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Honeybee colonies have increased exponentially in the Mediterranean Basin

Evidence for pollinator declines largely originates from mid-latitude regions in North America and Europe. Geographical heterogeneity in pollinator trends combined with geographical biases in pollinator studies can produce distorted extrapolations and limit understanding of pollinator responses to environmental changes. In contrast with the declines experienced in some well-investigated European and North American regions, honeybees seem to have increased recently in some areas of the Mediterranean Basin. The Mediterranean Basin is home to approximately 3300 wild bee species, or approximately 87% of those occurring in the whole western Palaearctic region. Because honeybees can have negative impacts on wild bees, it was hypothesized that a biome-wide alteration in bee pollinator assemblages may be underway in the Mediterranean Basin involving a reduction in the relative number of wild bees. This hypothesis was tested using published quantitative data on bee pollinators of wild and cultivated plants from studies conducted between 1963 and 2017 in 13 countries from the European, African and Asian shores of the Mediterranean Sea. The density of honeybee colonies increased exponentially and wild bees were gradually replaced by honeybees in flowers of wild and cultivated plants. The proportion of wild bees at flowers was four times greater than that of honeybees at the beginning of the period, the proportions of both groups becoming roughly similar 50 years later. The Mediterranean Basin is a world biodiversity hotspot for wild bees and wild bee-pollinated plants, and the ubiquitous rise of honeybees to dominance as pollinators could in the long run undermine the diversity of plants and wild bees in the region. informacion[at] Herrera (2020) Gradual replacement of wild bees by honeybees in flowers of the Mediterranean Basin over the last 50 years. Proc Royal Society B 287(1921). Doi 10.1098/rspb.2019.2657
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One century of crayfish invasions

One century of crayfish invasions

The red swamp crayfish (Procambarus clarkii), native to the southern United States and north-eastern Mexico, is currently the most widely distributed crayfish globally, as well as one of the invasive species with most devastating impacts on freshwater ecosystems. Reconstructing the introduction routes of invasive species and identifying the motivations that have led to those movements is necessary to accurately reduce the likelihood of further introductions. In this study, the temporal evolution of the scientific literature on the red swamp crayfish was reviewed, georeferenced, time-explicit records of the species to provide a comprehensive understanding of its global expansion process were compiled and the potential role of biological supply companies in the translocations of the red swamp crayfish was evaluated. The interest of the red swamp crayfish in scientific research increased steadily since the beginning of the twentieth century until stabilization in the late 1960s. The number of studies related to the use of the red swamp crayfish in aquaculture showed two peaking periods: the years elapsed between 1970s to mid-1980s, and a continuous increase since the mid-1980s. Research on the red swamp crayfish as an invasive species has only been numerically relevant in recent times, with the number of studies increasing since the 2000s to represent currently around 25% of the scientific production dealing with this species. Although the first introductions of the red swamp crayfish took place in the 1920s, this synthesis highlights the rapid expansion of the species since the 1960s, arguably promoted by the emergence of crayfish industry, but other introduction pathways such as the mitigation of schistosomiasis, potential releases from research experiments, school science programs or pet trade cannot be ruled out. Currently, the red swamp crayfish is present in 40 countries of four continents and there is still potential for further expansion. Commercial suppliers from native (Louisiana) and non-native (California or North Carolina) areas in the United States have provided live-specimens of the red swamp crayfish for scientific research around the world for decades, suggesting that the invasion process of the red swamp crayfish could be more complex than generally assumed. Tracing the introduction routes of invasive species and understanding the motivations that have led to those movements of species is key to reduce their spread and the likelihood of future introductions. informacion[at] Oficialdegui et al (2020) One century away from home: how the red swamp crayfish took over the world. Reviews in Fish Biology and Fisheries DOI: 10.1007/s11160-020-09594-z