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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 May 2020, Volume 63 Issue 5
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  • RESEARCH PAPERS
    Comparative analysis of the transcriptomes of male adult and the 5th instar larva of Spodoptera frugiperda (Lepidoptera: Noctuidae)
    LIAO Yong-Lin, LI Yan-Fang, YANG Bin, ZHAO Hua, GAO Yan, CHEN Wei-Ping, CAI Shi-Ke, WANG Ji-Hua
    2020, 63(5):  523-532.  doi:10.16380/j.kcxb.2020.05.001
    Abstract ( 768 )   PDF (12663KB) ( 282 )   PDF(mobile) (12663KB) ( 107 )     
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    【Aim】 The fall armyworm, Spodoptera frugiperda, is a newly invaded important pest in China. This study aims to comparatively analyze the transcriptomes of two developmental stages, male adult and the 5th instar larva, of S. frugiperda. 【Methods】 High-throughput sequencing technology was used to sequence and assembly the transcriptomes of male adult and the 5th instar larva of S. frugiperda, and the functional annotation and comparative analysis of transcriptome data were performed. 【Results】 After a de novo assembly, a total of 209 002 transcripts were obtained, with an average length of 687.55 bp and an N50 of 982 bp. A total of 46 198 (57.43%) unigenes were annotated in at least one database, among which 1 713 (2.13%) unigenes were annotated in all databases. In the GO database, 205 269 unigene annotations were obtained, mainly including 68 functional classifications. A total of 3 408 unigenes were annotated in KEGG database, involving 277 metabolic pathways. A total of 424 olfaction-related genes were identified and showed differential expression in male adults and the 5th instar larvae of S. frugiperda. By comparative transcriptome analysis, 9 162 up-regulated differentially expressed genes (DEGs) and 6 399 down-regulated DEGs were identified in male adult. Functional enrichment analysis revealed that the up-regulated DEGs were significantly enriched in the pathways involved in pheromone and signal transduction, while the down-regulated DEGs were significantly enriched in the pathways related to detoxification. 【Conclusion】 These transcriptome data provide some valuable information for exploring the functional genes related to the growth and development and olfaction and candidate molecular targets in S. frugiperda.
    Cloning of heat shock protein gene SfHsp90 and its expression under high and low temperature and UV-A stresses in Spodoptera frugiperda (Lepidoptera: Noctuidae)
    ZHOU Lü, MENG Jian-Yu, YANG Chang-Li, LI Jin, HU Chao-Xing, ZHANG Chang-Yu
    2020, 63(5):  533-544.  doi:10.16380/j.kcxb.2020.05.002
    Abstract ( 562 )   PDF (6353KB) ( 117 )   PDF(mobile) (6353KB) ( 18 )     
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    【Aim】 This study aims to explore the molecular mechanism of Spodoptera frugiperda in response to high and low temperature and UV-A stresses. 【Methods】 The heat shock protein Hsp90 gene of S. frugiperda was cloned by RT-PCR technique, and its sequence characteristics were analyzed using bioinformatics methods. The relative expression levels of Hsp90 in different developmental stages (egg, 1st-6th instar larva, pupa and adult), different adult tissues (head with antennae and compound eyes removed, thorax, abdomen, antenna, compound eye, leg, wing, midgut, testis and ovary) and adults exposed to high temperature of 36℃, low temperature of 4℃ and UV-A radiation for different time (0, 30, 60, 90, 120 and 150 min) were detected by RT-qPCR. 【Results】 The Hsp90 gene was cloned from S. frugiperda and named SfHsp90 (GenBank accession no.: MN832694). Its open reading frame (ORF) is 2 154 bp in length, encoding 717 amino acids, with the relative molecular weight of 82.52 kD and the isoelectric point (pI) of 5.01. The C-terminal sequence contains the conserved motif EEVD, suggesting that the protein is a cytoplasmic heat shock protein. Phylogenetic analysis showed that insect Hsp90 proteins are highly conserved. Developmental expression profile showed that the expression level of SfHsp90 was the highest in the 1st instar larva, and the tissue expression profile revealed that the expression levels of SfHsp90 were significantly higher in the antenna, compound eyes and head with antennae and compound eyes removed of male and female adults than in other tissues. High and low temperature stresses induced the expression of SfHsp90 obviously. The expression level of SfHsp90 in adults exposed to high temperature of 36℃ was significantly higher than that of the control group. After the adults were exposed to high temperature of 36℃, the expression level of SfHsp90 increased at first and then decreased with the increase of exposure time, and reached the maximum at 60 min after exposure in male adults, while its expression level in female adults increased gradually with the prolonging of exposure time. After the adults were exposed to low temperature of 4℃, the expression level of SfHsp90 increased firstly and then decreased in male adults with the prolonging of exposure time, and reached the maximum at 30 min after exposure, while its expression level in female adults increased gradually with the prolonging of exposure time. The expression of SfHsp90 in female and male adults was induced by UV-A stress. After the adults were exposed to UV-A radiation, the expression level of SfHsp90 increased firstly and then decreased with the increase of exposure time, and reached the highest at 90 min in male adults and at 60 min in female adults, respectively. 【Conclusion】 The differential expression of SfHsp90 in S. frugiperda adults under high and low temperature and UV-A stresses suggests that this gene plays an important role in the molecular mechanism in S. frugiperda in response to environmental stresses.
