Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Friday, 2018/08/17 | 06:26:18
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Daniel S. Karp, Rebecca Chaplin-Kramer, Timothy D. Meehan, Emily A. Martin, Fabrice DeClerck, Heather Grab, Claudio Gratton, Lauren Hunt, Ashley E. Larsen, Alejandra Martínez-Salinas, Megan E. O’Rourke, Adrien Rusch, Katja Poveda, Mattias Jonsson, Jay A. Rosenheim, Nancy A. Schellhorn, Teja Tscharntke, Stephen D. Wratten, Wei Zhang, Aaron L. Iverson, Lynn S. Adler, Matthias Albrecht, Audrey Alignier, Gina M. Angelella, Muhammad Zubair Anjum, Jacques Avelino, Péter Batáry, Johannes M. Baveco, Felix J. J. A. Bianchi, Klaus Birkhofer, Eric W. Bohnenblust, Riccardo Bommarco, Michael J. Brewer, Berta Caballero-López, Yves Carrière, Luísa G. Carvalheiro, Luis Cayuela, Mary Centrella, Aleksandar Ćetković, Dominic Charles Henri, Ariane Chabert, Alejandro C. Costamagna, Aldo De la Mora, Joop de Kraker, Nicolas Desneux, Eva Diehl, Tim Diekötter, Carsten F. Dormann, James O. Eckberg, Martin H. Entling, Daniela Fiedler, Pierre Franck, F. J. Frank van Veen, Thomas Frank, Vesna Gagic, Michael P. D. Garratt, Awraris Getachew, David J. Gonthier, Peter B. Goodell, Ignazio Graziosi, Russell L. Groves, Geoff M. Gurr, Zachary Hajian-Forooshani, George E. Heimpel, John D. Herrmann, Anders S. Huseth, Diego J. Inclán, Adam J. Ingrao, Phirun Iv, Katja Jacot, Gregg A. Johnson, Laura Jones, Marina Kaiser, Joe M. Kaser, Tamar Keasar, Tania N. Kim, Miriam Kishinevsky, Douglas A. Landis, Blas Lavandero, Claire Lavigne, Anne Le Ralec, Debissa Lemessa, Deborah K. Letourneau, Heidi Liere, Yanhui Lu, Yael Lubin, Tim Luttermoser, Bea Maas, Kevi Mace, Filipe Madeira, Viktoria Mader, Anne Marie Cortesero, Lorenzo Marini, Eliana Martinez, Holly M. Martinson, Philippe Menozzi, Matthew G. E. Mitchell, Tadashi Miyashita, Gonzalo A. R. Molina, Marco A. Molina-Montenegro, Matthew E. O’Neal, Itai Opatovsky, Sebaastian Ortiz-Martinez, Michael Nash, Örjan Östman, Annie Ouin, Damie Pak, Daniel Paredes, Soroush Parsa, Hazel Parry, Ricardo Perez-Alvarez, David J. Perović, Julie A. Peterson, Sandrine Petit, Stacy M. Philpott, Manuel Plantegenest, Milan Plećaš, Therese Pluess, Xavier Pons, Simon G. Potts, Richard F. Pywell, David W. Ragsdale, Tatyana A. Rand, Lucie Raymond, Benoît Ricci, Chris Sargent, Jean-Pierre Sarthou, Julia Saulais, Jessica Schäckermann, Nick P. Schmidt, Gudrun Schneider, Christof Schüepp, Frances S. Sivakoff, Henrik G. Smith, Kaitlin Stack Whitney, Sonja Stutz, Zsofia Szendrei, Mayura B. Takada, Hisatomo Taki, Giovanni Tamburini, Linda J. Thomson, Yann Tricault, Noelline Tsafack, Matthias Tschumi, Muriel Valantin-Morison, Mai Van Trinh, Wopke van der Werf, Kerri T. Vierling, Ben P. Werling, Jennifer B. Wickens, Victoria J. Wickens, Ben A. Woodcock, Kris Wyckhuys, Haijun Xiao, Mika Yasuda, Akira Yoshioka, and Yi Zou
PNAS August 7, 2018. 201800042; SignificanceDecades of research have fostered the now-prevalent assumption that noncrop habitat facilitates better pest suppression by providing shelter and food resources to the predators and parasitoids of crop pests. Based on our analysis of the largest pest-control database of its kind, noncrop habitat surrounding farm fields does affect multiple dimensions of pest control, but the actual responses of pests and enemies are highly variable across geographies and cropping systems. Because noncrop habitat often does not enhance biological control, more information about local farming contexts is needed before habitat conservation can be recommended as a viable pest-suppression strategy. Consequently, when pest control does not benefit from noncrop vegetation, farms will need to be carefully comanaged for competing conservation and production objectives. AbstractThe idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
See: http://www.pnas.org/content/early/2018/08/06/1800042115
Figure 2: Landscape effects on pest-control variables. After selecting the most predictive model for each pest-control response (N = 367) and redefining land-cover variables as natural (forest, grassland, and scrubland; green bars) versus crop (annual and perennial; orange bars), we tallied the number of pest-control responses for which models had either positive (solid), negative (diagonal hashed), or mixed (horizontal) estimates of the effect of each landscape predictor. Panels represent the seven pest-control variables, including abundance (A) and activity (B and C) of natural enemies; abundance (D and E) and activity (F) of pests; and crop yields (G). χ2 tests indicated that pest-control response variables showed heterogeneous patterns of association with the extent of surrounding natural habitat and cropland—with roughly equivalent numbers of pest-control responses having models with positive and negative effects (all P > 0.05). |
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