title: Field-scale roles of density, temperature, nitrogen, and predation on aphid population dynamics.
abstract: Robust analyses of noisy, stage-structured, irregularly spaced, field-scale data incorporating multiple sources of variability and nonlinear dynamics remain very limited, hindering understanding of how small-scale studies relate to large-scale population dynamics. We used a novel, complementary Bayesian and frequentist state-space model analysis to ask how density, temperature, plant nitrogen, and predators affect cotton aphid (Aphis gossypii) population dynamics in weekly data from 18 field-years and whether estimated effects are consistent with small-scale studies. We found clear roles of density and temperature but not of plant nitrogen or predators, for which Bayesian and frequentist evidence differed. However, overall predictability of field-scale dynamics remained low. This study demonstrates stage-structured state-space model analysis incorporating bottom-up, top-down, and density-dependent effects for within-season (nearly continuous time), nonlinear population dynamics. The analysis combines Bayesian posterior evidence with maximum-likelihood estimation and frequentist hypothesis testing using average one-step-ahead residuals.
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, California 94720-3114, USA. pdevalpine@nature.berkeley.edu
authors.forename: Perry
authors.initials: P
authors.lastname: de Valpine
authors.forename: Jay A
authors.initials: JA
authors.lastname: Rosenheim
mesh_terms: D000818:Animals; D001042:Aphids / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D001499:Bayes Theorem; D002140:California; D017753:Ecosystem; D003368:Gossypium / Q000469:parasitology*; D016013:Likelihood Functions; D008390:Markov Chains; D009010:Monte Carlo Method; D009584:Nitrogen / Q000378:metabolism*; D011156:Population Density; D011157:Population Dynamics; D011235:Predatory Behavior / Q000502:physiology*; D013045:Species Specificity; D013696:Temperature
chemical_list: D009584:Nitrogen