    Gustatory perception and feeding preference of Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae to four stimuli
    HOU Wen-Hua, SUN Long-Long, MA Ying, SUN Hui-Wan, ZHANG Jia-Jia, BAI Run-E, ZHAO Xin-Cheng, TANG Qing-Bo
    2020, 63(5):  545-557.  doi:10.16380/j.kcxb.2020.05.003
    Abstract ( 672 )   PDF (9139KB) ( 154 )   PDF(mobile) (9139KB) ( 35 )     
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    【Aim】 The aim of this study is to screen effective phagostimulants and deterrents, and to explore the gustatory perception mechanism of Spodoptera frugiperda larvae, so as to provide theoretical and practical references for the ecological control of the pest. 【Methods】 The single sensillum recording technique was used to investigate the electrophysiological characteristics of the medial sensillum styloconicum and the lateral sensillum styloconicum located on the maxillary galea of mouthparts of the day-2 5th instar larvae to four stimuli of sucrose, sinigrin, tannic acid, and quinine hydrochloride at different concentrations. The two-choice feeding assay was used to investigate the feeding choice of S. frugiperda larvae to these stimuli. 【Results】 Both the medial sensillum styloconicum and the lateral sensillum styloconicum of S. frugiperda larvae consist of gustatory receptor neurons sensitive to sucrose, sinigrin and tannic, with the responding activities of neurons changing based on stimuli and concentrations. However, the quinine hydrochloride only elicited electrophysiological responses of the medial sensillum styloconicum but not the lateral sensillum styloconicum. The responses of gustatory receptor neurons in both the medial and lateral sensilla styloconica to sucrose and sinigrin showed typical dose-dependent patterns, while the response of quinine hydrochloride to the medial sensillum styloconicum showed a reverse dose-dependent pattern. The results of behavioral choice showed that sucrose significantly induced the feeding choice of S. frugiperda larvae, while sinigrin, tannic and quinine hydrochloride inhibited their feeding choice in a dose-dependent pattern. 【Conclusion】 Gustatory receptor neurons housed in both the medial and lateral sensilla styloconica of S. frugiperda larvae respond to phagostimulants and deterrents. The two types of sensilla demonstrate different responding patterns in response spectrum and responding activities. Sucrose can be regarded as one candidate compound of phagostimulants, while quinine hydrochloride, sinigrin and tannic acid can be regarded as the candidate compounds of deterrents. The gustatory responding profiles of larvae may contribute to determining their feeding preference for these compounds. This study provides gustatory information for the ecological control of S. frugiperda.
