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8 results on '"Vollhardt, Ines M. G."'

3. Evaluation of three molecular markers for identification of European primary parasitoids of cereal aphids and their hyperparasitoids

Author

Ye, Zhengpei, Vollhardt, Ines M. G., Tomanovic, Zeljko, Traugott, Michael, and Desneux, Nicolas

Subjects
Computer and Information Sciences, Cell biology, Evolutionary Processes, Cellular structures and organelles, Arthropoda, Bioinformatics, Speciation, Wasps, Sequence Databases, lcsh:Medicine, Artificial Gene Amplification and Extension, Genes, Insect, Research and Analysis Methods, Biochemistry, Polymerase Chain Reaction, Host-Parasite Interactions, Database and Informatics Methods, RNA, Ribosomal, 16S, Cryptic Speciation, RNA, Ribosomal, 18S, Animals, Non-coding RNA, Molecular Biology Techniques, lcsh:Science, Molecular Biology, DNA sequence analysis, Taxonomy, Data Management, Evolutionary Biology, lcsh:R, fungi, Organisms, Biology and Life Sciences, food and beverages, Invertebrates, Insects, Nucleic acids, Biological Databases, Ribosomal RNA, Aphids, RNA, lcsh:Q, Sequence databases, Cryptic speciation, Sequence alignment, Polymerase chain reaction, Edible Grain, Sequence Analysis, Sequence Alignment, Ribosomes, Biomarkers, Research Article
Abstract

Aphids are major pests of cereal crops and a suite of hymenopteran primary parasitoids play an important role in regulating their populations. However, hyperparasitoids may disrupt the biocontrol services provided by primary parasitoids. As such, understanding cereal aphid-primary parasitoid-hyperparasitoid interactions is vital for a reliable parasitoid-based control of cereal aphids. For this, the ability to identify the different primary and hyperparasitoid species is necessary. Unfortunately, this is often difficult due to a lack of morphologically diagnostic features. DNA sequence-based species identification of parasitoids can overcome these hurdles. However, comprehensive DNA sequence information is lacking for many of these groups, particularly for hyperparasitoids. Here we evaluate three genes [cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S) and 18S ribosomal RNA (18S)] for their suitability to identify 24 species of primary parasitoids and 16 species of hyperparasitoids associated with European cereal aphids. To identify aphelinid primary parasitoid species and hyperparasitoids, we found 16S to be more suitable compared to COI sequences. In contrast, the Aphidiinae are best identified using COI due to better species-level resolution and a more comprehensive DNA sequence database compared to 16S. The 18S gene was better suited for group-specific identification of parasitoids, but did not provide resolution at the species level. Our results provide a DNA sequence database for cereal aphid primary parasitoids and their associated hyperparasitoids in Central Europe, which will allow further improvement of our understanding of cereal aphid-primary parasitoid-hyperparasitoid interactions in relation to aphid biological control. peerReviewed

Published
2017

6. Similar diversity of cereal aphid parasitoids in simple and complex landscapes.

Author

Vollhardt, Ines M. G., Tscharntke, Teja, Wäckers, Felix L., Bianchi, Felix J. J. A., Thies, Carsten, Vollhardt, Ines M. G., Tscharntke, Teja, Wäckers, Felix L., Bianchi, Felix J. J. A., and Thies, Carsten

Abstract

Structurally complex landscapes may enhance local species richness and interactions, which is possibly due to a higher species pool in complex landscapes. This hypothesis was tested using cereal aphid parasitoids (Hymenoptera, Aphidiidae) by comparing 12 winter wheat fields in structurally complex landscapes (>50% semi-natural habitats; n = 6) and structurally simple landscapes dominated by agricultural lands (>80% arable land; n = 6). Surprisingly, landscape structural complexity had no effect on aphid parasitoid species diversity. In complex landscapes 12 and in simple landscapes 11 species were found; 9 species occurred in both landscape types. Hence, arable fields in high-intensity agricultural landscapes with little non-crop area can support a similar diversity of cereal aphid parasitoids as structurally complex landscapes. This finding suggests that cereal aphid parasitoids may find necessary resources even in simple landscapes, making generalisations concerning the relationship between landscape composition and biodiversity in arable fields difficult.

Published
2008

7. Nectar vs. honeydew feeding by aphid parasitoids: does it pay to have a discriminating palate?

Author

Vollhardt, Ines M. G., Bianchi, Felix J. J. A., Wäckers, Felix L., Thies, Carsten, and Tscharntke, Teja

Subjects
*HONEYDEW, *NECTARIES, *PARASITOIDS, *PARASITES, *LONGEVITY
Abstract

As food items can vary in nutrient composition, diet selectivity can be an important trait to optimize nutrition. Most parasitoids depend as adults on various sugar-rich food sources such as nectar and honeydew. Nectar is often superior as a food source to honeydew, yielding higher parasitoid longevity. Little is known, however, of a preference parasitoids may have for one of these sugar sources and how this affects variation in their life-history traits. In this study, a combined empirical and modelling approach was adopted. First, it was investigated whether parasitoids show a feeding preference for nectar or honeydew in the laboratory and whether feeding history affects the preference of parasitoids. Second, using a process-based spatially explicit simulation model, it was evaluated how preference for nectar affects parasitoid life-history variables in fields with varying flower densities. The laboratory study revealed that naïve parasitoids showed no preference for either nectar or honeydew. However, when parasitoids had fed previously on honeydew and were then given the choice between nectar and honeydew, they preferred feeding on nectar to honeydew (with marginal statistical significance). Model simulations indicated that when nectar sources were present in the field, parasitoids that showed preference for nectar had a 1.3–1.8 times longer life span and parasitised up to 1.4 times more hosts than parasitoids that did not distinguish between honeydew and nectar. These combined empirical and modelling data suggest that aphid parasitoids may be able to discriminate between nectar and honeydew, and that a preference for nectar may enhance their longevity and reproduction in fields where nectar sources are available. [ABSTRACT FROM AUTHOR]

Published
2010
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8. The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis.

Author

Albrecht M, Kleijn D, Williams NM, Tschumi M, Blaauw BR, Bommarco R, Campbell AJ, Dainese M, Drummond FA, Entling MH, Ganser D, Arjen de Groot G, Goulson D, Grab H, Hamilton H, Herzog F, Isaacs R, Jacot K, Jeanneret P, Jonsson M, Knop E, Kremen C, Landis DA, Loeb GM, Marini L, McKerchar M, Morandin L, Pfister SC, Potts SG, Rundlöf M, Sardiñas H, Sciligo A, Thies C, Tscharntke T, Venturini E, Veromann E, Vollhardt IMG, Wäckers F, Ward K, Westbury DB, Wilby A, Woltz M, Wratten S, and Sutter L

Subjects
Agriculture, Bees, Biodiversity, Europe, Flowers, New Zealand, North America, Pest Control, Ecosystem, Pollination
Abstract

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future., (© 2020 The Authors. Ecology Letters published by John Wiley & Sons Ltd.)

Published
2020
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