Diversity and efficacy of beneficial arthropods related to landscape complexity

As many ecological processes and interactions may depend on scales larger than a single habitat, it is important to link spatial patterns, connectivity and environment of habitats at the landscape scale. Therefore, in this research project the diversity of predatory arthropods relative to landscape complexity, the efficacy of beneficial arthropods relative to landscape complexity, and factors affecting the reproduction and nutritional condition in arthropod predators are investigated. These largely unknown research topics are explored in thirty study areas, which cover different levels of complexity from structurally simple to structurally rich landscapes. In the centre of each study area (2 x 2 km) an oilseed rape field is situated serving as study site. Oilseed rape is explored as it is an economically important arable crop attacked by many potentially severe insect pests. Arthropods studied belong to different trophic groups comprising predators (Carabidae, Staphylinidae, Coccinellidae, Syrphidae, Araneae), parasitoid hymenopterans that are considered as potential beneficials, and herbivorous insect pests of oilseed rape. The effects of landscape complexity on population dynamics, beneficial-pest interactions and nutritional and reproductive state of arthropods are analysed at squares of 0.5 x 0.5, 1.0 x 1.0, 1.5 x 1.5 and 2.0 x 2.0 km, using stepwise multiple linear regression models. Landscape and habitat parameters that explain species communities significantly, and the relation between single predatory species and landscape and habitat parameters will be analysed with a canonical correspondence analysis. The proposed project contains two completely new research aspects. Firstly, the investigation of the efficacy of beneficial arthropods in dependency on landscape complexity and its consequences on economic threshold is a largely unknown research area. Secondly, the response of the diversity, efficacy and reproduction of beneficial arthropods to landscape complexity in dependence on different spatial scales has never been investigated before. Thus, it is significant to know how many semi-natural habitats at which spatial scale are necessary to suppress pest damage below an economic threshold. Both aspects may be groundbreaking for the understanding of man-made landscape alterations on beneficial-pest interactions, and may have fundamental consequences on agri-environment schemes that aim to enhance natural pest control.

As many ecological processes and interactions may depend on scales larger than a single habitat, it is important to link spatial patterns, connectivity and environment of habitats at the landscape scale. Therefore, in this research project the diversity of predatory arthropods relative to landscape complexity, the efficacy of beneficial arthropods relative to landscape complexity, and factors affecting the reproduction and nutritional condition in arthropod predators are investigated. These largely unknown research topics are explored in thirty study areas, which cover different levels of complexity from structurally simple to structurally rich landscapes. In the centre of each study area (2 x 2 km) an oilseed rape field is situated serving as study site. Oilseed rape is explored as it is an economically important arable crop attacked by many potentially severe insect pests. Arthropods studied belong to different trophic groups comprising predators (Carabidae, Staphylinidae, Coccinellidae, Syrphidae, Araneae), parasitoid hymenopterans that are considered as potential beneficials, and herbivorous insect pests of oilseed rape. The effects of landscape complexity on population dynamics, beneficial-pest interactions and nutritional and reproductive state of arthropods are analysed at squares of 0.5 x 0.5, 1.0 x 1.0, 1.5 x 1.5 and 2.0 x 2.0 km, using stepwise multiple linear regression models. Landscape and habitat parameters that explain species communities significantly, and the relation between single predatory species and landscape and habitat parameters will be analysed with a canonical correspondence analysis. The proposed project contains two completely new research aspects. Firstly, the investigation of the efficacy of beneficial arthropods in dependency on landscape complexity and its consequences on economic threshold is a largely unknown research area. Secondly, the response of the diversity, efficacy and reproduction of beneficial arthropods to landscape complexity in dependence on different spatial scales has never been investigated before. Thus, it is significant to know how many semi-natural habitats at which spatial scale are necessary to suppress pest damage below an economic threshold. Both aspects may be groundbreaking for the understanding of man-made landscape alterations on beneficial-pest interactions, and may have fundamental consequences on agri-environment schemes that aim to enhance natural pest control.