Land-use and local field management affect pollinators, pest damage and ultimately crop yields. Agroecology is
implemented as a sustainable alternative to conventional agricultural practices, but little is known about its
potential for pollination and pest management. Sub-Saharan Africa is underrepresented in studies investigating
the relative importance of pests and pollinators for crop productivity and how this might be influenced by
surrounding landscapes or agroecological practices. In Malawi, we selected 24 smallholder farms differing in
landscape-scale shrubland cover, implementation of manual pest removal as an indicator of an agroecological
pest management practice, and the number of agroecological soil practices employed at the household level, such
as mulching, intercropping and soil conservation tillage. We established pumpkin plots and assessed the abundance
and richness of flower visitors and damage of flowers (florivory) caused by pest herbivores on flowers.
Using a full-factorial hand pollination and exclusion experiment on each plot, we investigated the relative
contribution of pollination and florivory to pumpkin yield. Increasing shrubland cover decreased honeybee
abundance but increased the abundance and richness of non-honeybee visitors. Manual removal of herbivores
considered to be pests reduced flower visitors, whereas more agroecological soil management practices increased
flower visitors. Neither shrubland cover nor agroecological management affected florivory. Pollinator limitation,
but not florivory, constrained pumpkin fruit set, and increasing visitor richness decreased the relative differences
between hand- and animal-pollinated flowers. We recommend improved protection of shrubland habitats and
increasing agroecological soil practices to promote pollinator richness on smallholder farms.
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The effects of crop type, landscape composition and agroecological practices on biodiversity and ecosystem services in tropical smallholder farms
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 shrubland or grassland cover, on biodiversity and ecosystem services to fields remains unknown. We selected 24 villages situated in landscapes with varying shrubland and grassland cover in Malawi. In each village, we assessed biodiversity of eight taxa and ecosystem services in relation to crop type, shrubland and grassland cover and the number of agroecological pest and soil management practices on smallholder's fields of different crop types (bean monoculture, maize‐bean intercrop and maize monoculture). Increasing shrubland cover altered carabid and soil bacteria communities. Carabid abundance increased in maize but decreased in intercrop and bean fields with increasing shrubland cover. Carabid abundance and richness and wasp abundance increased with soil management practices. Carabid, spider and parasitoid abundances were higher in bean monocultures, but this was modulated by surrounding shrubland cover. Natural enemy abundances in beans were especially high in landscapes with little shrubland, possibly leading to lower bean damage in monocultures compared to intercropped fields, whereas maize monocultures had higher damage. In maize, grassland cover and pest management practices were positively related to damage. Carabid abundance was higher fields with high bean damage, and increased carabid richness in fields with high maize damage. Parasitoid abundance was negatively associated with bean damage.
- Award ID(s):
- 1852587
- NSF-PAR ID:
- 10401447
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Applied Ecology
- Volume:
- 60
- Issue:
- 5
- ISSN:
- 0021-8901
- Page Range / eLocation ID:
- p. 859-874
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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