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  • Monthly, Founded in 1950
    Supervisor:Chinese Academy of Sciences
    Sponsor:Institute of Zoology,Chinese Academy of Sciences
    The Entomological Society of China
    Domestic postal code: 2-153
    Foreign issuance code: Q61
    ISSN 0454-6296
    CN 11-1832/Q
Table of Content
20 February 2019, Volume 62 Issue 2
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  • RESEARCH PAPERS

    Molecular cloning and expression profiling of phospholipid hydroperoxide glutathione peroxidase genes in Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae)

    JIU Min, WANG Lun-Ji, REN Li-Na, DAI Wei, LI Jing-Jing, ZHAO Jun-Feng, ZHANG Min
    2019, 62(2):  141-149.  doi:10.16380/j.kcxb.2019.02.001
    Abstract ( 464 )   PDF (2238KB) ( 144 )     
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    Aim The objective of this study is to clone phospholipid hydroperoxide glutathione peroxidase (PHGPX) genes from Bemisia tabaci MEAM1 cryptic species, to identify their expression levels in whiteflies at different developmental stages and in female adults treated with imidacloprid for different time, and to elucidate their function in the whitefly in response to environmental pressure. Methods The cDNAs of PHGPX genes were cloned by 3RACE from B. tabaci MEAM1 cryptic species, and the putative amino acid sequences were analyzed by bioinformatics methods. The expression levels of PHGPX genes in the whitefly at different developmental stages and in female adults treated with imidacloprid for different time were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results The full-length cDNA sequences of two PHGPX genes were obtained from B. tabaci MEAM1 cryptic species, and named as BtB-PHGPX1 (GenBank accession no.: KY312116) and BtB-PHGPX2 (GenBank accession no.: KY312117), respectively. Sequence analysis indicated that the open reading frame of BtB-PHGPX1 is 732 bp in length encoding 243 amino acids, while that of BtB-PHGPX2 is 567 bp in length encoding 188 amino acids. Sequence alignment result showed that the encoded proteins of both genes have conserved cysteine, glutamine and tryptophan residues of glutathione peroxidase. The mRNA level of BtB-PHGPX1 in egg was significant higher than those in nymph, pseudopupa, female adult and male adult of the whitefly, while that of BtB-PHGPX2 in egg was significant lower than those in nymph, pseudopupa and female adult (P<0.05). The mRNA levels of both BtB-PHGPX1 and BtB-PHGPX2 in female adults were significant higher than those in male adults (P<0.05). Furthermore, the expression levels of BtB-PHGPX1 and BtB-PHGPX2 significantly increased in female adults at 2 h after treatment with imidacloprid as compared with their respective control (P<0.05), but decreased significantly at 5, 10 and 24 h after treatment (P<0.01). Conclusion In this study, the full-length sequences of two PHGPX genes were cloned from B. tabaci MEAM1 cryptic species, and their differential expression at different developmental stages and in female adults treated with imidacloprid for different time was clarified. It is speculated that PHGPX may play an important defense role in B. tabaci under environmental stress and insecticide treatment.

    Prokaryotic expression and ligand binding characteristics of odorant binding protein MmedOBP18 of the parasitoid wasp Microplitis mediator (Hymenoptera: Braconidae)

    SONG Xuan, SHAN Shuang, WANG Shan-Ning, TAO Yu-Xiao, LI Rui-Jun, ZHANG Yong-Jun
    2019, 62(2):  150-159.  doi:10.16380/j.kcxb.2019.02.002
    Abstract ( 582 )   PDF (2513KB) ( 103 )     
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    Aim To clarify the expression of the odorant binding protein MmedOBP18 inthe antenna of Microplitis mediator, and to investigate the ligand binding characteristics of the recombinant MmedOBP18. Methods The recombinant MmedOBP18 of M. mediator was expressed in the prokaryotic expression system. The localization of expression of MmedOBP18 inthe antenna of female wasps of M. mediator was evaluated using fluorescence immunohistochemistry assay. The binding characteristics of the recombinant MmedOBP18 protein to 99 candidate ligands were analyzed by fluorescence competitive binding assay. Results The recombinant MmedOBP18 protein was successfully expressed in the prokaryotic expression system. The immunofluorescence localization result showed that MmedOBP18 was mainly expressed in the lymph of sensilla basiconica type I of the antenna. The recombinant MmedOBP18 could strongly bind with 16 kinds of ligands. Among the low volatile compounds, 2-tridecanone, dodecyl aldehyde, myristic acid and undecylic acid showed the strongest binding capacities to the recombinant MmedOBP18, with the dissociation constant (Ki) values of 5.21, 6.42, 6.49 and 6.58 μmol/L, respectively. The non-volatile compounds palmitic acid, gossypol, quercetin and linolenic acid also showed strong binding capabilities to the recombinant MmedOBP18, with the Ki values of 3.86, 5.07, 5.08 and 6.51 μmol/L, respectively. In addition, the lepidopteran pheromone components (Z)-9-tetradecenal and (Z)-11-hexadecenal also showed strong binding capabilities to MmedOBP18, with the Ki values of 9.09 and 11.67 μmol/L, respectively, suggesting an important role of MmedOBP18 inhost localization. Conclusion The MmedOBP18 of M. mediator has strong binding capabilities to long-chain low volatile or non-volatile compounds. We speculated that MmedOBP18 may play a dual role in olfactory and taste recognition, and is mainly involved in the close range perception of chemical signals from host and host habitats.

