Diabrotica virgifera virgifera LeConte in confrontation mood : simultaneous geographical and host spectrum expansion in southeastern Slovenia

Diabrotica virgifera virgifera LeConte, in its original North American habitat also known as western corn rootworm beetle, actively continues its expansion to new territories and uses Homo sapiens as its prime vector. It took only 15 years to spread to and occupy the southeastern and central parts of Europe, so far with the exception of Denmark where it has not been documented as of 2007. Economic thresholds have been reached and surpassed only in Southeast European countries like Slovakia, Hungary, Serbia, Eastern Croatia, Romania and Northern Italy. But both, the area affected and the severity of symptoms are increasing. Model calculations by a number of authors (Baufeld & Enzian, 2005 a and b; Hongmei Li & al. 2006, CLIMEX model) indicate a definitive propensity of D. v. virgifera to expand its currently occupied territory to regions with moderate temperatures and Zea mays cultivation. East Africa and Eastern Asia are included in the list of potential candidates for future inadvertent introduction. In most discussions it is tacitly and erroneously assumed that Z. mays is the only or the only important host of D. v. virgifera. Our recent observations in Eastern Slovenia on the oil pumpkin Cucurbita pepo indicate, however, that this simplifying assumption is notlonger strictly valid. It has to be modified in light of new evidence. Here, we report a few field experiments conducted in August of 2006 clarifying the host status of C. pepo in a European country.Diabrotica virgifera virgifera LeConte (Coleoptera: Chysomelidae), im deutschsprachigen Raum als Westlicher Maiswurzelbohrer bekannt, ist ein von der Neuen Welt nach Europa eingeschleppter Schädling. Er gelangte in mindestens drei Einwanderungsschüben, die durch molekulargenetische Untersuchungen unterscheidbar sind, nach Europa. Innerhalb der letzten eineinhalb Jahrzehnte wurde, mit Ausnahme von Dänemark, die gesamte Fläche Südost- und Zentraleuropas vom Käfer besiedelt. In mehreren osteuropäischen Ländern ist die ökonomische Schadensschwelle bereits überschritten. Bis 2006 galt Zea mays als einzige bekannte europäische Wirtspflanze. Allerdings deuten neueste Beobachtungen in Ostslowenien vom August 2006 auf kleine Zahlen von Käfern am Ölkürbis Cucurbita pepo und damit auf eine Ausdehnung des Wirtsspektrums von D. v. virgifera hin. Der Käfer tritt in kleinen Zahlen als Besucher von Ölkürbisblüten mit einer Häufigkeit von 0,1 % auf. Er ist aber auch in geringer Häufigkeit in Kairomon- und Pheromonfallen in Ölkürbisfeldern südlich von Gaberje in Ostslowenien anzutreffen. Dieses Ergebnis stellt den zukünftigen Wert des Fruchtwechsels in Frage, der bisher als eine der wirksamsten und nachhaltigsten Methoden des integrierten Pflanzenschutzes galt

Evaluation of Insect Associated and Plant Growth Promoting Fungi in the Control of Cabbage Root Flies

Delia radicum L. or cabbage maggot is an important pest for Brassicaceous crops. There are currently no registered chemical control agents for its control in Slovenia. Fungal control agents for cabbage maggot were therefore sought among nine rhizosphere-compatible and plant growth-promoting, soil-adapted, and entomopathogenic species to cabbage maggots and were assayed in in vitro and soil laboratory bioassays. In the in vitro tests, the conidial suspensions were applied directly to cabbage maggot eggs. The soil tests mimicked pathways of natural exposure of various insect life stages to the fungal strains. Conidial concentrations used in soil tests were comparable to economic rates for in-furrow application. The following fungi were tested: Trichoderma atroviride P. Karst. (2 isolates), Trichoderma koningiopsis Samuels, C. Suárez & H.C. Evans (1), Trichoderma gamsii Samuels & Druzhin. (3), Beauveria brongniartii (Saccardo) Petch (1), Beauveria bassiana (Balsamo-Crivelli) Vuillemin (2), Metarhizium robertsii J.F. Bisch., Rehner & Humber (1), Metarhizium anisopliae (Metschn.) Sorokin (4), Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones & Samson (2), and Clonostachys solani f. nigrovirens (J.F.H. Beyma) Schroers (2). Abbott's corrected mortality in the in vitro tests ranged from 0.0 ± 18.9 to 47.6 ± 9.0% and in the soil test from 2.4 ± 13.0 to 68.2 ± 21.5%. Seven isolates (B. bassiana [isolate 1174], C. solani [1828], M. anisopliae [1154 and 1868], T. atroviride [1872], T. koningiopsis [1874], and T. gamsii [1876]) caused significant cabbage maggot mortality in either in vitro or soil tests. The importance of fungal ecology as a criterion during the screening of potential biological control agents is discusse

Isolation of non-pathogenic Agrobacterium spp. biovar 1 from agricultural soils in Slovenia

The disease crown gall, which causes damage on perennial agricultural crops, is economically important in many countries. We therefore explored the presence of Agrobacterium spp. in a variety of agricultural soils where fruit trees are grown. Most samples were collected in four regions of Slovenia where a majority of fruit tree plantations are situated. Crown gall-affected plants were not observed on any of the sampling sites. Members of Agrobacterium spp. biovar 1 were isolated from 63 of the 72 soil samples (88%), but none from forest soil. All isolates of this Agrobacterium species complex were determined to be non-pathogenic by biotests and were assigned to genomic species based on a recA allele sequence analysis. Fourty-three isolates were allocated into genomic species G1 and 26 isolates into G4. Among both genomic species, new alleles of the recA gene were recognized: seven new alleles in G1 (denominated G1-15 to G1-21) and four in G4 (G4-7 to G4-10). Two alleles predominated among the Slovenian strains, recA-G1-15 and recA-G4-2. Different colony morphologies were observed between strains of G1 and G4 on KB medium

