马铃薯块茎蛾生物防治研究进展与展望

马铃薯块茎蛾是马铃薯上重要的世界性害虫,会对马铃薯造成毁灭性的危害,该害虫目前已成为影响马铃薯产业发展的重要因素。化学农药的过度使用造成了马铃薯块茎蛾的抗药性增强,使用单一的化学防治并不能对该虫进行长久有效的控制。因此,近年来生物防治逐渐引起了研究人员的重视。本文从马铃薯块茎蛾的天敌种类、昆虫病原物、昆虫性信息素和植物提取物等方面概述了近些年马铃薯块茎蛾生物防治研究工作的进展。     

Cherry picking by pseudomonads: After a century of research on canker,genomics provides insights into the evolution of pathogenicity towards stone fruits

Bacterial canker disease is a major limiting factor in the growing of cherry and other Prunus species worldwide. At least five distinct clades within the bacterial species complex Pseudomonas syringae are known to be causal agents of the disease. The different pathogens commonly coexist in the field. Reducing canker is a challenging prospect as the efficacy of chemical controls and host resistance may vary against each of the diverse clades involved. Genomic analysis has revealed that the pathogens use a variable repertoire of virulence factors to cause the disease. Significantly, strains of P. syringae pv. syringae possess more genes for toxin biosynthesis and fewer encoding type III effector proteins. There is also a shared pool of key effector genes present on mobile elements such as plasmids and prophages that may have roles in virulence. By contrast, there is evidence that absence or truncation of certain effector genes, such as hopAB, is characteristic of cherry pathogens. Here we highlight how recent research, underpinned by the earlier epidemiological studies, is allowing significant progress in our understanding of the canker pathogens. This fundamental knowledge, combined with emerging insights into host genetics, provides the groundwork for development of precise control measures and informed approaches to breed for disease resistance.     

Saccharomyces Cerevisae and Arabidopsis Thaliana: Useful Model Systems for the Identification of Molecular Mechanisms Involved in Resistance of Plants to Toxins

Secondary metabolites produced by pathogens during the infection process are thought to play a role as pathogenicity or virulence determinants in many plant diseases. Baker's yeast and the plant Arabidopsis thaliana are attractive models for elucidating molecular mechanisms of resistance to toxic substances. For the Fusarium mycotoxin deoxynivalenol, the following resistance mechanisms were identified in yeast: (1) reduced toxin uptake due to the ABC transporter protein Pdr5p (molecular efflux pump), (2) detoxification by the acetyltransferase Ayt1p, and (3) modification of the ribosomal target by amino acid changes in the ribosomal protein L3 (Rpl3p). PDR5-like genes exist in plant genomes as large gene families and could play an important role as a first line of defence against a broad range of toxic metabolites. Amino acid alterations in the highly conserved RPL3 genes could likewise play a role in trichothecene resistance in plants. The knowledge obtained using model systems should be valuable in biotechnological approaches to disease control and marker-assisted resistance breeding.     

Gut bacteria associated with the Pacific Coast wireworm,<Emphasis Type="Italic">Limonius canus</Emphasis>, inferred from 16s rDNA sequences and their implications for control

A multitude of bacteria have been isolated from the guts of several insect species. Some of these have been modified to interfere with the development of the host insect or with the development and transmission of plant and animal pathogens transmitted by the host insect. We surveyed the gut flora of the Pacific Coast wireworm,Limonius canus LeConte, a serious pest of potato, at two sites in Oregon and Washington. Isolates were obtained from surface-sterilized triturated larvae by dilution plating on standard media. A rich diversity of species was found in 86 isolates, including spore-formers, non-spore-formers and aerobic and facultatively anaerobic species collected on four sampling dates at each location. Twenty-one of the isolates were identified to species based on rDNA sequence (nine distinct species). An additional 34 isolates were identified to genus from the sequence data while six isolates could be assigned only to family based on sequence comparisons. Twenty-seven additional isolates were identified to species (9), genus (17) or family (1) based on side-by-side morphological comparisons with isolates identified from rDNA sequence. The most frequently isolated bacterium wasBacillus megaterium, followed byRahnella aquatilis. A naturally occurring bacterium found in the gut and/or environment of a targeted insect that is modified to express toxins or other detrimental substances could provide certain advantages (such as persistence and recycling) over inundatively applied microbial control agents, particularly within soil habitats. The hypothesis that these species or others from the survey represent candidates for genetic modification to provide control options forL. canus is discussed.     

