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Abstract 1. In the tropics, smallholder farming characterizes some of the world’s most biodiverse landscapes. Agroecology as a pathway to sustainable agriculture has been proposed and implemented in sub-Saharan Africa, but the effects of agricultural practices in smallholder agriculture on biodiversity and ecosystem services are understudied. Similarly, the contribution of different landscape elements, such as shrub- or grassland cover, on biodiversity and ecosystem services to fields remains unknown. 2. We selected 24 villages situated in landscapes with varying landscape shrub- and grassland cover in Malawi. In each village, we assessed biodiversity of 8 taxa and ecosystem services in relation to crop type, shrub- and grassland cover and the number of agroecological pest management (APM) and agroecological soil management (ASM) on smallholder farm fields of different crop types (maize monoculture, maize-bean intercrop, and bean monoculture). 3. Increasing shrubland cover increased bee richness and altered carabid communities. Increased grassland cover decreased ant richness. Carabid richness increased in maize and intercrop but decreased in bean fields with increasing grassland cover. Carabid and parasitoid activity densities were higher in bean monocultures, but this was mediated by surrounding shrubland cover. Natural enemy activity in beans was especially high in landscapes with little surrounding shrubland. Possibly, this increased activity resulted in lower bean damage in monocultures compared to intercrop, whereas in maize, monocultures where more damaged, especially in landscapes high in grassland cover. In maize, APM was positively related to pest damage, and we find increased carabid activity and richness in fields with high maize damage. Increased ASM resulted in increased carabid richness and wasp activity density. 4. Synthesis and application: Our results suggest that maintaining biodiversity and ecosystem services on smallholder farms is not achievable with a “one size fits all” approach but should instead be adapted to the landscape context and the priorities of smallholders. Shrubland is important to maintain bee and carabid diversity, but legume cultivation beneficial to natural enemies could complement APM in landscapes with a lower shrubland cover. An increased number of ASM practices could lead to improved pest control whilst the effectiveness of APM needs to be re-evaluated. Keywords: agroecology, biodiversity, crop diversity, intercropping, landscape change, pest control, pollination, soil health.
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Ant Communities and Ecosystem Services in Organic Versus Conventional Agriculture in the U.S. Corn Belt
Abstract Reducing the use of synthetic fertilizers and pesticides can limit negative impacts of agriculture on insects and is a crucial step towards sustainable agriculture. In the United States, organic agriculture has the potential to reduce greenhouse gas emissions, pollutant runoff, and biodiversity loss in the Midwestern Corn Belt—an area extending over 500,000 km2 devoted to intensive production of corn Zea mays (Linnaeus 1753) (Poales: Poaceae), often in rotation with soy Glycine max (Linnaeus 1753) (Fabales: Fabaceae) or wheat Triticum aestivum (Linnaeus 1753) (Poales: Poaceae). Working in 30-yr-long landscape experiments in this region, we tested for impacts of conventional versus organic agriculture on ant communities (Hymenoptera: Formicidae) and potential ecosystem services they provide. Organic fields supported higher ant diversity and a slightly more species-rich ant assemblage than conventionally managed fields but did not otherwise differ in community composition. Despite similar community composition, organic and conventional fields differed in seasonal patterns of ant foraging activity and potential for natural pest suppression. Conventional plots experienced higher overall ant foraging activity, but with the timing skewed towards late in the growing season such that 75% of ant foraging occurred after crop harvest in a wheat year and was therefore unavailable for pest suppression. Organic fields, in contrast, experienced moderate levels of ant foraging activity throughout the growing season, with most foraging occurring during crop growth. Organic fields thus supported twice as much pest suppression potential as conventional fields. Our results highlight the importance of timing in mediating ecosystem services in croplands and emphasize the value of managing landscapes for multiple services rather than yield alone.
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- Award ID(s):
- 1832042
- PAR ID:
- 10331274
- Editor(s):
- Schmidt-Jeffris, Rebecca A
- Date Published:
- Journal Name:
- Environmental Entomology
- Volume:
- 50
- Issue:
- 6
- ISSN:
- 0046-225X
- Page Range / eLocation ID:
- 1276 to 1285
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/ee/nvab105
