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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 April 2024, Volume 67 Issue 4
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  • INTRODUCTION
    Rice pests: Research progresses and prospects
    LI You-Zhi, FANG Ji-Chao
    2024, 67(4):  443-455.  doi:10.16380/j.kcxb.2024.04.001
    Abstract ( 96 )   PDF (1864KB) ( 112 )     
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    Rice, as a major staple crop in China, is directly threatened by disease and pest infestations, which jeopardize its safe production. Rice pests are diverse, and their outbreak mechanisms are complex, making the development of green control technologies challenging. Indepth research into rice pest monitoring and early warning technologies, developmental and reproductive regulation mechanisms, chemical communication mechanisms, and novel control technologies not only helps elucidate the outbreak mechanisms of rice pests but also provides new effective control targets and techniques for integrated pest management. In recent years, Chinese scholars have made significant progress in the field of rice pest research, gaining important achievements in multiple research directions, and some recent research findings were presented in this special issue. In this article, we outline the latest progresses in rice pest research at home and abroad, introduce the main research contents of this special issue, and propose the following three research directions worthy of further attention: (1) intelligent monitoring and early warning of rice pests; (2) mechanisms and evolution patterns of rice pest outbreaks; and (3) exploration of green control targets for rice pests and the construction and application of sustainable control systems.
    RESEARCH PAPERS
    Functional analysis of the G-protein β-subunit gene in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    XU Hang-Peng, REN Peng-Peng, ZHANG Chuan-Xi, LU Jia-Bao
    2024, 67(4):  456-467.  doi:10.16380/j.kcxb.2024.04.002
    Abstract ( 113 )   PDF (34139KB) ( 123 )     
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    【Aim】This study aims to identify the G-protein β-subunit gene (NlGβ) in the brown planthopper, Nilaparvata lugens, and analyze its function, so as to supply a potential novel target gene for RNAi-based control of N. lugens. 【Methods】The coding sequence (CDS) of NlGβ of N. lugens was cloned and verified using PCR, and subjected to bioinformatics analysis. The spatiotemporal expression patterns of NlGβ were analyzed based on its transcriptome expression profiles in different developmental stages (egg, 1st-5th instar nymphs, and female and male adults) and adult tissues (head, leg, gut, cuticle, fat body, female reproductive system, and male reproductive system) of N. lugens. Microinjection of dsRNA against NlGβ was performed on the 2nd and 5th instar nymphs to silence NlGβ. Individual and female reproductive system phenotypes were observed, and the survival rate, number of eggs laid per female, and egg hatching rate were counted. Additionally, transmission electron microscopy was employed to observe the lateral oviduct intumescent region. 【Results】 The CDS of NlGβ (GenBank accession no.: XP_022200908.1) of N. lugens was 948 bp in length. The NlGβ protein comprised seven WD40 domains and four WD_REPEATS_1 motifs, indicating its conservation. Apart from the homologous proteins found in orthopteran insects, homologous NlGβs from other insect orders clustered well within the same evolutionary branch. The expression level of NlGβ exhibited periodic change during the 1st-3rd instar nymphal stages, and those in the 5th instar female nymphs and female adults were higher than those in the 5th instar male nymphs and male adults. NlGβ was expressed in various tissues of adults, with the highest expression level in the fat body, and the expression level of NlGβ in female reproductive system was higher than that in male reproductive system. Silencing NlGβ in the 2nd instar nymphs resulted in molting difficulty, leading to a significant decrease in the survival rate compared to the dsGFP control group. Silencing NlGβ in the 5th instar nymphs resulted in abnormal abdominal swelling in adult females, malformed ovarian development, a significant decrease in the number of eggs laid per female compared to the dsGFP control group, failure of egg hatching, an increase in secretion within the lateral oviduct intumescent region, and degradation of epithelial cells. 【Conclusion】 NlGβ is closely associated with the growth and development of N. lugens and the reproduction of its female individuals.
    Effects of seed soaking with Cordyceps javanica JS001 on rice growth and defense against Nilaparvata lugens (Hemiptera: Delphacidae)
    NIU Hong-Tao, ZHANG Zhi-Chun, ZHAO Dong-Xiao, WANG Na, WANG Li-Hua, CHEN Dan-Yan, GUO Hui-Fang
    2024, 67(4):  468-476.  doi:10.16380/j.kcxb.2024.04.003
    Abstract ( 49 )   PDF (3053KB) ( 61 )     
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    【Aim】 To clarify the role of the newly registered fungal insecticide Cordyceps javanica JS001 in regulation of rice growth and defense against the brown planthopper, Nilaparvata lugens.【Methods】 Rice seeds were soaked with different concentrations (1×104, 1×106 and 1×108 conidia/mL) of C. javanica JS001 conidial suspension for 48 h in laboratory, and those soaked with 0.01% Triton X-100 solution were used as the control. After 8 d of culture, the growth of rice seedlings was measured, and the behavior selection responses of N. lugens adults to rice seedlings were determined. Effects of seed soaking with 1×108 conidia/mL of C. javanica JS001 conidial suspension on the contents of secondary metabolic compounds in rice seedlings were analyzed by GC-MS/MS. The rice seeds were soaked for 48 h in a C. javanica JS001 conidial suspension at the concentration of 1×107 conidia/mL and clean water (control), respectively, and the individual numbers of rice planthoppers and spiders were investigated at 50 d after direct seeding in paddy fields.【Results】 The results showed that compared to the control, seed soaking in C. javanica JS001 conidial suspension at the concentrations of 1×106 and 1×108 conidia/mL not only significantly promoted rice seed germination, and root and shoot growth of rice seedlings, but also reduced the selectivity of N. lugens adults to rice seedlings. The results of compound analysis showed that the contents of defensive compounds such as hydrogen peroxide, oleic acid and octane were significantly higher in rice seedlings from seeds soaked with 1×108 conidia/mL of C. javanica JS001 conidial suspension than those in the control. Whereas the content of 2-nononone, a compound attracting N. lugens, was significantly lower in rice seedlings from seeds soaked with C. javanica JS001 conidial suspension than that in the control. Field trials showed that, compared with the control, seed soaking with 1×107 conidia/mL of C. javanica JS001 conidial suspension significantly reduced the number of rice planthoppers in paddy fields, but had no effect on the number of predatory spiders.【Conclusion】Seed soaking with C. javanica JS001 could not only promote the growth of rice seedlings, but also improve the defense of rice plants against N. lugens. Field trials further clarified the role of C. javanica JS001 in enhancing rice defense against rice planthoppers. These results can provide a new way for the application of C. javanica and the formulation of biological control strategies for rice planthoppers.