Genetic mapping and utilization of quantitative trichome-mediated insect resistance in potato

Introgression of trichome-mediated insect resistance from the wild speciesSolanum berthaultii has become a major focus of the potato improvement program at Cornell University during the past twelve years. Several quantitative characters are involved in this resistance which is effective against a wide range of pest types. Correlative biochemical assays have been developed to assay specific components of the resistance, and the effects of the resistance on the target pests have been studied. Quantitative laboratory assays and specific measurements of insect behavior and biology have increased the precision of selection and enable the investigation of the genetic control of the resistance.We are currently using restriction fragment length polymorphisms (RFLPs) for genetic mapping of factors controlling the trichome traits fromS. berthaultii. Backcrosses to both the wild and the cultivated species parents have been evaluated for phenotypes contributing to the resistance mechanism, including trichome density, sucrose ester and polyphenol oxidase production by the trichomes, and the enzymatic browning reaction responsible for insect entrapment. Genetic maps are being developed for these progenies, using RFLP markers previously mapped in potato. Field and greenhouse trials under insect infestations are also being conducted with the mapping progeny. Our goal is to locate genes responsible for quantitative insect resistance by correlating RFLP variation at mapped loci with the trichome phenotypes and insect resistance. Genetic markers for these traits will be useful in transfer of the effective wild chromosomal segments into and among tetraploid potatoes, and for a better understanding of the resistance mechanism.     

Insecticide Resistance in the Western Flower Thrips, Frankliniella occidentalis

The western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is a serious pest on a wide range of crops throughout the world. F. occidentalis is difficult to control with insecticides because of its thigmokinetic behaviour and resistance to insecticides. Pesticide resistance can have a negative impact on integrated pest management programmes with chemical control as one of the components. Resistance to a number of different insecticides has been shown in many populations of F. occidentalis. This flower thrips has the potential of fast development of resistance owing to the short generation time, high fecundity, and a haplodiploid breeding system. The mechanisms conferring insecticide resistance in insects can be divided into four levels. First, an altered behaviour can aid the insect to avoid coming into contact with the insecticide. Second, a delayed penetration through the integument will reduce the effect of the insecticide at the target site. Third, inside the insect, detoxification enzymes may metabolise and thereby inactivate the insecticide. Fourth, the last level of resistance mechanisms is alterations at the target site for the insecticide. Knowledge of resistance mechanisms can give information and tools to be used in management of the resistance problem. Recently, studies have been carried out to investigate the underlying mechanisms conferring resistance in F. occidentalis. It appears that resistance in F. occidentalis is polyfactorial; different mechanisms can confer resistance in different populations and different mechanisms may coexist in the same population. Possible resistance mechanisms in F. occidentalis include: reduced penetration, detoxification by P450-monooxygenases, esterases and glutathione S-transferases, and alterations of acetylcholinesterase, the target site for organophosphate and carbamate insecticides. Target site resistance to pyrethroids (knockdown resistance) may also be a resistance mechanism in F. occidentalis.     

Target the core: durable plant resistance against filamentous plant pathogens through effector recognition

Plant pathogens colonize their host through the secretion of effector proteins that modulate plant metabolism and immune responses to their benefit. Plants evolve towards effector recognition, leading to host immunity. Typically, pathogen effectors are targets for recognition through plant receptors that are encoded by resistance genes. Resistance gene mediated crop immunity puts a tremendous pressure on pathogens to adapt and alter their effector repertoire to overcome recognition. We argue that the type of effector that is recognized by the host may have considerable implications on the durability of resistance against filamentous plant pathogens. Effector genes that are conserved among pathogens and reside in core genome regions are most likely to hold indispensable virulence functions. Consequently, the cost for the pathogen to overcome recognition by the host is higher than for diversified, host‐specific effectors with a quantitative impact on virulence. Consequently, resistance genes that directly target conserved effector proteins without the interception of other effector proteins are potentially excellent resistance resources. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

我国植物害虫生物防治的研究现状及发展策略

植物害虫生物防治是指利用生物或生物代谢产物来控制农业害虫的一种害虫防治方法,具有安全、环境友好和可持续等优点。本文基于我国近年在天敌资源挖掘、天敌控害机制、天敌产业化应用和新方法探索等方面研究现状与存在问题的分析,探讨了我国植物害虫生物防治学科的体系建设及促进学科发展的主要策略。     

Understanding pathogen population structure and virulence variation for efficient resistance breeding to control cucurbit powdery mildews