    Toxicity of spinetoram and its effects on the detoxifying enzyme and acetyl cholinesterase activities in Spodoptera frugiperda(Lepidoptera: Noctuidae) larvae
    GAO Zu-Peng, GUO Jing-Fei, HE Kang-Lai, WANG Zhen-Ying
    2020, 63(5):  558-564.  doi:10.16380/j.kcxb.2020.05.004
    Abstract ( 679 )   PDF (1348KB) ( 218 )   PDF(mobile) (1348KB) ( 29 )     
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    【Aim】 The study aims to evaluate the toxicity and mechanism of action of spinetoram against the fall armyworm, Spodoptera frugiperda. 【Methods】 The LC50 and LC90 values of spinetoram against the 2nd, 3rd and 4th instar larvae of S. frugiperda were determined by diet-overlay bioassays with chlorantraniliprole as the control. The activities of mixed-functional oxidase (MFO), glutathione-S-transferase (GST), carboxylesterase (CarE) and acetyl cholinesterase (AchE) in the 3rd instar larvae of S. frugiperda treated by different concentrations of spinetoram (0.127, 0.183, 0.250, 0.400 and 0.572 mg/L) at 48 h post treatment were determined by enzyme-linked immunosorbent assay (ELISA). 【Results】 Compared with chlorantraniliprole, spinetoram had higher toxicity to S. frugiperda larvae. The LC50 values of spinetoram against the 2nd, 3rd and 4th instar larvae at 48 h post treatment were 0.21, 0.34 and 0.59 mg/L, and the LC90 values were 0.59, 0.75 and 2.01 mg/L, respectively. When the 3rd instar larvae were treated with spinetoram, the MFO and AchE activities increased significantly as the treatment concentration increased, and reached the highest (52.23 and 23.98 U/mg pro, respectively) at the concentration of 0.572 mg/L. When the 3rd instar larvae were exposed to the low concentrations of spinetoram (0.127 and 0.183 mg/L), the CarE activity showed no significant change as compared with the vehicle control (0.1% Tween-80), but significantly increased as the concentration increased to 0.400 and 0.572 mg/L. The GST activity increased significantly as the concentration of spinetoram increased, but showed no significant difference between the treatment concentrations of 0.400 and 0.572 mg/L. 【Conclusion】 Spinetoram is highly effective against S. frugiperda, especially to its 4th instar larvae, as compared with chlorantraniliprole. The activities of CarE, MFO and AchE in S. frugiperda larvae increase after exposure to different concentrations of spinetoram.
    Effects of three insecticides at the sublethal dose on the expression of cytochrome P450 genes in Spodoptera frugiperda (Lepidoptera: Noctuidae)
    ZHANG Bai-Zhong, SU Xu, LU Liu-Yang, ZHEN Cong-Ai, ZHU Bin, LI Ya-She, DONG Wen-Yang, WANG Geng, XU Yan-Bo, KONG Fan-Bin, LIU Run-Qiang, CHEN Xi-Ling, GAO Xi-Wu
    2020, 63(5):  565-573.  doi:10.16380/j.kcxb.2020.05.005
    Abstract ( 565 )   PDF (1630KB) ( 144 )   PDF(mobile) (1630KB) ( 13 )     
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    【Aim】 To determine the effects of insecticides at the sublethal dose on the expression of cytochrome P450 genes in the fall armyworm, Spodoptera frugiperda. 【Methods】 The toxicity of three insecticides (chlorantraniliprole, emamectin benzoate and Bacillus thuringiensis) against the 2nd instar larvae of S. frugiperda was assayed by leaf-dipping method, and the transcriptional levels of 16 P450 genes in the 2nd instar larvae of S. frugiperda treated with the sublethal dose (LC10) of the three insecticides were measured by real-time quantitative PCR (RT-qPCR) at 48 h post treatment. 【Results】 The LC10 values of chlorantraniliprole, emamectin benzoate and B. thuringiensis against the 2nd instar larvae of S. frugiperda were 0.931, 0.283, and 1 089.688 mg/L, respectively. In the 2nd instar larvae exposed to the LC10 of chlorantraniliprole, 13 P450 genes including CYP4G75, CYP6AB12, CYP6B50, CYP321A7, CY321A8, CYP321A9, CYP321A10, CYP321B1, CYP337B5, CYP9A59, CYP9A58, CYP6AE44, and CYP6AE43 were up-regulated, and the transcription level of CYP6AE44 was 34.60-fold as high as that of the control. In the 2nd instar larvae exposed to the LC10 of emamectin benzoate, 11 P450 genes including CYP4G75, CYP6AB12, CYP321A7, CY321A8, CYP321A9, CYP321A10, CYP321B1, CYP337B5, CYP9A58, CYP6AE44, and CYP6AE43 were up-regulated, and the expression level of CYP321B1 was 28.70-fold as high as that of the control. In the 2nd instar larvae exposed to the LC10 of B. thuringiensis, 11 P450 genes including CYP4G75, CYP6AB12, CYP6AN4, CYP321A7, CY321A8, CYP321A9, CYP321A10, CYP321B1, CYP337B5, CYP6AE44, and CYP6AE43 were up-regulated, and the expression level of CYP6AE44 was 40.80-fold as high as that of the control. 【Conclusion】 Multiple P450 genes are up-regulated in the 2nd instar larvae of S. frugiperda in response to the sublethal dose of the three insecticides, and the expressions of CYP4G75, CYP6AB12, CYP321A7, CY321A8, CYP321A9, CYP321A10, CYP321B1, CYP321B5, CYP6AE44, and CYP6AE43 are induced by all the three insecticides.
