ORIGINAL RESEARCH ARTICLE Geographic distribution and associated flora of native and introduced bumble bees (Bombus spp.) in Chile José Montalva1, Leah Dudley2, Mary Kalin Arroyo1, Hernán Retamales3 and Alberto H Abrahamovich4* 1Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Ñuñoa, Santiago, Chile. 2Department of Ecology, Evolution, and Marine Biology University of California, Santa Barbara, CA, USA. 3Laboratorio de Biología Vegetal, Departamento de Silvicultura/ Facultad de Ciencias Forestales, Universidad de Chile, Casilla 653, Ñuñoa, Santiago, Chile. 4División Entomología, Laboratorio de Apidologia, Museo de la Plata, Facultad de Ciencias Naturales y Museo, La Plata, Argentina. Received 22 June 2009, accepted subject to revision 18 August 2010, accepted for publication 15 November 2010. *Corresponding author: Email: albertoa@fcnym.unlp.edu.ar Summary In the present work, we update floral associations and geographical distribution for four species of Bombus present in Chile, two native (B. dahlbomii and B. funebris) and two introduced species (B. terrestris and B. ruderatus). We also examine possible associations among native or introduced bees with native or introduced plant species. We found a significant non-random plant association among non-native bumble bee species and non-native plant species. Because of the distributional overlap between B. dahlbomii with the two non-native bee species, it is likely that B. dahlbomii interacts with these non-native bees. Distribución geográfica y flora asociada de abejorros nativos (Bombus spp) e introducidos en Chile Resumen En este trabajo actualizamos las asociaciones florales y la distribución geográfica de las cuatro especies de Bombus presentes en Chile, dos especies nativas (B. dahlbomii y B. funebris) y dos especies introducidas (B. terrestres y B. ruderatus). Examinamos las posibles asociaciones entre abejas nativas o introducidas con las especies nativas o introducidas de plantas. Encontramos una asociación significativa no aleatoria entre especies de abejorros introducidos con especies de plantas introducidas. El solapamiento de la distribución de B. dahlbomii con los abejorros introducidos es probable que se produzca por la relación entre estas especies. Keywords: Bombus, associated flora, distribution, Chile Journal of Apicultural Research 50(1): 11-21 (2011) © IBRA 2011 DOI 10.3896/IBRA.1.50.1.02 Introduction Bumble bees (Bombus spp.) are a genus of polylectic bees of the family Apidae, distributed worldwide, principally in temperate areas of North America and Eurasia (Michener, 2007). For the Neotropics, a total of 42 - 43 species have been recorded in a great variety of habitats, ranging in altitude from sea level to about 4400 m in the Andes (Williams, 1998; Abrahamovich and Díaz, 2002, Moure et al., 2007). Bombus bees are important pollinators in natural and agricultural ecosystems, depending upon pollen and nectar from a great variety of plants (Traveset, 1999; Abrahamovich et al., 2001; Aizen et al., 2002; Morales and Aizen 2004; Smith-Ramírez et al., 2005). Preliminary understanding of the relationship between Bombus species and the plants they exploit begins with simple observations of visitations and feeding behaviour (Abrahamovich et al., 2001), which we attempt to summarize here for Bombus in Chile. Bumble bees have also been introduced into many countries to provide a pollination service for commercial crops. In new environments, introduce Bombus may threaten populations of native pollinators by transporting diseases and competing with natives for food resources and nest sites (Free, 1993; Delaplane and Mayer, 2000; Stout and Goulson, 2002; Goulson and Hanley, 2004; Goulson, 2003; Goulson, 2004; Morales, 2007). In addition, deliberate introductions often turn into invasions with negative impacts on native flora and fauna (Macfarlane and Gurr, 1995; Goulson, 2003). In Chile, several bees have been introduced for commercial purposes. Already reports have indicated naturalization, and in some areas large abundances (Ruz, 2002; Montalva et al., 2008). This raises the concern about whether