Acta Entomologica Sinica

Identification of circadian clock genes Gmper and Gmtim and their contributions to the emergence rhythm in Grapholita molesta (Lepidoptera: Tortricidae)

FANG Hai-Bo, ZHANG Jing, LIU Xiao-Xia, ZHANG Qing-Wen, LI Zhen

2020, 63(6): 655-666. doi:10.16380/j.kcxb.2020.06.001

Abstract ( 53 )

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【Aim】 The purpose of this study is to investigate the molecular characteristics and expression patterns of two circadian clock genes Gmper and Gmtim in the oriental fruit moth, Grapholita molesta, and to explore their regulatory roles in the emergence rhythm, so as to provide potential new targets for controlling G. molesta. 【Methods】 Based on the transcriptome data of G. molesta, the full-length cDNAs of two circadian clock genes Gmper and Gmtim were cloned by PCR. The expression levels of these two genes in the head, thorax, abdomen and leg of adults and their daily expression patterns in the pupal head were determined by RT-qPCR. Then the regulatory roles of Gmper and Gmtim in the emergence rhythm of G. molesta were explored by RNAi with siRNAs. 【Results】 The full-length cDNAs of Gmper (GenBank accession no.: MN862636) and Gmtim (GenBank accession no.: MN862637) were cloned from G. molesta. The open reading frame of Gmper is 2 862 bp in length, encoding 953 amino acids with two PAS domains and a PAC domain. The open reading frame of Gmtim is 3 048 bp in length, encoding 1 015 amino acids. The expression levels of Gmper and Gmtim in heads were higher than those in other tissues of both male and female adults. In pupal head, the expression levels of the two genes were significantly higher in the scotophase than in the photophase. The emergence rhythm changed after RNAi of both Gmper and Gmtim, and G. molesta in the RNAi group showed a more dispersed emergence pattern than that in the control group, and the amount of emerged adults during the emergence peak period decreased after RNAi. 【Conclusion】 Both Gmper and Gmtim in G. molesta show differential expression patterns among different tissues and between day and night, and they may play important regulatory roles in the emergence rhythm of G. molesta. The results provide clues to the development of monitoring and control technologies for G. molesta based on behavioral rhythm regulation.

cDNA cloning, prokaryotic expression and polyclonal antibody preparation of the olfactory receptor co-receptor AlepOrco from Athetis lepigone (Lepidoptera: Noctuidae)

TIAN Cai-Hong, LIU Xiao-Guang, HUANG Jian-Rong, WANG Ying, FENG Hong-Qiang

2020, 63(6): 667-678. doi:10.16380/j.kcxb.2020.06.002

Abstract ( 36 )

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【Aim】 The olfactory receptor co-receptor (Orco) and the typical olfactory receptor constitute the ion channel together, playing critical roles in the olfactory activity in insects. This study aims to clone, express and characterize the Orco gene from Athetis lepigone so as to provide a basis for further study on the function of this gene in A. lepigone. 【Methods】 One local transcriptome database was established based on the antenna transcriptome data of female and male adults of A. lepigone, and a homologous gene of Orco in A. lepigone, AlepOrco, was obtained from bioinformatic analysis of the local transcriptome database. The full-length cDNA sequence of AlepOrco was cloned from A. lepigone using RT-PCR. The open reading frame of AlepOrco was further subcloned into prokaryotic expression vector pGEX-6P-1/BL21(DE3) system. Anti-AlepOrco polyclonal antibody was prepared, and its specificity was examined by Western blot. The expression patterns of AlepOrco in different tissues (proboscis, antennae, head without antennae and proboscis, thorax, abdomen, legs and wings) of female and male adults of A. lepigone were also analyzed by qPCR. 【Results】 The full-length cDNA of AlepOrco (GenBank accession no.: MN583125) of A. lepigone is 1 422 bp in length, encoding 473 amino acids, with seven transmembrane regions, the predicted isoelectric point of 8.59 and the molecular weight of 53.40 kD. The SDS-PAGE and Western blot results showed that AlepOrco was successfully expressed in Escherichia coli. The Western blot results indicated that the prepared antibody could specifically recognize AlepOrco from the antenna of A. lepigone adults. The qPCR results revealed that AlepOrco exhibited a similar expression pattern in different tissues of female and male adults, with the highest expression level in the antenna and the lowest expression level in the wing. 【Conclusion】 AlepOrco was cloned and successfully expressed in E. coli. The prepared polyclonal antibody can specifically identify the AlepOrco in the antenna of A. lepigone adults. The results provide a basis for further study on the structure and function of AlepOrco in A. lepigone.

