New finds of the click beetle Agriotes sordidus (Illiger, 1807) and an overview on its current distribution in Germany

Die Schnellkäfergattung Agriotes beinhaltet einige der in Ackerbaukulturen schädlichsten Drahtwürmer. Von den fünf in Deutschland als wirtschaftlich bedeutend eingestuften Agriotes-Arten ist eine, Agriotes sordidus, als Neuankömmling mit rezent erfolgter Nordausbreitung zu betrachten. Diese ursprünglich westmediterrane, als sehr schädigend angesehene Art wird auch im bundesweiten Schnellkäfermonitoring erfasst. Sie hat inzwischen ein geschlossenes Gebiet im Oberrheingraben besiedelt, sich entlang einiger Rheinnebenflüsse weiter ausgebreitet und ist über den Mittelrhein bis an den südlichsten Rand der Kölner Bucht vorgestoßen. Dieser Standort Westerhausen stellt wahrscheinlich den ersten Fund für Nordrhein-Westfalen dar. Ein weiterer Fund bei Zusmars­hausen stellt den wohl ersten Fund für Bayern abseits des an den Oberrhein anknüpfenden Vorkommens entlang des Mains dar. Überraschend sind Funde in Küstennähe in Niedersachsen und Schleswig-Holstein weitab vom geschlossenen Verbreitungsgebiet im Südwesten Deutschlands. Norddeutsche Tiere unterschieden sich zwar optisch von den Tieren aus dem südlichen Verbreitungs­gebiet, aber die morphologische Bestimmung wurde mittels PCR bestätigt. A. sordidus ist demnach in Deutschland weiter verbreitet als angenommen. In den meisten Gebieten fehlt er aber noch, so z.B. im Osten Deutschlands. Die Habitatpräferenzen sowie das Schadpotential in den neu besiedelten Gebieten sind damit aber nicht geklärt. Die Ausbreitung dieser Art sollte weiter überwacht werden.    Some of the most damaging wireworms in middle European arable land belong to the genus Agriotes. One of the five species of this genus which are of economic importance in Germany, is a newcomer. The species in question, Agriotes sordidus, is essentially western Mediterranean in its distribution, however, showing a range ex­tension to the north in Western Europe in recent decades. In Germany A. sordidus now shows a continuous distribution along the Upper Rhine valley and its tributaries (e.g. Neckar, Nahe, Main), as was shown recently. The species is also recorded in the countrywide click beetle monitoring with additional finds at the southern edge of the Cologne lowland (first find in North Rhine-Westphalia), the region of Zusmarshausen in western Bavaria, and most surprising, two locations close to the North Sea coast in Lower Saxony and Schleswig-Holstein (first find in this federal state). The latter two sites and also the Bavarian site near Zusmarshausen are far from the area of continuous distribution in southwestern Germany. As northern German specimens differed visually from the southern German finds the morphological determination was verified by PCR. Therefore A. sordidus is already more widespread than previously thought, but still missing in most regions. No records exist from eastern Ger­many yet. However, the habitat preferences and the damage potential of this species are still not fully understood. The spread of A. sordidus should be monitored further.   &nbsp

Identification of Agriotes wireworms – Are they always what they appear to be?

