Testing multiple pathways for impacts of the non-native Black-headed Weaver Ploceus melanocephalus on native birds in Iberia in the early phase of invasion

Not all non-native species have strong negative impacts on native species. It is desirable to assess whether a non-native species will have a negative impact at an early stage in the invasion process, when management options such as eradication are still available. Although it may be difficult to detect early impacts of non-native species, it is necessary to ensure that management decisions can be based on case-specific scientific evidence. We assess the impacts of a non-native bird, the Black-headed Weaver Ploceus melanocephalus, at an early stage in its invasion of the Iberian Peninsula. To do this we identify potential pathways by which competition for shared resources by Black-headed Weavers could lead to population declines in two ecologically similar native species, and generate hypotheses to test for evidence of competition along these pathways. Black-headed Weavers could potentially impact native species by displacing them from nesting habitat, or by reducing habitat quality. We found no evidence for either potential competition pathway, suggesting that Black-headed Weavers do not currently compete with the two native species. However, it is possible that mechanisms that currently allow coexistence may not operate once Black-headed Weavers reach higher population densities or different habitats

Assessing indirect impacts of biological control agents on native biodiversity: a community-level approach

The safety of biological control methods is a subject that has received considerable attention for a long time. However, apparent competition (competition due to shared natural enemies)has been neglected when considering possible impacts of biological control agents. One of the reasons for the lack of studies in this area is the difficulty in assessing and predicting indirect effects due to apparent competition. In this paper we outline a methodology to predict and measure non-target impacts of biological control agents due to apparent competition

Avian malaria infections in western European mosquitoes

Avian malaria infections in western European mosquitoes. Ventim R, Ramos JA, Osório H, Lopes RJ, Pérez-Tris J, Mendes L. SourceInstitute of Marine Research (IMAR/CMA), Department of Life Sciences, University of Coimbra, Apartado 3046, 3001-401 Coimbra, Portugal. [email protected] Abstract In the complex life cycle of avian malaria parasites (Plasmodium sp.), we still have a poor understanding on the vector-parasite relationships. This study described the community of potential avian malaria vectors in four Portuguese reedbeds. We tested if their geographical distribution differed, and investigated on their Plasmodium infections. The mosquitoes' feeding preferences were evaluated using CO(2), mice, and birds as baits. The most abundant species were Culex pipiens, Culex theileri, and Ochlerotatus caspius (and, in one site, Coquillettidia richiardii). Plasmodium lineages SGS1 and SYAT05 were found in unengorged Cx. pipiens and Cx. theileri, respectively, suggesting that these mosquitoes were competent vectors of those lineages. The species' abundance was significantly different among sites, which may help to explain the observed differences in the prevalence of SGS1. At the study sites, SGS1 was detected in the most abundant mosquito species and reached a high prevalence in the most abundant passerine species. Probably, this parasite needs abundant hosts in all phases of its cycle to keep a good reservoir of infection in all its stages. Cq. richiardii showed an opportunistic feeding behavior, while Cx. pipiens appeared to be more mammophilic than previously described, perhaps because the used avian bait was not its preferential target. In one of the study sites, mosquitoes seem to be attracted to the Spotless Starling Sturnus unicolor, an abundant bird species that may be an important local reservoir of avian malaria infections. To our knowledge, this is the first report of detection of avian Plasmodium DNA from European mosquitoes