- Institutionen för ekologi, Sveriges lantbruksuniversitet
Despite spectacular increases in agricultural productivity per unit of land and labour and a continually growing awareness of the importance of sustainable agriculture, modern agriculture faces serious problems at scales ranging from individual fields to regions. Such problems include increased resistance of pests to pesticides, loss of soil fertility, and loss of diversified habitats in the landscape. In my thesis I aim to better understand how field and landscape scale management affects integrated pest management with a particular focus on pest abundance, pest resistance, and biological pest control by naturally occurring enemies. Using large scale landscape field studies, we investigated the effect of landscape composition on pollen beetle pesticide resistance and abundance, and on abundance of its natural enemies in oilseed rape (Papers I and II). We found that the amount of oilseed rape crop in the landscape increased pest abundance and pesticide resistance in the target pest. Negative effects of landscape intensity were found on specialist but not on generalist natural enemies. This suggests that generalist predator communities are well adapted to crop-dominated landscapes. Therefore, management of natural pest control services by generalist predators in oilseed rape in Sweden should prioritize local scale management practices. At the local scale, we investigated the impact of four major herbivores on oilseed rape yield. We found that under specific combinations of pests, attacks by several different pests have a positive effect on oilseed rape yield (Paper III). Increasing our knowledge about multiple pest–plant interactions has a potential for directly increasing yield while reducing pesticide input. Finally, we tested how local scale long-term fertilisation affects soil communities and natural pest control (Papers IV and V). Our results suggest that in intensively managed agricultural systems, biennial organic fertilisation is insufficient to promote diversity within the soil community in the long-term. Generalist predators, however, benefitted from high quality organic fertilisation in the long-term, which in turn exerted top-down control on the aphid pest.
biological control, pesticide resistance, landscape ecology, organic and mineral fertilisation
Acta Universitatis Agriculturae Sueciae
2017, nummer: 2017:28
ISBN: 978-91-576-8829-3, eISBN: 978-91-576-8830-9
Utgivare: Department of Ecology, Swedish University of Agricultural Sciences