Die Schnellkäfergattung Agriotes beinhaltet einige der in Ackerbaukulturen schädlichsten Drahtwürmer. Von den fünf in Deutschland als wirtschaftlich bedeutend eingestuften Agriotes-Arten sind insbesondere die drei Arten A. lineatus, A. obscurus, A. sputator im Larvalstadium schwierig zu unterscheiden. Eine genaue Identifikation ist jedoch entscheidend, um mögliche Unterschiede, zum Beispiel in der Präferenz für Bodenarten, für Bodenfeuchte oder in der Nahrungspräferenz, überhaupt zu erkennen. Aber wichtige morphologische Unterschiede, die in allgemein genutzten Bestimmungsschlüsseln für Drahtwürmer angegeben werden, ermöglichten nicht immer eine korrekte Bestimmung. Ebenso war es nicht in allen Fällen möglich, die Tiere über eine PCR zu identifizieren, da teils Kreuzreaktionen auftraten. Daher entwickelten wir neue Primer für die Arten. Nachfolgend wurden Populationen von verschiedenen Standorten untersucht, um zu überprüfen, ob die Anteile aberranter Exemplare sich zwischen den Standorten unterschieden. DOI: 10.5073/JfK.2015.04.03, https://doi.org/10.5073/JfK.2015.04.03Wireworms are internationally recognized as economically important pests with the most damaging wireworms in middle European arable land belonging to the genus Agriotes. From the five species of greater importance in Germany, three (A. lineatus, A. obscurus, A. sputator) are very difficult to identify in their larval stage. Precise identification is crucial when trying to determine whether there are eco­logical differences between these three widespread species, e.g. in the reactions to different soil types, to soil moisture or in food choice. We report on the differentiation of A. lineatus, A. obscurus and A. sputator wireworms by comparing the identification by morphological traits of the larvae with the identification by PCR using a part of the mitochondrial DNA. Morphological traits given in commonly used identification keys for wireworms were not always reliable. Likewise the PCR did not always produce results, in part due to cross reactions. Therefore we developed new primers for reducing cross-reactions previously encountered. In the following, samples from different populations from the three species were compared to investigate if the proportion of aberrant specimens differed at different locations. DOI: 10.5073/JfK.2015.04.03, https://doi.org/10.5073/JfK.2015.04.0

Auswirkungen von Untersaaten in Weißkohlkulturen auf die Populationsdynamik der Schadinsekten, die Unkräuter und den Ertrag

[no abstract

First records of the Z-Race of European Corn Borer Ostrinia nubilalis (Hübner 1796) from Scandinavia

Der Maiszünsler (Ostrinia nubilalis) ist einer der bedeutendsten Schädlinge im Mais in Europa und in den Gebieten seiner Einschleppung. Er tritt in 2 Pheromonrassen (E und Z) mit in Mitteleuropa derzeit unterschiedlichen Hauptwirtspflanzen auf. Die E-Rasse ist häufig in Beifuß (Artemisia vulgaris) zu finden, während die hauptsächlich im Mais auftretende Z-Rasse in Deutschland den ökonomisch bedeutenden Schaden verursacht. Beide Ras­sen können jedoch auch andere Pflanzen befallen. So kann beispielsweise die E-Rasse auch am Mais auftreten. Eine morphologische Unterscheidung der Rassen ist nicht möglich. Für Skandinavien lagen bisher zwar Daten über das Vorkommen des Maiszünslers vor, jedoch keine Berichte über das Auftreten in Mais. In 2010 wurden Maiszünsler-Larven an einem Standort im Mais auf der Insel Sjaelland (Seeland), Dänemark, gefunden. Ein Moni­toring in Dänemark 2011 mit Pheromonfallen für die Z-Rasse erbrachte keine weiteren Funde. 2011 wurden jedoch in Südschweden am Mais an 3 Standorten Befall durch Maiszünsler-Larven festgestellt. Mittels PCR wurden Larven von 2 Standorten untersucht und als zur Z-Rasse gehörig bestätigt. Unabhängig davon wurden in 2010 Falter von der schwedischen Ostseeinsel Gotland ebenfalls als Tiere der Z-Rasse bestätigt. Dies sind die ersten Nachweise der Z-Rasse für Skandinavien und in Europa bislang die nördlichsten belegten Funde dieser Rasse. Implikationen für den Pflanzenschutz werden diskutiert.    European Corn Borer (ECB, Ostrinia nubilalis) is among the main pests of maize in Europe and throughout its intro­duced range. Two morphologically indistinguishable phero­mone races of the species exist, the so-called E-race and Z-race. In Germany the E-race is most common in mugwort (Artemisia vulgaris) whereas the Z-race occurs mainly in maize and is responsible for the main proportion of the economic damage. But both races have several alternative host plants. For example, the E-race can also occur in maize. The species has been known from Scandinavia already for a considerable time period, but no occurrence in maize was reported until recently. In 2010 larvae were found in maize at one site on the isle of Sealand, Denmark. A monitoring with Z-race pheromone traps in Denmark in 2011 did not result in any catches of ECB. In the same year however, ECB larvae were found in maize at 3 sites in southern Sweden. Larvae from 2 sites were assigned to Z-race via PCR. Independently from these finds, adult moths caught on the isle of Gotland in 2010 were also confirmed to be Z-race by PCR. This is the first evidence of the occurrence of the Z-race in Scandinavia and the northernmost find of the Z-race in Europe so far. Implications for plant protection are discussed.   &nbsp