Cucurbit powdery mildew (CPM) is caused most frequently by well-differentiated obligate erysiphaceous ectoparasites Golovinomyces orontii and Podosphaera xanthii, which vary in their ecology and virulence. All economically important cucurbit crops host both of these CPM species. Breeding of cucurbits for CPM resistance is highly important worldwide, but adequate knowledge of CPM species determination, as well as virulence structure, population dynamics, and spatiotemporal variation of these pathogens, has not yet been achieved. New tools have been developed to enhance research on CPM virulence variation for more efficient breeding and seed and crop production. A set of differential genotypes of Cucumis melo, with high differentiation capacity, may contribute substantially to understanding of variation in CPM virulence at both individual and population levels. Long-term observations (2001–2012) of CPM pathogens in the Czech Republic were used to analyse virulence variation within and among annual CPM populations and demonstrate the utility of recently developed tools for studying species variability and virulence variation of CPM pathogens worldwide. Detailed analyses of diversity and spatiotemporal fluctuations in the composition of CPM populations provide crucial information for shaping breeding programmes and predicting the most effective sources of race-specific resistance. The primary aim of this work was to create a uniform framework for determination of CPM species structure and diversity, virulence phenotypes, virulence and phenotype frequencies, phenotype complexity, dynamics, and variation within and among CPM populations. In addition, practical advice is presented on how to select the most relevant data and interpret them for use in cucurbit resistance breeding.     

基于全长转录组测序的稻秆潜蝇解毒代谢相关基因筛选

为筛选水稻害虫稻秆潜蝇Chlorops oryzae潜在的解毒代谢酶基因，利用PacBio Sequel Ⅱ测序平台对稻秆潜蝇幼虫进行全长转录组测序，基于测序结果筛选稻秆潜蝇的解毒代谢相关基因谷胱甘肽S-转移酶（glutathione S-transferase，GST）基因、羧酸酯酶（carboxylesterase，CarE）基因和细胞色素P450（cytochrome P450，CYP450）基因，并检测其在稻秆潜蝇不同发育阶段的相对表达量。结果表明，对稻秆潜蝇进行测序得到18 100条去冗余转录本序列，共有16 283条序列得到注释。通过比对分析共筛选出8条GST、12条CarE和28条CYP450基因序列，这些基因在稻秆潜蝇不同发育阶段的表达量具有显著差异，表明不同虫态的稻秆潜蝇其解毒代谢能力可能不同。此外，还筛选到1 452个lncRNA序列，以及176个潜在的lncRNA靶基因序列，其中4个与解毒代谢基因相关。表明筛选获得的稻秆潜蝇解毒代谢酶基因及lncRNA靶基因可用于后续该虫的潜在抗药性研究及防治药剂筛选。     

The tomato borer Tuta absoluta in South America: pest status,management and insecticide resistance

The tomato borer Tuta absoluta (Lepidoptera: Gelechiidae) has been a recognized pest in South America since the 1960s, quickly spreading to the major tomato‐producing countries in the region. A series of studies regarding this pest's biology, ecology and management were conducted to contain tomato losses within acceptable levels. Although cultural control methods were attempted against T. absoluta, as were the development of resistant tomato varieties and the use of pheromones and natural enemies, insecticides are still the main control method used. The sex pheromone of T. absoluta was identified, confirmed and synthesized in the late 1990s and it is currently used for detection and monitoring of this species, but improved sampling plans are still necessary for its use in decision‐making regarding insecticide use. Insecticide use has shifted from earlier reliance on organophosphates, pyrethroids, cartap and abamectin to insect growth regulators and, more recently, to novel insecticides. Unfortunately, the overreliance on insecticide use led to problems with insecticide resistance in the region, which is a current matter of concern not only in South America, but also elsewhere since introduced strains may carry insecticide‐resistance genes at high frequency even without local selection in the site of introduction.     

Temporal dynamics of the arthropod community in pear orchards intercropped with aromatic plants

BACKGROUND: Increasing attention has been paid to enhancing biological control through habitat management in agricultural systems for enhanced pest management. Pest management benefits can be realised by intercropping, which can increase natural enemy abundance and, in turn, reduce pest abundance. In this study, the composition and temporal dynamics of arthropod communities in pear orchards when intercropped with aromatic plants were investigated, and the effectiveness and applicability of aromatic plants as intercrops for enhancing insect control were assessed. RESULTS: When compared with natural grasses or clean tillage, intercropping significantly reduced pest abundance and increased the ratio of natural enemies to pests. Intercropping also shortened the occurrence duration and depressed the incidence peak in annual dynamics curves of the pest subcommunity and the arthropod community, mainly because of the repellent effects of aromatic plants. Equally important, intercropping significantly reduced the numbers of major pests, such as Psylla chinensis, Aphis citricola and Pseudococcus comstocki, while their incidence period was delayed to varying degrees, and the numbers of their dominant natural enemies (Coccinella septempunctata, Phytoseiulus persimilis and Chrysoperla sinica) increased. CONCLUSION: Intercropping with aromatic plants led to a considerable improvement in arthropod pest management by enhancing the activity of the beneficial arthropod community within the pear orchard ecosystem. Copyright © 2011 Society of Chemical Industry     