Molecular cloning and prokaryotic expression of nitric oxide synthase gene from Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) and its expression profiling across different diapause stages

JIANG Xue-Bing, ZHANG Xue, DU Wen-Mei, ZOU Zhen, ZHANG Jun-Jie

2020, 63(6): 679-687. doi:10.16380/j.kcxb.2020.06.03

Abstract ( 20 )

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【Aim】 The aim of this study is to clone nitric oxide synthase (NOS) gene of Trichogramma dendrolimi, to express its coded protein and to investigate its expression profile during diapause in T. dendrolimi, so as to provide a new basis for the study of T. dendrolimi diapause. 【Methods】 The cDNA sequence of TdNOS of T. dendrolimi was obtained based on the transcriptome analysis, and its expression levels in prepupae and pupae at different diapause stages of T. dendrolimi were detected using qPCR. The cDNA sequence of TdNOS was cloned using RT-PCR, and the sequence features were analyzed by bioinformatics methods. The prokaryotic expression vector of TdNOS was constructed. The recombinant TdNOS was expressed using Escherichia coli expression system, purified using Ni-NTA agarose affinity chromatography and used to prepare polyclonal antibody. The expression levels of TdNOS at different diapause stages of T. dendrolimi were further detected using Western blot. Mass spectrometry (MS) was used to identify the purified protein. 【Results】 The mRNA abundance of TdNOS was significantly higher at the pupal stage after diapause than at other stages of T. dendrolimi. The cDNA sequence of TdNOS (GenBank accession number: MN650600) was obtained by PCR. Its open reading frame (ORF) is 1 014 bp in length, encoding 337 amino acids without signal peptide sequence and transmembrane structure. The encoded protein was predicted to have 33 serine phosphorylation sites, seven tyrosine phosphorylation sites, and 10 threonine phosphorylation sites. Phylogenetic analysis showed that TdNOS and NOS of T. pretiosum was closely related, forming an independent clade separated from NOS proteins of other hymenopteran insects. The recombinant TdNOS was expressed and purified, and the polyclonal antibody was prepared. The Western blot results showed that the expression level of TdNOS at the pupal stage after diapause was higher than that at other stages of T. dendrolimi. The results of MS showed that the purified protein was NOS. 【Conclusion】 TdNOS has higher mRNA and protein expression at the pupal stage after diapause. This study lays a foundation for further exploring the role of TdNOS in regulating diapause.

Trend analysis of differentially expressed genes in prepupae of Apis mellifera ligustica under low temperature stress

YAO Dan, ZHOU Shu-Jing, ZHOU Bing-Feng, XU Xin-Jian, ZHU Xiang-Jie

2020, 63(6): 688-696. doi:10.16380/j.kcxb.2020.06.004

Abstract ( 31 )

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【Aims】 Honey bees are of the holometabolous insects, whose brood is typically stenothermic. In order to understand the key genes involved in the sensitivity of the Italian honey bee, Apis mellifera ligustica to cold stress, we conducted a trend analysis of differentially expressed genes (DEGs) of cold-sensitive prepupae in response to cold stress. 【Methods】 The 3 d-old post-capped prepupae were exposed to cold temperature (20℃) for 18 (T18) and 36 h (T36), respectively, with those unexposed to cold stress used as the control (CK), and then subjected to transcriptomic sequencing based on Illumina HiSeq^TM. Short Time-series Expression Miner (STEM) software was applied to compare the shared DEGs among the three datasets. In addition, GO and KEGG pathway enrichment analyses were performed for DEGs with up- and down-regulation profiles. The expression profiles of five randomly selected DEGs were verified by RT-qPCR. 【Results】 Trend analysis showed that 1 062 DEGs shared by T18 vs CK and T36 vs CK were clustered into three significant profiles including two up-regulation profiles (Profile 6 covering 539 DEGs and Profile 7 covering 271 DEGs) and one down-regulation profile (Profile 1 covering 183 DEGs). GO and KEGG pathway enrichment analyses showed that insulin-like peptide gene (ILP) and forkhead box protein O gene (FoxO) were up-regulated in both FoxO signaling and longevity regulating pathways within Profile 6, suggesting that ecdysone signaling responds to cold stress during honey bee pupation. The CREB-binding protein gene (CBP) in Profile 7 was up-regulated, and CYP450 306a1 (phm) and WNT1 in Profile 1 were down-regulated, suggesting that these genes regulate cell development and ecdysone biosynthesis in response to low temperature. Besides, the expression profiles of the five selected genes based on RT-qPCR analysis were consistent with those based on the transcriptome. 【Conclusion】 The trend analysis of DEGs reveals that FoxO regulated by insulin signaling and ecdysone signaling in honey bees may act as a key gene that represses honey bee pupation in response to cold stress. Our data lay a foundation for exploring the molecular regulation mechanisms underlying metamorphosis in response to cold stress in honey bees.