    Cloning and spatio-temporal expression of serine protease gene HcSP1 and its expression in response to feeding on different host plants in Hyphantria cunea (Lepidoptera: Arctiidae)

    ZHAO Xu-Dong, SUN Yu-Hang, CHEN Chang-Yu, TIAN Shuo, TAO Rong, HAO De-Jun
    2019, 62(2):  160-169.  doi:10.16380/j.kcxb.2019.02.003
    Abstract ( 392 )   PDF (2940KB) ( 145 )     
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    Aim To lay a foundation for exploring the mechanism of digestive physiology of Hyphantria cunea (Drury) in host transformation. Methods We first cloned a serine protease gene by screening the H. cunea cDNA library. We then analyzed the expression patterns of this gene in different developmental stages of H.cunea by qPCR. The distribution and expression patterns of this gene in different tissues of the 5th instar larvae of H.cunea were analyzed by semi-quantitative RT-PCR and qPCR, respectively, and the expression patterns in the 4th instar larvae of H.cunea feeding on leaves of different host species (Populus deltoids, Cerasus serrulata var. lannesiana, Cerasus serrulata, Camptotheca acuminata and Platanus orientalis) were detected by qPCR. Results A serine protease gene HcSP1 (GenBank accession no.: MH663425) was successfully cloned from H. cunea. The open reading frame (ORF) of HcSP1 is 882 bp in length, encoding 293 amino acids, with the predicted molecular weight (MW) of 30.5 kD and the theoretical isoelectric point (pI) of 9.86. The predicted N-terminal hydrophobic region contains signal peptide consisting of 15 amino acid residues. The protein encoded by HcSP1 contains the enzyme activity catalytic center formulated with His, Asp and Ser residues, which is a typical feature of serine proteases. HcSP1 also possesses some typical features of putative trypsin precursors, such as containing a signal peptide, activation peptide and conserved N-terminus (IVGG). The NCBI BLAST alignment revealed that the amino acid sequence identities between HcSP1 of H. cunea and other lepidopteran serine proteases are between 50% and 70%. The qPCR results indicated that the expression of HcSP1 inH. cunea in different developmental stages showed dynamic change, increasing with the larval instar. Semi-quantitative RT-PCR results showed that HcSP1 was expressed in various tissues of the 5th instar larva of H. cunea including head, salivary gland, midgut, fat body, cuticle, Malpighian tubules and hemolymph, and qPCR results further revealed that this gene had the highest expression level in the midgut. The expression level of HcSP1 was significantly higher in larvae of H. cunea feeding on C. acuminata leaves than in larvae feeding on other host plants. Conclusion In this study, we obtained a serine protease gene HcSP1 inH. cunea, and detected its developmental and tissue expression patterns, and its expression levels in the 4th instar larvae of H. cunea feeding on leaves of different host species. The results lay a foundation for exploring the mechanism of digestive physiology of H. cunea in host transformation, and also provide new insight for the development of new management tools for H. cunea.