    Analysis of the reduced pesticide use and enhanced effectiveness in controlling rice pests through transplanting insecticide-pretreated rice seedlings
    WEI Qi, ZHANG Ming, ZHU Xu-Hui, HE Jia-Chun, LIU Lian-Meng, LAI Feng-Xiang, WANG Wei-Xia, WAN Pin-Jun, LIU Long-Sheng, FU Qiang
    2024, 67(4):  477-489.  doi:10.16380/j.kcxb.2024.04.004
    Abstract ( 44 )   PDF (1771KB) ( 46 )     
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    【Aim】 Taking the novel, highly effective, and long-lasting insecticides triflumezopyrim and tetraniliprole as examples, this study aims to investigate the practical significance of reduced pesticide use and enhanced effectiveness in controlling rice pests through transplanting insecticide-pretreated rice seedlings. 【Methods】 Laboratory simulation experiments involving transplanting insecticide-pretreated rice seedlings were conducted to assess the toxicity and duration of efficacy of triflumezopyrim (active ingredient, a.i.) exposure to rice seedlings at the doses of 1.95, 5.85 and 9.75 mg a.i./m2 against the adults or nymphs of the brown planthopper, Nilaparvata lugens, and the white-backed planthopper, Sogatella furcifera, respectively. Field experiments for transplanting high-dose insecticide-pretreated rice seedlings were carried out to evaluate their control efficacy against the rice stem borer, Chilo suppressalis, and rice planthoppers, as well as the impact of different modes of pesticide application on the population dynamics of parasitic wasps in paddy fields, in Hangzhou, Zhejiang Province, and Hengyang, Hunan Province, respectively, for early-, mid-, and late-season rice crops. 【Results】 In the laboratory, transplanting rice seedlings pretreated with 5.85 and 9.75 mg a.i./m2 of triflumezopyrim caused exceeding 75% corrected mortality rates in N. lugens adult females and the 3rd instar nymphs at 35 d after transplanting (DAT). The corrected mortality rate of S. furcifera adult females exceeded 80% when transplanting rice seedlings exposed to 5.85 mg a.i./m2 of triflumezopyrim at 28 DAT. For controlling C. suppressalis in early-season rice, the applications of tetraniliprole at the doses of 12.75 and 25.50 mg a.i./m2 resulted in a corrected control efficacy of over 85% at 35 DAT. The comprehensive analysis of the field experiment results in both mid- and late-season rice in Hangzhou and Hengyang revealed that transplanting rice seedlings exposed to 5.85 mg a.i./m2 of triflumezopyrim and 25.50 mg a.i./m2 of tetraniliprole could reduce pesticide applications once or twice and the usage of effective pesticide ingredients by over 98%. Moreover, this practice of pesticide application method maintained control efficacy comparable to conventional spraying, resulting in an increase in the total number of parasitic wasp species by 29.0%-49.7% and their total number of individuals by 61.2%-69.3%, respectively. 【Conclusion】The application of highly effective and long-lasting insecticides to rice seedlings before transplanting could reduce the frequency and quantity of pesticide use during the early stage of rice cultivation, thus yielding favorable economic and ecological benefits. This study offered valuable guidelines to promote environmentally friendly management of rice diseases and pests through the application of transplanting pesticide-pretreated rice seedlings.