Effects of queen mandibular pheromone on the expression of candidate sex pheromone receptor genes in honeybee drones

LIU Jun-Feng, LI Mang, WANG Zi-Long, HE Xu-Jiang, ZENG Zhi-Jiang

2020, 63(6): 697-707. doi:10.16380/j.kcxb.2020.06.005

Abstract ( 46 )

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【Aim】 Sex pheromone receptors (PRs) are important receptors for the perception of queen mandibular pheromone (QMP) in honeybee drones. The aim of this study is to analyze the expression characteristics of candidate sex pheromone receptor genes in the antennae and brains of Apis cerana cerana and Apis mellifera ligustica drones subjected to QMP stimulation, so as to provide the theoretical basis for further studies on the biological function of odorant receptor (OR) genes in honeybees. 【Methods】 qRT-PCR was employed to detect and analyze the mRNA expression levels of four OR genes including Or10, Or11, Or18 and Or170 in the antennae and brains of flying and crawling drones of A. c. cerana and A. m. ligustica exposed to 10 μL QMP ［7.04 μg/μL (E)-9-oxodec-2-enoic acid (9-ODA)+1.26 μg/μL 9-hydroxydec-2-enoic acid (9-HDA)+0.03 μg/μL methylp-hydroxybenzoate (HOB)］ and 10 μL 7.04 μg/μL 9-ODA, respectively. 【Results】 The results showed that QMP and 9-ODA significantly inhibited the transcription of Or11 in the antennae and brains of A. c. cerana and A. m. ligustica drones compared to the blank control group. The mRNA expression levels of AcOr18 and AcOr170 in the antennae of A. c. cerana drones were down-regulated significantly by QMP and 9-ODA. Moreover, QMP and 9-ODA significantly decreased the mRNA expression levels of Or170 in the brains of drones of the two bees. After A. c. cerana drones were subjected to the stimulation of QMP or 9-ODA, the mRNA expression level of AcOr11 was significantly higher in the brain of flying drones than in the brain of crawling drones, whereas showed no significant difference in the antennae between flying drones and crawling drones. 【Conclusion】 Or11 in the antennae and brains of A. c. cerana and A. m. ligustica drones can respond to 9-ODA stimulation, and its expression is down-regulated after 9-ODA stimulation.

Differentially expressed proteins associated with energy metabolism in diapause and non-diapause pupae of Lysiphlebus testaceipes(Hymenoptera: Braconidae)

LIU Min, HAN Hai-Bin, LIU Ai-Ping, GAO Shu-Jing, XU Lin-Bo, YUE Fang-Zheng, HUANG Hai-Guang

2020, 63(6): 708-716. doi:10.16380/j.kcxb.2020.06.006

Abstract ( 23 )

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【Aim】 This study aims to elucidate the regulation of multi-proteins behind diapause pupae of Lysiphlebus testaceipes, with focus on the screening of diapause-associated proteins related to energy metabolism and analysis of their functions, and is helpful to better understand the metabolic mechanism of diapause in L. testaceipes. 【Methods】 The protein contents in diapause and non-diapause pupae of L. testaceipes were compared by isobaric tags for relative and absolute quantification (iTRAQ), and the differentially expressed proteins (DEPs) in diapause and non-diapause pupae of L. testaceipes were analyzed and identified using bioinformatics methods based on GO and KEGG databases. 【Results】 A total of 135 DEPs in diapause and non-diapause pupae of L. testaceipes, including 38 up-regulated proteins and 97 down-regulated proteins, were found. GO and KEGG enrichment analysis showed that the proteins related to the terms of aspartate transport, L-glutamate transport, choline dehydrogenase activity and glycine betaine biosynthetic process from choline, and the pathway of oxidative phosphorylation were up-regulated. 【Conclusion】 The proteins associated with oxidative phosphorylation pathway are significantly up-regulated during diapause of L. testaceipes, indicating that energy metabolism is closely related to diapause. It is so speculated that oxidative phosphorylation process provides not only the main energy but also heat energy for the basic activities of diapause pupae.

