Messor barbarus

The harvester ant, Messor barbarus, causes 46–100% of the seed losses in arable fields in northeastern Spain (Westerman et al. 2012). In irrigated fields in Valencia, M. barbarous represents the majority of the ant population (Urbaneja et al. 2006).

Distribution based on Regional Taxon Lists
Palaearctic Region: Algeria, Balearic Islands, Bulgaria, Egypt, France, Gibraltar, Iberian Peninsula, Monaco, Morocco, Portugal, Romania, Spain, Tunisia.

Biology
A 2013 study of 55 citrus orchards in eastern Spain (Atanackovic et al., 2015) found: Messor barbarus was the only granivorous species present, with nests found on the field edges and between the tree rows in the field. No nests were observed under the trees, which is most likely related to the lack of insulation. The nests were large in size (quantified by having several nest entrances and a high number of workers), while small colonies were detected in only a few fields. The number of nests was approximated to be zero-to-five nests per field, based on observations from the diagonal transect, as well as between the rows. Seed predation was observed in almost all the fields with M. barbarus. The harvester ants mostly removed Lolium rigidum and Solanum spp. seeds, although in one orchard, Conyza spp. seeds were observed surrounding the nest entrances."

M. barbarus were the main ant species that were observed in the fields, as confirmed by previous studies in this area (Monzó et al. 2013). They are present in citrus orchards during most of the year, except in the winter months of November to April (Urbaneja et al. 2006). Messor barbarus never climbs on trees, but forages on the soil surface; therefore, it is a species that does not damage citrus fruits (Platner et al. 2012). In the surveyed fields, ant nests were located both in the field and on the borders. This differed from the drip-irrigated citrus orchards in Valencia, where the ants were settled only along the edge (Monzó et al. 2013). Cerdà et al. (2009) did not find differences in the nest numbers between the margins and the inner part of the citrus orchards.

Nomenclature

 *  barbarus. Formica barbara Linnaeus, 1767: 962 (w.) MOROCCO. Mayr, 1861: 67 (q.m.); Wheeler, G.C. & Wheeler, J. 1953b: 65 (l.). Combination in Aphaenogaster: Roger, 1863b: 29; in A. (Messor): Forel, 1890a: lxviii; in Messor: Forel, 1894d: 8; in Stenamma (Messor): Emery, 1898c: 125; in Messor: Ruzsky, 1903b: 315; Bingham, 1903: 278. Senior synonym of binodis, juvenalis: Smith, F. 1858b: 162; of megacephala: Mayr, 1863: 395; of rufitarsis Foerster: Roger, 1863b: 29; of ambiguus, nigriceps: Collingwood, 1978: 68; of sordida: Cagniant & Espadaler, 1998: 424. Current subspecies: nominal plus gallaoides, mediosanguineus, politus, sahlbergi, santschii, varrialei.
 * binodis. Formica binodis Fabricius, 1775: 393 (w.) EGYPT. [Unresolved junior primary homonym of Formica binodis Linnaeus, 1763: 413 (now in Tetramorium).] Junior synonym of barbarus: Smith, F. 1858b: 162.
 * juvenilis. Formica juvenilis Fabricius, 1804: 405 (w.) FRANCE. Junior synonym of barbarus: Smith, F. 1858b: 162.
 * megacephala. Formica megacephala Leach, 1825: 292 (w.q.m.) FRANCE. [Unresolved junior primary homonym of Formica megacephala Fabicius, 1793: 361 (now in Pheidole).] Junior synonym of barbarus: Mayr, 1863: 395.
 * rufitarsis. Myrmica rufitarsis Foerster, 1850b: 485 (w.) ALGERIA. [Unresolved junior primary homonym of rufitarsis Fabricius, above.] Junior synonym of barbarus: Roger, 1863b: 29.
 * sordida. Aphaenogaster (Messor) barbara r. sordida Forel, 1892g: 452 (w.) SPAIN. Santschi, 1917e: 89 (s.). Combination in Messor: Emery, 1897f: 239. Subspecies of barbarus: Santschi, 1925g: 342 (in key); Wheeler, W.M. 1927g: 104. Raised to species: Bondroit, 1918: 152; Cagniant, 1964: 88; Bernard, 1967: 145. Junior synonym of barbarus: Cagniant & Espadaler, 1998: 424.
 * ambiguus. Messor barbarus var. ambiguus Santschi, 1925g: 342 (w.) TUNISIA. Junior synonym of barbarus: Collingwood, 1978: 68.
 * nigriceps. Messor barbarus var. nigriceps Santschi, 1925g: 341 (w.q.) SPAIN. Junior synonym of barbarus: Collingwood, 1978: 68.