Seasonal abundance and diversity of native bees in a patchy agricultural landscape in Southern Mexico

Abstract

Diversity and abundance of native bees was measured in four sites of an agricultural landscape dominated by soybean crops in Southern Mexico. Bees were sampled from June 2014 to May 2015 using entomological nets along five 500 m long transects in each site. Two sites (S1 and S2) were fully anthropized (100% of urban and agricultural land use) and the two other sites (R1 and R2) were on average less anthropized with 27.5% of forest relicts. Overall, we collected 2115 specimens; the most abundant species were Augochlora (Oxystoglossella) aurifera (12.8%), Trigona fuscipennis (9.2%), and T. fulviventris (8.6%). The highest diversity was observed in June and July (rainy season), in sites S2 and S1. Site S2 had the greatest diversity and abundance (56 species, 885 individuals), followed by S1 (41 species, 577 individuals), R2 (38 species, 289 individuals) and R1 (25 species, 117 individuals). However, rarefaction analysis showed no significant difference among four sites. Compared to studies carried out in protected natural areas with similar climatic conditions, our results suggest that small-scale agriculture in southern Mexico apparently does not affect detrimentally pollinator populations as expected. Thus, this study suggest that the presence of preserved patches contributes to the richness and abundance of bees, due to the maintenance of wild flowers and ruderal plants in patches next to the crop fields, providing a continuous source of pollen, nectar and shelters. Nonetheless, further studies are necessary to examine the connections between the different elements in the agricultural landscape and to understand in depth the response of the pollinator communities.