Landscape simplification and altitude affect biodiversity, herbivory and Andean potato yield

Abstract

Summary1. The simplification of agricultural landscapes through the increase in cropped area has caused the loss of habitats for many species that fulfil important ecosystem services such as pest control and production. Evidence for detrimental effects on ecosystem services is scarce, particularly in tropical regions. 2. We studied the effect of the percentage of cropped land in the landscape and altitude in tropical agro-ecosystems in relation to crop pest regulation and yield. In the Colombian Andes, we established potato Solanum tuberosum plots along gradients of altitude and increasing proportion of cropped area to assess the effects on herbivores, their natural enemies, potato production and overall biodiversity. 3. Increasing altitude and percentage cropped land reduced the richness and abundance of herbivores and their natural enemies, except for the specialist Guatemalan potato moth Tecia solanivora, which showed the opposite response. 4. Potato yield was negatively affected by the presence of the Guatemalan potato moth, which increased in density as the percentage of cropped land and altitude increased. Other herbivores and natural enemies did not affect yield. 5. Synthesis and applications. Tropical landscapes at lower altitude or with smaller areas of cropped land suffered less from the presence of the potato moth, which had a negative effect on yield. Our results suggest that conservation of natural habitats like the endangered Andean ecosystems would benefit farmers through ecosystem services such as reduced pest damage, higher yield and increased functional biodiversity.

Contrasting effects of landscape composition on crop yield mediated by specialist herbivores

“…We chose to measure these landscape metrics because previous studies have shown that they could affect the dynamics and distribution of lepidopteran pests (Poveda et al. ), aphids (Woltz et al. ) and flea beetles (Banks , Andersen et al.…”

“…Yet, far fewer studies have evaluated the effects of such pest–natural‐enemy complexities on crop yield (but see Poveda et al. , Liere et al. ).…”

“…And last, we hypothesized that (3) a greater proportion of non‐crop habitats in the landscape would decrease overall plant damage, and thereby increase crop yield, via indirect effects on both pests (Poveda et al. ) and natural enemy abundance (Liere et al. ).…”

Climate change and crop diversity: farmers’ perceptions and adaptation on the Bolivian Altiplano

“…The increasing problem of pests and diseases experienced by farmers is associated with rising temperatures and further exacerbated by shifts towards monoculture, pest-susceptible varieties, and abbreviated crop rotation schedules (Parsa 2010;Perez et al 2010;McDowell and Hess 2012;Poveda et al 2012). Adaptation actions reported in our study communities (e.g.…”

Landscape changes have greater effects than climate changes on six insect pests in China

“…We expected that landscape changes and climate changes would be related to pest damage, based on the hypothesis that crop simplification and global warming would affect biological control agents (Zhao et al, 2015b;Poveda et al, 2012). Based on the resource concentration hypothesis and habitat management, it was hypothesized that (i) landscape change and climate change would have a great effect on pest damage, and pest damage would increase with increasing landscape simplification and global warming, and (ii) landscape change would be the key driving factor and would have a greater influence on pest damage than climate change due to the polydirectional temperature fluctuations during the past 60 years in China (Figure 1).…”