Diversity and life-history traits of wild bees in intensive agricultural landscapes in the Rolling Pampa, Argentina.

VIOLETTE LE FÉON; SANTIAGO L. POGGIO; JUAN PABLO TORRETTA; COLETTE BERTRAND, GONZALO A. R. MOLINA, FRANÇOISE BUREL, JACQUES BAUDRY & CLAUDIO M. GHERSA

JOURNAL OF NATURAL HISTORY

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2016 vol. 50 p. 1175 - 1196

0022-2933

>Bee decline is a major concern due to their vital rolein pollinating many crops and wild plants. Communities of wild bees have beenscarcely studied in South America, particularly in the Pampas. This region hasbeen intensively transformed for agriculture, being presently one of the mostproductive areas of agricultural commodities in the world. Here, we aim toprovide first insights on the taxonomical and functional composition of beeassemblages in the Rolling Pampa, the most intensively managed part of thePampas, and the corn-belt of Argentina. Soybean (herbicide tolerant geneticallymodified varieties) is the predominant crop in this region. Bees were sampledwith colored pan traps during three different periods of the warm season.Sampling points were located on field margins either in the cropped or thesemi-natural grassland area of a farmland site devoted to annual cropping. Atotal of 2384 wild bee individuals were caught, representing 33 taxa (mainlyspecies and morphospecies). The subgenus Lasioglossum (Dialictus) largelydominated captures (78% of the total abundance) and was relatively abundant inthe entire study area, suggesting that some species of this group are likely toreach their ecological requirements in cropped areas. No-tilled fields probablyprovide large areas for below-ground nesting species, while their polylecticfood preferences allow them to collect pollen on a wide range of plant species,among them possibly soybean. On the contrary, the richness and the abundance ofother taxa were higher in the semi-natural area than in the cropped area.Above-ground nesting, oligolectic, or oil-collecting species were scarce andlargely rely on the nesting and food resources provided by the semi-naturalarea to survive. Our findings highlight (1) the large dominance of Lasioglossum(Dialictus) species in this highly intensively managed landscape, (2) theurgent need of preserving semi-natural habitats to maintain species-rich andfunctionally diverse bee communities in the Pampas.