    Gene cloning, characterization and expression profiling of a group chitinase from Helicoverpa armigera (Lepidoptera: Noctuidae)

    Maimaitiaili ABUDUNASIER, MA Ji, LIU Ning, WANG Wei, LI Meng-Ge, GU Xin-Rong, WANG Xin, LIU Xiao-Ning
    2019, 62(2):  170-180.  doi:10.16380/j.kcxb.2019.02.004
    Abstract ( 448 )   PDF (6367KB) ( 115 )     
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    Aim Insect chitinases are mainly involved in such important physiological processes as molting, degradation of peritrophic membranes and immune defense. This study aims to clone a group IV chitinase gene from Helicoverpa armigera and to analyze its expression profiles so as to provide the theoretical basis for the control of this insect using the gene as a molecular target. Methods A group IV chitinase gene was cloned from the midgut of H. armigera using RT-PCR and RACE techniques and subjected to multiple sequence alignment by DNAMAN, and the phylogenetic tree was constructed by MEGA. Its recombinant protein was expressed in Escherichia coli (DE3) and verified by Western-blot. The enzymatic properties of the recombinant protein were characterized after purification with Ni-NTA. The expression levels of this gene in different developmental stages and tissues of the 6th instar larvae of H. armigera were analyzed by qPCR. Results A chitinase gene was cloned from H. armigera and designated as HaCHT4 (GenBank accession no.: MH500771). Its full-length cDNA is 1 624 bp in length and contains an ORF of 1 527 bp that encodes 509 amino acids with a predicted molecular weight of 55.2 kD. Its encoded protein contains a signal peptide, one catalytic domain (CAD) and one chitin binding domain (CBD). Both multiple sequence alignment and phylogenetic analysis showed that HaCHT4 has the conserved domain of chitinase and belongs to group IV chitinases. The recombinant His-HaCHT4 was successfully expressed in E. coli. The purified recombinant protein exhibited the activity of digesting chitin, with the optimum reaction temperature of50and pH value of 7. The values of kinetic parameters Km and Vmax of the recombinant protein were 1.76±0.35 mg/mL and 0.0220±0.0012 μg/mL·s, respectively. qPCR results revealed that the relative expression levels of HaCHT4 inthe 1st and 2nd larval instars of H.armigera were significantly higher than those in other larval instars and the pre-pupal stage, and HaCHT4 was predominantly expressed in the midgut and fat body of the 6th instar larva, but lowly expressed in the integument and head. Conclusion The results suggest that HaCHT4 may participate in chitin degradation in the peritrophic matrix in H. arrmigera. These results lay a foundation for the further function study of HaCHT4 and provide useful information for pest control.

    Proteomic identification of the peritrophic membrane of Helicoverpa armigera (Lepidoptera: Noctuidae)

    LIANG Zhen-Pu, WANG Liang, LI Peng-Juan, WANG Zhao-Xing, XIAO Yu-Bo, ZHANG Xiao-Xia
    2019, 62(2):  181-192.  doi:10.16380/j.kcxb.2019.02.005
    Abstract ( 518 )   PDF (6396KB) ( 112 )     
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    Aim The peritrophic membrane (PM) is the first natural barrier against the invasion of microbes ingested with foods in insects. This study aims to identify the total protein constituents of the peritrophic membrane of the cotton bollworm, Helicoverpa armigera, a major agricultural insect, so as to lay a foundation for further revealing the formation mechanism of PM and developing novel pest control strategies. Methods The PMs of the 5th instar larvae of H. armigera were peeled off and then treated with trifluoromethane-sulfonic acid (TFMS). The peritrophic membrane proteome of larvae was identified by liquid chromatography and mass spectrometry (LC-MS/MS), and the identified results were subjected to bioinformatics analysis.Results In this study we identified a total of 169 peritrophic membrane proteins from H. armigera larvae, which is the highest number of PM proteins identified in H. armigera up to date. GO analysis revealed that these identified proteins could be divided into three major categories, i.e., cellular component (CC), molecular function (MF) and biological process (BP). The KEGG enrichment results showed that the identified proteins could be enriched in 12 metabolic pathways. The results of protein-protein interaction (PPI) analysis indicated that ACC and CG3011 proteins could serve as the core proteinprotein interaction network. Conclusion In this study 169 peritrophic membrane proteins were identified from H. armigera larvae and subjected to GO, KEGG and PPI analyses. The results are helpful to comprehensively understand the molecular structure and function of PM in insects.

