Data and code from: Invertebrate attack rates in crop fields are driven by prey toughness rather than size

Abstract Insect pest complexes associated with a given crop or crop rotation usually consist of insect pests of various size and toughness depending on species and life stage. However, it is unclear how this affects attack rates (or ‘biocontrol’), which filter prey traits apply to the predator community, and which role the activity density and traits of carabids play in this. Trait data of sentinel prey (size, toughness) and carabids (size, bite force) was obtained in the laboratory. Field data were collected using standardised prey cards comprising six different dead sentinels: aphids (Hemiptera: Sitobion avenae), ‘pinky’ maggots (Diptera: Lucilia sp.), pupae (Diptera: Calliphora sp.), small and large mealworms (Coleoptera: Tenebrio molitor), and wax moth larvae (Lepidoptera: Galleria mellonella). These were deployed across multiple sites and landscapes (12 sites in six landscapes) in Lower Franconia, Bavaria, Germany. Camera surveillance was used to identify predator taxa and document interaction events. Attack rates calculated from prey cards alone were compared to those obtained from camera data, with particular emphasis given to the time dimension (e.g. prey items attacked/removed per unit of time). The contribution of different predator groups to the attack and removal of different prey types was assessed visually. The relationship of size and toughness of the prey types was elucidated using a cluster analysis. The influence of carabid activity density on their engagement in prey attack, as monitored by cameras, was analysed. Competing events of carabids and other taxa on the prey was analysed using cumulative incidence functions (variant of survival analysis). Trait matching of carabids and prey was visually assessed by plotting carabids attacking a given prey type in a coordinate system of carabid size and bite force, and then comparing the data spread across prey types. Our results suggest that the effectiveness with which ground-dwelling predator communities control insect pests in conventional cereal fields depends on prey toughness. Therefore, the choice of prey used to assess ecosystem function can bias measured attack rates by reflecting certain predator groups selectively. Increasing the abundance of predators, especially carabid beetles, may enhance the control of medium soft pests (e.g. comparable to wax moth larvae), whereas harder-bodied species or life stages (e.g. comparable to Calliphora sp. pupa) likely require different or additional predators. Data usage Please refer to the README file and the provided metadata (.txt) for details on the datasets, analysis and visualisation. Funding Bundesministerium für Forschung, Technologie und Raumfahrt (BMFTR): ConservES Project via the European Biodiversity Partnership Biodiversa+ Ecological Society of Germany, Austria and Switzerland (GfÖ): Forschungsförderung 2024