Analysis of the antennal transcriptome and olfaction-related genes of Coccinella septempunctata (Coleoptera: Coccinellidae)

YANG Xue-Jiao, ZHANG Man, JIANG Yu-Hang, TANG Qi-He, ZHANG Qi-Lin, LIN Lian-Bing, CHEN Jun-Yuan

2020, 63(6): 717-726. doi:10.16380/j.kcxb.2020.06.007

Abstract ( 41 )

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【Aim】 Coccinellidae show highly diverse feeding. This study aims to explore the relationships between olfaction-related genes in antennae and feeding divergence based on the establishment of the antennal transcriptome of Coccinella septempunctata. 【Methods】 The antennal transcriptome of C. septempunctata adults was sequenced using an Illumina HiSeq 4000 platform and subjected to assembly, annotation and comparative analysis with the previously published transcriptomes of Henosepilachna viginyioctopunctata, and the olfaction-related genes were identified. 【Results】 A total of 31 775 unigenes were obtained in C. septempunctata antennal transcriptome, 69.71% of which were annotated, and the highest number of unigenes (20 539) were annotated in the NR database. According to the annotation information, 27 olfaction-related genes including 1 odor binding protein (OBP) gene, 13 chemoreceptor protein (CSP) genes, 4 odorant receptor (OR) genes, 7 gustatory receptor (GR) genes and 2 sensory neuron membrane protein (SNMP) genes were identified. In parallel, 38 olfaction-related genes were identified in the transcriptomes of H. viginyioctopunctata, including 1 ionotropic receptor (IR) gene that was not found in C. septempunctata. Among the various types of olfaction-related genes, the proportion (13.16%) of OBP genes in the transcriptomes of H. viginyioctopunctata was higher than that (3.70%) in the antennal transcriptome of C. septempunctata, while the proportion (25.93%) of GR genes in the antennal transcriptome of C. septempunctata was higher than that (13.16%) in the transcriptomes of H. viginyioctopunctata. 【Conclusion】 The number of olfaction-related genes in the antennae may not make a predominant contribution to insect feeding divergence. This study obtained the antennal transcriptomic data of C. septempunctata and preliminarily explored the relationships between olfaction-related genes and feeding divergence in ladybirds, providing information for understanding the molecular basis of feeding divergence in ladybirds and even in insects.

Expression, localization and function of trehalase 3 in Nosema bombycis (Microsporidia)

ZHANG Yi-Ling, LI Jun-Hao, NING Jia-Xing, Bismark KYEI, SHEN Zhong-Yuan

2020, 63(6): 727-734. doi:10.16380/j.kcxb.2020.06.008

Abstract ( 21 )

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【Aim】 The purpose of this study is to preliminarily clarify the function of trehalase 3 (NbTre3) in Nosema bombycis, so as to provide theoretical basis and clues for the prevention and treatment of pebrine disease of Bombyx mori. 【Methods】 NbTre3 was amplified by PCR, and the prokaryotic expression vector pET28a-NbTre3 was constructed. The recombinant protein NbTre3 was expressed in Escherichia coli with IPTG induction and identified by Western blot. The recombinant protein NbTre3 was purified via Ni column affinity chromatography, and the polyclonal antibody was prepared by immunizing New Zealand rabbits with the obtained NbTre3. The localization of NbTre3 in mature spore of N. bombycis was investigated by indirect immunofluorescence assay. After N. bombycis infected the 5th instar larvae of B. mori, the transcription levels of NbTre3 in the midgut at different post-infection time were detected by qRT-PCR. The RNAi was carried out by injection of siRNA-1, siRNA-2 and siRNA-3, respectively, and the transcription levels of NbTre3 and 16S rRNA in the midgut of the 5th instar larvae of B.mori infected by N. bombycis at different time post RNAi were detected by qRT-PCR. 【Results】 The recombinant target protein NbTre3 was successfully expressed in E. coli and purified, with a size of about 34 kD. After immunizing the New Zealand rabbits, the serum was collected, and the polyclonal antibody of NbTre3 was obtained by purification and verified by Western blot. Indirect immunofluorescence result showed that NbTre3 was mainly distributed in the sporoplasm in mature spores of N. bombycis. The qRT-PCR results showed that the expression level of NbTre3 in the midgut of the 5th instar larvae of B. mori was the highest at 6 h post infection of N. bombycis. After the expression of NbTre3 was inhibited by siRNA, there was no significant change in the transcription level of 16S rRNA of N. bombycis. 【Conclusion】 The results suggest that NbTre3 may play an important role in the germinating process of the initial infection of N. bombycis.

