Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2019
Abstract
We studied the effect of three Pandora neoaphidis isolates from one Sitobion avenae population, three temperatures, and two aphid species namely S. avenae and Rhopalosiphum padi on (i) aphid mortality, (ii) time needed to kill aphids, and (iii) aphid average daily and lifetime fecundity. A total of 38% of S. avenae and 7% of R. padi died and supported fungus sporulation. S. avenae was killed 30% faster than R. padi. Average daily fecundity was negatively affected only in S. avenae inoculated with, but not killed by, P. neoaphidis. Nevertheless, lifetime fecundity of both aphid species inoculated and sporulating with P. neoaphidis was halved compared to lifetime fecundity of surviving aphids in the control. Increased temperature resulted in higher mortality rates but did not consistently affect lethal time or fecundity. Results suggest that (i) temperature effects on virulence differ between isolates, even when obtained within the same host population, and (ii) even though an isolate does not kill a host it may reduce its fecundity. Our findings are important for the understanding of P. neoaphidis epizootiology and for use in pest-natural enemy modelling.
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Authors
Kamila S. Zając Bjørn Arild Hatteland Barbara Feldmeyer Markus Pfenninger Anna Filipiak Leslie Robert Noble Dorota Lachowska-CierlikAbstract
Arion vulgaris Moquin-Tandon, 1855 is regarded as one of the 100 most invasive species in Europe. The native distribution range of this species is uncertain, but for many years, the Iberian Peninsula has been considered as the area of origin. However, recent studies indicate that A. vulgaris probably originated from France. We have investigated the genetic structure of 33 European populations (Poland, Norway, Germany, France, Denmark, Switzerland) of this slug, based on two molecular markers, mitochondrial cytochrome c oxidase subunit I (COI, mtDNA) and nuclear zinc finger (ZF, nDNA). Our investigation included published data from two previous studies, giving a total of 95 populations of A. vulgaris from 26 countries. This comprehensive dataset shows comparable haplotype diversity in Central, North and Western Europe, and significantly lower haplotype diversity in the East. All haplotypes observed in the East can be found in the other regions, and haplotype diversity is highest in the Central and Western region. Moreover, there is strong isolation by distance in Central and Western Europe, and only very little in the East. Furthermore, the number of unique haplotypes was highest in France. This pattern strongly suggests that A. vulgaris has originated from a region spanning from France to Western Germany; hence, the slug is probably alien/invasive in other parts of Europe, where it occurs. Our results indicate the necessity to cover as much of the distribution range of a species as possible before making conclusive assumptions about its origin and alien status.
Abstract
Although supporting high productivity, modern agriculture caused a long-term impact on natural trophic interactions, releasing pests from pressure linked with their natural enemies. Studies have demonstrated that volatiles released under herbivory can recruit natural enemies of pests from a distance. Here, we used a novel biodegradable formulation loaded with induced and food-signalling volatiles with the aim to attract the green lacewing, Chrysoperla carnea, and increase biological control of two cereal aphids Sitobion avenae and Rhopalosiphum padi. The new product consisted of a biodegradable matrix loaded with a 3-component blend of methyl salicylate, acetic acid and phenylacetaldehyde in a 1:1:1 ratio. Field experiments were carried out in a barley field in Norway. Single plants were provided with a 1 ml dollop of the new formulation or with a standard polyethylene emballage dispenser loaded with the same amount of compounds. The number of lacewing eggs and larvae as well as the attraction of additional natural enemies was recorded both on the treated and surrounding plants by visual inspection. At the same time, an assessment of aphid infestation was carried out. A higher local density of lacewing adults, eggs and larvae over an 8-week period was observed for both the standard and the biodegradable formulation in comparison with untreated plants. Chemical analysis of the volatiles emitted from the slow-release matrix showed an active emission of the blend over at least a 4-week period. Significant biological control of aphid was measured in the vegetation surrounding the odour source. Both aphid populations were significantly reduced, with no difference between the new and the standard treatment. While coccinellids and hoverflies were not affected by the treatment, a lower number of mummified aphids were measured in some of the treated plants in comparison with untreated ones. Results show the potential for semiochemical-based targeted attraction of lacewings to enhance biological control of aphids in a prevalent monoculture field setting. Additional studies are required to support the development of practical integrated pest management guidelines, including optimization of application density, threshold value for pest and natural enemies and practical recommendation for the establishment of non-crop vegetation within and around the crop.
Authors
Gunda ThömingAbstract
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Abstract
Upon herbivory, plants release herbivore-induced plant volatiles (HIPVs), which induce chemical defenses in the plant as well as recruit natural enemies. However, whether synthetic HIPVs can be employed to enhance biological control in a cultivated crop in the field is yet to be explored. Here we show that a biodegradable formulation loaded with induced and food-signaling volatiles can selectively recruit the common green lacewing, Chrysoperla carnea, and reduce pest population under field conditions. In apple orchards, the new formulation attracted lacewing adults over a 4-week period, which correlated well with independent assessments of the longevity of the slow-release matrix measured through chemical analyses. In barley, lacewing eggs and larvae were significantly more abundant in treated plots, whereas a significant reduction of two aphid species was measured (98.9% and 93.6% of population reduction, for Sitobion avenae and Rhopalosiphum padi, respectively). Results show the potential for semiochemical-based targeted recruitment of lacewings to enhance biological control of aphids in a field setting. Further research should enhance selective recruitment by rewarding attracted natural enemies and by optimizing the application technique.
Authors
Marie Reimer Björn Ringselle Göran Bergkvist Sally Westaway Raphaël Wittwer Jörg Peter Baresel Marcel G. A. van der Heijden Kjell Mangerud Maria R. Finckh Lars Olav BrandsæterAbstract
Reducing soil tillage can lead to many benefits, but this practice often increases weed abundance and thus the need for herbicides, especially during the transition phase from inversion tillage to non-inversion tillage. We evaluated if subsidiary crops (SCs, e.g., cover crops) can mitigate the effects of non-inversion tillage on weed abundance. Two-year experiments studying SC use, tillage intensity, and nitrogen (N) fertilization level were carried out twice at six sites throughout northern and central Europe. SCs significantly reduced weed cover throughout the intercrop period (−55% to −1% depending on site), but only slightly during the main crops. Overall weed abundance and weed biomass were higher when using non-inversion tillage with SCs compared to inversion tillage without SCs. The effects differed due to site-specific weed pressure and management. With increasing weed pressure, the effect of SCs decreased, and the advantage of inversion over non-inversion tillage increased. N fertilization level did not affect weed abundance. The results suggest that SCs can contribute by controlling weeds but cannot fully compensate for reduced weed control of non-inversion tillage in the transition phase. Using non-inversion tillage together with SCs is primarily recommended in low weed pressure environments.
Abstract
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