2019 Vol. 18 No. 4 Previous Issue    Next Issue

    Special Issue: Plant protection: Current status, progress and challenges in China
    Research Article

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    Special Issue: Plant protection: Current status, progress and challenges in China
    Editorial- Plant protection: Current status, progress and challenges in China
    WAN Fang-hao
    2019, 18(4): 703-704.  DOI: 10.1016/S2095-3119(19)62645-6
    Abstract ( )   PDF (315KB) ( )  
    China is one of the countries in the world that is severely damaged by crop diseases, pests, and weeds.  There are more than 1 700 species of agricultural pests occurring annually, 53 of which are on the list of the 100 worst pests in the world (Chen and Wang 2014; Wu 2018).  Currently, China is still greatly challenged by a growing problem of agricultural pests that threaten the economy and health and pose ecological risks under the conditions of global climate change, economic integration, crop structure adjustment and so on.  Plant protection against crop diseases, insect pests and noxious weeds is necessary to ensure high-quality crop production and food safety.  However, traditional strategies of plant protection have mainly involved chemical pesticides, which bring a series of other problems, such as pesticide residues, pest resistance and resurgence.  During the past decades, Chinese scientists have been committed to
    research on developing new plant protection methods through integrated pest management (IPM) in a safe, cost-effective and sustainable manner.  In this field, we organized this special issue to provide the most updated theories and technologies of plant protection.

    There are 21 manuscripts accepted for publication in this special issue, including 13 reviews and eight research articles.  The 13 reviews involved a variety of relevant disciplines, such as insect ecology and molecular biology, phytopathology, biological invasions and pest management science.  Three papers documented the progress in insect ecology and molecular biology.  Bao and Zhang (2019) reported the recent molecular research in Nilaparvata
    lugens on its endosymbionts, virus transmission, insecticide resistance, and host interaction.  Li et al. (2019) gave an overview of the discovery, biogenesis and functions of four kinds of ncRNAs, including miRNA, piRNA, circRNA and lncRNA in insects, and Xue et al. (2019) investigated thermal adaptation of Drosophila from three aspects of behavior, plastic responses and micro-evolution under global climate change.  Two papers investigated the threats from pathogenic microbes, Chinese wheat mosaic virus and fire blight disease, to wheat and pear production, respectively, in China, and provided cost-effective countermeasures to control these diseases in the future (Guo et al. 2019; Zhao Y Q et al. 2019).  Four other papers mainly focused on the introduction routes, expansion process (adaptation and interactions), ecological effects and control of invasive insects, including Bemisia tabaci, Phenacoccus solenopsis, Bactrocera dorsalis and Solenopsis invicta (Chu et al. 2019; Liu H et al. 2019; Tong et al. 2019; Wang et al. 2019a).  Additionally, there were three papers that provided sound prospects for improving the strategies currently employed in agricultural control, biological control and chemical control (Lu et al. 2019; Pan et al. 2019; Wang et al. 2019b).  Finally, Liu (2019) evaluated the current status and challenges of rodent biology and management in China.  

    The eight research articles mainly involved the three aspects of reproductive biology and chemical ecology of pests, safety assessments of genetically modifed crop and weed control (He et al. 2019; Huang et al. 2019; Liu  Y M et al. 2019; Lü et al. 2019; Muhammad et al. 2019; Xiu et al. 2019; Zhao C C et al. 2019; Zheng et al. 2019).  Among those, there were two papers that explored the tradeoffs between reproduction and energy reserves (Huang et al. 2019; Zhao C C et al. 2019).  Liu Y M et al. (2019) proved that Bt maize expressing cry1Ab/2Aj or cry1Ac genes posed a negligible risk to adult Chrysoperla sinica.  In addition, Muhammad et al. (2019) and He et al. (2019) evaluated the effects of weed control under wheat stubble management and different culture patterns, respectively.

    I believe these articles in this special issue should be of broad interest to a diverse audience at multiple levels in the areas of plant protection, and they are well-suited for the readers of Journal of Integrative Agriculture.  I sincerely appreciate all the authors who gave their high-quality contributions and efforts to this special issue.