Screening and identification of the protein interacting with the NSs protein of Tomato zonate spot virus in Franiklinella ocicdentalis(Thysanoptera: Thripidae) by yeast two-hybrid technique

ZHAO Xing-Yue, CHEN Jian-Bin, WANG Shu-Guang, ZHANG Xiao-Lin, MU Ye, WEI Hui, ZHAO Li-Hua, CHEN Yong-Dui, ZHENG Xue, CHEN Yong, ZHENG Li-Min, ZHANG Jie

2020, 63(6): 735-743. doi:10.16380/j.kcxb.2020.06.009

Abstract ( 26 )

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【Aim】 To screen and identify the protein interacting with the tomato zonate spot virus (TZSV) NSs protein in the western flower thrips, Franiklinella ocicdentalis. 【Methods】 The protein in F. ocicdentalis interacting with TZSV NSs was screened by yeast two-hybrid technique. After sequence analysis, the captured protein and NSs genes were cotransformed into yeast cells, and their interaction was identified by nutrient deficient medium. Furthermore, GST Pull-down was used to confirm the interaction of NSs and the identified protein in F. ocicdentalis in vitro. 【Results】 pGBKT7-NSs, a yeast two-hybrid bait plasmid of TZSV NSs, was constructed, and it showed no toxicity and no autoactivition to AH109 yeast cell. Sequence analysis showed that a voltage-dependent anion-selective channel-like (VDAC) protein of F. ocicdentalis interacted with TZSV NSs. The cotransformation test results showed that there was a specific interaction between TZSV NSs and VDAC in yeast cell. The GST Pull-down results showed that there was interaction between TZSV NSs and VDAC in vitro. 【Conclusion】 The specific interaction between TZSV NSs and F. ocicdentalis VDAC was confirmed in yeast cell and in vitro by yeast two-hybrid and GST Pull-down techniques, respectively. The results are helpful to reveal the mechanism of the protein VDAC regulating the transmission of persistent-propagative plant viruses in F. ocicdentalis and provide a theoretical basis for the prevention and control of insect-borne virus diseases.

Infection process and pathogenicity of entomopathogenic fungus Lecanicillium longisporum strain TF-2 to Acyrthosiphon pisum(Hemiptera: Aphididae)

ZHANG Ting-Feng, WANG Rui, LIU Chang-Zhong

2020, 63(6): 744-750. doi:10.16380/j.kcxb.2020.06.010

Abstract ( 35 )

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【Aim】 The pea aphid, Acyrthosiphon pisum, is an important agricultural pest in the world and causes great economic losses to legume crops. In this study, based on the previous screening of the pathogen Lecanicillium longisporum strain TF-2 of A. pisum, the virulence effect and infection mode of conidia of this pathogen on A. pisum were detected, so as to provide a theoretical basis for the control of A. pisum by entomogenic fungi. 【Methods】 The pathogenicity of L. longisporum strain TF-2 to A. pisum adults dipped into serial concentrations of conidial suspension (1.0×10³-1.0×10⁷ conidia/mL) of L. longisporum strain TF-2 was assayed by feeding method with detached leaves in the laboratory. The external infection symptoms and process of L. longisporum strain TF-2 to A. pisum adults infected with the TF-2 strain (1.0×10⁷ conidia/mL) were observed under scanning electron microscope (SEM) and stereoscopic microscope (SM). 【Results】 The pathogenicity of different concentrations of conidia of L. longisporum strain TF-2 to A. pisum adults gradually enhanced with the increase of conidial concentration. The medium lethal concentration (LC₅₀) of the TF-2 strain to A. pisum adults at 6 d after treatment was 3.26×10⁴ conidia/mL, and the medium lethal time (LT₅₀) of this strain at the highest treatment concentration (1.0×10⁷ conidia/mL) was 2.92 d. The results of SEM observation showed that the conidia of L. longisporum strain TF-2 germinated and bud tubes and appressorium formed on the epidermis of A.pisum adults at 24 h after inoculation. Bud tubes elongated and a network structure formed in compound eyes, the base of antennae, the basal segment of legs, the end of the abdomen reproductive segment, etc. of A.pisum adults, at 48 h after inoculation. At 96 h after inoculation, hyphae covered the whole body of A. pisum adults and new conidia produced. 【Conclusion】 L. longisporum strain TF-2 has a strong pathogenicity to A. pisum adults, and the SEM observation revealed the infection process of its conidia. These results provide the theoretical basis and references for the further application of entomogenous fungi in biological control.