    Genotype and mutation frequency of ace-1, the target gene of organophosphorus and carbamate insecticides, in field populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) in China
    LI Yan, GONG Li-Feng, WANG Huan-Huan, LI Xi, SUN Ge, GU Shao-Hua, LIANG Pei, GAO Xi-Wu
    2020, 63(5):  574-581.  doi:10.16380/j.kcxb.2020.05.006
    Abstract ( 543 )   PDF (1935KB) ( 97 )   PDF(mobile) (1935KB) ( 10 )     
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    【Aim】 The objective of this study is to detect the genotype of ace-1, the target gene of organophosphorus and carbamate insecticides, in field populations of Spodoptera frugiperda in China, and to identify the frequency of resistance genes, so as to provide guidance for the scientific use of insecticides in the field. 【Methods】 Samples of S. frugiperda larvae were collected from maize fields in 12 provinces in China, and the genomic DNA was extracted individually. Then the ace-1 gene fragment was cloned using gene specific primers, and the genotype and resistance gene frequency of three amino acid mutation sites, A201S, G227A and F290V, were analyzed through base and amino acid sequence alignment, DNA sequencing and peakTrace Basecaller analysis. 【Results】 The genotype and mutation frequency of the ace-1 gene of 589 individuals of field populations of S. frugiperda from 12 provinces in China analyzed through DNA detection method revealed that 137 individuals exhibited resistant heterozygous genotype at locus A201S, and the resistance gene frequency reached 11.6%. Meanwhile, no resistant homozygous genotype was found. At locus G227A, all the 589 individuals displayed susceptible homozygous genotypes. The resistance gene frequency at locus F290V was the highest (57.1%), and there were 523 individuals carrying homozygous or heterozygous resistance genes, accounting for 88.8% of the total samples. 【Conclusion】 The results indicate that S. frugiperda invading in China carries a high-level frequency of resistance genes to organophosphorus and carbamate insecticides. Organophosphorus and carbamate insecticides should not or less be used in the field control of S. frugiperda, and resistance monitoring in fields should be strengthened.
    Detection of insecticide sensitivity and target site mutations in field populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) in four regions of Hubei, central China
    GUO Zhi-Min, DENG Xiao-Qian, LI Jing, YUAN Mao-Jun, WAN Hu, LI Jian-Hong, MA Kang-Sheng
    2020, 63(5):  582-589.  doi:10.16380/j.kcxb.2020.05.007
    Abstract ( 564 )   PDF (1731KB) ( 89 )   PDF(mobile) (1731KB) ( 19 )     
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    【Aim】 The aim of this study is to evaluate the sensitivity of field populations of the fall worm, Spodoptera frugiperda, in Hubei, central China to four insecticides, and to detect the genotype and mutation frequency of the insecticide target genes Ace-1, VGSC and RyR, so as to ascertain the insecticide sensitivity of field populations of S. frugiperda in Hubei and to provide guidance for scientific application of pesticides. 【Methods】 The sensitivity of S. frugiperda larvae collected from corn fields in four regions, Huanggang, Wuxue, Xianning and Jingzhou of Hubei to four insecticides, chlorantraniliprole, spinetoram, indoxacarb and methylamino abamectin benzoate, was investigated using a standard leaf-dip bioassay. Eighty larvae from 4 regions were used for total RNA isolation and cDNA synthesis, and the target fragments were amplified by PCR using specific primers. Besides, the genotypes and target site mutation frequencies of Ace-1, VGSC, and RyR were determined by sequence alignment and sequencing chromatogram peak analysis. 【Results】 Toxicity assays showed that the four field populations of S. frugiperda larvae in Hubei were susceptible to all the tested insecticides, and the sensitivity of these populations to four insecticides was as follows: methylamino abamectin benzoate>spinetoram>chlorantraniliprole>indoxacarb. The sequencing results demonstrated that in the four field populations of S. frugiperda the resistant heterozygote of all three mutations of Ace-1 (A201S, G227A, and F290V) was detected, while the resistant homozygote of F290V was detected. However, no site mutation in VGSC and RyR was detected in all the tested field populations of S. frugiperda. 【Conclusion】 Though the four field populations of S. frugiperda in Hubei are susceptible to the four tested insecticides (chlorantraniliprole, spinetoram, indoxacarb and methylamino abamectin benzoate), these field populations have already carried resistant genes conferring resistance to organophosphorus and carbamate insecticides and possess high resistance risk to these insecticides. Therefore, resistance monitoring needs to be strengthened.