    Analysis of the ex vivo transformation of ovarian cells of Spodoptera exigua (Lepidoptera: Noctuidae) based on transcriptome sequencing

    TANG Kai, YU Xu-Peng, MENG Qian, LI Miao-Miao, QIN Qi-Lian, TANG Ping, ZHANG Huan
    2019, 62(2):  193-204.  doi:10.16380/j.kcxb.2019.02.006
    Abstract ( 469 )   PDF (7615KB) ( 67 )     
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     Aim The aim of this study is to analyze the whole process of establishing cell lines from Spodoptera exigua pupal ovarian cells, and to explore the changes of gene expression at the transcriptional level from in vivo to in vitro culture, so as to provide a theoretical basis for the establishment of insect in vitro culture models. Methods In this study, the transcriptomes of various stages of S. exigua pupal ovarian cells during ex vivo culture were sequenced by using second-generation transcriptome sequencing technology Illumina Hiseq, and the differentially expressed genes and their related signaling pathways were analyzed. The expression of some cell cycle-related genes (cycd and cdk4), regulatory genes (cdc20, apc1, skp2 and mad1), and proliferation-related molecular markers (mcm4 and pcna) in different stages of S. exigua pupal ovarian cells during ex vivo culture were verified by real-time PCR. Results The process of ex vivo culture of S. exigua pupal ovarian cells includes five stages: anatomical obtaining of ex vivo ovarian tissues, primary cells isolated after adherent culture of ovarian tissues, transformed cells with re-proliferation ability, first generation cells capable of continuous passage, and cell lines capable of continuous passage for more than 15 generations. A total of 46 796 unigene sequences were obtained from the five stages of S. exigua pupal ovarian cells during ex vivo culture by RNA sequencing, with good sequence length integrity of the assembly. The splicing length distribution of unigene sequences was reasonable, and the Q30 of the sample base was above 94%. Based on the KEGG database, 1 473 unigenes were annotated to be involved in 20 signaling pathways closely related to cellular processes, and 92 unigenes in the cell cycle signaling pathway. Cluster analysis showed that the gene expression patterns of ovarian cells in a rapidly developing state in vivo were very close to that of cell lines which were also in a proliferative state. In addition, 619 differentially expressed genes were screened at the critical transformation stage of primary cells from transient stagnant growth to clustered cells. The expression of cdk4 significantly decreased ex vivo, and the expression level of cycd significantly increased after the critical stage of cell transformation. The expression levels of Cdc20, apc1, skp2, and mad1 were significantly higher in ovarian tissues and cell lines than in primary cells, key transformed cells, and first passage cells. From primary cells to passage, the expression level of cycd was significantly increased by 8.7-fold, which was significantly higher than those of mcm4 and pcna. Conclusion The sequence quality of five stages of S. exigua pupal ovarian cells during ex vivo culture by transcriptome sequencing met with the basic requirements for transcriptome data analysis. The differentially expressed genes in S. exigua pupal ovarian cells during ex vivo culture were obtained. The reverse cell proliferation of primary cells may be related to the expression of cell cycle regulatory genes such as cdk4, cycd, skp2 and mad1. In addition, cycd can be used as a marker for the ability of primary cells to pass through.

    Ultrastructure of sensilla on labial palps and the central projection of their sensory neurons in Plutella xylostella (Lepidoptera: Plutellidae) adults

    YAN Xi-Zhong, WANG Zhi-Yu, DUAN Yu, FENG Xue-Meng, DENG Cai-Ping, WU Ai-Hua, FU Shu-Hui, SUN Xue-Jun, HAO Chi
    2019, 62(2):  205-214.  doi:10.16380/j.kcxb.2019.02.007
    Abstract ( 469 )   PDF (14242KB) ( 120 )     
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    Aim This study aims to characterize the morphology of sensilla on labial palps and the central projection of their sensory neurons in adults of the diamondback moth, Plutella xylostella. Methods The structures of labial palps and their sensilla type were observed under light and scanning electron microscopy, and the central projection of the sensory neurons of sensilla on labial palps were observed by using neuronal backfills and confocal microscope. Results The labial palp of P. xylostella adults consists of three segments, on which there are five types of sensilla, including Böhm bristles, sensilla campaniformia, sensilla squamiformia, sensilla basiconica, and microtrichia, and a labial-palp pit organ (LPO). Böhm bristles are spine-like, sensilla campaniformia have circular dome surrounded by a cuticular rim, and both of the two sensilla were found only on the 1st segment of labial palp, without significant differences in size between sexes. Sensilla squamiformia are willow leaf-like, sensilla basiconica are thick and straight, and both are scattered on the 2nd and 3rd segments, with significant differences in size between sexes. Sensilla squamiformia in females are significantly larger than those in males, and this sexual dimorphism suggests that this type of sensilla of female are likely associated with sensing of host plant odours. The LPO is located in the middle and upper part of the 3rd palpus segment, and the width of the pit is 5.68±0.33 μm in males and 6.03±0.23 μm in females, without significant difference between sexes. Many microtrichia with smooth surface are located in inner pit. The sensory neurons on the labial palp project to the subesophageal ganglion, labial pit organ glomerulus (LPOG) in each antennal lobe and the ventral nerve cord. Conclusion The morphology of sensilla on labial palps and the central projection of their sensory neurons in P. xylostella adults have been illustrated in this study, providing a basis for further investigation on their physiology and function.

