Ground beetle conservation biocontrol: Potential for pest control ecosystem services using predation activity and trait-based analysis
Date
2023-12-08
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Abstract
Removal of non-crop vegetation (e.g., forest and grassland patches) to expand crop fields threatens the natural enemies of crop pests, like the ground beetle family (Coleoptera: Carabidae), that may use these areas for overwintering. An argument for maintaining non-crop vegetation is its potential to support the supply of ecosystem services, such as pest control, to the surrounding crop. A common proxy for this service is the activity-density of natural enemy species. Evidence that predators like ground beetles are attacking pests in crops has been less frequently studied as have the mechanisms for why non-crop vegetation may influence pest predation within the crop. Studying the traits of natural enemies that are both impacted by the environment and affect their predation activity, may provide a mechanism for how non-crop vegetation influences pest control. Traits, like the size of carabids, may influence both their dispersal from non-crop vegetation and their predatory activity. I sampled a gradient of distances from non-crop vegetation in 20 field sites. I estimated the potential for pest attacks by carabids through bite marks on sentinel prey (plasticine ‘caterpillars’ made to look like potential prey items) and measured the body size of 20,407 carabids. I also conducted prey choice experiments with the carabid Pterostichus melanarius. Generalized additive models show that the frequency of bite marks increased to 50 m into the crop before declining at 100 m, but carabids in pitfall traps increased linearly as distance from non-crop vegetation increased. Results also showed the smallest six quantiles of carabids increased in size with distance from non-crop vegetation areas and larger P. melanarius showed a trend towards preying upon larger prey than smaller prey, though we could not reject a null hypothesis of no effect (alpha=0.05; P=0.08). These findings show predation activity may be associated with non-crop vegetation and the carabid community size distribution, rather than being predicted by activity-density. These findings support conservation of non-crop vegetation to support the predation of a diverse array of pests.
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Keywords
Carabidae, biocontrol, spill-over, ecosystem service, sentinel prey, activity-density, functional trait, response-effect
Citation
Neame, T. J. (2023). Ground beetle conservation biocontrol: potential for pest control ecosystem services using predation activity and trait-based analysis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.