Agricultural insect hybridization and implications for pest management

Biological invasions, the expansion of agricultural frontiers, and climate change favor encounters of divergent lineages of animals and plants, increasing the likelihood of hybridization. However, hybridization of insect species and its consequences for agroecosystems have not received sufficient attention. Gene exchange between distinct and distant genetic pools can improve the survival and reproduction of insect pests, and threaten beneficial insects in disturbed agricultural environments. Hybridization may be the underlying explanation for the recurrent pest outbreaks and control failures in putative hybrid zones, as suspected for bollworm, corn borer, whiteflies, and stink bugs. Reliable predictions of the types of changes that can be expected in pest insect genomes and fitness, and of their impacts on the fate of species and populations remain elusive. Typical steps in pest management, such as insect identification, pest monitoring, and control are likely affected by gene flow and adaptive introgression mediated by hybridization, and we do not have ways to respond to or mitigate the problem. To address the adverse effects of farming intensification and global trade, we must ensure that current integrated pest management programs incorporate up‐to‐date monitoring and diagnostic tools. The rapid identification of hybrids, quantification of levels of introgression, and in‐depth knowledge of what genes have been transferred may help to explain and predict insect population outbreaks and control failures in the future. © 2019 Society of Chemical Industry     

Ecological pest management and control by using allelopathic weeds (Ageratum conyzoides,Ambrosia trifida,and Lantana camara) and their allelochemicals in China

The development of pest management and control is striving toward a future of sustainable agriculture. Weeds cause serious problems in agricultural ecosystems and attempts to control them have met with limited success. However, many weeds are allelopathic; that is, they can produce and release allelochemicals to interact with other plant competitors and to attack microbes or insect and other animal predators. These allelopathic weeds and their allelochemicals may be put into use for ecological pest management and control or employed for other uses. Currently, little attention has been paid to how allelopathic weeds and their allelochemicals potentially can be utilized as an important part of pest management and control in agricultural ecosystems. This review outlines recent research regarding the potential for pest management and control by allelopathic weeds and their allelochemicals by studying the cases of Ageratum conyzoides, Ambrosia trifida, and Lantana camara and provides examples of allelopathic weeds and their allelochemicals that have been incorporated into ecological pest management and control in China.     

Biological Control of the Hibiscus Mealybug, Maconellicoccus Hirsutus Green (Hemiptera: Pseudococcidae) in the Caribbean

The hibiscus mealybug, Maconellicoccus hirsutus Green, was first reported in the Caribbean in 1994 in Grenada. This was the first record of the insect as a major pest in the New World. By the beginning of 2001, the pest had spread to over 25 territories from Guyana and Venezuela in the South to Bahamas in the North. The pest has also extended its distribution to Central America (Belize) and North America (California, USA). Early attempts to control the pest using pesticides resulted in failure and a classical biological control approach was adopted. Several exotic natural enemies were introduced but control was attributed to Anagyrus kamali Moursi and Cryptolaemus montrouzieri Mulsant. In all countries where biological control was implemented, this resulted in success. This paper reviews the remarkable success story. Information is provided on the distribution and factors leading to rapid spread of the pest, its pest status and resultant economic losses, and implementation of the biological control effort.     

The role of allelopathy in agricultural pest management

Allelopathy is a naturally occurring ecological phenomenon of interference among organisms that may be employed for managing weeds, insect pests and diseases in field crops. In field crops, allelopathy can be used following rotation, using cover crops, mulching and plant extracts for natural pest management. Application of allelopathic plant extracts can effectively control weeds and insect pests. However, mixtures of allelopathic water extracts are more effective than the application of single-plant extract in this regard. Combined application of allelopathic extract and reduced herbicide dose (up to half the standard dose) give as much weed control as the standard herbicide dose in several field crops. Lower doses of herbicides may help to reduce the development of herbicide resistance in weed ecotypes. Allelopathy thus offers an attractive environmentally friendly alternative to pesticides in agricultural pest management. In this review, application of allelopathy for natural pest management, particularly in small-farm intensive agricultural systems, is discussed.     

