Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
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, PNAS, http://www.pnas.org/content/early/2018/08/01/1800042115
The 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.