Kumschick S., Schmidt-Entling M.H., Bacher S., Hickler T., Espadaler X., Nentwig W. (2009) Determinants of local ant (Hymenoptera: Formicidae) species richness and activity density across Europe. Ecological Entomology. 34: 748-754.LinkDoi: 10.1111/j.1365-2311.2009.01127.x
1. Species richness is influenced by local habitat features and large-scale climatic gradients. Usually, both influences are studied in isolation because of the divergent spatial scales at which they occur. Here, we compared the influence of large-scale climate and local habitat type on European ants using a continent-wide, standardised sampling programme. 2. We investigated species richness and activity density from pitfall traps distributed over four habitat types at 17 locations from northern Sweden to Spain and Greece. Species richness and activity density were analysed with respect to ambient energy [equilibrium evapotranspiration (EET)] and productive energy (net primary productivity). Furthermore, we compared ant richness and activity density between the four habitat types: arable land, scrubland, grassland, and forest. 3. Species richness and activity density of ants increased with equilibrium evapotranspiration (EET), explaining 30.2% of the total variation in species richness and 24.2% of activity density. Habitat type explained an additional 19.2% of the variation in species richness and 20.2% of activity density, and was not related to productivity. Species richness and activity density were highest in scrubland and significantly lower in forest and (marginally significant) in arable land. 4. The increase in EET and the decrease in forest confirms the pronounced thermophily of ants, whereas the decrease in arable land is probably caused by soil disturbance. © 2009 The Royal Entomological Society.
Miñarro M., Espadaler X., Melero V.X., Suárez-Álvarez V. (2009) Organic versus conventional management in an apple orchard: Effects of fertilization and tree-row management on ground-dwelling predaceous arthropods. Agricultural and Forest Entomology. 11: 133-142.LinkDoi: 10.1111/j.1461-9563.2008.00403.x
1 Organic and conventional management of apple orchards may have a different effect on arthropod communities. 2 We conducted a 3-year study to assess the effect of two strategies of fertilizer treatment (organic versus chemical) and three tree-row management systems (straw mulching, tillage and herbicide) on activity-density and biodiversity of epigeic predators. Ground beetles (Carabidae), rove beetles (Staphylinidae), ants (Formicidae) and spiders (Araneae) were sampled monthly with pitfall traps in the same apple orchard during 2003, 2004 and 2005. 3 A total of 4978 individuals were collected. Carabids (56.8% of the total catches) were the most abundant taxonomic group, followed by spiders (20.7%), ants (14.8%) and rove beetles (7.7%). Tree-row management had a greater influence on predator catches than fertilizer treatment. Total predator catches were lower under the mulch. Mulching also reduced carabid abundance, but increased staphylinid catches. 4 Tree row management also had a significant effect on biodiversity parameters. Species richness did not significantly differ among treatments for ants, spiders or the total catches, but was higher on herbicide-treated plots for carabids and on mulched plots for staphylinids. Shannon-Wiener's diversity index was significantly greater in the mulched and herbicide treated plots for total predators and carabids. For staphylinids, this index was significantly greater on the mulched plots. Fertilizer application strategy only influenced the species richness of rove beetles, which was greater in the chemically-treated plots. 5 The results showed that a change from conventional to organic fertilizer treatment of apple trees may be performed without differential effects on predator activity-density or biodiversity. However, a change from herbicide treatment to mulching or mechanical weed control may be significant, depending on the taxonomic group. © 2008 The Royal Entomological Society.
Paris C.I., Espadaler X. (2009) Honeydew collection by the invasive garden ant Lasius neglectus versus the native ant L. grandis. Arthropod-Plant Interactions. 3: 75-85.LinkDoi: 10.1007/s11829-009-9057-8
Honeydew collection performed by the invasive ant Lasius neglectus and by the native ant L. grandis was compared. The invasive ant collected 2.09 kg of honeydew per tree while the native ant collected 0.82 kg. The aphid Lachnus roboris was visited by both ant species. In holm oaks colonized by L. neglectus, aphid abundance tended to increase and its honeydew production increased twofold. The percentage of untended aphids was lower in holm trees occupied by L. neglectus. As tending ants also prey on insects, we estimated the percentage of carried insects. The native ant workers carried more insects than the invasive ant. Both ant species preyed mainly on Psocoptera and the rarely tended aphid, Hoplocallis picta. We conclude that the higher honeydew collection achieved by L. neglectus was the consequence of (1) its greater abundance, which enabled this ant to tend more Lachnus roboris and (2) its greater level of attention towards promoting an increase of honeydew production. © Springer Science+Business Media B.V. 2009.
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.LinkDoi: 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.LinkDoi: 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.
Espadaler X, García F, Gómez K, Serrano S, Vila R (2009) Hormigas (Hymenoptera, Formicidae) del desfiladero de Mont-Rebei (Pallars Jussà). Boletín de la Sociedad entomológica Aragonesa 44: 393-399.
Wetterer JK, Wild AL, Suárez AV, Roura-Pascual N, Espadaler X (2009) Worldwide spread of the Argentine ant, Linepithema humile (Hymenoptera: Formicidae). Myrmecological News 12: 187-194.
Sunamura E, Espadaler X, Sakamato H, Suzuki S, Terayama M, Tatsuki S (2009) Intercontinental union of Argentine ants: behavioral relationships among introduced populations in Europe, North America , and Asia. Insectes Sociaux doi: 10.1007/s00040-009-0001-9 56: 143-147.
Herrainz JA, Espadaler X (2009) Lasius cinereus Seifert: descripción de la reina y datos biológicos. Boletín Sociedad Entomológica Aragonesa 44: 143-146.
García F, Espadaler X, Gómez K (2009) Primera cita de Amblyopone impressifrons (Emery, 1869) para la Península Ibérica y de Proceratium melinum (Roger, 1860) para Cataluña (Hymenoptera, Formicidae). Boletín de la SEA 45: 357-360.
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