Low pathotype diversity in a recombinant Puccinia striiformis population through convergent selection at the eastern Himalayan centre of diversity (Nepal)

Worldwide Puccinia striiformis f. sp. tritici (Pst) epidemics have been reported to be driven by few genetic lineages, while a high diversity is evident at the Pst Himalayan centre of diversity. This study investigated the relationship between pathotype diversity and genetic structure in Nepal, the eastern Himalayan region, which has been largely unexplored. Despite the high genetic diversity and recombinant structure detected through microsatellite genotyping, characterization of virulence phenotypes for 62 isolates identified only eight pathotypes, with two pathotypes predominant over all the populations. This is in contrast to the Pakistani and Chinese recombinant populations, where high pathotype diversity is associated with genetic diversity. The most prevalent Nepali pathotype was not a unique clonal lineage, but was represented by seven multilocus genotypes from four distinct genetic subgroups, suggesting strong directional selection on virulence genes, resulting in convergent pathotypes in distinct genetic groups. This convergent selection is discussed in comparison with clonal French and recombinant Pakistani populations. Additionally, the Nepali Pst population carried virulence to 17 out of 24 tested yellow rust resistance genes (Yr), with the absence of virulence to Victo and Early Premium and resistance genes Yr5, Yr10, Yr15, Yr24 and Yr26. Virulence to Yr2, Yr7, Yr27 and YrSu were fixed in all isolates, in line with the deployment of these resistance genes in Nepal. The results reflect the influence of resistance gene deployment on selection of virulence and pathotypes in a recombinant pathogen population, which must be considered in the context of durable resistance gene deployment.     

Bacillus thuringiensis as a biofertilizer in crops and their implications in the control of phytopathogens and insect pests

BACKGROUND

Bacillus thuringiensis (Bt) is a spore-forming bacterium that produces insecticidal proteins and other virulence factors and is considered one of the most successful bioinsecticides available to control pests in agriculture. Currently, some Bt strains have been reported as endophyte or rhizospheric bacteria.

RESULTS

Little is known about the implications of plant-Bt interaction in crop protection. Here, we review if Bt can establish as an endophyte/rhizobacterium and evaluate if Bt as an endophyte/rhizobacterium can simultaneously act against different phytopathogens (fungi, bacteria, insects and viruses) plus promote plant growth.

CONCLUSION

Although Bt produce an arsenal of proteins with toxic effects against insect, the current knowledge suggests that Bt can be considered as a promising new plant growth promotion bacterium (PGPB). The implications of the proposed review will broaden our understanding of Bt as a versatile entomopathogen that may be able to exhibit differential behavior depending on context. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Pests,Predators, and Parasites

Abstract

The development of resistance to insecticides and the hazards inherent in their use present ever-increasing problems in insect control today. The difficulties and dangers have given impetus to research on other means of combating pests. Australia has always been prominent in the field of biological control, and the CSIRO Division of Entomology is an important centre, keenly seeking controls for both insects and weeds. Progress in the search for and establishment of parasites of Sirex, the pine pest, was described in Rural Research 64. This article reviews six other projects of particular interest, namely those involving potato moth, buffalo fly, white wax scale, green vegetable bug, lantana, and skeleton-weed.     

Evidence of soil-located competition as the cause of the reduction of sunflower verticillium wilt by entomopathogenic fungi

The increasing limitation of agrochemicals for disease control is a major challenge for European agriculture and a spur to developing environmentally friendly approaches such as biological control. Entomopathogenic fungi, which have been used in the control of insect pests for a long time, also have other uses, such as being antagonists of fungi, including plant pathogens. We determined the in vitro effect of three strains of Metarhizium brunneum and two of Beauveria bassiana against Verticillium dahliae and Cadophora helianthi, causal agents of sunflower wilts. Both M. brunneum and B. bassiana were able to inhibit the mycelial growth of the sunflower pathogens and, according to the dual culture and microscopy results, two types of antagonism were observed as being dependent on the strain: competition and/or antibiosis. Greenhouse experiments showed that, after soil treatments with entomopathogens and plant inoculation by root immersion in conidial suspensions of V. dahliae, the entomopathogens were able to efficiently persist in the soil, and three of the four strains even significantly reduced the severity of symptoms in sunflowers. Interestingly, molecular analysis showed that all the strains were able to establish themselves as endophytes in sunflowers in the absence of V. dahliae. When the plants were inoculated with V. dahliae, we detected the pathogen, but not the entomopathogen, in the sunflowers by molecular methods. The results of this work suggest that the protection conferred by M. brunneum and B. bassiana against verticillium wilt might not be plant-located, but is probably the consequence of their competition with V. dahliae in the soil.