Long-term temporal dynamics of three aphid species and a shared predator
Timothy W. Leslie, email@example.com, Penn State University, Department of Entomology, 501 ASI Building, University Park, PA, Wopke Van der Werf, Wageningen University, Department of Plant Sciences, P.O. Box 430, Wageningen, Netherlands, Felix J. J. A. Bianchi, Alterra Green World Research, P.O. Box 47, Wageningen, Netherlands, and Alois Honek, Research Institute of Crop Production, Drnovska 507, Praha-Ruzyne, Czech Republic.
From 1987 through 2005, populations of three cereal-inhabiting aphid species and one aphidophagous coccinellid species were monitored in organically managed winter wheat in the Praha-Ruzyné region of the Czech Republic. All populations exhibited highly variable fluctuations in year-to-year densities. To better understand the dynamics of aphid pests in cereals, we investigated whether these fluctuations could be explained by a predator-prey relationship and/or other environmental variables. Using regression, we examined the influence of coccinellid densities and weather variables on aphid peak densities. Additionally, we used non-linear times series analysis to detect pattern in aphid dynamics that may indicate a predator-prey relationship. While aphids displayed a bottom-up relationship with coccinellids, there was no evidence of coccinellids regulating the aphids. However, the non-linear times series analysis of aphid peak densities displayed a pattern of 1st order density dependence, pointing towards possible regulation due to natural enemies. There was also evidence of extreme weather conditions influencing aphid population size. No insecticide use in the winter wheat may have contributed to more stable aphid dynamics through increased predator-prey interaction, enabling pattern in the population dynamics to emerge. Detecting underlying pattern in agricultural pest population dynamics can strengthen predictive capabilities and subsequent pest management.
Species 1: Coleoptera Coccinellidae Coccinellaseptempunctata (sevenspotted lady beetle) Species 2: Hemiptera Aphididae Metopolophiumdirhodum (rose-grain aphid) Species 3: Hemiptera Aphididae Sitobionavenae (English grain aphid)