    Comparison of bioassay methods for the toxicities of chemical insecticides against Spodoptera frugiperda (Lepidoptera: Noctuidae)
    LÜ​ Sheng-Lan, WANG You-Bing, GU Shao-Hua, LIANG Pei, ZHANG Lei, GAO Xi-Wu
    2020, 63(5):  590-596.  doi:10.16380/j.kcxb.2020.05.008
    Abstract ( 331 )   PDF (1149KB) ( 112 )   PDF(mobile) (1149KB) ( 23 )     
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    【Aim】 This study aims to identify the most repeatable and convenient bioassay method to assess the toxicities of chemical insecticides of different types against larvae of the fall armyworm, Spodoptera frugiperda. 【Methods】 The toxicities of seven insecticides of different types (chlorantraniliprole, emamectin benzoate, acephate, lambda-cyhalothrin, spinetoram, chlorfenuron and lufenuron) against the 3rd instar larvae of S. frugiperda were detected with topical application method, diet incorporation method and leaf dipping method, respectively. 【Results】 Detected with topical application method, emamectin benzoate showed the highest toxicity to the 3rd instar larvae of S. frugiperda among the seven insecticides, with the LD50 value of 0.375 μg/g at 24 h after treatment, and lufenuron showed the lowest toxicity, with the LD50 value of 261.107 μg/g at 72 h after treatment. Detected with diet incorporation method, emamectin benzoat showed the highest toxicity and acephate showed the lowest toxicity to the 3rd instar larvae of S. frugiperda, with their LC50 values of 0.061 and 9 426.217 μg/g, respectively, at 24 h after treatment. Detected with leaf dipping method, emamectin benzoate showed the highest toxicity and lambda-cyhalothrin showed the lowest toxicity to S. frugiperda larvae, with their LC50 values of 0.062 and 471.343 mg/L, respectively, at 24 h after treatment. The bioassay data obtained in topical application method had the smallest chi-square value and the largest P-value. At the same time, S. frugiperda populations showed higher genetic consistency in topical application method and leaf dipping method than in diet incorporation method. 【Conclusion】 Topical application method is the optimal bioassay method for all the tested insecticides except for lufenuron, including chlorantraniliprole, emamectin benzoate, acephate, lambda-cyhalothrin, spinetoram, and chlorfenuron. Compared with diet incorporation method and leaf dipping method, topical application method can not only accurately reflect the genetic purity of S. frugiperda populations, but also show the highest repeatability of bioassay results. However, diet incorporation method and leaf dipping method are recommended in lufenuron bioassay.
