Wireworm management in conservation agriculture

Conservation Agriculture (CA), which combines three principles, (1) limitation of soil disturbance, (2) its permanent cover and (3) crop diversification, is growing worldwide as a low-input system. By limiting soil disturbance, this farming system provides favourable conditions for the development of soil-dwelling organisms including insect pests. Despite potentially high wireworm densities in CA systems, economic damage to maize crop is rarely observed. In this study, we investigated the long-term influence of three tillage practices of decreasing intensity (mouldboard ploughing, surface tillage and no tillage) on wireworm density to confirm that reducing tillage intensity does increase wireworm density. In addition, we hypothesised that the presence of crop residues can limit damage caused by wireworms by diverting them from the main crop and altering their feeding behaviour. Accordingly, we examined whether covering the soil with a mulch at sowing date or leaving below-ground residues of a cover crop grown before maize sowing can limit wireworm damage on maize compared to leaving the soil bare. This study, using CA systems as a case study, improves our understanding of how cover crop management can help reducing wireworm damage for the following crop and illustrates the interest of manipulating pest feeding behaviour to design promising strategies of Integrated Pest Management.