PM 7/36 (2) Diabrotica virgifera virgifera

Specific scope

This Standard describes a diagnostic protocol for Diabrotica virgifera virgifera. This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.

Specific approval and amendment

Approved in 2003‐09. Revised in 2017‐02.     

Efficiency of pheromone traps for monitoring Diabrotica virgifera virgifera LeConte

Mark–release–recapture trials with male western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) beetles were conducted to better understand capture data of pheromone traps produced in Europe during monitoring programmes. Median recapture rate in maize fields in Hungary, Italy and Switzerland was 10%. Two types of sex pheromone trap (sticky sheet and non‐sticky container traps), placed inside or outside maize fields, showed no differences in efficiency. Logit analyses of recapture data in maize showed that at distances of <1 m fewer than 20% of beetles ended up in the traps. A beetle in a 1 ha maize field would have about a 5% chance of being caught in a trap placed in the centre of the field.     

RNAi as a management tool for the western corn rootworm,Diabrotica virgifera virgifera

The western corn rootworm (WCR), Diabrotica virgifera virgifera, is the most important pest of corn in the US Corn Belt. Economic estimates indicate that costs of control and yield loss associated with WCR damage exceed $US 1 billion annually. Historically, corn rootworm management has been extremely difficult because of its ability to evolve resistance to both chemical insecticides and cultural control practices. Since 2003, the only novel commercialized developments in rootworm management have been transgenic plants expressing Bt insecticidal proteins. Four transgenic insecticidal proteins are currently registered for rootworm management, and field resistance to proteins from the Cry3 family highlights the importance of developing traits with new modes of action. One of the newest approaches for controlling rootworm pests involves RNA interference (RNAi). This review describes the current understanding of the RNAi mechanisms in WCR and the use of this technology for WCR management. Further, the review addresses ecological risk assessment of RNAi and insect resistance management of RNAi for corn rootworm. © 2016 Society of Chemical Industry     

玉米根萤叶甲的抗逆性与防治研究进展

玉米根萤叶甲（Diabrotica virgifera virgifera Leconte）在美国是最重要的玉米害虫。它不仅对一些环戊二烯、有机磷类和氨基甲酸盐类化学杀虫剂产生了很强的抗药性,还对玉米 大豆轮作和调整播期等农业防治措施产生了适应性。此外,该虫有较广的适生性和扩展性。在过去的60年内,它从美国中西部传到了东北部沿海地区,并入侵欧洲定殖为害。新近采用的防治方法主要是种植转Bt基因抗虫玉米。表达经生物工程改良并导入的某个Bt毒素基因如Cry3Bb1、Cry34Ab1/Cry35Ab1或mCry3A的转基因抗虫玉米可毒杀取食的玉米根萤叶甲。但在转Bt基因玉米使用数年后,田间观察和温室筛选研究显示,玉米根萤叶甲具有对转基因玉米的潜在抗性。本文对该叶甲与防治有关的生物学特性、抗逆性及其机制、防治措施做了综述和讨论,旨在对该害虫的检疫防除有所帮助。     

The western corn rootworm (Diabrotica virgifera virgifera): a new maize pest threatening Europe

The western corn rootworm Diabrotica virgifera virgifera is one of the most dangerous pests in maize in the USA. For many years, US growers have had to control this pest in maize fields by soil treatment or spraying. Ten years ago, this pest was also 'imported' into Europe. It was the job of the plant protection advisers and officials to inform endangered countries about the appearance of this pest, to develop control strategies for Europe and to establish research programmes to prevent further spread. This paper presents the history of this pest in Europe, its biology, the situation in 2001 and corn rootworm management scenarios for the future.     

A comparison of methods for combining maps in pest risk assessment: application to Diabrotica virgifera virgifera

Host area, potential pest impact and probability of pest presence are frequently displayed on maps by pest risk assessors. These variables can be mapped separately, but it is also important to map combinations of these variables in order to define the area of potential establishment and the endangered area to assist decision‐making processes. This paper presents different methods for combining maps, and discusses their advantages and disadvantages. Different methods are shown that can be used to combine maps depending on whether the individual maps were derived from continuous quantitative variables or from discrete variables. The authors suggest combining maps derived from continuous variables using simple mathematical equations in order to compute expected invaded areas and expected potential impacts. Maps derived from discrete variables (e.g. scores) can be combined using a risk matrix, but the results may be highly dependent on the chosen matrix. The practical interest of these methods is illustrated in a case study on Diabrotica virgifera virgifera. The authors recommend combining the original continuous variables when such variables are available. The combination of categories defined from continuous variables led to a loss of information and may decrease the values of the maps. Risk matrices should be used only if the individual variables are discrete and if the underlying continuous variables are not available.     