Screening of Lecanicillium strains with high virulence to Myzus persicae (Hemiptera: Aphididae)

LIU Ming-Ke, YAN Fang-Fang, QI Yu-Zhe, HUANG Yan, YAN Xue-Li, QIAN Yi-Bin, LI Mao-Ye

2020, 63(6): 751-758. doi:10.16380/j.kcxb.2020.06.011

Abstract ( 22 )

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【Aim】 The green peach aphid, Myzus persicae, is an important crop pest distributed worldwide. This pest has developed resistance to a variety of chemical pesticides in recent years. The purpose of this study is to screen Lecanicillium strains with high virulence against M. persicae and excellent performance in cultivation. 【Methods】 Seven strains of two Lecanicillium species, namely three strains of L. psalliotae (HFLP006, HFLP021 and HFLP025) and four strains of L. attenuatum (HFLA032, HFLA041, HFLA064 and HFLA066), were selected, and the colony growth and spore production of these strains cultivated on SDAY plates were observed. The lethality and the medium lethal time (LT₅₀) of these strains against the apterous adults of M. persicae were measured by immersion method using a 2.0×10⁷ conidia/mL spore suspension, and the medium lethal concentration (LC₅₀) values of HFLP006 and HFLA032 strains were determined with a graded series of concentrations of spore suspension (1.0×10⁴-1.0×10⁸conidia/mL). The symptoms of apterous adults infected by HFLP006 strain at the concentration of 1.0×10⁸ conidia/mL spore suspension were observed under stereoscopic microscope. 【Results】 The colony morphology of the seven strains of Lecanicillium on the SDAY plate was basically similar. The HFLP006 and HFLA032 strains showed better growth and spore-producing traits, with the colony diameter of 50.75 and 51.13 mm, and the spore yields of 13.90×10⁷ and 11.50×10⁷ conidia/cm², respectively, at 15 d after inoculation. The spore germination rates of all the strains were above 96.00%, with the HFLP006 strain showing the germination rate of 99.28%. The HFLP006 strain also displayed the highest pathogenicity against the apterous adults of M. persicae, causing an 83.56% corrected accumulative mortality at 7 d after treatment, which was significantly higher than those caused by the other fungal strains. Moreover, the LT₅₀value of the HFLP006 strain against the apterous adults of M. persicae was 3.74 d, which was significantly lower than those of the other strains. The HFLA032 strain also had good performance against the apterous adults of M. persicae, causing a corrected accumulative mortality of 63.01% and a LT5₀ of 5.75 d against the apterous adults of M. persicae. Furthermore, virulence determination revealed that the LC₅₀ values of HFLP006 and HFLA032 strains against the apterous adults of M. persicae at 7 d after treatment were 0.21×10⁶ and 1.86×10⁶ conidia/mL, respectively. The HFLP006 strain at a concentration of 1.0×10⁸ conidia/mL spore suspension impaired the vitality of M. persicae adults on the 2nd day after treatment, and brown spots were observed on the abdomen of aphid body. Then the thorax and abdomen became brown, the legs and antennae became white, and the whole body became very wizened. Finally, a large amount of white filamentous hyphae grew out from aphid body. 【Conclusion】 The HFLP006 strain is a candidate biological control agent against M. persicae since it causes the highest mortality and the shortest lethal time against the apterous adults of M. persicae. In addition, the HFLP006 strain shows an excellent cultivation performance on SDAY medium. The results of this study provide a theoretical basis for further largescale fermentation of this fungal strain.

