Diphaglossa gayi Spinola, 1851

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 : 71-74

Diphaglossa gayi Spinola, 1851

Localities and nesting sites.

The observations were carried out during November 8th, 2009 and February 10th, 2011 beside the Río Negro Bridge (42°57.433'S, 72°39.233'W) and during November 9th, 2009 and February, 15th, 2011 at Lonconao (43°13.007'S, 71°55.143'W), both localities from the Palena province (Region de Los Lagos, Chile). The nesting sites occur in the glades of hygrophilous evergreen forests with a MAT around 11° C and MAP around 2500-3000 mm. Two nests were excavated. The first nest was located in a steep slope in a farm beside the Río Negro Bridge ( Fig. 38 ), where as the second was excavated in a low vertical section of the soil in another farm at Lonconao ( Fig. 39 ). At both localities, the soil, composed of silty to very fine sandy material and devoid of rocks, contained grass rhizomes, some roots, and earthworm burrows. The soil cover consisted of a combination of dense grasses and dicots ( Fig. 38 ), and the subsurface contained a thin ash layer produced by the Chaiten eruption of May 2008.

Daily activity.

On November 8th, 2009 the first nest was found around 06:00 pm and the female was observed entering the nest with pollen around 07:00 pm. On November 9th, 2009 the second nest was found also around 06:00 pm and the female was inside the main tunnel.

Description of nests.

The Rio Negro nest showed an open circular entrance, 0.5 cm in diameter, which was surrounded by an eccentric tumulus, roughly 4.6 cm wide and 5.2 cm long. The tumulus was composed of soil pellets, probably of the recently deposited subsurface ash layer, which were paler than the soil surface ( Fig. 40 ). The Lonconao nest was located in a vertical cut, thus the entrance, 0.7 in diameter, lacked a tumulus. Both nests share the same general structure. The main tunnel, circular in cross section, 32-38 cm long, was nearly straight and slightly inclined downwards, ending in a vertical segment 8 cm long ( Figs 41 and 42 ). Its maximum diameter was 0.7-1.0 cm. Each nest contained four closed cells arranged in two pairs, one pair near the middle portion of the main tunnel, and the other near the end. It is possible that both cells were connected to the main tunnel by a common lateral, filled with soil when the nest was excavated ( Fig. 42 ). The cellswere vertical, rounded at the bottom, and the neck was strongly curved ( Figs 42 and 43 ). The vertical portion of the cells was 2 cm long and 1 cm in maximum diameter (n: 8). The neck was 0.7 cm in diameter. The inner surface of cells and the neck was lined with a whitish semitransparent, cellophane-like material. The cells in both nests contained one egg laying on top of the semiliquid provisions. The cell closure was not observed.

Figures

Figures 38 - 43. Diphaglossa gayi Spinola, 1851. 38 General view of the nesting site beside the Rio Negro Bridge, Chile 39 general view of nesting site at Lonconao, Chile 40 tumulus of soil pellets and open entrance 41 main tunnel 42 nest architecture 43 cell, neck with lining, and egg laying on provisions.