    Detection and phylogenetic analysis of Wolbachia in Aphis gossypii (Hemiptera: Aphididae) populations from different areas of Henan province, central China

    LI Shao-Jian, GAO Meng, WANG Na, CUI Xiao-Wei, SANG Su-Ling, FAN Wan-Wan, WANG Zhen-Yu
    2019, 62(2):  215-221.  doi:10.16380/j.kcxb.2019.02.008
    Abstract ( 463 )   PDF (1588KB) ( 96 )     
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     Aim This study aims to investigate the infection of secondary endosymbiont Wolbachia in Aphis gossypii populations from different areas of Henan province, central China, and further to ascertain its infection type and phylogeny. Methods A. gossypii samples were collected from 13 areas ofHenanprovince during 2016-2017, and identified by amplifying the COI gene. The infection rate of Wolbachia was detected by amplification of the wsp gene sequence from the Wolbachia in different A. gossypii populations. The phylogenetic relationship of Wolbachia in different A. gossypii populations was constructed with neighbor-joining method. Results The infection rates of Wolbachia in 13 populations of A. gossypii collected from different areas ofHenanprovince were different, being the highest (46.67%) in Zhengzhou (ZZ) population and the lowest (6.67%) in Xinyang 2 (XY2) population. The infection rates of Wolbachia in the 13 populations ranged from 6.67% to 46.67%, with the average value of 28.35%. The phylogenetic relationship based on wsp gene indicated that Wolbachia strains in both Anyang and Xinyang populations of A. gossypii were identified as supergroup B, while those in other populations were supergroup A. Conclusion The infection rate of Wolbachia in different A. gossypii populations of Henan province varies distinctly, and either supergroup A or B Wolbachia is present in these A. gossypii populations.

    Bioefficacy and searching effect of entomopathogenic nematode Steinernema feltiae SF-SN treated with thiamethoxam on Bradysia odoriphaga (Diptera: Sciaridae) larvae
    WU Hai-Bin, GONG Qing-Tao, CHEN Zhen-Zhen, FAN Kun, GONG Yi, XU Yong-Yu, SUN Rui-Hong
    2019, 62(2):  222-232.  doi:10.16380/j.kcxb.2019.02.009
    Abstract ( 351 )   PDF (1831KB) ( 82 )     
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    Aim After the entomopathogenic nematodes (EPN) are exposed to chemical pesticides, their potential bioefficacy and searching effect on insect pests might change. This study aims to investigate the bioefficacy and searching effect of entomopathogenic nematodes treated with thiamethoxam on Bradysia odoriphaga larvae. Methods The lethal and searching effects of S. feltiae SF-SN strain (Sf) treated with thiamethoxam (15 mg/L) on the 3rd instar larvae of B. odoriphaga were tested under laboratory conditions using a filter-paper culture method, and the differences in the functional responses and searching effect between the thiamethoxam-treated Sf and the untreated Sf were evaluated. Results The corrected mortality of B. odoriphaga larvae exposed to thiamethoxam-treated Sf was significantly higher than that exposed to the untreated Sf, and was increased by 2.13 times as compared with that exposed to the untreated Sf at 6 h post treatment. When the concentration of Sf was 6 400 IJs/petri dish, the functional responses for killing action of untreated and thiamethoxam-treated Sf on the 3rd instar larvae of B. odoriphaga could be described by Hollings type II and disc equation. The attack rate (a=0.5592) of thiamethoxam-treated Sf increased by 42.76%, the handling time (Th=0.0081 d) (the cumulative time taken in searching, parasitizing and killing the host) decreased by 44.90%, the consumption rate (a/Th) increased by 2.59 times, and the daily maximum lethal amount (Namax) increased by 1.81 (Hollings type II) and 1.41 (Hollings type III) times, respectively, as compared with those of the untreated Sf. The searching effect of both untreated and thiamethoxam-treated Sf decreased with increasing larval density of B. odoriphaga. When the larval density of B. odoriphaga was 40 per petri dish, the lethal effect of thiamethoxam-treated and untreated Sf increased with increasing Sf concentrations, while the searching effect first increased and then decreased. The searching parameter and mutual interference parameter of thiamethoxam-treated Sf were higher than those of the untreated Sf. Conclusion The corrected mortality of B. odoriphaga larvae and the attack rate, consumption rate, daily maximum lethal amount and searching effect of thiamethoxam-treated Sf on B. odoriphaga larvae are higher than those of the untreated Sf, while the handling time is shorter than that of the untreated Sf.