    Effects of four adjuvants on the toxicity of botanical pesticide 1% azadirachtin WG against the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    CHANG Xiang-Qian, LŰ Liang, ZHENG Zheng-An, WANG Jing, DENG Ying-Jun, YANG Xiao-Lin, WANG Zuo-Qian, ZHANG Shu
    2024, 67(4):  490-497.  doi:10.16380/j.kcxb.2024.04.005
    Abstract ( 41 )   PDF (1331KB) ( 34 )     
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    【Aim】 This study aims to explore the effects of four adjuvants, namely orange peel essential oil (OPEO), γ-aminobutyric acid (GABA), lecithin and diethyl maleate (DEM), on the toxicity of the botanical pesticide 1% azadirachtin (AZ) water dispersible granule (WG), and to screen adjuvants with synergistic effect as tank-mix adjuvants of 1% AZ WG to control the brown planthopper, Nilaparvata lugens. 【Methods】 The toxicity of AZ and AZ with adjuvants OPEO, GABA, lecithin or DEM to the 3rd instar nymphs of N. lugens was evaluated by the rice seedling dipping method and continuous immersion method, and the activities of glutathione S-transferase (GST), carboxylesterase (CarE) and acetylcholinesterase (AChE) in the 3rd instar nymphs of N. lugens after treatment with 20 mg a.i./L AZ or 20 mg a.i./L AZ with adjuvants were determined. The effect of adding adjuvants on the contact angle of AZ solution (40 mg a.i./L) on the leaf of rice was evaluated. 【Results】At 96 h after the rice seedling dipping treatment, the addition of DEM had a significant synergistic effect on the gastric toxicity of AZ, with the synergistic ratio of 1.512, while at 72 h after the continuous immersion treatment, the addition of OPEO or DEM significantly increased the systemic activity of AZ, with the synergistic ratios of 1.486 and 1.560, respectively. The GST activities in the 3rd instar nymphs of N. lugens in treatments with AZ plus OPEO and AZ plus DEM were decreased by 69.4% and 65.5%, respectively, and the CarE activity in treatment with AZ plus DEM was decreased by 88.2% as compared to those in just AZ treatment. After adding OPEO or DEM, the initial contact angles of liquid droplets of AZ solution on the adaxial leaf of rice was reduced from 110° to 64.5° and 67.9°, respectively. 【Conclusion】 Adding OPEO or DEM can significantly improve the toxicity of AZ to N. lugens, and improve the wetting ability of AZ solution on the leaf of rice. So, the two substances have some potential value as tank-mix adjuvants of 1% AZ WG to control N. lugens.
    Monitoring of chlorantraniliprole resistance in the rice leaffolder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) and the cross-resistance of its chlorantraniliprole-resistant populations to other diamide insecticides
    WANG Li, DONG Bei-Bei, LIU Si-Tong, CHEN Yun-Xiao, YANG Feng-Xia, ZHANG Shuai, GAO Cong-Fen
    2024, 67(4):  498-506.  doi:10.16380/j.kcxb.2024.04.006
    Abstract ( 65 )   PDF (1190KB) ( 63 )     
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    【Aim】 The objective of this research is to clarify the resistance level and resistance stability of chlorantraniliprole in the rice leaffolder, Cnaphalocrocis medinalis, and to determine whether there are cross-resistance to other diamide insecticides in chlorantraniliprole-resistant populations. 【Methods】 The rice seedling dipping method was adopted to determine the resistance of 32 field populations of C. medinalis collected from nine provinces (autonomous regions) to chlorantraniliprole and tetraniliprole, the cross-resistance to other diamide insecticides in two chlorantranilipeole-resistant populations, and the resistance stability when the populations from Youxian, Hunan, Qianshan, Anhui, Lujiang, Anhui and Xing′an,Guangxi were not exposed to chlorantraniliprole in laboratory. 【Results】 The resistance of chlorantraniliprole in C. medinalis field populations kept increasing during 2019-2022. Lujiang, Xing′an, Wuxue, Danyang and Qianshan populations were monitored for the first time to have developed high level of resistance to chlorantraniliprole (102.3-135.1-fold), and other populations also reached moderate level of resistance (10.3-97.1-fold) in 2022. To tetraniliprole, all the monitored field populations kept susceptible during 2019-2021, while the populations monitored in 2022 have developed moderate level of resistance (41.9-98.0-fold). Moreover, the cross-resistance experiment results revealed that Jiaxing and Qianshan populations which appeared about 100-fold resistance to chlorantraniliprole also showed 31.6-100.5-fold cross-resistance to cyhalodiamide, tetraniliprole, cyantraniliprole, cyclaniliprole and tetrachlorantraniliprole. In addition, the chlorantraniliprole resistance of field populations decreased rapidly after 2-4 generations of successive rearing without exposure to insecticides in laboratory. 【Conclusion】 The field populations of C. medinalis have developed moderate to high level of resistance to chlorantraniliprole and tetraniliprole. Moderate to high level of cross-resistance to five other diamide insecticides was found in chlorantraniliprole-resistant populations. Besides, the resistance to chlorantraniliprole was unstable in C. medinalis field populations. So, we strongly suggested limiting or suspending the application of diamide insecticides in order to delay the resistance development and postpone the application of diamide insecticides in C. medinalis control in the future.