PCR-RFLP diagnostic method for identifying Globodera species in Slovenia

Species identification within the genus Globodera is based on the morphological and morphometrical characters of the cysts and second stage juveniles, and these are included in the majority of identification keys. Morphometrical methods are fast and can be applied to most of samples but they demand a trained and experienced specialist. Furthermore, some morphometrical characters may overlap between populations and beetwen species, leading to inaccurate identification. To confirm and complement the morphometrical identification of Globodera species molecular methods have been developed. Sequences of the internal transcribed spacer regions ITS1 and ITS2 of the rDNA gene cluster proved to be useful for identifying nematode species identification. A PCR-RFLP molecular method was used to identify Globodera rostochiensis, G. pallida, G. tabacum and G. achilleae. Globodera rostochiensis, G. pallida, G. tabacum and G. achilleae can be distinguished with PCR-RFLP analysis of the rDNA ITS fragment using five restriction enzymes. The RFLP patterns of G. rostochiensis, G. tabacum and G. achilleae were species-specific, while those of G. pallida varied. South American populations of G. pallida differed from other populations as their RFLP patterns were demonstrated to be distinct by in silico restriction of the ITS sequences deposited at NCBI

THE INFLUENCE OF POTATO CYST NEMATODE G. ROSTOCHIENSIS INFESTATION ON DIFFERENT POTATO CULTIVARS

The potato cyst nematode Globodera rostochiensis is one of the most serious pests of potato in Slovenia. Precise nematode identification and knowledge about potato cultivars, which are most suitable for growing in the Slovenian climate conditions and most resistant to G. rostochiensis, are necessary to develop an effective integrated pest control. Here we report the results of the influence of G. rostochiensis pathotype Ro1/4 on the yield of different potato cultivars: the susceptible cultivar Desiree, the resistant cultivars White Lady, Miranda, Aladin, Sante and Adora, and the clone KIS 94-1/5-14. The yield of cv. White Lady was the highest and that of susceptible cv. Desiree the lowest. The influence of several resistant and one susceptible potato cultivars on population dynamics of G. rostochiensis was also determined. The total number of cysts/100 cm3 and the number of eggs and juveniles per cyst increased in the susceptible cv. Desiree and decreased in the resistant cultivars White Lady, Sante and Adora

Scientific Opinion on the pest categorisation of Strawberry vein banding virus

The Panel on Plant Health performed a pest categorisation of Strawberry vein banding virus (SVBV) for the European Union (EU) territory. SVBV is a well-defined virus species of the genus Caulimovirus for which the entire genome sequence is known and molecular detection assays are available. SVBV is transmitted by vegetative multiplication of infected hosts and through the activity of aphid vectors, the most efficient being Chaetosiphon spp. The virus is reported from all continents and is present in three EU Member States: the Czech Republic, Italy and Slovakia. The host range of SVBV is restricted to cultivated and wild strawberries. It is listed in Annex IAI of Directive 2000/29/EC. SVBV is not expected to be affected by ecoclimatic conditions wherever its hosts are present and has the potential to establish in large parts of the EU territory, and to subsequently spread through the action of its Chaetosiphon fragaefolii vector, which is present in many Member States. SVBV does not cause severe symptoms, and modern cultivars are mostly symptomless if infected with SVBV alone. SVBV can, however, contribute to more severe symptoms when it occurs in mixed infections with other strawberry viruses. Despite this, SVBV is considered a minor problem in strawberry production as a consequence of modern practices including the systematic use of certified planting materials and the use of short crop cycles, which have greatly reduced the impact of strawberry viruses. Overall, SVBV does not have the potential to be a quarantine pest as, given current agricultural practices, it does not fulfil the pest categorisation criteria defined in the International Standards for Phytosanitary Measures No 11 of having a severe impact. However, SVBV has the potential to be a regulated non-quarantine pest because it fulfils all pest categorisation criteria defined in the International Standards for Phytosanitary Measures No 21

Scientific Opinion on the pest categorisation of Eotetranychus lewisi

The Panel on Plant Health performed a pest categorisation of the Lewis spider mite, Eotetranychus lewisi, for the European Union (EU). The Lewis spider mite is a well-defined and distinguishable pest species that has been reported from a wide range of hosts, including cultivated species. Its distribution in the EU territory is restricted to (i) Madeira in Portugal; and to (ii) Poland where few occurrences were reported in glasshouses only. The pest is listed in Annex IIAI of Council Directive 2000/29/EC. A potential pathway of introduction and spread is plants traded from outside Europe and between Member States. The Lewis spider mite has the potential to establish in most part of the EU territory based on climate similarities with the distribution area outside the EU and the widespread availability of hosts present both in open fields and in protected cultivations. With regards to the potential consequences, one study is providing quantitative data on impact showing that the pest can reduce yield and affect quality of peaches and poinsettias, and only few studies describe the general impact of the pest on cultivated hosts. Although chemical treatments are reported to be effective in controlling the Lewis spider mite, it is mentioned as a growing concern for peaches, strawberries, raspberries and vines in the Americas. Overall, Eotetranychus lewisi meets the pest categorisation criteria defined in the International Standards for Phytosanitary Measures No 11 for a quarantine pest and in No 21 for a regulated non-quarantine pest