    Parasitoid wasps as effective biological control agents
    WANG Zhi-zhi, LIU Yin-quan, SHI Min, HUANG Jian-hua, CHEN Xue-xin
    2019, 18(4): 705-715.  DOI: 10.1016/S2095-3119(18)62078-7
    Abstract ( )   PDF (764KB) ( )  
    Biological control (biocontrol) is a safe, sustainable approach that takes advantage of natural enemies such as predators, parasitic insects or pathogens to manage pests in agroecosystems.  Parasitoid wasps, a very large evolutionary group of hymenopteran insects, are well-known biological control agents for arthropod pests in agricultural and forest ecosystems.  Here, we summarize the recent progress on the application of parasitoid wasps in biocontrol in China for the last five years.  These include species diversity of parasitoid wasps, identification of dominant parasitoid wasps associated with insect pests and biocontrol practices (three types of biological control, i.e., classical, augmentative and conservation biological control) in several Chinese agroecosystems.  We then treat different mass-rearing and release technologies and the commercialization of several parasitoid wasp species.  We also summarize other work that may have a potential use in biocontrol, including the effect of plant volatiles on parasitoids and recent advance in the molecular mechanisms underlying the host regulation by parasitoid wasps.  Future research area and applied perspectives are also discussed, noting that advances in biocontrol technologies in Chinese agriculture informs research at the global level.
    Recent advances in molecular biology research of a rice pest, the brown planthopper
    BAO Yan-yuan, ZHANG Chuan-xi
    2019, 18(4): 716-728.  DOI: 10.1016/S2095-3119(17)61888-4
    Abstract ( )   PDF (771KB) ( )  
    The brown planthopper, Nilaparvata lugens Stål, has become a major threat in tropical Asian and China since the rice green revolution of the 1960s.  Currently, insecticide application remains the primary choice for controlling this rice insect pest, but heavy use of insecticides poses dangerous risks to beneficial natural enemies and pollinators, and stimulates N. lugens reproductivity, and has caused a resurgence of the pest in the major rice-planting regions throughout Asia.  Achieving the long-lasting goal of sustainable management of N. lugens requires understanding of the molecular basis of outbreaks of the pest and the development of environment-friendly pest-control strategies.  Here, we review the recent molecular advances in N. lugens research on the aspects of its endosymbionts, virus transmission, insecticide resistance, and interaction between N. lugens and rice plants.  We also put forward further research directions that may shed some lights on management of the rice pest.
    Progress and prospects of noncoding RNAs in insects
    LI Mei-zhen, XIAO Hua-mei, HE Kang, LI Fei
    2019, 18(4): 729-747.  DOI: 10.1016/S2095-3119(18)61976-8
    Abstract ( )   PDF (622KB) ( )  
    With the rapid development of high-throughput sequencing technology and bioinformatics algorithms, great progress has been made in the field of noncoding RNA (ncRNA) in the last decade.  RNA molecules have been regarded only as a messenger between DNA and protein for decades, but now they have new roles in the biological process as ncRNAs.  A growing number of ncRNAs have been identified in insects from the RNA-Seq data of small RNA libraries or transcriptomes.  ncRNAs have varied regulatory functions at the epigenetic, transcriptional, or post-transcriptional levels, and participate in almost all types of biological processes.  Here, we review the research progress of four kinds of ncRNAs, including microRNA (miRNA), Piwi-interacting RNA (piRNA), circular RNA (circRNA), and long noncoding RNA (lncRNA) in insects.  The discovery, biogenesis mechanisms, and regulatory functions of these ncRNAs are presented here to provide a comprehensive understanding of insect ncRNAs and to promote the application of ncRNAs in insect pest control. 
