TY - JOUR A1 - Martin, Emily A. A1 - Reineking, Björn A1 - Seo, Bumsuk A1 - Steffan-Dewenter, Ingolf T1 - Pest control of aphids depends on landscape complexity and natural enemy interactions JF - PeerJ N2 - Aphids are a major concern in agricultural crops worldwide, and control by natural enemies is an essential component of the ecological intensification of agriculture. Although the complexity of agricultural landscapes is known to influence natural enemies of pests, few studies have measured the degree of pest control by different enemy guilds across gradients in landscape complexity. Here, we use multiple natural-enemy exclosures replicated in 18 fields across a gradient in landscape complexity to investigate (1) the strength of natural pest control across landscapes, measured as the difference between pest pressure in the presence and in the absence of natural enemies; (2) the differential contributions of natural enemy guilds to pest control, and the nature of their interactions across landscapes. We show that natural pest control of aphids increased up to six-fold from simple to complex landscapes. In the absence of pest control, aphid population growth was higher in complex than simple landscapes, but was reduced by natural enemies to similar growth rates across all landscapes. The effects of enemy guilds were landscape-dependent. Particularly in complex landscapes, total pest control was supplied by the combined contribution of flying insects and ground-dwellers. Birds had little overall impact on aphid control. Despite evidence for intraguild predation of flying insects by ground-dwellers and birds, the overall effect of enemy guilds on aphid control was complementary. Understanding pest control services at large spatial scales is critical to increase the success of ecological intensification schemes. Our results suggest that, where aphids are the main pest of concern, interactions between natural enemies are largely complementary and lead to a strongly positive effect of landscape complexity on pest control. Increasing the availability of seminatural habitats in agricultural landscapes may thus benefit not only natural enemies, but also the effectiveness of aphid natural pest control. KW - insect populations KW - metaanalysis KW - biodiversity-ecosystem functioning KW - cabbage Brassica oleracea var. capitata KW - proportion of seminatural habitat KW - South Korea KW - land use intensification KW - trophic interactions KW - agroecosystems KW - biological control KW - agricultural landscapes KW - pest KW - biodiversity KW - herbivores Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148393 VL - 3 IS - e1095 ER - TY - JOUR A1 - Bartomeus, Ignasi A1 - Potts, Simon G. A1 - Steffan-Dewenter, Ingolf A1 - Vaissiere, Bernard E. A1 - Woyciechowski, Michal A1 - Krewenka, Kristin M. A1 - Tscheulin, Thomas A1 - Roberts, Stuart P. M. A1 - Szentgyoergyi, Hajnalka A1 - Westphal, Catrin A1 - Bommarco, Riccardo T1 - Contribution of insect pollinators to crop yield and quality varies with agricultural intensification JF - PEERJ N2 - Background. Up to 75% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production. Methods. We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe. For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes. Results. Insect pollination enhanced average crop yield between 18 and 71% depending on the crop. Yield quality was also enhanced in most crops. For instance, oilseed rape had higher oil and lower chlorophyll contents when adequately pollinated, the proportion of empty seeds decreased in buckwheat, and strawberries' commercial grade improved; however, we did not find higher nitrogen content in open pollinated field beans. Complex landscapes had a higher overall species richness of wild pollinators across crops, but visitation rates were only higher in complex landscapes for some crops. On the contrary, the overall yield was consistently enhanced by higher visitation rates, but not by higher pollinator richness. Discussion. For the four crops in this study, there is clear benefit delivered by pollinators on yield quantity and/or quality, but it is not maximized under current agricultural intensification. Honeybees, the most abundant pollinator, might partially compensate the loss of wild pollinators in some areas, but our results suggest the need of landscape-scale actions to enhance wild pollinator populations. KW - biodiversity KW - pollination KW - honeybee KW - wild bees KW - agroecosystems KW - native pollinators KW - species richness KW - bee pollinators KW - wild KW - ecosystemservices KW - fruit-quality KW - oilseed rape KW - land-use KW - honey KW - patterns Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-116928 SN - 2167-9843 VL - 2 IS - e328 ER -