Spatial patterns of bee captures in North American bowl trapping surveys

Abstract

Abstract. 1. Bowl and pan traps are now commonly used to capture bees (Hymenoptera: Apiformes) for research and surveys. 2. Studies of how arrangement and spacing of bowl traps affect captures of bees are needed to increase the efficiency of this capture technique. 3. We present results from seven studies of bowl traps placed in trapping webs, grids, and transects in four North American ecoregions (Mid‐Atlantic, Coastal California, Chihuahuan Desert, and Columbia Plateau). 4. Over 6000 specimens from 31 bee genera were captured and analysed across the studies. 5. Based on the results from trapping webs and distance tests, the per bowl capture rate of bees does not plateau until bowls are spaced 3–5 m apart. 6. Minor clumping of bee captures within transects was detected, with 26 of 56 transects having index of dispersion values that conform to a clumped distribution and 39 transects having positive Green’s index values, 13 with zero, and only four negative. However, degree of clumping was slight with an average value of only 0.06 (the index ranges from −1 to 1) with only five values >0.15. Similarly, runs tests were significant for only 5.9% of the transects. 7. Results indicate that (i) capture rates are unaffected by short distances between bowls within transects and (ii) that bowls and transects should be dispersed throughout a study site.

Preliminary results of bowl trapping bees (Hymenoptera, Apoidea) in a southern Brazil forest fragment

“…This method has recently gained increased attention among melittologists, especially after the contribution of Droege et al (2010). Published studies from Brazil reached to different conclusions about the performance of this sampling method, some reporting efficient captures (Krug & Alves-Dos-Santos 2008;Souza & Campos 2008), but others reporting very poor performances (Gonçalves & Brandão 2008;Gonçalves et al 2012).…”

“…Also, they have a low performance when compared with hand-netting and malaise traps in dense forested areas (Gonçalves & Brandão 2008;Gonçalves et al 2012). Other important issues are related to the type and placement of bowl traps, which can influence their efficiency (Gollan et al 2010), such as spacing among each unit (Droege et al 2010), elevation of the traps (Campbell & Hanula 2007;Tuell & Isaacs 2011), bowl colors and selectivity of bees (Campbell & Hanula 2007;Krug & Alves-dos-Santos 2008;Wilson et al 2008), habitat heterogeneity (Droege et al 2010), and fragment size (Aizen & Feinsinger 1994). …”

“…Bowl traps are considered better standard procedure for sampling effort, because there is not collector biases and easily replicated for sampling multiple transects simultaneously (Krug & Alves-dos-Santos 2008;Droege et al 2010). Another important issue when designing sampling is the low cost-benefit of bowl traps (Westphal et al 2008): commercial plastic bowls are cheap and only water and soap are added.…”

Description of two techniques to increase efficiency in processing and curating minute arthropods, with special reference to parasitic Hymenoptera

“…Participation in large-scale biodiversity studies and other ecological research projects (Delabie et al 2000;Droege et al 2010;Fisher 2005;LaPolla et al 2007) involving the collection of arthropods with passive collection techniques (Darling and Packer 1988;Fraser et al 2008;Noyes 1989;Townes 1962) generates not only a massive biomass of interest to the conducting researcher, but also a large volume of non-target material, or 'by-catch.' Both of these fractions must be dealt with in an efficacious manner to ensure maximal preservation of the morphological and genomic information of the specimens (Quicke et al 1999).…”

Atypical Wing Venation inDialictusandHemihalictusand Its Implications for Subgeneric Classification ofLasioglossum

“…This cosmopolitan genus includes many commonly collected bees which can, in both temperate and tropical areas, dominate the bee fauna in terms of number of individuals (see [2] for Ontario, [3] for Louisiana, [4] for North Carolina, and [5] for Maryland, Chihuahuan desert, and Columbia plateau, Ngo et al in prep. for Costa Rica].…”