    Invasion genetics of alien insect pests in China: Research progress and future prospects
    CHU Dong, QU Wan-mei, GUO Lei
    2019, 18(4): 748-757.  DOI: 10.1016/S2095-3119(17)61858-6
    Abstract ( )   PDF (434KB) ( )  
    An unwelcome side effect of the globalization of the world’s economy and dramatic increase in human mobility and trade has been a marked increase in species invasions that have posed severe threats to the ecological, economic, and/or social stability of the introduced regions.  In this review, we analyzed the application of molecular markers in invasion genetics of invasive alien insect pests (IAIPs) in China based on a bibliometric survey.  Our report discusses the considerable progress that has been made during the past two decades in understanding the invasion genetics of IAIPs in China.  We reviewed the major findings in the main topics including the effects of origin and routes of invasion on genetic structure, spatial and temporal genetic changes, factors contributing to the genetic changes of IAIPs, and genetic mechanisms involved in IAIPs’ invasions.  On the other hand, some of these research areas remain relatively unexplored in China, especially those pertaining to spatial and temporal genetic changes of IAIPs and genetic mechanisms of IAIPs’ invasions.  Finally, the future research prospects of IAIPs in China are discussed.  We hope this review will stimulate an interest in and provide an increased understanding of the field of invasion genetics of IAIPs in China, and provide a basis for future research in this area.
    Invasion biology of the cotton mealybug, Phenacoccus solenopsis Tinsley: Current knowledge and future directions
    TONG Hao-jie, AO Yan, LI Zi-hao, WANG Ying, JIANG Ming-xing
    2019, 18(4): 758-770.  DOI: 10.1016/S2095-3119(18)61972-0
    Abstract ( )   PDF (825KB) ( )  
    The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), which is native to North America, emerged as a major invasive insect pest of multiple crops in Asia at the beginning of the 21st century.  Considering the economic significance of this insect and its rapid worldwide spread, we examined the possible factors driving its invasions.  In this paper, we summarize the life history traits of P. solenopsis conceivably related to population development in invaded regions; these traits include its use of diverse host plants, reproductive capacity and mode, adaptation to temperature, response to food shortage, and insecticidal resistance.  Then, focusing on the multiple trophic interactions that may promote or hinder invasion, we review the mutualistic relationship of this mealybug with ants and predation and parasitism by natural enemies.  Finally, we suggest topics for future research and provide our perspective on the biological invasions of this mealybug.  We speculate that specific biological factors associated with this mealybug, particularly its wide host range, high reproductive potential, evolved changes in life history traits, and mutualism with ants have played important roles in its invasions, allowing this pest to become established and rapidly increase its population upon its introduction into new regions.
    Invasion, expansion, and control of Bactrocera dorsalis (Hendel) in China
    LIU Huan, ZHANG Dong-ju, XU Yi-juan, WANG Lei, CHENG Dai-feng, QI Yi-xiang, ZENG Ling, LU Yong-yue
    2019, 18(4): 771-787.  DOI: 10.1016/S2095-3119(18)62015-5
    Abstract ( )   PDF (818KB) ( )  
    The Oriental fruit fly, Bactrocera dorsalis (Hendel), is among the most destructive fruit/vegetable-eating agricultural pests in the world, particularly in Asian countries such as China.  Because of its widespread distribution, invasive ability, pest status, and economic losses to fruit and vegetable crops, this insect species is viewed as an organism warranting severe quarantine restrictions by many countries in the world.  To understand the characteristics and potential for expansion of this pest, this article assembled current knowledge on the occurrence and comprehensive control of the Oriental fruit fly in China concerning the following key aspects: invasion and expansion process, biological and ecological characteristics, dynamic monitoring, chemical ecology, function of symbionts, mechanism of insecticide resistance, control index, and comprehensive control and countermeasures.  Some suggestions for the further control and study of this pest are also proposed.
    Impact of the red imported fire ant Solenopsis invicta Buren on biodiversity in South China: A review
    WANG Lei, XU Yi-juan, ZENG Ling, LU Yong-yue
    2019, 18(4): 788-796.  DOI: 10.1016/S2095-3119(18)62014-3
    Abstract ( )   PDF (746KB) ( )  
    The red imported fire ant, Solenopsis invicta, is a problematic invasive species in China since at least 2003.  Over the past 15 years, a numerous studies were published on the impacts of this species on flora, fauna, and ecosystem function in natural and agricultural systems.  We reviewed the literature on S. invicta invasion biology and impacts on biodiversity in South China.  Both monogyne and polygyne colonies of S. invicta were introduced to China and polygyne colony is the dominant type.  The range expansion rate of S. invicta may reach 26.5–48.1 km yr–1 in China. S. invicta forage activities occur year-round, peaking in the summer and fall in South China and show a preference for insects and plant seeds.  We describe the ecological impacts of S. invicta on various habitats in South China, including arthropod community structure disruption and decreases in diversity and abundance of native ant species.  S. invicta can replace the role of native ants in mutualisms between ants and honeydew-producing Hemiptera, which results in loss of important food resources for native ants and natural enemies of hemipterans.  Further research is required to assess the complex ecosystem-level impacts of S. invicta in introduced areas. 