    Comparison of the feeding and growth characteristics of larvae of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), on corn and wheat
    LÜ​ Liang, LI Yu-Qing, CHEN Cong-Liang, CHANG Xiang-Qian, ZHANG Shu, XU Dong, WAN Peng
    2020, 63(5):  597-603.  doi:10.16380/j.kcxb.2020.05.009
    Abstract ( 590 )   PDF (1471KB) ( 128 )   PDF(mobile) (1471KB) ( 27 )     
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    【Aim】 To assess the risk of damage and outbreak caused by the fall armyworm, Spodoptera frugiperda, shifted to wheat. 【Methods】 The feeding and growth characteristics and population life table parameters of S. frugiperda on corn and wheat under 23℃ in the laboratory were determined and compared by indoor breeding and survey statistics. 【Results】 S. frugiperda could complete its life cycle on wheat, and the food intake and body weight of larvae after the 3rd instar fed on wheat were significantly higher than those fed on corn at the same time after treatment, but the food utilization efficiency, larval survival, larval duration, and egg hatching rate fed on wheat were significantly lower than those fed on corn. There were no significant differences in such indexes as the average pupal weight, pre-oviposition period, and number of eggs laid per female of S. frugiperda fed on corn and wheat. In addition, the comparison of life table parameters showed that there were no significant differences in the mean generation time (T), intrinsic rate of increase (rm), and finite rate of increase (λ) of S. frugiperda fed on corn and wheat, but the net reproductive rate (R0) of S. frugiperda fed on corn was 303.55±2.04, which was significantly higher than that fed on wheat. 【Conclusion】 S. frugiperda fed on wheat grows and develops fast and can complete the life cycle. However, the food utilization efficiency and population reproductive ability of S. frugiperda fed on wheat are lower than those on corn, suggesting that S. frugiperda is more suitable for feeding on corn. There is a risk of shifting to damage wheat by S. frugiperda. But considering the source of the pest, natural temperature and other conditions, S. frugiperda is less likely to have an outbreak during damaging wheat. The results of this study provide basic data for clarifying the risk of S. frugiperda damage and outbreak on wheat and the scientific control of S. frugiperda.
    Feeding and oviposition preference and fitness of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), on rice and maize
    QIU Liang-Miao, LIU Qi-Quan, YANG Xiu-Juan, HUANG Xiao-Yan, GUAN Rui-Feng, LIU Bi-Pao, HE Yu-Xian, ZHAN Zhi-Xiong
    2020, 63(5):  604-612.  doi:10.16380/j.kcxb.2020.05.010
    Abstract ( 684 )   PDF (2298KB) ( 189 )   PDF(mobile) (2298KB) ( 41 )     
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    【Aim】 This study aims to clarify the feeding and oviposition preference and fitness of the fall armyworm, Spodoptera frugiperda, on host plants rice and maize and then to analyze its damage risk to rice. 【Methods】 The feeding and oviposition preference of S. frugiperda were tested by free choice method. The development, survival rate and fecundity of S. frugiperda fed on maize and rice seedlings were investigated, and the fitness of S. frugiperda on rice was evaluated by the population growth trend index (I). 【Results】 There were significant differences in the feeding and oviposition preference of S. frugiperda to rice and maize. The choice rate of larvae to feed on maize increased with time during 2-48 h post infestation, while that on rice decreased with time. At 48 h post infestation, the choice rates of the 2nd and 4th instar larvae to feed on maize were 93.06% and 59.72%, respectively, which were 66.95 and 21.48 times as high as those to rice. In terms of oviposition preference, the number of eggs laid on maize was 8.64 times as high as that on rice after a free oviposition period of 6 d. The individuals of S. frugiperda fed on rice seedlings had longer developmental duration, lower egg hatching rate, larval growth rate, pupation rate, adult emergence rate and proportion of females, shorter female longevity and less eggs laid per female as compared to those fed on maize seedlings. The population growth trend index (I) of S. frugiperda fed on maize seedlings was 165.93, and the relative fitness of S. frugiperda on rice seedlings was 0.21. 【Conclusion】 S. frugiperda prefers to feed and lay eggs on maize rather than on rice, and shows a higher fitness on maize. Rice is a non.preferable host to S. frugiperda that has invaded China, but it can feed on rice seedlings to grow and develop normally and finish its life cycle. The results suggest that S. frugiperda may become a potential threat to rice production when it has a high population density and its preferable host plants are absent.
