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Understanding patterns in predator:prey systems and the mechanisms that underlie trophic interactions provides a basis for predicting community structure and the delivery of natural pest control services. The functional response of predators to prey density is a fundamental measure of interaction strength and its characterisation is essential to understanding these processes. We used mesocosm experiments to quantify the functional responses of five ground beetle species that represent common generalist predators of north-west European arable agriculture. We investigated two mechanisms predicted to be key drivers of trophic interactions in natural communities: predator:prey body size ratio and multiple predator effects. Our results show regularities in foraging patterns characteristic of similarly sized predators. Ground beetle attack rates increased and handling times decreased as the predator:prey body-mass ratio rose. Multiple predator effects on total prey consumption rates were sensitive to the identity of the interacting species but not prey density. The extent of interspecific interactions may be a result of differences in body mass between competing beetle species. Overall these results add to the growing evidence for the importance of size in determining trophic interactions and suggest that body mass could offer a focus on which to base the management of natural enemy assemblages.

Understanding patterns in predator:prey systems and the mechanisms that underlie trophic interactions provides a basis for predicting community structure and the delivery of natural pest control services. The functional response of predators to prey density is a fundamental measure of interaction strength and its characterisation is essential to understanding these processes. We used mesocosm experiments to quantify the functional responses of five ground beetle species that represent common generalist predators of north-west European arable agriculture. We investigated two mechanisms predicted to be key drivers of trophic interactions in natural communities: predator:prey body size ratio and multiple predator effects. Our results show regularities in foraging patterns characteristic of similarly sized predators. Ground beetle attack rates increased and handling times decreased as the predator:prey body-mass ratio rose. Multiple predator effects on total prey consumption rates were sensitive to the identity of the interacting species but not prey density. The extent of interspecific interactions may be a result of differences in body mass between competing beetle species. Overall these results add to the growing evidence for the importance of size in determining trophic interactions and suggest that body mass could offer a focus on which to base the management of natural enemy assemblages.

This study investigated how local habitat type and landscape structure affects the biomass, species richness and functional diversity of ground beetles sampled from a 1000 ha UK arable farm. At a local scale habitat type was either crop (winter wheat and oilseed rape) or one of five field margin habitats. Surrounding each of these sampling areas, landscape structure was defined using remote sensed data from Specim AISA Eagle (400–970 nm) and Hawk (970–2450 nm) hyperspectral sensors. Ground beetles were divided into predatory and phytophagous trophic levels. Local habitat type only affected phytophagous ground beetle biomass, which was lowest within crops. Total biomass of predatory beetles was negatively correlated, and species richness positively correlated, with landscape habitat diversity. Only the functional diversity of predatory ground beetles responded to landscape structure, showing positive correlations with the proportion of Tussock Grass field margins. Predatory ground beetles show a greater dependence on landscape structure than phytophagous species, a response that is attributed to their high mobility needed for movement between dynamically variable food resources.

Analysis of seeds collected from rust (Puccinia hysterium) infected and uninfected Tragopogon pratensis, located within the Park Grass Experiment at Rothamsted Research, has shown a significant difference in the number of seeds produced and also in the subsequent number of successful germinations between seeds set by infected and uninfected plants. This supports the hypothesis that P. hysterium significantly suppresses reproduction in T. pratensis. Furthermore, seeds from infected individuals have significantly shorter pappi and seed mid-lengths whilst having no significant difference in seed mass, indicating that seeds from infected hosts have altered growth form.

This study investigated how local habitat type and landscape structure affects the biomass, species richness and functional diversity of ground beetles sampled from a 1000 ha UK arable farm. At a local scale habitat type was either crop (winter wheat and oilseed rape) or one of five field margin habitats. Surrounding each of these sampling areas, landscape structure was defined using remote sensed data from Specim AISA Eagle (400–970 nm) and Hawk (970–2450 nm) hyperspectral sensors. Ground beetles were divided into predatory and phytophagous trophic levels. Local habitat type only affected phytophagous ground beetle biomass, which was lowest within crops. Total biomass of predatory beetles was negatively correlated, and species richness positively correlated, with landscape habitat diversity. Only the functional diversity of predatory ground beetles responded to landscape structure, showing positive correlations with the proportion of Tussock Grass field margins. Predatory ground beetles show a greater dependence on landscape structure than phytophagous species, a response that is attributed to their high mobility needed for movement between dynamically variable food resources.

Analysis of seeds collected from rust (Puccinia hysterium) infected and uninfected Tragopogon pratensis, located within the Park Grass Experiment at Rothamsted Research, has shown a significant difference in the number of seeds produced and also in the subsequent number of successful germinations between seeds set by infected and uninfected plants. This supports the hypothesis that P. hysterium significantly suppresses reproduction in T. pratensis. Furthermore, seeds from infected individuals have significantly shorter pappi and seed mid-lengths whilst having no significant difference in seed mass, indicating that seeds from infected hosts have altered growth form.