Un outil moléculaire simple et abordable pour identifier les larves de taupins du genre Agriotes

National audienc

Alternative Strategies for Controlling Wireworms in Field Crops: A Review

International audienceWireworms, the soil-dwelling larvae of click beetles (Coleoptera: Elateridae), comprise major pests of several crops worldwide, including maize and potatoes. The current trend towards the reduction in pesticides use has resulted in strong demand for alternative methods to control wireworm populations. This review provides a state-of-the-art of current theory and practice in order to develop new agroecological strategies. The first step should be to conduct a risk assessment based on the production context (e.g., crop, climate, soil characteristics, and landscape) and on adult and/or larval population monitoring. When damage risk appears significant, prophylactic practices can be applied to reduce wireworm abundance (e.g., low risk rotations, tilling, and irrigation). Additionally, curative methods based on natural enemies and on naturally derived insecticides are, respectively, under development or in practice in some countries. Alternatively, practices may target a reduction in crop damage instead of pest abundance through the adoption of selected cultural practices (e.g., resistant varieties, planting and harvesting time) or through the manipulation of wireworm behavior (e.g., companion plants). Practices can be combined in a global Integrated Pest Management (IPM) framework to provide the desired level of crop protection

Pathogenicity of Metarhizium and Cordyceps isolates against larvae of different Agriotes species and populations in correlation with conidial size and germination

Entomopathogenic fungi offers a promising approach to control Agriotes larvae, although virulence varies for different Agriotes species. Therefore, the first step was to look for a highly virulent fungal strain for different Agriotes species. To achieve this, six Metarhizium and two Cordyceps strains were studied. Several Metarhizium strains were highly efficient and achieved over 90% mortality over four months by dip treatment. The most promising strain to control A. lineatus and A. obscurus was the M. brunneum strain JKI-BI-1450, while M. robertsii strain JKI-BI-1442 was most effective against A. sputator. The Cordyceps strains had no pathogenic effect. In the second step, we investigated whether fungal strain-specific characteristics such as conidial size and germination could be related to the effect of the strains against Agriotes larvae. A correlation could not be confirmed for A. lineatus and A. obscurus. In contrast, against larvae of A. sputator shorter and wider conidia as well as those that germinate later and show a lower germination rate after 96 h were more effective. In the third step, we investigated whether populations of the same Agriotes species, differ in their susceptibility to entomopathogenic fungi. Different populations of A. obscurus larvae showed variable susceptibility. Significant differences in the Restricted Mean Time Lost (RMTL), but not in the final mortality, were determined for different populations of A. sputator larvae. In contrast, the efficacy on A. lineatus was similar among the various populations tested. Our study indicates highly specific and complex interactions between the Agriotes species and the Metarhizium strains

Results of an international ring test with the dung fly Musca autumnalis in support of a new OECD test guideline

A standardized bioassay using the face fly, Musca autumnalis L (Diptera: Muscidae), was developed to test the lethal and sublethal toxicity of parasiticide residues in livestock dung. The repeatability of this test was assessed for the parasiticide ivermectin in seven tests performed in four laboratories in Germany and France. Additional results of limit tests were provided by two laboratories from the UK. Test results had an acceptable range of heterogeneity. The calculated effect concentration at which 50% emergence was observed (EC50) averaged 4.65 +/- 2.17 (Standard Deviation (SD) mu g ivermectin/kg fresh dung (range: 1.20-7.7)). Effects on emergence were, with one exception, not observed below the No Observed Effect Concentration (NOEC) ranging between 1.11 and 3.33 mu g ivermectin/kg. No effect on development time was observed. We conclude that the face fly is suitably sensitive, and the methods sufficiently repeatable, to support use of this standardized bioassay by the international community in the registration of new veterinary pharmaceuticals. Following these considerations, this species was accepted as a possible test organism in a recently published OECD Guideline (No. 228). (c) 2010 Elsevier B.V. All rights reserved