Effect of landscape composition and arrangement on biological control agents in a simplified agricultural system: A cost–distance approach

摘要: Abstract Landscape simplification has been clearly demonstrated to have negative impacts on the in-crop density and biological-control activity of natural enemies in agricultural landscapes. The role spatial arrangement landscape, however, not investigated agroecosystems. We applied cost–distance modeling investigate relationship between structural connectivity non-crop land uses surrounding crops within Australian cotton further compared explanatory power this approach with more commonly used spatially specific proportional-area approach, which considers landscape composition terms proportional area a given use radius. Cost–distance metrics offered significant explanation for predatory beetle Dicranolaius bellulus (Coleoptera: Melyridae) than did approach. species was positively significantly correlated wooded 3000 m However, enemy taxa that responded characteristics at smaller scales (within 750 m radius), namely Oxyopes spp. (Araneae: Oxyopidae) Trichogramma spp., (Hymenoptera: Trichogrammatidae), gave density. Herbivore weakly all showed no correlation metrics. Findings indicate potential simplified landscapes be ‘selectively’ manipulated enhance colonization crop by enemies, but herbivores, improving resources, through presence woody vegetation.