Carabids for Natural-Enemy Pest Control: combining ecology and knowledge exchange to bridge the gaps

Carabid beetles are proven predators of crop pests and weed seeds. Agri-environmental measures, such as grass margins and beetle banks, are beneficial to the abundance and diversity of carabids. However, there is a lack of consensus over which measures are most effective in terms of Natural enemy Pest Control (NPC) by carabids, and interactions with the surrounding landscape. This thesis aimed to improve the efficacy and applicability of farm management interventions that increase the abundance and diversity of carabid species that contribute to NPC. I analysed data from the Farm Scale Evaluation experiment to determine the effects of landscape features and crop management on species abundance and diversity. To investigate further, I undertook trapping campaigns on a plot-scale and a farm-scale experiment. For this I used novel subterranean traps and standard pitfall traps to capture both above and below ground activity. Data were analysed with Linear Mixed Models, Generalised Linear Mixed Models, multivariate and spatial statistical methods. Central to my findings was that the response of key species varied differentially according to crop type, distance from field edge, adjacent habitat, and boundary feature. By incorporating below-ground sampling, I was able to deliver new understanding of the distribution of soil-dwelling carabid larvae relative to adults, and argue for the inclusion of predatory larvae in the estimation of ecosystem services provided by carabids. To incentivise farm management for NPC it is essential to understand the key motivations of farmers. To that end, I surveyed farmers to discover awareness, attitudes, and behavioural intent towards carabid beetles. Knowledge exchange interventions were also deployed. Farmer attitudes to carabids were positive, and experimental knowledge exchange treatments had a significant effect on behavioural intent. By drawing experimental and behaviour findings together, I was able to recommend specific actions favourable to farmers that were likely to boost NPC.