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Dear Friends and Colleagues

Study Finds Farm Biodiversity and Pest Problems Inversely Related

Agroecosystems represent the dominant biome on Earth (25 to 40% of land is devoted to agriculture). Recent shifts in agricultural practices have resulted in altered pesticide use patterns, land use intensification, and landscape simplification, all of which threaten biodiversity in and near farms.

Pests are major challenges to food security, and responses to pests can incur unintended socio-economic and environmental costs. There is, however, a poor understanding of biological communities within agroecosystems and how community complexity contributes to ecosystem functions and influences pest populations on farms.

To address this gap, a new study examines how species diversity and the network of linkages in speciesabundances affect pest abundance on maize farms across the Northern Great Plains in the U.S. The results show that increased species diversity, community evenness, and linkage strength and network centrality within a biological network all correlate with significantly reduced pest populations. For example, reducing tillage, increasing vegetation diversity on farms (using cover crops, intercropping, crop rotations, etc.), and developing minimal-till organic agriculture should help increase biodiversity.

In line with this, the research results show that using pest management practices that reduce biodiversity and species interactions will create systems where pests will continually pose problems (i.e., the pesticide treadmill). This finding provides further justification for diversification of agroecosystems to improve the profitability, safety, and sustainability of food production systems.

The full paper is available at http://advances.sciencemag.org/content/1/6/e1500558

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Third World Network
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Trading biodiversity for pest problems
Jonathan G. Lundgren, and Scott W. Fausti

Science Advances 31 Jul 2015: Vol. 1, no. 6, e1500558
DOI: 10.1126/sciadv.1500558

Abstract

Recent shifts in agricultural practices have resulted in altered pesticide use patterns, land use intensification, and landscape simplification, all of which threaten biodiversity in and near farms. Pests are major challenges to food security, and responses to pests can represent unintended socioeconomic and environmental costs. Characteristics of the ecological community influence pest populations, but the nature of these interactions remains poorly understood within realistic community complexities and on operating farms. We examine how species diversity and the topology of linkages in species’ abundances affect pest abundance on maize farms across the Northern Great Plains. Our results show that increased species diversity, community evenness, and linkage strength and network centrality within a biological network all correlate with significantly reduced pest populations. This supports the assertion that reduced biological complexity on farms is associated with increased pest pop ulations and provides a further justification for diversification of agroecosystems to improve the profitability, safety, and sustainability of food production systems. Bioinventories as comprehensive as the one conducted here are conspicuously absent for most agroecosystems but provide an important baseline for community and ecosystem ecology and the effects of food production on local biodiversity and ecosystem function. Network analyses of abundance correlations of entire communities (rather than focal interactions, for example, trophic interactions) can reveal key network characteristics, especially the importance and nature of network centrality, which aid in understanding how these communities function.

 


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