martes, 19 de junio de 2018


EN LO MICRO Y EN LO MACRO. SOBRE LA IMPORTANCIA DE LAS INTERACCIONES EN LA AGROECOLOGÍA by Gabriela Rodríguez on Scribd

Pollen grains, as viewed under a microscope (Found at: @ExploreWellcome)
Landscape simplification reduces classical biological control and crop yield

Heather Grab, Bryan Danforth, Katja Poveda and  Gregory M Loeb

Agricultural intensification resulting in the simplification of agricultural landscapes is known to negatively impact the delivery of key ecosystem services such as the biological control of crop pests. Both conservation and classical biological control may be influenced by the landscape context in which they are deployed; yet studies examining the role of landscape structure in the establishment and success of introduced natural enemies and their interactions with native communities are lacking. In this study, we investigated the relationship between landscape simplification, classical and conservation biological control services and importantly, the outcome of these interactions for crop yield. We showed that agricultural simplification at the landscape scale is associated with an overall reduction in parasitism rates of crop pests. Additionally, only introduced parasitoids were identified, and no native parasitoids were found in crop habitat, irrespective of agricultural landscape simplification. Pest densities in the crop were lower in landscapes with greater proportions of semi-natural habitats. Furthermore, farms with less semi-natural cover in the landscape and consequently, higher pest numbers, had lower yields than farms in less agriculturally dominated landscapes. Our study demonstrates the importance of landscape scale agricultural simplification in mediating the success of biological control programs and highlights the potential risks to native natural enemies in classical biological control programs against native insects. Our results represent an important contribution to an understanding of the landscape-mediated impacts on crop yield that will be essential to implementing effective policies that simultaneously conserve biodiversity and ecosystem services.

Parasitism rates of Lygus lineolaris nymphs by Peristenus digoneutis are positively related to the proportion of open semi-natural habitats at 500 m surrounding the sampling location within each strawberry field   (PDF) Landscape simplification reduces classical biological control and crop yield. 

A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes

Lichtenberg et al., 2017.

Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species rich- ness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversi- fication on abundance, local diversity (communities within fields), and regional diver- sity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem ser- vice providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacom- munities that may provide temporal and spatial stability of ecosystem service provi- sioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.

Effects of farm management schemes on abundance (a, b) and richness (c, d) of common vs. rare taxa in simple and complex landscapes. Mean log- response ratios (SE) of (left column) adopting organic farming and (right column) promoting in-field plant diversity. A“*”below a pair of means indicates a significant difference between rare and common taxa within a landscape complexity category (determined via paired t-tests; a=0.1; Tables S19.
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Cupid as pollinator? 
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Thornton, Robert John, 1837.
New illustration of the sexual system of Carolus von Linnaeus :and the temple of Flora, or garden of nature. 
https://www.biodiversitylibrary.org/bibliography/16#/summary
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lunes, 18 de junio de 2018

domingo, 17 de junio de 2018

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FAO: Family farms produce about 80% of the world’s food
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sábado, 16 de junio de 2018

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"The power of a theory is exactly proportional to the diversity of situations it can explain." 

 Elinor Ostrom 
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