Communication new technique in the excavation of ground-nest bee burrows Hymenoptera : Apoidea )

Bees have a diversified natural history, thus the methods applied to study such diversity are varied. When it comes to studies of nesting biology, bees which nest in pre-existing cavities have been reasonably well studied since researchers started using trap-nests. However, bees whose nests are built underground are poorly studied due to the difficulty of finding natural nesting areas and the absence of a method that facilitates bee nest excavation. The latter is evidenced by the lack of accurate descriptions in literature of how nests are excavated. In this study we tested cylindrical rubber refills of eraser pen as a new material to be used as a tracer of underground nest galleries in a natural nesting area of two species of Epicharis Klug, 1807 (Apidae). We compared this technique directly with plaster in powder form mixed with water and poidea rood cells ethodology olitary bees our results with other methodological studies describing alternative methods and materials. The rubber refill technique overcame the main issues presented by materials such as plaster, molten metal alloys and bioplastic, namely: death of the organisms by high temperatures and/or formation of plugs and materials unduly following the roots inside the galleries. © 2017 Sociedade Brasileira de Entomologia. Published by Elsevier Editora Ltda. This is an open he CC access article under t Bees are insects with a very diversified natural history. Most pecies are solitary (about 85%) and each female takes care of its wn brood cells (Batra, 1984; Michener, 2007). Their nests are built ith several materials, like resin, leaves, Dufour’s gland secretions, tc. and on several substrates, such as rocks, wood, plant branches, nside pre-existing cavities or directly in the ground (Batra, 1984). onsidering this bionomical diversity, the methods used to study hese organisms are also diversified (Linsley et al., 1952; Michener t al., 1955). Apids and Megachilids which nest in pre-existing cavities in the ood, for instance, have their biology better understood due to he advent of the trap-nest method (Krombein, 1967). However, he majority of bees build their brood cells underground (Batra, 984), and subsequently, little is known about the process of nest onstruction and associated aspects of the biology of these species, ostly due to the difficulty of finding natural nesting areas and to btain data collection from their underground nests. Several methodological studies were developed regarding ymenoptera ground-nesting habits (Michener et al., 1955; illiams and Lofgren, 1988), but the majority of them were focused ∗ Corresponding author. E-mail: diego.mp89@gmail.com (D. Marinho). https://doi.org/10.1016/j.rbe. 2017.11. 003 085-5626/© 2017 Sociedade Brasileira de Entomologia. Published by Elsevier Editor reativecommons.org/licenses/by-nc-nd/4.0/). BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). on ants (Tschinkel, 2010, 2013). For studies that propose specific methods for collecting underground bee nests, the materials used are plaster (Linsley et al., 1952; Michener et al., 1955; Norden et al., 1994), molten metal alloys, paraffin wax (Linsley et al., 1952) and bioplastic (Howell, 1960). From 1960 onwards, to the best of our knowledge, no methodological studies have been published focusing on methods of collecting underground bee nests, evidencing the lack of literature concerning alternative ways to study such nests. Furthermore, several studies on the biology of ground-nesting bees do not describe in detail how excavation is performed (see Gaglianone, 2005; Gaglianone et al., 2015; Rocha-Filho et al., 2008; Roubik, 1980; Rozen, 2016; Thiele and Inouye, 2007), hindering the possibility of comparison of the methods used. In this context, we aim to propose a new practical method for tracing the nest tunnels and collecting brood cells from underground nests. Additionally, we compare it with other methodological studies present in literature.