Multiple mating of Chilo suppressalis (Lepidoptera: Pyralidae) and its effect on the oviposition of female moths

FENG Bo, LIU Tian-Wei, LU Ming-Hong, ZHONG Ling, GUO Rong, LIU Wan-Cai, GUO Qian-Shuang, DU Yong-Jun

2020, 63(6): 759-768. doi:10.16380/j.kcxb.2020.06.012

Abstract ( 29 )

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【Aim】 The effectiveness of controlling and monitoring the striped rice stem borer, Chilo suppressalis, by pheromone trapping had been verified in the field. However, since the male moth can mate multiple times, the mass trapping control strategy of C. suppressalis has been in debate for decades. The purpose of this study is to explore the mating frequency of male moths of C. suppressalis and its effect on the fecundity of female moths, and to understand the mechanism of pest control by pheromone mass trapping. 【Methods】 The mating frequency and duration of mating of male moths of C. suppressalis paired in different female to male ratios (1∶1, 4∶1 and 10∶10) were investigated by behavioral methods. The effects of mating frequency on the size of testis, bursa copulatrix and spermatophore and the number of eggs laid by female moths were observed and analyzed by behavioural and anatomical methods. 【Results】 When the female and male moths were paired in the 1∶1 ratio, the proportions of male moths mating at least once and mating multiple times were 74.0% and 36.0%, respectively, and the average mating frequency of male moths was 1.7 times. The first mating was always found in the male at the 0-1-day-old. Most of the male moths mating multiple times were firstly mated at the 0-1-day-old. When the female and male moths were paired in the 4∶1 ratio, the proportions of male moths mating at least once and multiple times were 69.4% and 51.3%, respectively, and the average mating frequency was 2.1 times, which was significantly higher than that of male moths paired with females in the 1∶1 ratio. When the female and male moths were paired in the 10∶10 ratio, the proportions of male moths mating at least once and multiple times were 65.5% and 37.8%, respectively, and the average mating frequency was 1.9 times. The duration of the 3rd mating of males was significantly longer than that of the 1st and the 2nd mating, but there was no significant difference in the testicular volume among males mating once, twice and thrice. There was no significant difference in the volume of bursa copulatrix and spermatophore of female and in the number of eggs laid per female, which mated with males at different mating frequencies. 【Conclusion】 Only a portion of C. suppressalis male moths can mate multiple times and their first mating mainly occurred at the 0-1-day-old. A significant number of male moths do not mate in their life. Our results provide a theoretical basis for controlling C. suppressalis with pheromone trapping.

Analysis of the genetic diversity of geographical populations of Liriomyza chinensis (Diptera: Agromyzidae) in China based on mtCOI gene sequence

ZHONG Yu-Jun, DU Su-Jie, PAN Li-Ting, WANG Yu-Sheng, WANG Fu-Lian, LIU Wan-Xue

2020, 63(6): 769-778. doi:10.16380/j.kcxb.2020.06.013

Abstract ( 23 )

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【Aim】 Liriomyza chinensis, a serious economic pest of onions and garlics, is widely distributed in China. This study aims to analyze the genetic differentiation among the geographical populations of L. chinensis in China. 【Methods】 A total of 253 individuals from 12 different geographical populations from 8 provinces were used as samples, and their mtDNA COI gene was sequenced. The genetic diversity, gene flow levels and genetic variation of the geographical populations of L. chinensis were analyzed by MEGA7.0, DnaSP 6.1 and Arlequin 3.5 based on the obtained mtCOI gene sequences. 【Results】 From the 253 individuals 13 haplotypes of the mtCOI gene fragment of 759 bp in length were defined, and the K2P genetic distance between haplotypes was less than 0.02. Haplotype Hap1 was shared by the 12 geographical populations, and the total occurrence frequency was up to 81.82%. The haplotype diversity (H_d) of all geographical populations was low (0.327), the nucleotide diversity (Pi) was 0.00159, and the average number of nucleotide difference (K) was 1.21011. The total population had generated moderate genetic differentiation (F_ST=0.06971), and the gene flow was relatively sufficient (Nm=3.33629). The results of molecular variance analysis (AMOVA) showed that the source of genetic variation was within population, and the Tajima’s D test value was significantly negative. Mantel test results showed that the genetic distance was not related to the geographical distance. 【Conclusion】 The geographical populations of L. chinensis in China show low genetic diversity, relatively sufficient gene flow and moderate genetic differentiation, and the geographical distance does not affect the degree of genetic differentiation between geographical populations. The total population of L. chinensis has not experienced significant population expansion and population growth in the recent historical period.

Contents of Vol. 63 Issue 6

2020, 63(6): 779-779.

Abstract ( 12 )

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