Rodrigo A, Martínez-Vilalta J, Piñol J, Lloret F, Ribas A, Retana J, Losarcos J (2009) Diseño y aplicación de una propuesta de aprendizaje cooperativo de los contendios del area de Ecología mediante el estudio de casos (inclou versió en anglés) . En “Hacia el espacio europeo de educación superior (EEES). Experiencias docentes innovadoras d e la UAB en ciencias sociales y en ciencias humanas”. Maite Martínez y Elena Añaños (eds.). Unitat d’Innovació Docent en Educació Superior. Universitat Autònoma de Barcelona, Servei de Publicacions.
Lloret F, Piñol J, Castellenou M (2009) Wildfires. In: J. Woodward (ed.). The Physical Geography of the Mediterranean. Oxford University Press 541- 558.
Piñol J., Espadaler X., Cañellas N., Pérez N. (2009) Effects of the concurrent exclusion of ants and earwigs on aphid abundance in an organic citrus grove. BioControl. 54: 515-527.EnllaçDoi: 10.1007/s10526-008-9203-8
Based on the well-known mutualism between ants (Hymenoptera: Formicidae) and aphids (Homoptera: Aphididae), we conducted a five-year experiment of ant-exclusion from the canopies of citrus trees as a possible method of biological control of aphids. However, our results showed that the exclusion of ants from the canopies increased, instead of reducing, aphid abundance. To explain this unexpected result, we reasoned that the exclusion of ants from the canopies might also have excluded crawling insects that prey on aphids, such as the European earwig (Forficula auricularia L., Dermaptera: Forficulidae). Such a possibility is supported by the negative relationship between aphid density and the abundance of earwigs, consistent with a top-down control of aphids by earwigs. In contrast, the abundance of other aphid predators (Coleoptera: Coccinellidae, and Heteroptera) had no such negative effect on aphid density but a positive one, suggesting a bottom-up control, and showed no differences between control and ant-excluded trees. Thus, the most likely explanation for the increase in aphid abundance in the ant-excluded trees is the absence of earwigs from the canopies of the experimental trees, providing further evidence of the major role that earwigs play as control agents of aphids in cultivated trees. © International Organization for Biological Control (IOBC) 2008.
Piñol J., Espadaler X., Pérez N., Beven K. (2009) Testing a new model of aphid abundance with sedentary and non-sedentary predators. Ecological Modelling. 220: 2469-2480.EnllaçDoi: 10.1016/j.ecolmodel.2009.06.031
Aphid population dynamics has been thoroughly investigated, especially in tree-dwelling aphids. Among the controls of the aphid rate of increase are the negative effects of antagonists, the positive effects of mutualists, the density-dependence of the aphid dynamics, and the non-stationary quality of plant tissues. Here we present a mechanistic model of aphid growth that considers most of these governing factors using a simple formulation. What is new in this model is that it considers two kinds of antagonists. The first kind is a guild of aphid predator specialists that includes ladybirds (Coleoptera: Coccinellidae), but also species of some families of Hemiptera, Diptera, and Neuroptera. The second kind of antagonists consists of omnivores or generalist predators and in this particular setting is exemplified by the European earwig Forficula auricularia (Dermaptera: Forficulidae). The model developed here compared the effects of these two different kinds of aphid predators, the second one always at the site (sedentary predators) and the first one that arrives in important numbers only once the aphid population has already developed to some degree (non-sedentary predators). Multiple model parameter sets, representing different hypotheses about controls on aphid populations, were evaluated within the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. The model correctly reproduced the experimental data obtained in an organic citrus grove showing the important effect that sedentary predators as earwigs can have on the aphid populations. Low densities of sedentary predators or even low predation rates can have a disproportionate effect on the final aphid density, as they prey on small populations, when the per capita effect on the aphid population is higher. During the main spring peak of aphids the role of non-sedentary predators is secondary, as they track the aphid density rather than control it. However, these non-sedentary predators are important within the proposed model to keep the second autumn peak of aphids at low values. © 2009 Elsevier B.V. All rights reserved.
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