native and introduced species are interacting (Morales and Aizen, 2004; Madjidian et al., 2008). Here, we compile and update information about floral associations and geographic distribution of the species of Bombus present in Chile. Secondly, we address whether associations between native or introduced Bombus and native or introduced plant species are random or not. We specifically ask: 1) whether native and introduced Bombus species overlap in distribution; and 2) whether introduced Bombus and native Bombus are associated with similar plant groups (i.e. native or introduced)? Materials and methods Floral associations and geographical distribution of Bombus in Chile were gathered from personal collections (n = 48), field observations, specimens housed in entomological collections (n = 473): Pontificia Universidad Católica de Valparaíso (PUCV); American Museum of Natural History New York (A.M.N.H.); Museo Nacional de Historia Natural Chile (M.N.H.N); Instituto de Entomología de la Universidad Metropolitana de Ciencias de la Educación (U.M.C.E); Institute Miguel Lillo, Argentina (I.M.L); Museo Argentino de Ciencias Naturales Bernardino Rivadavia” (MACN); Instituto Patagónico de Ciencias Naturales San Martín Los Andes (I.P.C.N); Museo de La Plata, La Plata, Argentina (M.L.P); from the primary literature: (Spinola, 1851; Ruiz, 1923; Frison, 1925; Claude-Joseph, 1926; Montealegre, 1927; Ruiz 1941; Milliron, 1973; Arroyo et al., 1982; Arretz and MacFarlane, 1986; Peña, 1986; Toro, 1986; Pérez and Petersen, 1989; Telleria, 1993; Toro and Chiappa, 1996; Abrahamovich and Díaz, 2001, Abrahamovich et al., 2001; Ruz and Herrera, 2001; Abrahamovich and Díaz, 2002; Aizén et al., 2002; Morales and Aizen, 2002; Ruz, 2002; Rasmussen, 2003; Abrahamovich et al., 2004; Humaña and Valdivia, 2004; Rebolledo et al., 2004; Abrahamovich et al., 2005; Ruz and Vivallo, 2005; Smith-Ramírez et al., 2005; Valdivia and Niemeyer, 2005; Muñoz et al., 2006; Pérez et al., 2006; Rovere et al., 2006; Torreta et al., 2006; Valdivia and González, 2006; Michener 2007; Morales, 2007; Montalva et al., 2008; Montalva and Ruz, 2010) and congress proceedings (Retamales and Morales, 2006). We prepared the information for each Bombus species, recording the following features of each: location, date, and associated plant information. We pooled all data from the different sources, performed a χ2 test to examine associations between native or introduced bees with plant species. Results Native taxa summaries Bombus (Fervidobombus) dahlbomii Guérin-Méneville Species with yellowish brown wings, and orange hairs, (varying from orange ferruginous to very pale or whitish yellows) (Fig. 1) Queens start to build their nests early in growing season. They are usually located in irregular soil cavities. Colonies are small compared to other species of the same genus. Distribution: From regions IV to XII in Chile (Fig. 2), from the coast to the Andes, with individuals seen over 3200 m. This is one of few species of native bees presents on the Chiloé island. Recently, there have been reports indicating its declination in the IV, V and Metropolitan Regions. Associated flora: B. dahlbomii is associated with 84 plant species, 63 native and 21 introduced, belonging to 42 families (Table 1): Myrtaceae (9), Asteraceae (6), Fabaceae (6), Lamiaceae (5), Alstroemeriaceae (3), Berberidaceae (3), Elaeocarpaceae (3), Gesneriaceae (3), Loasaceae (3), Anacardiaceae (2), Bignoniaceae (2), Boraginaceae (2), Brassicaceae (2), Liliaceae (2), Mutisiaceae (2), Onagraceae (2), Philesiaceae (2), Proteaceae (2), Rosaceae (2), Scrophulariaceae (2), Tropaeolaceae (2), Apiaceae (1), Caryophyllaceae (1), Convolvulaceae (1), Cunoniaceae (1), Desfontaineaceae (1), Ericaceae (1), Escalloniaceae (1), Eucryphiaceae (1), Fumariaceae (1), Gentianaceae (1), Hydrangeaceae (1), Hydrophyllaceae (1), Lobeliaceae (1), Loranthaceae (1), Mimosaceae (1), Oxalidaceae (1), Sapotaceae (1), Saxifragaceae (1), Solanaceae (1), Thymelaeaceae (1), and Verbenaceae (1). 