    Application of vetiver grass Vetiveria zizanioides: Poaceae (L.) as a trap plant for rice stem borer Chilo suppressalis: Crambidae (Walker) in the paddy fields
    LU Yan-hui, ZHENG Xu-song, LU Zhong-xian
    2019, 18(4): 797-804.  DOI: 10.1016/S2095-3119(18)62088-X
    Abstract ( )   PDF (801KB) ( )  
    Rice is an important staple food in China and it is at risk of attack by rice striped stem borer Chilo suppressalis, which occurs in most rice growing areas.  In recent years, severe C. suppressalis outbreaks have been observed in China mainly due to changes in the rice cultivation systems, wide adoption of hybrid varieties and resistance to the dominant insecticides.  Management relies primarily on chemical insecticides and resistance is an important contributing factor in these outbreaks.  As a result, food safety of agricultural produce is reduced and the ecological and environmental integrities are threatened as well.  Recently, environmentally friendly pest management measures, such as trap plants have been introduced for C. suppressalis management and this method can greatly reduce insecticide use.  Our previous results indicated that the vetiver grass (Vetiveria zizanioides) is a dead-end trap plant that can effectively attract the adult females of C. suppressalis to lay eggs on it but where larvae are unable to complete their life cycle.  This paper further explored the application of vetiver grass as a trap plant to manage C. suppressalis in the paddy fields.  This environment-friendly tool can not only reduce C. suppressalis populations, it can also increase the diversity and abundance of natural enemies that can provide better environmental conditions for rice production.
    Adaptation of Drosophila species to climate change - A literature review since 2003
    XUE Qi, Muhammad Zeeshan Majeed, ZHANG Wei, MA Chun-sen
    2019, 18(4): 805-814.  DOI: 10.1016/S2095–3119(18)62042–8
    Abstract ( )   PDF (793KB) ( )  
    Global climate warming has been exerting impacts on agricultural pests.  Pests also take some strategies to adapt to climate change.  Understanding such adaptation could benefit more accurate predictions and integrated management of pest.  However, adaptation to climate change has not been widely investigated in agricultural pests but has been well documented in model species, Drosophila, and reviewed by Hoffmann before 2003.  To provide recent progress and references for agricultural entomologists who interested in thermal biology, here we have reviewed literatures since 2003 about adaptation to temperature changes under climate change.  We mainly summarized thermal adaptation of Drosophila (especially to high temperatures) from three aspects, behaviors, plastic responses and micro-evolution and discussed how Drosophila increases their heat tolerance through these three mechanisms.  Finally, we summarized the measures of thermotolerance and concluded the main progress in recent decade about the behavioral thermoregulation, mortality risks driven by limited evolutionary and plastic response under climate change, geographic distribution based on basal rather than plastic thermotolerance.  We propose future work focus on better understanding adaptation of organisms including agricultural pests to climate change.
    Fire blight disease, a fast-approaching threat to apple and pear production in China
    ZHAO Yu-qiang, TIAN Yan-li, WANG Li-min, GENG Guo-min, ZHAO Wen-jun, HU Bai-shi, ZHAO You-fu
    2019, 18(4): 815-820.  DOI: 10.1016/S2095-3119(18)62033-7
    Abstract ( )   PDF (4840KB) ( )  
    Fire blight, caused by Erwinia amylovora, is a devastating disease of apples and pears, causing enormous economic losses around the world.  The disease is indigenous to North America and has spread to more than 50 countries since its discovery in 1870s.  Recent reports of the disease in China’s neighboring countries, including South Korea, Kyrgyzstan, and Kazakhstan, pose great threat to the world’s leading producer of apples and pears.  This mini-review intends to provide an update on the disease, pathogen biology, epidemiology, and control.  It will also provide some perspectives and suggestions for the apple and pear industry and growers in China, which will face the imminent threat of this devastating disease.  