    Calling and mating behaviors of Sesamia inferens (Lepidoptera: Noctuidae) adults in the environment of high-dose sex pheromone for mating disruption
    GUI Jia-Wei, WANG Wei-Ying, YAO Xiao-Ming, WU Shao-Long, LIU Tian-Bo, LIN Yu-Feng, ZHAO Hong, GUO Qian-Shuang, DU Yong-Jun
    2024, 67(4):  507-516.  doi:10.16380/j.kcxb.2024.04.007
    Abstract ( 35 )   PDF (1810KB) ( 22 )   PDF(mobile) (1810KB) ( 1 )     
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    【Aim】 Through the laboratory study on the calling and mating behaviors of the pink stem borer, Sesamia inferens, in a high-dose sex pheromone environment, the differences in inhibiting the calling and mating of S. inferens adults between the sex pheromone compounds cis-11-hexadecenal (Z11-16∶Ald) and cis-11-hexadecenyl acetate (Z11-16∶Ac) were analyzed and compared, to provide technical parameters for effective mating disruption technology of S. inferens in the field.【Methods】 In the wind tunnel, a high-dose sex pheromone environment was simulated, and the moving distance, calling and mating rates of female and male adults, as well as sex pheromone titers of female adults of S. inferens were measured through a combination of 2-D behavioral recording and analysis, behavioral observation and ovarian dissection, as well as extraction and GC-MS analysis of sex pheromone. The efficacy of mating disruption by synthetic sex pheromone was evaluated in the field by using active pheromone aerosol dispensers.【Results】 The moving distance of the male adults of S. inferens in the 1st hour of scotophase was longer than that in the other time periods. The moving distance of the male adults of S. inferens in the Z11-16∶Ac environment accounted for 51.8%±9.3% of the moving distance during the entire scotophase, and was much longer than that in the control (no sex pheromone released) and Z11-16∶Ald environments, however, no significant difference was found in the moving distance of female adults among different time periods of scotophase. The proportions of ovipositor extrusion of female adults in the Z11-16∶Ac and Z11-16∶Ald environments were significantly lower than that in the control environment. In the control environment, the proportion of ovipositor extrusion of the 1-day-old female adults was 76.7%±14.6%, which was significantly higher than those in the Z11-16∶Ald and Z11-16∶Ac environments [(29.2%±13.1%) and (26.7%±11.7%), respectively]. However, there was no significant difference in the time and duration of ovipositor extrusion of female adults at different day-old in various mating disrupted environments. In the control environment, the mating rate of female and male adults was 72.2%±5.6%, but that in the Z1116∶Ac environment was 40.5%±3.4%, and that in the Z11-16∶Ald environment was only 45.2%±3.1%, suggesting that the mating rate in the control group was significantly higher than those in the mating disruption groups. In different mating disrupted environments, there was no significant difference in the pheromone titers of Z11-16∶Ald and 16∶Ac in female adults. Significant reduced sex pheromone titers of Z11-16∶OH and Z11-16∶Ac were found in the treatment by Z11-16∶Ac. The sex pheromone titers of Z11-16∶OH and Z11-16∶Ac in female adults in the control environment were (3.79±2.56) and (7.29±4.49) ng, respectively, and reduced to only (0.80±0.59) and (1.99±0.45) ng in the Z11-16∶Ac environment, respectively. The pheromone titers of Z11-16∶OH and Z11--16∶Ac in the Z11-16∶Ald environment showed no significant difference from those in the control environment. Field experiments verified the efficacy of mating disruption. Z11-16∶Ac exhibited more stable and efficient efficacy of mating disruption than Z11-16∶Ald, and the efficacy of mating disruption of Z11-16∶Ald might be related to geographical populations. 【Conclusion】 Z11-16∶Ac is required for the stable and efficient mating disruption of S. inferens adults. It is not enough to rely only on Z11-16∶Ald for mating disruption because its efficacy is associated with geographical populations. Z11-16∶Ac not only interrupts with the calling of male adults, but also affects the sex pheromone titer of female adults and the mating of female and male adults, therefore, it can improve the control efficacy in many aspects.
    Effects of a sublethal concentration of abamectin and chlorpyrifos on the growth, development and reproduction of Cnaphalocrocis medinalis (Lepidoptera: Crambidae) with the experience of host switch
    GUO Jia-Wen, CHENG Yi-Sha, YANG Ya-Jun, SUN Tian-Yi, QIAN Jia-Ning, LU Yan-Hui, XU Hong-Xing , WU Yan , LŰ Zhong-Xian
    2024, 67(4):  517-527.  doi:10.16380/j.kcxb.2024.04.008
    Abstract ( 44 )   PDF (1689KB) ( 54 )     
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    【Aim】 The aim of this study is to clarify whether the experience of host switch will alter the effects of sublethal concentrations of insecticides on the growth, development and reproduction of Cnaphalocrocis medinalis, so as to provide a theoretical basis for the rational use of insecticides and the integrated management of C. medinalis. 【Methods】 Eggs were collected from the rice and wheat populations of C. medinalis, and transferred to other host plants for feeding until the 2nd instar, as larvae with different experience of host switch [rice population feeding on rice (R-R), rice population feeding on wheat (R-W), wheat population feeding on wheat (W-W), and wheat population feeding on rice (W-R)]. At 48 h after treatment of these larvae with the sublethal concentration (LC25) of abamectin and chlorpyrifos on rice or wheat leaves using the in vitro leaf impregnation method, the growth and development of the 3rd-5th instar larvae, the reproductive ability and longevity of adults were determined. 【Results】 Without insecticide treatment, host switching significantly affected the total duration of the 3rd-5th instar larvae, pupation rate, and pupal weight of C. medinalis, but had opposite effects on the rice and wheat populations. Treatments with the LC25 of abamectin and chlorpyrifos to the 2nd instar larvae significantly prolonged the total duration of the 3rd-5th instar larvae, but the degree of extension varied depending on the experience of host switch. LC25 of abamectin significantly reduced the pupation rate of larvae undergoing different host switches (except for the R-R group). LC25 of chlorpyrifos only significantly reduced the pupation rate of the W-W group. The pupal weight of the W-W and W-R groups significantly decreased after exposure of the 2nd instar larvae to LC25 of abamectin. The effects of host switching on the pupation rate and pupal weight of rice populations disappeared after treatment with LC25 of abamectin, while the effects of host switching on the pupation rate and pupal weight of wheat populations disappeared after treatment with LC25 of abamectin and chlorpyrifos. No matter which host switch experience or treatments with LC25 of abamectin and chlorpyrifos were used, the adult emergence rate, adult mating rate, and number of eggs laid per female were not affected. Host switching only significantly affected the egg hatching rate of the rice populations without insecticide treatment, but the egg hatching rate was not affected by treatments with LC25 of abamectin and chlorpyrifos. Compared with non-subjected to insecticide treatment, treatments with LC25 of abamectin and chlorpyrifos did not affect the female adult longevity, but treatment with LC25of chlorpyrifos significantly increased the male adult longevity in the W-W group. 【Conclusion】 The experience of host switch can affect the sublethal effects of abamectin and chlorpyrifos on C. medinalis. After treatment with LC25 of abamectin and chlorpyrifos on C. medinalis larvae with the experience of host switch, the growth and development of larvae and pupae were affected to varying degrees, but the effects on adult reproduction and longevity were relatively small. When using insecticides targeting C. medinalis and conducting toxicological experiments, the potential impact of host plant should be considered.