    Occurrence and control strategy of Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize plants in fields in Dongyang, Zhejiang, eastern China
    HAN Hai-Liang, ZHANG Jin-Ming, XU Hong-Xing, BAO Fei, LIU Min, ZHAO Fu-Cheng, LÜ​ Yao-Bin, LÜ​ Zhong-Xian, WANG Gui-Yue
    2020, 63(5):  613-623.  doi:10.16380/j.kcxb.2020.05.011
    Abstract ( 402 )   PDF (1946KB) ( 85 )   PDF(mobile) (1946KB) ( 26 )     
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     【Aim】 This study aims to clarify the occurrence and control methods of Spodoptera frugiperda on fresh-eating maize varieties in Zhejiang Province, eastern China. 【Methods】 The population dynamics of S. frugiperda adults was monitored by light trap and sex pheromone trap in Dongyang, Zhejiang in 2019. The oviposition and damage characteristics of S. frugiperda larvae on maize plants were observed in field, and the damage differences of S. frugiperda to different waxy and sweet maize varieties were determined by field investigation. The highly effective insecticides for field application were screened by field test. 【Results】Theresultsoflighttrapandsexpheromonetrapshowed that there were two peaks of S. frugiperda adults in Dongyang, Zhejiang, which happened in late June and mid-September, respectively, and the peak in September was significantly higher than that in June. The moth tended to lay eggs on the young maize plants, and 80% of the eggs were laid on the upperside of leaves of maize. The larval feeding showed a significant tendency toward tender tissues, damaging heart leaves and ears of maize. The damage rates of S. frugiperda to different maize varieties were quite different, being 0-28.41% to sweet corn, and 0-42.50% to waxy corn. Emamectin benzoate, lufenuron, spinetoram, methoxyfenozide, phlorfenapyr, profenofos, methomy, indoxacarb, Celastrus angulatus and Mamestra brassicae NPV (MbNPV) were screened out as the highly effective pesticides to control S. frugiperda in the filed test in Dongyang, Zhejiang in 2019, the larval population decreased by 87.61%-98.99% at 3 d post pesticide application, and the persistence period was about 7-10 d in the field. 【Conclusion】 S. frugiperda not only injures leaves of maize plants, but also ears. The damage in autumn is significantly serious than that in spring. For the control of S. frugiperda on maize plants, the integrated control measures including chemical control, biocontrol and physical induction control methods should be adopted. The control strategies also need to pay attention to seedling conservation at the seeding stage and ear conservation at the later stage, and to appropriately relax the control threshold from the jointing stage to the tassel stage.
    REVIEW ARTICLES
    Research status and prospects of Spodoptera frugiperda (Lepidoptera: Noctuidae) in China
    LIANG Pei, GU Shao-Hua, ZHANG Lei, GAO Xi-Wu
    2020, 63(5):  624-638.  doi:10.16380/j.kcxb.2020.05.012
    Abstract ( 334 )   PDF (2352KB) ( 196 )   PDF(mobile) (2352KB) ( 33 )     
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    The fall armyworm, Spodopterar frugiperda, has posed a great threat on food security of China since its invasion into China in December 2018. To effectively control this pest insect, the entomologists in China worked hard in last year, made many important progresses in studies concerning its taxonomy and biotype identification, investigation of its host crops, cold-hardiness and diffusion law, prediction of its potential geographical distribution and migration routes, its biological and chemical control, etc., and published more than 250 related papers. The results revealed that the fall armyworm invaded in China is mainly the corn strain and has caused harm to 15 crops. It has two migration routes, namely the east route and the west route, and can occur in all provinces of China. A total of 31 natural enemies of the fall armyworm were identified, and a batch of insecticides with good control efficacy against this pest was screened out. In this article, we summarized these works and put forward some suggestions on future research topics including enhancing the study on intelligent identification and automatic forecasting of the fall armyworm, accelerating the industrialization of dominant natural enemies and Bt corn, enhancing the monitoring of insecticide resistance and frequencies of insecticide resistance related genes, developing highly effective sex attractants and food attractants, and deepening the studies on the regulation mechanisms of important life processes and the molecular mechanisms of resistance to chemical insecticides and different Bt proteins, so as to provide the necessary theoretical basis and technical support for the sustainable management of the fall armyworm.