    Chinese wheat mosaic virus: A long-term threat to wheat in China
    GUO Liu-ming, HE Jing, LI Jing, CHEN Jian-ping, ZHANG Heng-mu
    2019, 18(4): 821-829.  DOI: 10.1016/S2095-3119(18)62047-7
    Abstract ( )   PDF (8544KB) ( )  
    In China, a soil-borne virus causing a disease of winter wheat and associated with Polymyxa graminis, has been reported for many years and is now recognized as a new species, Chinese wheat mosaic virus (CWMV).  Since the determination of its genomic sequence, more progress has been made in understanding its genomic structure and functions.  Molecular and serological methods have been developed to help survey the distribution of the virus and to provide the basic information needed for disease forecasting and control.  At present, the best countermeasure is cultivation of resistant wheat varieties.  In addition, development and application of some auxiliary countermeasures, such as rotation of non-host crops, delayed seed-sowing, reasonable application of nitrogen fertilizer, and treatment of imported seeds with fungicides before sowing, may be helpful for controlling the disease.  The viral distribution and damage, virion properties, genome organization and spontaneous mutation, temperature sensitivity, and disease management options are here reviewed and/or discussed to help in developing more cost-effective countermeasures to control the disease in the future.
    Progress of the discovery, application, and control technologies of chemical pesticides in China
    LIU Xiao-hui
    2019, 18(4): 830-839.  DOI: 10.1016/S2095-3119(18)61943-4
    Abstract ( )   PDF (726KB) ( )  
    China experiences serious agricultural damages from rodents, and, correspondingly, researchers in China are actively studying rodent biology and management.  Following the popularization of ecologically-based rodent pest management and extension of the basic state policy of Ecological Civilization Construction in China, recent efforts in rodent control technologies are mainly focused on eliminating side effects of rodenticides and developing environmentally friendly techniques.  Considering ecological functions of rodents to test their interaction with the environment is a promising design for understanding rodent populations in local ecosystems and for developing ecologically-based rodent management.  Using ecological phenotypes and applying advanced techniques of molecular biology, genetics, and epigenetics might be useful for illustrating the deep regulatory mechanisms of fluctuations in rodent populations.  However, facing the dual characteristics of rodents as pests and their roles as keystone species in many ecosystems, it is still a challenge to establish reasonable local thresholds to balance rodent management with the negative effects of rodent control on the environment in the future. 
    Progress of the discovery, application, and control technologies of chemical pesticides in China
    PAN Xing-lu, DONG Feng-shou, WU Xiao-hu, XU Jun, LIU Xin-gang, ZHENG Yong-quan
    2019, 18(4): 840-853.  DOI: 10.1016/S2095-3119(18)61929-X
    Abstract ( )   PDF (817KB) ( )  
    Pesticides, which have the dual characteristics of being both helpful and harmful, are important materials for ensuring food security and human health.  Therefore, the rational development, scientific application, and effective control of pesticides are very important.  In this paper, from the perspectives of pesticide discovery, formulation processing, application mode, residue monitoring, and pollution elimination and prediction, trends in the research progress and development of pesticides in China were systematically summarized to provide an important reference for the development of pesticides with high efficiency and low risk and for the reduction of pesticide application.