    Inhibitory effect of high temperature during the pupal stage on Cnaphalocrocis medinalis (Lepidoptera: Crambidae) populations
    ZHU A-Xiu, LIU Xiang-Dong
    2024, 67(4):  528-537.  doi:10.16380/j.kcxb.2024.04.009
    Abstract ( 50 )   PDF (1848KB) ( 61 )     
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    【Aim】This study aims to clarify the sensitivity of pupae of the rice leaf folder, Cnaphalocrocis medinalis, to high temperature, and to provide some biological indexes and models for predicting the developmental trend of populations at the pupal stage based on temperature.【Methods】The 1-5-day-old pupae of C. medinalis were exposed once to 37, 39 and 41 ℃ for 1-7 h, and the 1-day-old pupae were exposed to 37, 39 and 41 ℃ for 1-7 h/d in consecutive 2 and 3 d. The pupae reared at 27 ℃ were used as the control group. The eclosion rates of pupae, pupal duration, numbers of eggs laid per female, and egg hatching rates of the heat shock treatment groups and control group were measured. The relationships of the eclosion rate of pupae, pupal duration, number of eggs laid per female, and egg hatching rate with the heat shock duration were established using the linear regression method. 【Results】 After a single exposure of the 1-5-day-old pupae of C. medinalis to 37, 39 and 41 ℃ for 1-7 h, the pupal duration was prolonged, and the eclosion rate of pupae, number of eggs laid per female, and egg hatching rate decreased with the temperature rising as compared with those of the control group. At the same high temperature, the pupal duration was prolonged linearly, and the eclosion rate of pupae, number of eggs laid per female and egg hatching rate decreased linearly as the heat shock duration increased, and the rates of change were almost the same among treatments for different day-old pupae. After exposure to 37 and 39 ℃, the pupal duration of the 1-day-old pupae group was longer than that of the 3-5-day-old pupae group, while the eclosion rates of pupae of the former were lower than those of the latter. After consecutive heat shock on the 1-day-old pupae under 37 and 39 ℃, the pupal duration was shortened with the heat shock duration per day increasing. Similar trend was also observed in the heat shock under 41 ℃ for 2 d, but after 3 d of heat shock under 41 ℃ for 7 h/d, the pupal duration was elongated. The eclosion rate of pupae, number of eggs laid per female, and egg hatching rate decreased linearly as the heat shock duration per day extended, with the decrease magnitude increasing with the increased temperature, but they exhibited no significant difference between 2 and 3 d of heat shock. After exposure to 37, 39 and 41 ℃ with extended 1 h/d heat shock in 2 and 3 d, the eclosion rates of pupae decreased by 3.25%, 4.95% and 7.49%, respectively, the numbers of eggs laid per female decreased by 5.02%, 7.80% and 10.82%, respectively, and the egg hatching rates decreased by 2.20%, 3.31% and 5.05%, respectively, indicating the inhibitory effect of heat shock on the population development.【Conclusion】The pupae of C. medinalis are sensitive to high temperature and heat shock affects their development, survival, and fecundity. Therefore, the population size of C. medinalis will be predicted based on the degree and duration of high temperature at the pupal stage.
