Wild solitary bees and their use of bee hotels in southwest Spain

Abstract

There is an increasing interest in preserving and, if possible, increasing wild bee populations as evidenced by increasing investigations into providing supplemental nesting resources, commonly called bee hotels. The study presented here was carried out in 2017 and 2018 with two objectives: a) to understand the role that insect refuges could have on beneficial arthropod fauna, especially bees, and b) to evaluate different materials and which species used them. We present the preliminary results of three constructed refuges in Seville, Spain: Hymenoptera visited the refuges most frequently (88.7% of the visitors), of which the social wasps (Polistes dominula (Christ)) were most common, followed by bees. Bees were observed visiting bamboo canes, Arundo canes, drilled logs, and grooved boards. Drilled logs were the most used material (31.5 and 37.6% occupied in 2017 and 2018, respectively), followed by bamboo canes (14.1 and 17.4% of occupied in 2017 and 2018, respectively). For drilled logs, holes of 4.9–6.5 mm (2017) and 7.0–9.2 mm (2018) were preferred, whilst diameters of 2.6/2.7–4.9/5.0 mm (both 2017 and 2018) were preferred for bamboo canes. For grooved boards, holes of 5.0 mm (only 2018) were preferred. The bee species most frequently nesting in bamboo canes were Ceratina cucurbitina (Rossi) and Ceratina dentiventris Gerstacker, whereas in drilled logs Hoplitis lepeletieri (Pérez) was most common, but Hoplitis adunca (Panzer) was also recorded. Their abundance throughout the study period varied between species, and their role in biodiversity and sustaining wild flora is discussed.

Keywords:

• insect refuge
• materials
• wild bees
• Ceratina cucurbitina
• Ceratina dentiventris
• Hoplitis lepeletieri

Acknowledgements

We thank all the field support personnel of the Department of Ciencias Agroforestales of the University of Seville for their collaboration in the maintenance of the refuges, and especially Noemí Zurita for her advice and expertise in the construction of the three refuges used in this work. We also express our gratitude to Dr. Francisco P. Molina, from CSIC-Doñana Experimental Station (Sevilla, Spain), for the identification of many of the hymenopterous species found in this work. Several of the photographs taken along the observations were uploaded in the Biodiversidad Virtual webpage (https://www.biodiversidadvirtual.org/insectarium/), and their experts helped to identify some of the species and groups.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was not economically supported by any official agency or private organisation.

Supplementary material

The supplementary material is available via the ‘Supplementary’ tab on the article’s online page (http://dx.doi.org/10.1080/00218839.2021.1892416).