Methods for rearing ground-nesting bees under laboratory conditions Ryan J. Leonard, Alexandra N. Harmon-Threatt To cite this version: Ryan J. Leonard, Alexandra N. Harmon-Threatt. Methods for rearing ground-nesting bees under laboratory conditions. Apidologie, 2019, 50 (5), pp.689-703. 10.1007/s13592-019-00679-8. hal- 02915933 HAL Id: hal-02915933 https://hal.archives-ouvertes.fr/hal-02915933 Submitted on 17 Aug 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Apidologie (2019) 50:689–703 Review article * INRA, DIB and Springer-Verlag France SAS, part of Springer Nature, 2019 DOI: 10.1007/s13592-019-00679-8 Methods for rearing ground-nesting bees under laboratory conditions Ryan J. LEONARD, Alexandra N. HARMON-THREATT Department of Entomology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA Received 15 March 2019 – Revised 21 June 2019 – Accepted 15 July 2019 Abstract – Ground-nesting bees are largely undervalued, both in terms of their use as model species for behavioural studies, and in terms of their agricultural benefit as pollinators in crop systems. But, why? One potential barrier limiting their use as model species may be our understanding of how to effectively establish and maintain ground- nesting bees in the laboratory. Here we review how artificial nests are used to study ground-nesting bees and provide guidelines for building, starting and maintaining artificial nests. Ultimately, appropriate design and maintenance of artificial nests will allow researchers to explore a suite of interesting questions related to this important group of pollinating insects, from natural history to the origins of eusociality and the effects of environmental contaminants. ground-nesting bee / artificial nest / rearing / Lasioglossum 1. INTRODUCTION bee species globally (Cane 1991; Michener 2000). The artificial nests used to study this group For over a century, artificial nests have formed (termed nest boxes) typically contain a sheltered a cornerstone of research efforts to understand the collection of few to several hundred nesting cav- behaviour of bees. Indeed, the oldest definitive ities composed of porous material (e.g. 15–20-cm example of artificial nest use dates between 3000 wood, polystyrene blocks, stems or reeds) opened BCE and 500CE, when humans first provided at one end (reviewed by MacIvor (2017)). In the honey bees with artificial nest cavities (Kritsky same way nest boxes continue to facilitate the 2010). Whilst especially common in managed study and understanding of above-ground cavity species (e.g. Apis mellifera ), artificial nest use is nesting bees (Forrest and Thomson 2011; also increasingly employed to study populations MacIvor and Packer 2015; Staab et al. 2018), of wild bees (Bosch and Kemp 2005; Moroń et al. artificial nests also stand to provide critical insight 2012; Fortel et al. 2016). To date, artificial nest into the ecology of lesser studied ground-nesting use in wild bees has largely been restricted to bee species. above-ground, cavity nesting species, a group that Much like their above-ground counterparts, ar- comprise less than 15% of the estimated 20,000 tificial nest use in ground-nesting bees has varied considerably over time. Since their inception in the early 1900s, artificial nests for ground-nesting Electronic supplementary material The online version of bees have evolved from rudimental soil-filled this article (https://doi.org/10.1007/s13592-019-00679-8) contains supplementary material, which is available to buckets (Malyshev 1925; Hartman 1943) (also authorized users. summarised by Linsley et al. (1952)), to in situ field and laboratory observation nests where nest Corresponding author: R. Leonard, [email protected]. Leonard, [email protected] structure and behaviour could be observed Manuscript editor: James Nieh (Michener et al. 1955;Batra1964). Among the 690 R. J. Leonard, A. N. Harmon-Threatt first examples of artificial nests are clay blocks (see Batra (1964) and Michener and Brothers constructed by Soviet entomologist S.I. Malyshev (1971)), they have also facilitated research on in 1925 to study the nesting biology of several additional species including Anthophora acervorum (Malyshev 1925). Over L. hemichalceum (Jeanson et al. 2005), L. NDA- time, researchers began constructing artificial 1 (Holbrook et al. 2013)andMacrotera portalis nests in situ. To this end, researchers dug down (Danforth 1991a, b). beside field nests of species including Despite advances in the design and experimen- Lasioglossum zephyrum , and installed glass ‘win- tal use of artificial nests, they remain an dows’ made of microscope slides and/or glass underutilised resource for studying fundamental tubes (Michener et al. 1955). These glass win- behaviours including ‘stress’-mediated ecological dows allowed researchers to observe behaviours responses. Indeed, very few studies use artificial within the upper parts of the nest, a task previous- nests to investigate the effects of environmental ly impossible using soil or clay blocks. The grow- stressors on developmental, behavioural and ing need for researchers to view behaviours oc- physiological phenotypes in ground-nesting bees curring deeper in the nest led to the construction of (but see Kamm (1974)). Most studies on ground- structures capable of holding whole nests in the nesting bees instead quantify changes in forager laboratory. Such nests were essentially soil-filled abundance and diversity, along gradients of envi- cavities sandwiched between two sheets of glass ronmental stress or following field exposure to or Perspex (Figure 1) that allowed researchers to certain stressors (e.g. urbanization, agricultural observe entire within-nest activity (e.g. cell con- practices, pollution) (Kim et al. 2006; Kearns struction, brood provision and egg laying, and and Oliveras 2009;Kratschmeretal.2018). behavioural interactions within social nests). Ar- Whilst such studies provide novel ecological and tificial nests of this type were originally described conservation insight, the systematic use of artifi- by Batra (1964) and subsequently refined by cial nests stands to afford a greater mechanistic Michener and Brothers (1971), Kamm (1974), understanding of stress-mediated ecological re- Bell et al. (1974) and Greenberg (1982b). Al- sponses in this important group. This is especially though originally used to study L. zephyrum relevant to discussions regarding the proposed Figure 1. Schematic diagram of a open and b closed observation nest. Methods for rearing ground-nesting bees 691 suitability of ground-nesting bees as test organ- provide more experimental control (i.e. limit con- isms for regulatory decisions on pesticide approv- founding factors) and, when paired with careful al (European Food Safety Authority 2013). De- experimental manipulations, will likely provide spite their proposed suitability, there are currently greater insight into ground-nesting bee physiolo- no widely accepted guidelines for laboratory stud- gy and responses to disturbances (e.g. disease, ies and very limited information concerning semi- pesticide application, soil moisture). field or field test methods (Ruddle et al. 2018). Closed nests are constructed much like their The goal of this review is to aid researchers in open-nest counterparts, except plastic tubing is constructing and maintaining artificial nests for glued to the top of the nest to prevent bees from ground-nesting bees. Having reviewed the litera- escaping (Figure 1). A short piece of additional ture on this group of pollinating insects (Supple- tubing (e.g. 3–5-cm length, < 4-mm inside diam- mentary Table 1), we summarise relevant consid- eter) attached to a plastic container (e.g. 3 cm high erations relating to the types of nests used and and 3.5-cm diameter) containing food is inserted factors significantly affecting nesting success in- into the top of the nest, allowing bees to feed cluding nesting substrate, food provision and abi- (Kamm 1974). Bees maintained in closed obser- otic factors (e.g. temperature). We also explore vation nests do not appear to suffer adverse side strategies facilitating nest establishment in the effects attributed to the confined space. To date, laboratory, as well as colony and individual col- closed nests have been used to effectively answer lection. Whilst this review will ultimately help in questions relating to within-nest interactions in standardising the establishment and maintenance social species including the effects of colony size of artificial nests for ground-nesting bees, many of on colony activity (Kukuk and May 1991), and the techniques reviewed here may also be useful queen-worker behaviour (Greenberg and Buckle in the study of other understudied ground-nesting 1981; Buckle 1982). They have also been groups including wasps (e.g. Vespula sp.) and employed in controlled dietary studies where re- beetles (e.g. Cicindelinae and Scarabaeoidea sp.). sponse variables included development (Roulston and Cane 2002), and reproductive physiology 2. ARTIFICIAL NEST TYPES