Zikanapis tucumana (Moure, 1945)

Sarzetti, Laura C., Genise, Jorge F., Sanchez, M. Victoria, Farina, Juan L. & Molina, M. Alejandra, 2013, Nesting behavior and ecological preferences of five Diphaglossinae species (Hymenoptera, Apoidea, Colletidae) from Argentina and Chile, Journal of Hymenoptera Research 33, pp. 63-82 : 64-66

Zikanapis tucumana (Moure, 1945)

Localities and nesting sites.

Observations on the biology and nest structure of this species were carried out during November 24th-30th, 2008 and through February 3rd-5th, 2009 at Vinchina (28°49.117'S, 68°11.433'W) and Anillaco (28°48.517'S, 66°55.867'W), both at La Rioja province, northwestern Argentina. The localities are included in xeric environments of the Larrea 's shrubland with a mean annual temperature (MAT) around 17° C and a mean annual precipitation (MAP) around 250 mm. Nest entrances were exposed in open areas and were never hidden by stones or shrubs. At Vinchina, nests formed an aggregation at the border of a formerly plowed open area frequently flooded by irrigation ( Fig. 1 ). The ground surface was flat, compacted, and devoid of rocks. The soil was composed principally of fine sand to silt bridged by sparse clayish material. The vegetation was sparse and basically comprising plants of Solanum sp. (10 to 20 cm tall) and grasses ( Fig. 1 ). At Anillaco the nests were found at the surroundings of the CRILAR (Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de Anillaco, La Rioja). The ground surface was flat, and the soil consisted of fine sand and numerous rocks of different sizes, which hindered excavation. The vegetation was sparse, consisting of some grasses, and scarce herbaceous plants, such as Mirabilis ovata and Solanum sp., some cacti, and trees ( Salix sp. and Prosopis sp.). The nests at both localities were located among plants of Solanum sp. or near them.

Daily activity.

Zikanapis tucumana was the only species in this study that clearly demostrated dim-light, matinal foraging. At 04:30 am, still at night, the flower buds of Solanum sp. were still closed and no bee activity was observed. Females became active around 05:00 am, still at night, when the flower buds of Solanum sp. began to open ( Fig. 2 ). After 05:20 am, with twilight, females were completely active. With sunrise, around 07:00 am, the foraging activity of the bees ceased almost completely. The activity ended definitively around 07:30 with full daylight, when the entrance of nests were closed from inside with a soil plug. The number of foraging trips per bee during these 150 minutes for the five nests observed was around 8. The females with pollen remained inside nests about 2-3 minutes before leaving again. Their foraging trips lasted about 14 to 17 minutes. During November, males of Zikanapis tucumana were also observed flying around nests 1-2 m above ground.

Description of nests.

The entrance of nests was surrounded by a tumulus that ranged from 5 to 10 cm in diameter and 1 cm high (n: 6). Some nests also had a consolidated turret of 0.8 cm in maximum diameter and 1.7-2 cm high above the entrance ( Fig. 3 ). The entrance, circular and 0.8 cm in diameter, was located at the center of the tumulus. The main tunnel, circular in cross section, was plugged with soil at approximately 10 cm from the entrance when the female was inside the nest. The main tunnel, 16-24 cm long (n: 9), was vertical and mostly straight at Vinchina but sinuous at Anillaco. Three nests had one cell and three other nests two cells. Cells, oriented vertically, were found at depths from 17 to 31 cm. They were disposed radially around the main tunnel, and connected with it by lateral tunnels 6-8 cm long. Lateral tunnels were subhorizontal or slightly inclined downwards and filled with soil when connected with closed cells. They ended in a raised, curved, entrance tunnel connected with the vertical portion of the cell ( Figs 4, 5 and 7 ). Once lined and sealed, the distal part of the entrance tunnel became the curved neck of the cell. The vertical portion of the cells was 1.3-1.8 cm long and 0.9-1 cm in maximum diameter (n: 7). The neck was 0.7-0.8 cm in diameter (n: 2). The inner cell wall, including the neck, was smooth and lined with a whitish, semitransparent, cellophane-like material ( Fig. 6 ). Two cells obtained during November from Vinchina contained eggs. The eggs, whitish, elongate, and slightly curved, were 2.3 mm long and 0.9 mm in maximum diameter. They were laid over the semiliquid provisions. The two cells collected during February at Anillaco contained an egg and a larva respectively. The larva, whitish, immobile and curved was located over a layer of remaining provisions at the base of the cell.

Figures

Figures 1 - 7. Zikanapis tucumana (Moure, 1945). 1 General view of the nesting site at Vinchina (La Rioja province) before sunrise 2 Female of Zikanapis tucumana during foraging activity 3 Tumulus, turret andopennest entrance 4 Main and lateral tunnel showing one cell at the end (arrow) 5 General view of nest architecture, scale line: 1 cm 6 Remains of a cell with part of the provisions. Note the curvature of neck 7 Nestarchitecture.