    Research Article
    Selection of reference genes for RT-qPCR analysis of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) sex-dimorphic development
    ZHENG Lu-ying, ZHANG Zhi-jun, ZHANG Jin-ming, LI Xiao-wei, HUANG Jun, LIN Wen-cai, LI Wei-di, LI Chuan-ren, LU Yao-bin
    2019, 18(4): 854-864.  DOI: 10.1016/S2095-3119(18)61973-2
    Abstract ( )   PDF (2568KB) ( )  
    Mealybugs, such as Phenacoccus solenopsis, are highly sexually dimorphic.  Winged adult males present such remarkable morphological differences from females that, to the untrained eye, conspecific adults of both sexes of P. solenopsis may be considered as two different insect species.  A method to investigate sex-dimorphic mechanisms is by evaluating gene expression using RT-qPCR.  However, the accuracy and consistency of this technique depend on the reference gene(s) selected.  In this study, we analyzed the expression of 10 candidate reference genes in male and female P. solenopsis at different development stages, using common algorithms including the ?Ct method, NormFinder, geNorm, BestKeeper, and a web-based analysis tool, RefFinder.  The results showed that EF1-β, RP-L32 and RP-18S were selected as the most stable genes by both the ?Ct method and NormFinder; TUB-α was the most stable gene identified by BestKeeper; and RP-L40 and RP-L32 were the most stable genes ranked by geNorm.  RefFinder, a comprehensive analysis software, ranked the ten genes and determined EF1-β and RP-L32 as the most suitable reference genes for the various developmental stages in male and female P. solenopsis.  Furthermore, the two most suitable reference genes were validated by examining expression of the juvenile hormone acid O-methytransferase (JHAMT) gene.  Results of the validation portion of the study showed that JHAMT expression was sex-biased towards males and exhibited a dynamic and classic expression pattern among the P. solenopsis developmental stages.  The results can help further our knowledge on the molecular mechanisms underlying sexual dimorphic development in P. solenopsis.
    Tradeoff between triglyceride consumption and ovariole development in Plutella xylostella (L.) released in mixed-host environments
    HUANG Bin, SHI Zhang-hong, HOU You-ming
    2019, 18(4): 865-872.  DOI: 10.1016/S2095-3119(17)61842-2
    Abstract ( )   PDF (1022KB) ( )  
    After exposure to mixed environments with multiple hosts, the frequency of flight take-offs for Plutella xylostella (L.) is known to increase with a concomitant decrease in female fecundity.  The objective of the present study was to elucidate the physiological mechanism underlying the increased flight activity and decreased fecundity of P. xylostella in mixed-host environments.  We measured ovariole length, and triglyceride and vitellogenin (Vg) content in P. xylostella females after they were released into different host environments consisting of either a single host (Brassica campestris, Brassica oleracea or Brassica juncea) or a mixture of all three hosts.  Our results indicated that ovariole length varied significantly between female adults from different host environments.  Females from the B. campestris environment had the longest ovarioles, whereas those from the mixed environment had the shortest ones.  A negative correlation was found between ovariole length and the flight take-off frequency of P. xylostella adults.  Additionally, there were significant differences in the triglyceride content of P. xylostella females from different host environments.  Our data revealed that more triglyceride was consumed by P. xylostella female adults from B. oleracea and the mixed environments than those from environments containing only B. campestris or B. juncea.  In contrast, the relative Vg content in P. xylostella females from the mixed environment was lower than that in females from the B. campestris-, B. juncea- or B. oleracea-only environments.  In conclusion, the mixed environment caused increased consumption of available energy resources (triglyceride) at the cost of retarding ovarian development and decreasing the amount of Vg produced. 
    Volatiles from Sophora japonica flowers attract Harmonia axyridis adults (Coleoptera: Coccinellidae)
    XIU Chun-li, XU Bin, PAN Hong-sheng, ZHANG Wei, YANG Yi-zhong, LU Yan-hui
    2019, 18(4): 873-883.  DOI: 10.1016/S2095-3119(18)61927-6
    Abstract ( )   PDF (1027KB) ( )  
    The multicolored Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae), is a common generalist predator in China and is occasionally found gathering on the Chinese pagoda tree, Sophora japonica, in summer.  In a field investigation, we found that H. axyridis adults preferred S. japonica during its flowering period even though their optimal prey (aphid) is absent at this time.  In addition, male and female adults were attracted to S. japonica flowers to a similar extent in a Y-tube olfactometer assay.  Using coupled gas chromatography-electroantennogram detection (GC-EAD), we identified a flower odor component (nonanal) that elicited a significant electrophysiological response in H. axyridis.  Electroantennogram (EAG) dose-dependent responses revealed that the amplitude of the adult beetle’s EAG response increased with increasing concentration of nonanal, peaking at 10 mg mL–1.  In Y-tube olfactometer behavioral tests, H. axyridis adults preferred a 10 mg mL–1 nonanal source over a 100 mg mL–1 diluent.  Under field conditions, the adults were significantly attracted to both concentrations (10 and 100 mg mL–1), and high concentrations generally had greater attraction.  All these results suggest that nonanal, a volatile compound of S. japonica flowers, greatly attracts H. axyridis adults.  This study provides a basis for the development of synthetic attractants of H. axyridis, with the potential to promote biocontrol services of this generalist predator in the native area (e.g., China) and to suppress its population by mass trapping in its invasive areas. 