    Effects of emamectin benzoate and avermectin on the fecundity of Nilaparvata lugens (Hemiptera: Delphacidae) and the pest control capacity of parasitic wasp, Anagrus nilaparvatae (Hymenoptera: Mymaridae)
    HE Jia-Chun, WANG Kang-Yi, Mubashar HUSSAIN, WEI Qi, WAN Pin-Jun, LAI Feng-Xiang, WANG Wei-Xia, FU Qiang
    2024, 67(4):  538-548.  doi:10.16380/j.kcxb.2024.04.010
    Abstract ( 27 )   PDF (1644KB) ( 21 )     
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    【Aim】To evaluate the effects of ebamectin benzoate and avermectin on the fecundity of Nilaparvata lugens and its parasitic natural enemy Anagrus nilaparvatae, to explore the reasons leading to the resurgence of N. lugens in the field caused by the two insecticides.【Methods】 The effects of application of 225 mL/hm2 of 5% ebamectin benzoate microemulsion (ME) and 240 mL/hm2 of 5% avermectin suspension concentrate (SC) on the population density of N. lugens and parasitism rate of A. nilaparvatae adults were investigated in the field conditions. The toxicity of the two insecticides to the 4th instar nymphs of N. lugens was tested with rice stem-dipping method in the laboratory. In addition, the effects of different concentrations (LC15, LC30, LC50 and LC75) of the two insecticides on the fecundity of N. lugens and the survival and parasitic ability of A. nilaparvatae adults were also tested with rice stemdipping method in the laboratory. The toxicity of the two insecticides to A. nilaparvatae adults was determined by the method of residual film in glass tube, and their risk levels were evaluated. 【Results】 The field investigations showed that the application of either 5% emamectin benzoate ME or 5% avermectin SC significantly increased the population density of N. lugens in the fields, and significantly reduced the parasitism rates of A. nilaparvatae adults. The laboratory bioassay results revealed that the LC50 values of ebamectin benzoate and avermectin against the 4th instar nymphs of N. lugens were 1.20 and 2.03 mg/L, respectively. The number of eggs laid per female adult of N. lugens treated by either ebamectin benzoate (LC15-LC75) or avermectin (LC15-LC50) was significantly higher than that of the control. The LC50 values of ebamectin benzoate and avermectin against A. nilaparvatae adults were 0.0145 and 0.0205 mg/L, respectively. The safety factors for the dosage of emamectin benzoate and avermectin used in fields were 4.52×10-4-9.05×10-4 and 8.52×10-4-14.22×10-4, respectively, suggesting that the two insecticides have extremely high risk to A. nilaparvatae adults.【Conclusion】 The field application of ebamectin benzoate or avermectin could cause the resurgence of N. lugens because of two reasons. The first was that both insecticides would stimulate the oviposition of female adults of N. lugens, and the second was that both insecticides had high risk to A. nilaparvatae and greatly weakened the control efficacy of this important parasitic wasp on N. lugens. Therefore, we should decrease the use of the two insecticides in paddy fields to avoid the resurgence of N. lugens.
    Exogenous application of paclobutrazol induces the resistance of rice to planthoppers
    SUN Kai-Di, KUAI Peng, LV Jing, LOU Yong-Gen
    2024, 67(4):  549-558.  doi:10.16380/j.kcxb.2024.04.011
    Abstract ( 40 )   PDF (1587KB) ( 55 )     
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    【Aim】 Utilizing chemical elicitors to enhance the resistance of plants to insects and suppress pests is a new green pest management strategy. In this study, we investigated the underlying mechanisms of a chemical elicitor paclobutrazol (PBZ) in inducing the resistance of rice (Oryza savita) to rice planthoppers, to lay a foundation for future application in pest management. 【Methods】 Xiushui 110 rice plants were respectively grown in nutrient solutions containing different concentrations of PBZ for 24 h, then the newly hatched larvae of the brown planthopper, Nilaparvata lugens, or the white-backed planthopper, Sogatella furcifera were introduced, and their nymphal survival rates were determined at different time post insect infestation. The survival rates of N. lugens nymphs fed with the artificial diets containing 5 mg/L PBZ, 10 mg/L PBZ and defensive compounds [caffeoyl putrescine, carlinoside and prunin (1 and 10 mg/L), and mustard acyl agmatine (0.1 and 1 mg/L)], or sprayed with 5 and 20 mg/L PBZ solutions, were also measured. Moreover, the contents of signal molecules including salicylic acid (SA), hydrogen peroxide (H2O2) and ethylene (ET), and the defensive compounds mustard acyl agmatine, caffeoyl putrescine, carlinoside and prunin in rice plants grown in nutrient solutions with 5 mg/L PBZ, infested by N. lugens nymphs, and grown in nutrient solution with 5 mg/L PBZ and then infested by N. lugens nymphs were detected. 【Results】 When N. lugens nymphs fed on rice plants that were grown in nutrient solution containing 5 mg/L PBZ, their survival rate was reduced by 33.3% at 3 d after feeding, as compared to that in the control [grown in nutrient solution without PBZ], and when feeding on rice plants grown in nutrient solution containing 20 mg/L PBZ, nearly all nymphs died at 4 d. However, PBZ itself showed no direct toxic effects on N. lugens nymphs. The SA content in rice plants grown in nutrient solution with 5 mg/L PBZ for 24 h but without BPH infestation for another 24 h, and the H2O2 content in rice plants grown in nutrient solution with 5 mg/L PBZ for 24 h and then infested by N. lugens nymphs for 72 h significantly increased, and the contents of ET emitted from the rice plants grown in nutrient solution with 5 mg/L PBZ for 24 h but without BPH infestation for another 48-96 h, infested by N. lugens nymphs for 24-72 h, and grown in nutrient solution with 5 mg/L PBZ for 24 h and then infested by N. lugens nymphs for 48-96 h significantly reduced as compared with those in the control group . In addition, treatment with 5 mg/L PBZ induced the significant enhancement in the contents of two phenolic amine compounds (caffeoyl putrescine and mustard acyl agmatine) and two flavonoid compounds (carlinoside and prunin). The survival rates of N. lugens nymphs were significantly reduced when they fed on the artificial diets containing 1 or 10 mg/L caffeoyl putrescine, mustard acyl agmatine, carlinoside or prunin. 【Conclusion】 PBZ is an effective chemical elicitor that can significantly enhance the resistance of rice plants to rice planthoppers by activating the SA and H2O2 pathways, and inhibiting the ET pathway, as well as inducing the synthesis of related defensive compounds in rice.
