworm genome database and characterized 48 carboxypeptidases, including 34 metal carboxypeptidases (BmMCP1–BmMCP34) and 14 serine carboxypeptidases (BmSCP1–BmSCP14), to better understand their diverse functions. Compared to other insects, our results indicated that carboxypeptidases from silkworm have more family members. These silkworm carboxypeptidases could be divided into four families: Peptidase_M2 carboxypeptidases, Peptidase_M14 carboxypeptidases, Peptidase_S10 carboxypeptidases and Peptidase_S28 carboxypeptidases. Microarray analysis showed that the carboxypeptidases had distinct expression patterns, whereas quantitative real-time PCR demonstrated that the expression level of 13 carboxypeptidases significantly decreased after starvation and restored after re-feeding. Overall, our study provides new insights into the functional and evolutionary features of silkworm carboxypeptidases.