    Composition and temporal dynamics of insect community in the tundra zone in ChangbaiMountains,Northeast China

    LIU Sheng-Dong, MENG Xin, SHANG Jun-Ye, YANG Ming-Yue, MENG Qing-Fan, GAO Wen-Tao, WANG Ge-Rong
    2019, 62(2):  233-240.  doi:10.16380/j.kcxb.2019.02.010
    Abstract ( 424 )   PDF (1384KB) ( 100 )     
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    Aim Tundra is a polar natural landscape. The species composition and temporal dynamics of insects were investigated in the tundra zone inChangbaiMountains,Northeast Chinafor providing a basis for the protection of insects and the research of co-evolution of insects and plants in tundra. Methods During 2005-2007, insect individuals were collected in the west and north slopes within the tundra zone in Changbai Mountains by using the net, lamp and pitfall methods from June to September in each year. Results In total, 4 634 specimens belonging to 550 species of 105 families of 11 orders were collected in the tundra zone in Changbai Mountains during 2005-2007. The species numbers and individual numbers of Lepidoptera, Coleoptera, Hymenoptera and Diptera were dominant, and their peaks occurred in July. The correspondence analysis showed that Lepidoptera was more adaptable to July, Coleoptera was more adaptable to August and September, and Hymenoptera and Diptera were more adaptable to June, respectively. The species number (382), individual number (2 571) and diversity index (4.673) of insects were the highest in July in tundra, while the species number and the individual number were the lowest in September, with only 22 species and 265 individuals. The species number and the individual number of insects in tundra were significantly positively correlated (R=0.992). The similarity of insects was very low between different months, with the similarity coefficient lower than 0.20. Conclusion The diversity of insects is low in the tundra zone in Changbai Mountains. The occurrence peak of insects is in July, and the individual number and the species number are the least in September. The species richness of Lepidoptera is the highest in the tundra, and Lepidoptera shows relatively strong adaptability to July with better environmental conditions. The Coleoptera insects adapt to environmental changes better than other groups and play an important role in maintaining the ecological balance of the tundra zone.

    Phylogenetic analysis of the genus Scymnus Kugelann (Coleoptera: Coccinellidae) from Chinabased on 12S, 16S and 28S rRNA gene sequences