    Effects of decoyinine on the resistance of rice varieties Xudao 10 and Xiangliangyou 900 to the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    GUI Wei, SHE Sheng-Yao, SHENG Chao-Qi, ZHANG Yuan-Yuan, YANG Guo-Qing, XU Gang
    2024, 67(4):  559-571.  doi:10.16380/j.kcxb.2024.04.012
    Abstract ( 27 )   PDF (2708KB) ( 31 )   PDF(mobile) (2708KB) ( 0 )     
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    【Aim】 Decoyinine (DCY) is a new plant growth regulator. The aim of this study is to explore the effects of seed soaking with DCY on the resistance of commercial rice varieties Xudao 10 and Xiangliangyou 900 to the brown planthopper, Nilaparvata lugens. 【Methods】 After the newly hatched nymphs fed on Xudao 10 and Xiangliangyou 900 rice plants pretreated with different concentrations [0(clean water as the control), 25, 50 and 100 mg/L] of DCY by seed soaking, the growth and development, adult fecundity and population life table parameters of N. lugens were determined and compared by age-stage, two-sex life table, and the population growth was simulated within 60 d. The effects of seed soaking with 100 mg/L DCY on the honeydew excretion, body weight, and feeding and oviposition preference of the female adults of N. lugens were also investigated. 【Results】 When N. lugens fed on rice variety Xudao 10 pretreated with different concentrations of DCY by seed soaking, the nymphal duration was significantly prolonged, the fecundity (number of eggs laid per female) was significantly decreased, the population parameters including net reproductive rate R0, intrinsic rate of increase rm and finite rate of increase λ were significantly decreased, and the mean generation time T and doubling time DT were significantly increased, as compared with those in the control. When N. lugens fed on Xiangliangyou 900 rice plants pretreated with different concentrations of DCY by seed soaking, the nymphal duration was significantly shortened, the number of eggs laid per female was significantly decreased, and only the mean generation time T was significantly increased, while the other population parameters showed no significant change, as compared with those in the control. The results of 60-d population simulation showed that the population size of the three treatment groups was smaller than that of the control group. The honeydew excretion and body weight of female adults of N. lugens after feeding on Xudao 10 and Xiangliangyou 900 rice plants pretreated with 100 mg/L DCY by seed soaking were significantly lower than those of female adults feeding on rice plants of the control group. The feeding and oviposition preference tests indicated that the female adults of N. lugens preferred to feed and oviposit on the control rice plants. 【Conclusion】 The resistance of commercial rice varieties Xudao 10 and Xiangliangyou 900 to N. lugens is enhanced by seed soaking treatment with DCY.
    BP neural network method for monitoring the population size of Nilaparvata lugens (Hemiptera: Delphacidae) based on multi-source data collected from rice canopy
    XIONG Zhi-Qiang, WANG Jia-Han, LIU Xiang-Dong
    2024, 67(4):  572-581.  doi:10.16380/j.kcxb.2024.04.013
    Abstract ( 36 )   PDF (1756KB) ( 25 )     
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    【Aim】 The automation and intelligence of population monitoring of the brown planthopper, Nilaparvata lugens, have not been resolved now. The aim of this study is to explore the relationship of canopy spectrum and temperature, and leaf chlorophyll content with the number of N. lugens on rice plants, and to establish a back propagation (BP) neural network to monitor the population size of N. lugens based on multi-source information fusion of hyperspectral, thermal imaging, and chlorophyll, so as to provide a new method for the development of automation and intelligence in monitoring N. lugens populations. 【Methods】 Under controlled conditions, rice was cultivated using the square plastic box, and different pairs (0, 1, 2, 3, 4, 5, 6 and 7 pairs) of female and male adults of N. lugens (female to male ratio=1∶1) were released onto rice plants at the tillering stage. Then, the number of N. lugens on rice (number of individuals per 4 hills of rice) was investigated on day 16, 27, 32, 44 and 60 post original infestation, and the spectral reflectance and temperature of rice canopy were measured using a hyperspectral spectrometer and a thermal imager, respectively. The relative content of chlorophyll in leaves was measured using a chlorophyll meter (soil and plant analyzer development, SPAD) as SPAD readings. The Pearson correlation method was used to analyze the correlations between these measured indexes and the number of N. lugens. The multivariate scattering correction was used to process the spectral reflectance data to reduce noise. The successive projection algorithm was adopted for dimensionality reduction and screening the sensitive band of hyperspectral reflectance. Using single source of spectral reflectance information and its multi-source information fusion with canopy temperature and SPAD readings as inputs, the modeling methods, the general (BPNN) and optimized BP neural networks by particle swarm optimization (PSO-BPNN) were used to establish the neural network models to monitor the population sizes of N. lugens damaging different periods. 【Results】 The reflectance from rice canopy at the near-infrared band 730-930 nm was significantly negatively correlated with the number of N. lugens damaging rice plants, and the temperature difference between rice canopy and air (TDC) and the SPAD readings of leaves were also significantly negatively correlated with the number of N. lugens. The coefficient of determination R2 of the prediction set for monitoring the population size of N. lugens using the BPNN based on the noise reduction value of reflectance at the sensitive band of rice canopy screened by the successive projection algorithm could reach up to 0.504-0.892. The R2 of the predication set for monitoring the number of N. lugens by the BP neural network based on multi-source information fusion of canopy reflectance, TDC, and leaf SPAD readings could reach up to 0.640-0.975. Further, on the basis of multi-source information, the BP neural network optimized by particle swarm optimization (PSO) algorithm improved the accuracy for monitoring the number of N. lugens, and the R2 value of the predication set was up to 0.931-0.991. 【Conclusion】 The PSO-BP neural network method based on multi-source information fusion of rice canopy hyperspectral and thermal imaging, as well as leaf SPAD readings, has high accuracy and good effectiveness in monitoring the number of N. lugens, and is expected to be applied for automatic monitoring of N. lugens populations in paddy fields.