    Quantitative impact of mating duration on reproduction and offspring sex ratio of Phytoseiulus persimilis (Acari: Phytoseiidae)
    Lü Jia-le, ZHANG Bao-he, JIANG Xiao-huan, WANG En-dong, XU Xue-nong
    2019, 18(4): 884-892.  DOI: 10.1016/S2095-3119(18)61974-4
    Abstract ( )   PDF (3227KB) ( )  
    Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide.  To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and deflation of its spermathecae as a function of time and copulation duration, and the quantitative impact of copulation termination on volume of spermatheca vesicle, fecundity, and offspring sex ratio.  After mating started, at least one spermatheca started to inflate immediately, but no egg was produced until spermatheca volume reached 1 021 μm3.  Beyond this size, cumulative fecundity was linearly correlated with vesicle volume.  Producing one egg required 36 μm3 volume increase of the vesicle.  Each spermatheca vesicle reached its peak size at the end of mating duration (ca. 2.38 h after mating started), and started to shrink immediately.  In 24 h, ca. 71% individuals had one completely shriveled spermatheca, while in 72 h all individuals had at least one shriveled spermatheca.  The estimated maximum cumulative fecundity per female after a single mating is (69.4±7.7) eggs.  No significant impact of mating termination on offspring sex ratio was observed after mating duration reached 60 min, while higher proportion of male offspring was observed when mating duration is 15 or 30 min.  This study is the first step to investigate possible male impact on offspring sex ratio in P. persimilis.  Our results suggested the number of sperms received during mating be a restriction factor of P. persimilis offspring sex ratio regulation.
    No detrimental effect of Bt maize pollen containing Cry1Ab/2Aj or Cry1Ac on adult green lacewings Chrysoperla sinica Tjeder
    LIU Yan-min, LI Yun-he, CHEN Xiu-ping, SONG Xin-yuan, SHEN Ping, PENG Yu-fa
    2019, 18(4): 893-899.  DOI: 10.1016/S2095-3119(17)61887-2
    Abstract ( )   PDF (759KB) ( )  
    Adult Chrysoperla sinica Tjeder is a common pollen feeder in maize fields.  They are thus directly exposed to insecticidal proteins by consumption of genetically engineered maize pollen containing Bacillus thuringiensis (Bt) proteins.  Here we assessed the potential effects of Cry1Ab/2Aj- or Cry1Ac-containing Bt maize pollen on the fitness of adult C. sinica via a dietary-exposure assay under laboratory conditions.  Survival, pre-oviposition, fecundity and adult dry weight did not differ between adult C. sinica consuming Bt or the corresponding non-Bt maize pollen.  The stability of the Cry protein in the food sources and uptake of the Cry protein by adult C. sinica during the feeding experiment were confirmed by ELISA.  These results demonstrate that adult C. sinica are not affected by the consumption of Cry1Ab/2Aj- or Cry1Ac-containing maize pollen, suggesting that production of Bt maize expressing cry1Ab/2Aj or cry1Ac genes will pose a negligible risk to adult C. sinica.