    Key words: 
    SHORT COMMUNICATIONS
    Ovary structure and development of Spodoptera frugiperda (Lepidoptera: Noctuidae) from fields in different regions of China
    FENG Bo, GUO Qian-Shuang, MAO Bi-Peng, ZHONG Ling, SONG Jian-Hui, XIAO Ming-Hui, DU Yong-Jun
    2020, 63(5):  639-648.  doi:10.16380/j.kcxb.2020.05.013
    Abstract ( 589 )   PDF (16807KB) ( 207 )   PDF(mobile) (16807KB) ( 43 )     
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    【Aim】 This study aims to explore and understand the ovary developmental status of Spodoptera frugiperda and its variation in fields so as to provide accurate monitoring basis for the occurrence and migration dynamics of S. frugiperda populations. 【Methods】 The morphological differences of female ovary of S. frugiperda at different ages (day-old) and from fields of different regions in China were compared by systematic dissection of female reproductive system. The relationship between ovarian maturation and mating of female moths was analyzed. 【Results】 The reproductive system of female moth of S. frugiperda is composed of ovaries, oviducts, copulatory pouch, afferent duct, spermatheca, accessory glands and ovipositors. According to the morphological characteristics, eggs of field female moths can be divided into three stages: pre-vitellogenesis, vitellogenesis and maturation. The eggs in the ovaries of 1-day old female moths barely reach the middle stage of vitellogenesis with the ovarian stalk empty. The ovaries start to differentiate at the 3-day old female moth stage. Some ovaries in the 3-day old female moths are still similar to those in the 1-day old moths, but some ovaries have mature eggs. The differentiation of ovary lasts till the 11-day old female moth stage. Some female moths from fields of Jiangcheng County and Mile County of Yunnan Province, Tianyang County of Guangxi Province, and Rui′an County and Zhenhai County of Zhejiang Province had immature ovaries until death, which accounted for 61.5%, 51.7%, 41.7%, 42.1% and 35.5% of the total ovaries, respectively. A proportion of 39.6% of the first generation female moths reared indoors still had immature ovaries at the time of death, which was similar to that of the field female moths. The ovaries of mated female moths could be mature and immature, but the proportion of immature ovaries was only 18.0%±5.0%. 【Conclusion】 The results suggest that field female moths of S. frugiperda have a mixture of migratory and non-migrating individuals in the same generation, and their proportions vary with the location and season. The results of this study explain to some extent the uncertainty of occurrence and damage of S. frugiperda populations and provide a basis for monitoring the migratory status and green control of S. frugiperda in the field.
    Predation capability of Orius sauteri (Hemiptera: Anthocoridae) on the 1st instar larvae of Spodoptera frugiperda (Lepidoptera: Noctuidae)
    DAI Xiao-Yan, WANG Yu, ZHAI Yi-Fan, ZHOU Hao, LI Li-Li, ZHENG Li, CHEN Hao
    2020, 63(5):  649-654.  doi:10.16380/j.kcxb.2020.05.014
    Abstract ( 366 )   PDF (1151KB) ( 107 )   PDF(mobile) (1151KB) ( 42 )     
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     【Aim】 To evaluate the predation capability and biological control potential of the minute pirate bug, Orius sauteri to the fall armyworm, Spodoptera frugiperda. 【Methods】 The predatory capacity of the 3rd, 4th and 5th instar nymphs and female adults of O. sauteri on the 1st instar larvae of S. frugiperda were assayed in the laboratory. The Holling-type II model was used to fit the functional response and searching efficiency of O. sauteri on the 1st instar larvae of S. frugiperda. 【Results】 The predation of the 3rd, 4th and 5th instar nymphs and female adults of O. sauteri on the 1st instar larvae of S. frugiperda followed a Holling-type II functional response. The female adults of O. sauteri preying on the 1st instar larvae of S. frugiperda had the highest predation rate, with the a′/Th value of 15.85 individuals per day, 1/Th value of 23.26 individuals per day and handling time of 0.043 d, respectively. The 4th instar nymphs of O. sauteri preying on the 1st instar larvae of S. frugiperda had the lowest predation rate, with the a′/Tvalue of 10.85 individuals per day. The predation amount of O. sauteri to the 1st instar larvae of S.frugiperda was positively correlated with the prey density, while its searching efficiency was negatively correlated with the prey density. 【Conclusion】 The results indicate that O. sauteri has a good control potential on S. frugiperda. These results provide a theoretical basis for evaluating the potential of O. sauteri as a biological control for S. frugiperda.
    CONTENTS
    Contents of Vol. 63 Issue 5
    2020, 63(5):  655-655. 
    Abstract ( 311 )   PDF (496KB) ( 34 )     
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