    Analysis of the relationship between main insect pests and natural enemies in paddy fields in Jianghan Plain, Central China
    PU Lei, CAI Wan-Lun, HUA Hong-Xia, SHEN Li-Yang, ZHU Hong-Yuan, LI Shao-Qin
    2024, 67(4):  582-588.  doi:10.16380/j.kcxb.2024.04.014
    Abstract ( 24 )   PDF (1083KB) ( 22 )     
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    【Aim】 This study aims to investigate and analyze the species composition of arthropod community in paddy fields and the interaction between main insect pests and natural enemies in Jianghan Plain of Central China, so as to provide a scientific basis for the development of a green management system for rice pests. 【Methods】The numbers of species and individuals of arthropods in 28 paddy fields in Jianli City, Qianjiang City, Jiangling County, and other cities and counties in Jianghan Plain were investigated at the tillering stage, booting stage and full heading stage of rice by suckingmachine method and sweeping-net method from 2019 to 2020. The effects of principal components on arthropod community in paddy fields and the interactions between the population size of main insect pests and the population size of natural enemies were analyzed by principal component analysis and grey correlation analysis. 【Results】 There were 169 arthropod species in paddy fields investigated in Jianghan Plain during 2019-2020. According to the nutrient feeding relationship, the arthropod community in paddy fields was divided into four subcommunities, including 6 orders, 33 families and 57 species of phytophagous species, 7 orders, 30 families and 50 species of predatory species, 2 orders, 15 families and 44 species of parasitic species, and 5 orders, 16 families and 18 species of neutral species. In the arthropod community in paddy fields, Sogatella furcifera and Nephotettix bipunctatus had the main contribution to the 1st principal component, Orius tantillus and Paederus fuscipes had the main contribution to the 2nd principal component, and Cnaphalocrocis medinalis and Laodelphax striatellus had the main contribution to the 3rd principal component. The first three natural enemies whose population size had high correlations with the population size of the main pest C. medinalis were ranked in a descending order as follows: Hylyphantes graminicola>Pardosa pseudoannulata>Misumenops tricuspidatus, while those whose population size had high correlations with the population size of the main insect pest S. furcifera were ranked in a descending order as follows: Tetragnatha nitens>Cyrtorhinus lividipennis>P. pseudoannulata. 【Conclusion】 The difference of arthropod community composition in paddy fields originates mainly from the population size of the dominant phytophagous insects and predatory natural enemies. The population size of H. graminicola shows the closest coupling pattern to that of C. medinalis, and similar coupling pattern exists in the predator T. nitens to S. furcifera, indicating that these predators play dominant roles in controlling the respective preys.
    REVIEW ARTICLES
    Research progresses of the regulatory mechanisms of wing polyphenism in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    CHEN Sun-Jie, XU Hai-Jun
    2024, 67(4):  589-594.  doi:10.16380/j.kcxb.2024.04.015
    Abstract ( 56 )   PDF (992KB) ( 57 )     
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    Insect wing polyphenism, as a typical example of the developmental plasticity of organisms, is the result of evolutionary adaptation to complex and variable environments. The brown planthopper (BPH), Nilaparvata lugens, is a representative model of insect wing polyphenism, and its nymphs have the option of developing into shortwinged or longwinged adults. The ability of developing into longwinged morphs enables BPHs to migrate over long distances, causing an infestation over a wide geographic rice planting area in Asia. Since the 1960s, there has been extensive research into the mechanisms behind wing polyphenism in BPHs, revealing that numerous environmental factors such as population density, host plant quality, temperature and photoperiod, and juvenile hormone can all influence the proportion of wing morphs. In the past 20 years, facilitated by the rapid development of biotechnologies in genomics, RNAi and gene editing, a breakthrough finding has been achieved in wing polyphenism of BPHs. FoxO has been identified as a switch gene for wing polyphenism in BPHs, where silencing or knocking out FoxO leads to the development of long-winged adults. Meanwhile, the insulin signaling pathway can inhibit FoxO from entering the nucleus by phosphorylating it, thus participating in wing polyphenism regulation. The zinc finger transcription factor Zfh1 can regulate the transcription of FoxO through promoter binding, paralleling the insulin signaling pathway in controlling wing polyphenism. Another zinc finger transcription factor, Rotund, can interact with FoxO to co-regulate wing polyphenism of BPHs. Additionally, the sex determination gene Transformer-2 and the c-Jun N-terminal kinase pathway can also influence wing polyphenism, indicating the presence of diverse molecular regulatory mechanisms for wing polyphenism in BPHs. Given the differences in the mechanisms of wing polyphenism among different suborders of Hemiptera, the elucidation of mechanisms in BPHs is far from fully explaining the mechanisms of wing polymorphism in Hemiptera or even the entire class of insects. However, these findings position themselves at the edge of wing polyphenism in insects and deepen our understanding of developmental plasticity and evolution of insect wings as well as other tissues.
    CONTENTS
    Contents of Vol. 67 Issue 4
    2024, 67(4):  595-595. 
    Abstract ( 19 )   PDF (531KB) ( 6 )     
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