    Relationship between copulation and cold hardiness in Ophraella communa (Coleoptera: Chrysomelidae)
    ZHAO Chen-chen, YUE Lei, WANG Yao, GUO Jian-ying, ZHOU Zhong-shi, WAN Fang-hao
    2019, 18(4): 900-906.  DOI: 10.1016/S2095-3119(19)62591-8
    Abstract ( )   PDF (830KB) ( )  
    Ophraella communa (Coleoptera: Chrysomelidae), the ragweed leaf beetle, is a biological control agent of the invasive common ragweed, Ambrosia artemisiifolia (Asterales: Asteraceae).  Adults can survive cold conditions that occur during winter.  The adults mate before entering overwintering.  Understanding the connection between copulation and overwintering will be useful for determining O. communa seasonality.  Determining the relationship between overwintering and copulation required comparison of mated and unmated beetles at mean lethal temperature (LTemp50) exposures for 2 h.  Cold-related physiological indices, including the water ratio, super cooling point (SCP), cryoprotectant levels, and energy reserve levels, were also measured.  Mating treatment decreased the LTemp50 of both sexes by reducing their mean SCP and water ratios.  Although the changes of cryoprotectant levels in mated adults were not precisely consistent in between the genders, they increased greatly in both males and females.  Body sugar may play a role in copulation and may also elevate cold hardiness in O. communa
    Weed growth, herbicide efficacy, and rice productivity in dry seeded paddy field under different wheat stubble management methods
    Muhammad Zia-Ul-Haq, Abdul Khaliq, Qiang Sheng, Amar Matloob, Saddam Hussain, Saba Fatima, Zeshan Aslam
    2019, 18(4): 907-926.  DOI: 10.1016/S2095-3119(18)62004-0
    Abstract ( )   PDF (1875KB) ( )  
    To ascertain the influence of wheat stubble management options and chemical weed control methods on weed growth and productivity of dry direct-seeded fine rice, a two years’ field study was undertaken at the Agronomic Research Farm, University of Agriculture, Faisalabad, Pakistan in 2013 and 2014.  Different wheat stubble management methods, viz., incorporation, burning and retention were executed during seed-bed preparation.  While, herbicide treatments comprised of a weed check, weed free, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl, and bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl.  Results revealed that weed control efficacy of both herbicide treatments ranged from 84 to 94%.  Herbicide treatments significantly reduced weed density (88–90%) and dry weight (86–88%), while improved the rice growth attributes compared with weed check.  Application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention recorded 226 and 273% increase in kernel yield over weedy check in 2013 and 2014, respectively.  In stubble incorporation, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl was more effective in increasing (256–293%) rice yields over weedy check.  Among different treatment combinations, the maximum net benefits (1 397.49–1 472.22 USD ha–1), net returns (636–700 USD ha–1), benefit cost ratio (1.77–1.83) and marginal rate of return (2 187–2 330%) were recorded with the application of bispyribac sodium followed by fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention.  In crux, application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention is efficient approach to control weeds, and get maximum rice productivity and net economic returns under dry seeded system.
    An investigation of weed seed banks reveals similar potential weed community diversity among three different farmland types in Anhui Province, China
    HE Yun-he, GAO Ping-lei, QIANG Sheng
    2019, 18(4): 927-937.  DOI: 10.1016/S2095-3119(18)62073-8
    Abstract ( )   PDF (1086KB) ( )  
    Crop type is one of main factors influencing weed community structure.  However, the identity of weed communities associated with the cultivation of different crops in farmlands remains largely unclear.  A field survey of weed seed banks was conducted in 2 280 fields at 228 sites of 62 locations representing three different types of farmland (95 paddy, 73 summer-ripe, and 60 autumn-ripe farmlands) along the bank of the Yangtze River in Anhui Province, China.  A total of 43 families and 174 species of weeds were found in these weed seed banks.  A comparison of the composition of weed groups in the seed banks showed that the species number and density percentage of grass, sedge and broadleaf weed groups were similar among the different types of farmland.  The seed banks of all three farmland types shared 71 common weed species, accounting for 40.80% of the total number of species.  These common weeds, which were both associated and not associated with crops, accounted for 91.71% of the total dominance degree among all farmland types.  The crop-associated weed species were distributed in all soil layers of each farmland type.  The Shannon-Wiener index (description of species diversity which is more sensitive to dense species) and Pielou’s evenness index J (description of species evenness) in summer-ripe farmland were similar to those in autumn-ripe farmland but differed from those in paddy farmland.  However, the Simpson’s index D (description of species diversity which is more sensitive to sparse species) was similar among all three farmland types.  The results of similarity comparison indicated that although the aboveground weed community differed among the different cropping patterns, the weed species composition in the soil seed bank was still similar.  Consequently, our results demonstrate that after the implementation of long-term monoculture patterns, weed species compositions in the soil seed bank in different farmlands become homogenized regardless of the crop type.