Der Westliche Maiswurzelbohrer Diabrotica virgifera virgifera LeConte (Col.: Chrysomelidae) auf dem Weg nach Deutschland

Zusammenfassung Der Westliche Maiswurzelbohrer, Diabrotica virgifera virgifera (Dvv) LeConte (Coleoptera: Chrysomelidae), ist einer der wichtigsten Maisschädlinge in Nordamerika. Seit seiner Einschleppung nach Serbien und seinem Nachweis bei Belgrad im Jahr 1993 breitet er sich schnell über Südosteuropa und von dort zunehmend nach Zentraleuropa aus. Bis 2004 war Deutschland zwar noch frei von Dvv, ist aber außer an seiner Nordost- und Nordflanke von Ländern mit nachweislichen Dvv-Populationen umgeben. Es gibt außer stets möglichen Einschleppungen durch Flugzeuge drei Hauptrichtungen für das terrestrische Vordringen auf deutsches Staatsgebiet. Von diesen ist die südlich-nördliche Stoßrichtung von der Lombardei in Norditalien über den Tessin und die Nordschweiz bis nach Südbaden die wahrscheinlichste. Sie folgt einem sehr gut ausgebauten Straßen- und Schienennetz durch die Schweiz mit hochentwickelten Verteilungszentren für Güter und Dienstleistungen, womit die aktive Mitwirkung des Menschen als Verbreitungsvektor des Schädlings unterstrichen wird. Erzwungene Fruchtfolgevorschriften im Schweizer Kanton Tessin konnten die Ausbreitung nach Norden zwar bremsen, aber nicht verhindern. In Anbetracht seines jüngsten Vordringens bis an die deutschen Grenzen dürfte die Einschleppung von Dvv auf deutsches Staatsgebiet bevorstehen und als längerfristig unvermeidlich gelten.     

Validation of RNA interference in western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) adults

BACKGROUND: RNA interference (RNAi) is commonly used in insect functional genomics studies and usually involves direct injection of double‐stranded RNA (dsRNA). Only a few studies have involved exposure to dsRNAs through feeding. For western corn rootworm (Diabrotica virgifera virgifera) larvae, ingestion of dsRNA designed from the housekeeping gene, vacuolar ATPase (vATPase) triggers RNAi causing growth inhibition and mortality; however, the effect of dsRNA feeding on adults has not been examined. In this research, WCR adults were fed with vATPase‐dsRNA‐treated artificial diet containing a cucurbitacin bait, which is a proven feeding stimulant for chrysomelid beetles of the subtribe Diabroticina to which rootworms belong. RESULTS: Real‐time PCR confirmed suppression of vATPase expression and western blot analysis indicated reduced signal of a protein that cross‐reacted with a vATPase polyclonal antiserum in WCR adults exposed to artificial diet treated with dsRNA and cucurbitacin bait. Continuous feeding on cucurbitacin and dsRNA‐treated artificial diet resulted in more than 95% adult mortality within 2 weeks while mortality in control treatments never exceeded 20%. CONCLUSIONS: This research clearly demonstrates the effect of RNAi on WCR adults that have been exposed to dsRNA by feeding and establishes a tool to screen dsRNAs of potential target genes in adults. This technique may serve as an alternative to target screening of larvae which are difficult to maintain on artificial diets. Copyright © 2011 Society of Chemical Industry     

玉米根萤叶甲在中国的潜在适生区域与检疫措施研究

玉米根萤叶甲(Diabrotica virgfera virgifera Leconte)是一种原产北美洲南部和中美洲北部并于1992年以来在欧洲快速传播扩散的危险性玉米害虫.该虫对我国玉米生产构成严重威胁.为了防范其入侵,本文在概述其生物学和传播蔓延趋势的基础上,利用基于生态位概念的GARP软件对该虫在我国的潜在适生区域进行了预测.研究显示适生区广布于黑龙江、吉林、辽宁、内蒙古、新疆、河北、北京、天津、山东、山西、陕西、宁夏、甘肃、江苏、安徽、河南、湖北、四川、云南和西藏等省区,其中最适生区主要位于东北平原的南部、华北平原的南部、渭河平原及其南北附近地区.据此结果,对其远距离传入中国的可能途径做了分析,对高危地区进行了分析判断,最终提出了检疫与防范建议.