Ecological valuation of crop pollination in traditional Indonesian homegardens
Final Report Abstract
In this project, we aimed to shed light on the relative importance of pollination services, common management practices and their interaction. We evaluated the benefits from pollination services for cucumber (Cucumis sativus) production and how wild bees are influenced by management on three different spatial scales. Yield increased significantly with increasing number of bee individuals, which translates into a net income decline of 47% if half of the bees would be lost. The percentage of flower cover per homegarden predicted pollinator attraction best, if, a higher percentage of homegardens surrounded the study garden. In addition, distance to the rainforest had also a significant effect on total bee flower visitor. This effect was dominated by small bees which increased closer to the forest. We also tested how different management practices (insect pollination, weed control, fertilization and herbivore control) affect cucumber fruit set and yield and how these variables influence each other. We found that insect pollination, fertilization and weed control increased crop fruit set and yield in an additive way. However, fertilization and weed control alone could not compensate for pollination loss, which was the most important driver and accounted for 75 % of the yield. In contrast, insecticides to control herbivores did not influence yield. We furthermore assessed income loss due to dis-services from seed predating ants and if ant seed predation differs with or without insecticide and herbicide applications. We found that ant seed predation was high for all crops, potentially reducing farmers’ net income by half. Application of insecticides and herbicides did not influence ant seed predation or total ant abundance, but influenced ant species-specific abundances positively or negatively mediated through functional redundancy of ant species. In addition, we assessed the effectiveness of stingless bees and the Asian honey bee for cucumber fruit set and yield. Only the honey bee is an effective pollinator for cucumber, as the stingless bee did not have any pollination effect. This makes the Asian honey bee the most important cucumber pollinator in the Kebun Kopi area, however, also the only effective pollinator.
Publications
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(2013) Ant seed predation, pesticide applications and farmers' income from tropical multi-cropping gardens. Agricultural and Forest Entomology 15: 245-254
Motzke, I., Tscharntke, T., Sodhi, N., Klein, A.M., Wanger, T.C.
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(2013) Wild pollinators enhance fruit set of crops regardless of honey-bee abundance. Science 339: 1608-1611
Garibaldi, L.A., Steffan-Dewenter, I., Winfree, R., Aizen, M.A., Bommarco, R., Cunningham, S.A., Kremen, C., Carvalheiro, L.G., Harder, L.D., Afik, O., Bartomeus, I., Benjamin, F., Boreux, V., Cariveau, D., Chacoff, N.P., Dudenhöffer, J.H., Freitas, B.M., Ghazoul, J., Greenleaf, S., Hipólito, J., Holzschuh, A., Howlett, B., Isaacs, R., Javorek, S.K., Kennedy, C.M., Krewenka, K., Krishnan, S., Mandelik, Y., Mayfield, M.M., Motzke, I., Munyuli, T., Nault, B.A., Otieno, M., Petersen, J., Pisanty, G., Potts, S.G., Rader, R., Ricketts, T.H., Rundlöf, M., Seymour, C.L., Schüepp, C., Szentgyörgyi, H., Taki, H., Tscharntke, T., Vergara, C.H., Viana, B.F., Wanger, T.C., Westphal, C., Williams, N., Klein. A.M.
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(2014) Local management and landscape context effects on bee pollination, ant seed predation, and yield in Indonesian homegardens
Iris Motzke
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(2014) Pollination mitigates cucumber yield gaps more than pesticide and fertilizer use in tropical smallholder gardens. Journal of Applied Ecology 52: 261-269
Motzke, I., Tscharntke, T., Wanger, T.C., Klein, A.M.
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(2015) Trait matching of flower visitors and crops predicts fruit set better than trait diversity. Journal of Applied Ecology 52: 1436-1444
Garibaldi, L., Bartomeus, I., Bommarco, R., Klein, A.M., Cunningham, S.A., Aizen, M.A., Boreux, V., Garratt, M.P.D., Carvalheiro L-G., Kremen, C., Morales, C.L., Schüepp, C., Chacoff, N.P., Freitas, B.M., Gagic, V., Holzschuh, A., Klatt, B.K., Krewenka, K.M., Krishnan, S., Mayfield, M.M., Motzke, I., Otieno, M., Petersen, J., Potts, S.G., Ricketts, T.H., Rundlöf, M., Sciligo, A., Sinu, P.A., Steffan- Dewenter, I., Taki, H., Tscharntke, T., Vergara, C.H., Viana, B.F., Woyciechowski, M.