    HUANG Wei-Dong, LIANG Xin-Yue, XIE Xiu-Feng, WANG Xing-Min, CHEN Xiao-Sheng
    2019, 62(2):  241-254.  doi:10.16380/j.kcxb.2019.02.011
    Abstract ( 403 )   PDF (3374KB) ( 114 )     
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    Aim The genus Scymnus Kugelann is one of the most economically significant genera of natural enemy insects due to its predatory activity against pests including scale insects and aphids. However, the classification of this genus is still ambiguous, and the relationship of the subgenera within this genus is still in dispute. In order to establish a reasonable classification system of the genus Scymnus, the phylogenetic analysis is needed to further refine the taxonomic status of the subgenera within this genus. Methods The partial sequences of 12S, 16S and 28S rRNA genes from 44 species belonging to five subgenera within the genus Scymnus preserved in the Collection of South China Agricultural University were amplified using PCR. The inter-species genetic distance among the Scymnus species was calculated based on Kimura-2-parameter model using MEGA 7.0. The base composition of 12S rRNA, 16S rRNA and 28S rRNA genes was analyzed by using MEGA 7.0. The phylogeny trees were generated by maximum-likelihood (ML) and Bayesian-inference (BI) methods. Results The mean length of the 12S, 16S and 28S rRNA gene sequences amplified from the 44 species of Scymnus are 356, 351 and 315 bp, respectively. The average contents of A, T, G and C of 12S rRNA gene sequence are 38.8%, 43.5%, 11.9% and 5.8%, respectively, those of 16S rRNA gene sequence are 37.6%, 403%, 14.4%, and 7.7%, respectively, and those of 28S rRNA gene sequence are 26.7%, 18.3%, 31.4% and 23.5%, respectively. The inter-species genetic distance is 0.004-0.276 based on the concatenated sequence data, and the average genetic distance is 0.115. The phylogenetic analysis revealed that the genus Scymnus is monophyletic, while the subgenera Scymnus (Scymnus) Kugelann, Scymnus (Neopullus) Sasaji, Scymnus (Pullus) Mulsant and Scymnus (Parapullus) Yang are paraphyletic. Conclusion The phylogenetic analysis of Scymnus based on 12S, 16S and 28S rRNA gene sequences illustrated that the molecular classification system of this genus is not consistent well with its morphological classification system. In order to establish a reasonable classification system, other valid morphological characteristics should be explored to distinguish the relationships among the subgenera. Moreover, more research is needed to further refine the taxonomic status of the subgenera.
    REVIEW ARTICLES

    Age-stage, two-sex life table and its application in population ecology and integrated pest management

    CHI Hsin, FU Jian-Wei, YOU Min-Sheng
    2019, 62(2):  255-262.  doi:10.16380/j.kcxb.2019.02.012
    Abstract ( 1529 )   PDF (3931KB) ( 493 )   PDF(mobile) (3931KB) ( 303 )     
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    Life tables are the prime tool in population ecology and pest management. Because traditional female age-specific life tables are not capable of describing the stage differentiation and ignore males entirely, the age-stage, two-sex life table is being widely used by many scientists. In this article, we first overviewed the basic principles of the age-stage, two-sex life table, including the stage differentiation of insect populations, the effect of sex ratio on population growth, the difference between the total preoviposition period and adult preoviposition period, and the difference between the oviposition period and oviposition days. We then explained the advantages of life table analyses based on the bootstrap technique. Finally, we introduced the major applications of the computer programs (TWOSEX-MSChart, CONSUME-MSChart, and TIMING-MSChart), i.e., population projection and timing of pest management, correct analyses of the predation rate of predators and the consumption rate of pests, prediction of the population growth of predators and their predation potential, and guidance of mass-rearing and harvesting of natural enemies. As a powerful tool for data analysis, insect life tables have been extensively used in population ecology and pest managements. Looking forward to the future, we expect that they will be widely adopted in studies involving insect physiology, pesticide resistance, sublethal effect of pesticides, symbionts, etc.

    Adhesion mechanisms of insect legs

    HUA Deng-Ke, HE Zhang-Zhang, DU Tian-Hua, LIANG Peng, SHI Yong-Fang, YANG Xuan, ZHANG You-Jun, WU Qing-Jun, GUI Lian-You
    2019, 62(2):  263-274.  doi:10.16380/j.kcxb.2019.02.013
    Abstract ( 481 )   PDF (2301KB) ( 158 )     
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    The excellent crawling and attachment abilities of insects strongly depend on their attachment devices. As the attachment devices of insects are morphologically different, they can be divided into two major groups, either hairy or smooth. Both of them can contact with almost all known surfaces via adhesive fluid, irrespective of whether the surface is rough or smooth, and the contact between the two types of adhesive pads and the substrate is operated by van der Waals forces. In this article, we reviewed the progress in the adhesion mechanisms of insect legs including the structures of the hairy and smooth adhesive pads and their adhesion mechanisms, and the functions, compositions and releasing mechanisms of the adhesive pad secretion. We also illustrated how insects resolve the contradictions between firm attachment and rapid detachment movements of adhesive pads of their legs, and discussed the influence of environmental factors such as physicochemical properties of the contact substrate and environmental humidity on insect adhension, aiming to help deeply understand the adhesion mechanisms of insect legs and to provide theoretical basis for its application in bionics.
    CONTENTS
    Contents of Vol. 62 Issue2
    2019, 62(2):  275-275. 
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