TY  - JOUR
A1  - Hancock, Christine
A1  - Wäschke, Nicole
A1  - Schumacher, Uta
A1  - Linsenmair, Karl Eduard
A1  - Meiners, Torsten
A1  - Obermaier, Elisabeth
T1  - Fertilizer application decreases insect abundance on Plantago lanceolata - a large-scale experiment in three geographic regions
T2  - Arthropod-plant interactions : an international journal devoted to studies on interactions of insects, mites, and other arthropods with plants
N2  - Humans have substantially altered the nitrogen cycle of ecosystems through the application of agricultural fertilizer. Fertilization may not only affect plant species diversity, but also insect dynamics by altering plant nitrogen supplies. We investigated the effect of experimental fertilization on the vegetation, with the ribwort plantain as the focal plant, and on higher trophic levels on differently managed grasslands throughout Germany. Over a period of 2 years, we examined two specialist herbivores and their parasitoid on Plantago lanceolata L., and the composition and structure of the surrounding vegetation. Over 70 sites in three geographic regions, within the large-scale project "German Biodiversity Exploratories", were included in the study. The model system consisted of the host plant P. lanceolata L., the monophagous weevils Mecinus labilis Herbst and M. pascuorum Gyllenhal, and their parasitoid Mesopolobus incultus Walker. Fertilization decreased plant species richness and host plant abundance, whereas it enhanced the total vegetation growth. The increased size and heigher leaf nitrogen content did not improve herbivore performance. On the contrary, the abundance of the two herbivores was decreased by fertilization. The parasitoid depended on the abundance of one of its hosts, M. pascuorum (positively density-dependent). Reduced herbivore abundance due to fertilization might be explained by a lower abundance of the host plant, a lower stalk number, and by changed patterns of host localization within higher vegetation. Fertilization negatively affected the third trophic level by cascading up via host abundance. The relationships between fertilization, surrounding vegetation and the tritrophic system were measured throughout the three regions and over the 2-year period. Our findings present consequences of intensification for a plant-herbivore-parasitoid system, and may have significant implications for the conservation of multitrophic systems in managed grasslands.
KW  - Fertilization
KW  - Nitrogen
KW  - Tritrophic interaction
KW  - Plant species richness
KW  - Grassland management
KW  - Vegetation structure
Y1  - 2013
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/35117
SN  - 1872-8855
SN  - 1872-8847
VL  - 7
IS  - 2
SP  - 147
EP  - 158
PB  - Springer
CY  - Dordrecht
ER  -