Bees in the Southwest Pacific: Origins, Diversity and Conservation Scott Groom, Michael Schwarz
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Bees in the Southwest Pacific: Origins, diversity and conservation Scott Groom, Michael Schwarz To cite this version: Scott Groom, Michael Schwarz. Bees in the Southwest Pacific: Origins, diversity and conservation. Apidologie, Springer Verlag, 2011, 42 (6), pp.759-770. 10.1007/s13592-011-0079-8. hal-01003616 HAL Id: hal-01003616 https://hal.archives-ouvertes.fr/hal-01003616 Submitted on 1 Jan 2011 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 (2011) 42:759–770 Review article * INRA, DIB-AGIB and Springer Science+Business Media B.V., 2011 DOI: 10.1007/s13592-011-0079-8 Bees in the Southwest Pacific: Origins, diversity and conservation Scott V. C. GROOM, Michael P. SCHWARZ School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia Received 20 December 2010 – Revised 4 May 2011 – Accepted 9 May 2011 Abstract – Bee diversity of the Southwest Pacific has been reported as depauperate despite the otherwise rich biodiversity and complex geological history for this region. However, due to a lack of bee-specific sampling, there is potential for higher bee diversity than previous studies suggest. Here, we review the current literature to summarise the extant diversity for each of the main island groups, the likely passages of species dispersal, and outline the main threats to Southwest Pacific populations. As key pollinators for both cultivated and native angiosperms, ensuring the persistence of native bee populations is critical for both food security and biodiversity conservation. With impending threats from land use change, invasive species and climate change, among others, understanding the true species diversity is important for assigning conservation priorities. We argue that future research in the region must encourage local expertise and build this into global research directions in an effort to address a lack of fundamental knowledge of bee diversity in island ecosystems. bees / conservation / biodiversity / biogeography / Pacific 1. INTRODUCTION genesis of island biota resulting from vicariance and dispersal. There is a broad array of challenges for In this review, we summarise the current understanding bee diversity and evolution in the knowledge of bee taxonomy and diversity in the Southwest Pacific (SWP) region. These chal- SWP. Moreover, we outline the major vicariance lenges result from a confluence of three factors: and dispersal hypotheses for origins of the SWP (1) the lack of detailed field sampling that biota and combine these two research areas to would allow true bee diversity to be reliably suggest how future bee studies may help documented; (2) a lack of taxonomic revisions understand how SWP bee fauna arose and how for many key island faunas so that identification island ecologies may have been influenced. We of species, and the distributional extent of finish by considering conservation issues sur- species, is poorly known; and (3) the highly rounding endemic bees in the SWP and their variable geological history among SWP islands, potential importance for pollination of both ranging from Gondwanan elements through to agricultural crops and non-crop endemic plants. comparatively recent subaerial origins, provid- ing potentially fascinating insights into the 2. DIVERSITY AND TAXONOMY OF NATIVE BEES IN THE SOUTHWEST PACIFIC Corresponding author: S.V.C. Groom, [email protected] The bee fauna of the SWP has been the Manuscript editor: Stan Schneider subject of a number of descriptive studies 760 S.V.C. Groom and M.P. Schwarz beginning with Smith (1879, 1953), Kohl a situation very unlike anywhere else in the (1908), Friese (1909) and, most recently, Pauly world and one that led Michener (1965)to and Villemant (2009). Although these studies claim that Australia has the most unusual bee have resulted in a moderate number of species fauna of any continent in the world. Of the descriptions, many taxonomic assignments were remaining half, Halictidae represent almost a not well determined and have required numer- quarter (385 species), with Apidae (197 spe- ous revisions (Michener 1965). However, these cies), Megachilidae (168 species) and the revisions have often been regionally restricted. Australian endemic Stenotritidae (21 species) The only taxonomic revisions of SWP bees that comprising the remaining quarter. New Zea- provide identification keys for a region’s bee land also contains a high proportion of Colle- fauna are for Halictinae in Vanuatu (Perkins and tidae, comprising two thirds (28 of 40 species) Cheesman 1939), Micronesia (Krombein 1950) of the recognized bee species. Halictidae, and the Solomon Islands (Krombein 1951), Megachilidae and Apidae account for the along with Homalictus in Fiji (Michener remaining third with five, five and three 1979b) and New Guinea (Pauly 1986). These species, respectively (Donovan 1983). Of the studies were not based on material from 40 total species, eight were deliberate exotic intensive bee-focussed regional sampling, nor bee introductions to aid crop pollination, did they entail methodologies that demonstrated including four bumblebee (Bombus) species species delimitation among islands other than (Howlett and Donovan 2010). through gross morphology entailing small sam- ple sizes. Our understanding of bee diversity in 2.2 New Guinea the SWP is therefore very limited. The composition of bee diversity in the SWP New Guinea exhibits a similar family may be very important for understanding the representation to Australia. Given the history roles of dispersal and vicariance in the assem- of the landmasses’ frequent connection, this blage of island bee faunas and how these may is not surprising (Smith et al. 1994;Hall interact with insect-pollinated angiosperm com- 2009). Michener (1965)notesthatofthe40 munities. Studies to date suggest a generally groups of bees known from New Guinea, only low level of bee diversity in the SWP, though six are not found in Australia, although this is these studies do not indicate the reasons for this largely based on the original descriptions by low diversity. The change in species represen- Friese (1909). Colletidae represent 109 of the tation of bee families across the SWP, illustrated 230 described species, including many Palae- in Figure 1, provides some very interesting orhiza, with Halictidae (55 species), Mega- patterns. Moving eastwards from Australia, chilidae (34 species) and Apidae (32 species) Colletidae representation declines whilst the making up the remaining half (Friese 1909; proportion of Halictidae and Megachilidae Cheesman 1948; Michener 1980;Hirashima species increases. Moreover, Vanuatu has no 1988). Pauly (1986) investigated the Halicti- representatives of Apidae and Colletidae despite dae of the region and described 21 new species their presence in neighbouring island groups. of the Lasioglossum subgenus Homalictus. The species composition of each major island Despite much of New Guinea being inacces- group is summarised below and tabulated in sible, his study highlights the impact that Table I. thorough sampling can have on known species diversity. 2.1 Australia and New Zealand 2.3 Solomon Islands Of the 1,650 named species of Australian bees (Batley and Hogendoorn 2009), over half The bee fauna of the Solomon Islands was (879 species) are represented by the Colletidae, first summarised by Cockerell (1911), but the Bee conservation in the Southwest Pacific 761 Figure 1. Map of the Southwest Pacific showing total species number and proportions of bee family representation for each island group. first descriptions were completed by Krombein lower species richness in the former, with (1949, 1951) and Pauly (1984). Despite the distinct differences in species representation of close proximity of the Solomon Islands to Colletidae, Halictidae and Megachilidae New Guinea, bee family representation shares (Donovan 1983). Recently, the species of a closer affinity with Vanuatu (Pauly and New Caledonia were reported by Pauly and Munzinger 2003). Halictidae (17 species) and Munzinger (2003) as comprising 21 species, Megachilidae (13 species) comprise two thirds consisting of eight species of Megachilidae, of the 45 species, with Apidae (eight species) seven species of Halictidae and six species of and Colletidae (seven species) accounting for Colletidae, although the authors noted that the remaining third. However, since these earlier their study was far from exhaustive. Two new descriptions, there have been few studies on Lasioglossum species were described, Lasio- native bee fauna of the region, with the glossum (Homalictus) cocos and Lasioglossum exception of Pauly (1986). (Chilalictus) delobeli, both collected from non- native angiosperm species. An undetermined 2.4 New Caledonia Hylaeus species collected by Pauly and Munzinger (2003) is interesting in that along A comparative study of New Caledonia and with Hylaeus fijiensis of Fiji, it comprises the New Zealand bee fauna confirmed a much only records for the genus in the SWP islands. 762 Table I. Summary of native bee genera