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Hódmezővásárhely, Hungary

Hiltpold I.,University of Neuchatel | Toepfer S.,CABI Europe | Kuhlmann U.,CABI Europe Switzerland | Turlings T.C.J.,University of Neuchatel
Chemoecology | Year: 2010

Because the ferocious maize pest Diabrotica virgifera virgifera LeConte can adapt to all currently used control strategies, focus has turned to the development of novel, more sustainable control methods, such as biological control using entomopathogenic nematodes (EPN). A good understanding of the biology and behaviour of these potential control agents is essential for their successful deployment. Root systems of many maize varieties emit (E)-β-caryophyllene (EβC) in response to feeding by larvae of the beetle D. v. virgifera. This sesquiterpene has been shown to attract certain species of EPN, thereby enhancing their control potential. In this study, we tested the effect of this root-produced volatile on the field efficacy of the three EPN Heterorhabditis bacteriophora, Heterorhabditis megidis and Steinernema feltiae against D. v. virgifera larvae in southern Hungary. By comparing beetle emergence and root damage for two maize varieties, one that emits EβC and one that does not, it was found that root protection by H. megidis and S. feltiae was higher on the emitting variety, but this was not the case for H. bacteriophora. Overall, all three nematode species showed good control potential. We conclude that, if properly applied and in combination with the right maize variety, the release of these nematodes can be as effective as other control methods. © 2009 Birkhäuser Verlag, Basel/Switzerland. Source


Carrasco L.R.,Imperial College London | Carrasco L.R.,UK Environment Agency | Harwood T.D.,Imperial College London | Toepfer S.,CABI Europe | And 7 more authors.
Annals of Applied Biology | Year: 2010

Europe is attempting to contain or, in some regions, to eradicate the invading and maize destroying western corn rootworm (WCR). Eradication and containment measures include crop rotation and insecticide treatments within different types of buffer zones surrounding new introduction points. However, quantitative estimates of the relationship between the probability of adult dispersal and distance from an introduction point have not been used to determine the width of buffer zones. We address this by fitting dispersal models of the negative exponential and negative power law families in logarithmic and non-logarithmic form to recapture data from nine mark-release-recapture experiments of marked WCR adults from habitats as typically found in the vicinity of airports in southern Hungary in 2003 and 2004. After each release of 4000-6300 marked WCR, recaptures were recorded three times using non-baited yellow sticky traps at 30-305 m from the release point and sex pheromone-baited transparent sticky traps placed at 500-3500 m. Both the negative exponential and negative power law models in non-log form presented the best overall fit to the numbers of recaptured adults (1% recapture rate). The negative exponential model in log form presented the best fit to the data in the tail. The models suggested that half of the dispersing WCR adults travelling along a given bearing will have travelled between 117 and 425 m and 1% of the adults between 775 and 8250 m after 1 day. An individual-based model of dispersal and mortality over a generation of WCR adults indicated that 9.7-45.3% of the adults would escape a focus zone (where maize is only grown once in 3 consecutive years) of 1 km radius and 0.6-21% a safety zone (where maize is only grown once in 2 consecutive years) of 5 km radius and consequently current European Commission (EC) measures are inadequate for the eradication of WCR in Europe. Although buffer zones large enough to allow eradication would be economically unpalatable, an increase of the minimum width of the focus zone from 1 to 5 km and the safety zone from 5 to 50 km would improve the management of local dispersal. © 2009 Association of Applied Biologists. Source


Toepfer S.,CABI Europe | Kurtz B.,CABI Europe Switzerland | Kurtz B.,University of Gottingen | Kuhlmann U.,CABI Europe Switzerland
Journal of Pest Science | Year: 2010

The use of entomopathogenic nematodes is one potential non-chemical approach to control the larvae of the invasive western corn rootworm (Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) in Europe. This study investigated the efficacy of Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Heterorhabditis megidis Poinar, Jackson and Klein (Rh., Heterorhabditidae) and Steinernema feltiae Filipjev (Rh., Steinernematidae) in reducing D. v. virgifera as a function of soil characteristics. A field experiment was repeated four times in southern Hungary using artificially infested maize plants potted into three different soils. Sleeve gauze cages were used to assess the number of emerging adult D. v. virgifera from the treatments and untreated controls. Results indicate that nematodes have the potential to reduce D. v. virgifera larvae in most soils; however, their efficacy can be higher in maize fields with heavy clay or silty clay soils than in sandy soils, which is in contrast to the common assumption that nematodes perform better in sandy soils than in heavy soils. © 2010 The Author(s). Source


Li H.,CABI Europe Switzerland | Toepfer S.,CABI Europe | Kuhlmann U.,CABI Europe Switzerland
Journal of Applied Entomology | Year: 2010

Morphometric traits and body weight are often used to study changes in fitness. For the invasive alien maize pest, Diabrotica virgifera virgifera LeConte, little information is available regarding the possible relationship between morphometric traits and adult activity, which reflects the ability to disperse and invade. Flight and crawling activities of D. v. virgifera adults were investigated in relation to six different morphometric traits as well as body weight, sex and age. This laboratory study revealed that flight activity of D. v. virgifera differed between sexes and changed with age. Young adults of both sexes flew more frequently and took off faster than mature adults. Males flew more frequently and took off faster than females, regardless of age-class. No such differences were found for crawling frequency, but young males crawled faster than young females. Further analysis revealed that fresh body weight and morphometric traits of young adults were better predictors of flight and crawling activity than the same measurements made on mature adults. Particularly pronotum and elytra measurements on young adults are recommended for bioassay studies on activity parameters of D. v. virgifera. © 2009 Blackwell Verlag, GmbH. Source


Gaskin J.F.,U.S. Department of Agriculture | Schwarzlander M.,University of Idaho | Williams III L.,U.S. Department of Agriculture | Gerber E.,CABI Europe | Hinz H.L.,CABI Europe
Biological Invasions | Year: 2012

Perennial pepperweed (Lepidium latifolium L.) is a Eurasian plant species that is invasive in North America. The invasion often forms large, dense monocultural stands. We investigated the genetic diversity along transects in dense populations in the western USA using Amplified Fragment Length Polymorphisms. We also analyzed transect collections from the native Eurasian range for comparison. In addition, we conducted crossing studies to determine possible modes of seed production (sexual outcrossing vs. self-fertilization vs. apomixis). In our study of seed production we determined that self-fertilization and outcrossing both produce germinable seed in perennial pepperweed. Genetic diversity in the USA was unexpectedly low, with only three genotypes in 388 plants, and those three had genetic similarity of ≥98%. Up to 97% of the plants from Turkey and Russia transects were unique genotypes, while <4% of USA plants in a transect were unique. This lack of diversity in the USA samples suggests that perennial pepperweed, despite its success as an invader, is not well-positioned to adapt to new selective pressures, or to recruit pre-adapted genotypes that may vary in resistance or tolerance to disease or herbivory. Because 99% of the USA plants were genetically identical, we were unable to determine if increases in stand size were due to spread by rhizomes or seed derived from outcrossing between genetically identical parents or self-fertilization, as each of these methods produces shoots genetically identical to parental plants. © 2012 Springer Science+Business Media B.V. (outside the USA). Source

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