Browsing by Author "Espadaler, Xavier"
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- Ants (Hymenoptera: Formicidae) of the Madeiran ArchipelagoPublication . Wetterer, James K.; Espadaler, Xavier; Wetterer, Andrea L.; Aguin-Pombo, Dora; Franquinho-Aguiar, António M.The subtropical Atlantic archipelago of Madeira is part of the Macaronesian biogeographic subregion. Absence of important mainland competitors and predators on Macaronesian islands has allowed the survival of many relicts of the subtropical biota that once inhabited the Mediterranean area. In the 19th century, however, two highly destructive exotic ant species, the big-headed ant (Pheidole megacephala) and the Argentine ant (Linepithema humile), invaded Madeira. Many authors have assumed that these invaders exterminated most or all native ants of Madeira, despite no research actually documenting such impact. In the present study, we compiled records and evaluated the native versus exotic status of all ant species collected in Madeira. We examined specimens of 27 ant species from Madeira: Cardiocondyla emeryi, Cardiocondyla mauritanica, Hypoponera eduardi, Hypoponera punc tatissima, Hypoponera sp. 1, Lasius grandis, Linepithema humile, Messor structor, Monomorium carbonarium, Monomorium pharaonis, Monomorium subopacum, Myrmecina graminicola, Paratrechina jaegerskioeldi, Paratrechina longicornis, Pheidole megacephala, Pheidole pallidula, Plagiolepis schmitzii, Pyramica membranifera, Solenopsis sp. 1, Solenopsis sp. 2, Strumigenys silvest rii, Tapinoma madeirense (new status), Technomyrmex pallipes, Temnothorax unifasciatus, Temnothorax wollastoni, Tetramorium bicarinatum, and Tetra morium caldarium. One previously reported species, Camponotus sylvaticus, we could not verify with specimens, but accept it was correctly identified, at least to genus. We determined that one ant taxon reported from Madeira is a junior synonym of another taxon present: Plagiolepis schmitzii madeirensis (= P. schmitzii, new synonymy). In addition, published records of eight ant taxa reported from Madeira appear to be misidentifications of other species present. Based on their known distribution and ecology, ten ant species (including the seven most common species) appear to be native to Madeira. Only one native ant species, T. wollastoni, has not been collected recently (1995 or later) in Madeira. Although exotic ants may have exterminated T. wollastoni, it seems likely that this species still survives.
- Long-term impact of exotic ants on the native ants of MadeiraPublication . Wetterer, James K.; Espadaler, Xavier; Wetterer, Andrea L.; Aguin-Pombo, Dora; Franquinho-Aguiar, António M.1. The earliest exotic records for two notorious invasive ants, the big-headed ant ( Pheidole megacephala ) and the Argentine ant ( Linepithema humile ), both come from the Atlantic islands of Madeira, where the two species underwent population explosions in the 1850s and 1890s respectively. Researchers have long assumed that these invaders spread across all of Madeira and exterminated most or all native ants, despite no research actually documenting such impact. 2. Re-examination of first-hand nineteenth century accounts suggest that P. megacephala and L. humile may never have spread beyond coastal lowland areas, representing < 10% of Madeira’s land area. In 2002, native ants dominated most of Madeira; P. megacephala and L. humile were restricted to ≈ 0.3% and ≈ 6% of Madeira’s land area respectively. 3. Of the 10 native ant species known from Madeira, only one ( Temnothorax wollastoni ) was not present in 1999 – 2002 surveys. Although exotic ants may have exterminated T. wollastoni , it seems likely that this species still survives. 4. Thus, even after 150 or more years of residence, P. megacephala and L. humile have come to occupy only a small part of Madeira, and appear to have had little impact. 5. Most of Madeira may be too cool for P. megacephala and perhaps too moist for L. humile to dominate. Also, Madeira’s vast natural areas may generally lack weedy vegetation that can support high densities of plant-feeding Hemiptera critical for the ecological dominance of invasive ants. Finally, a dominant native ant, Lasius grandis , inhabiting ≈ 84% of Madeira, may actively exclude P. megacephala and L. humile