12 Montalva, Dudley, Arroyo, Retamales, Abrahamovich Fig. 1. Photo of Bombus dahlbomii on Galega officinalis L. Bombus (Funebribombus) funebris Smith Species with abundant black hairs, except a whitish circular or oval patch on the thoracic disc between wing bases, and the metasomal T4-5. Nesting or other biological characteristics remain unknown. Distribution: It has only been found in Putre of the Parinacota Province, Arica Region (Fig. 2). B. funebris, seems well suited to high altitudinal ranges with individuals found up to 4400 m. This species was mistakenly catalogued for the IV Region, first by Milliron (1973) in his Monograph of the Western Hemisphere Bumble bees (Hymenoptera: Apidae, Bombinae) and later by Toro (1986) in the “Lista Preliminar de los Apidos Chilenos”. This error was probably generated by Luis Peña who deposited a sample in the Collection of Kansas indicating Bombus and their associated flora in Chile 13 Las Vacas (Cochabamba), Bolivia as the location instead of the true one, Las Vacas (Coquimbo), Chile (Fig. 2). Associated flora: B. funebris has been associated with eight plant species, five native and three introduced, belonging to seven families (Table 1): Solanaceae (2), Asteraceae (1), Brassicaceae (1), Caesalpinaceae (1), Fabaceae (1), Lamiaceae (1), and Loasaceae (1). Introduced taxa summaries Bombus (Megabombus) ruderatus (Fabricius) Species with yellow, black and white hairs, mesosoma typically golden -yellow with well-defined band on the inter-wing black, metasomal terga yellow, black, and ending in white hairs. This species has a rare, completely black colour morph. Queens start to build their nests early in the growing season. Nests are usually located in irregular soil cavities such as in abandoned rodent dens. Colonies may be large. Distribution: Region V to the south of Puerto Montt (Fig. 2). B. ruderatus was introduced to Chile in 1982-1983 from New Zealand (although its primary origin was England) with the purpose of pollinating red clover, Trifolium pratense L. The species was used in Cunco and Coipue, south of Temuco, in the IX region. In the last two decades, B. ruderatus has expanded from its area of introduction, and is currently considered naturalized from Regions V to X, possibly by spreading north from the VII region. This species was described as a new species by Asperen de Boer (1992) who assigned the name of Bombus (Megabombus) villaricaensis, by describing 74 queens, 36 workers and one male collected in Region IX, specifically near Lake Villarrica. Later, the same author realized that this species was B. ruderatus, and in 1993 published a clarification that identified Bombus villaricaensis as a synonym for B. ruderatus. Associated flora: B. ruderatus has been associated with 18 plant species of which four are native and 14 introduced belonging to the 10 families (Table 1): Fabaceae (7), Rosaceae (2), Alstroemeriaceae (1), Boraginaceae (1), Convolvulaceae (1), Lamiaceae (2), Mimosaceae (1), Proteaceae (1), Scrophulariaceae (1), and Violaceae (1). Bombus (Bombus) terrestris (Linnaeus) Body typically a combination of yellow, black and white hair, anterior mesosoma with yellow dorsal hairs, and the rest black; the metasoma has black hair on terga 1,3, yellow on terga 2, and whitish hair on the posterior half of tergum 4 and all of tergum 5. The nests typically by mining in underground galleries mostly in abandoned rodent dens, but it has been observed nesting in wooden walls in strongly urbanized areas. Fig. 2. Distribution according to museum labels examined here of the four Bombus species presents in Chile: B. dahlbomii (*); B. funebris (F); B. terrestris (T); B. ruderatus (R). Abbreviations: I-XII, regions of Chile; RM, región metropolitana. 14 Montalva, Dudley, Arroyo, Retamales, Abrahamovich Associated plant species Plant Type Bombus species B.d. B.f B.r B.t AGAPANTHACEAE Agapanthus africanus L. + ALSTROEMERIACEAE Alstroemeria cummingiana (Herb.) Ehr. Bayer Native + Alstroemeria aurea Graham Native + + Alstroemeria umbellata Meyen Native + ANACARDIACEAE Lithraea caustica (MOL.) Hook. & Arn. Native + + Schinus latifolius (Gill. Ex Lindl.) Engler Native + + APIACEAE Eryngium paniculatum Cav. et Domb. ex Delar. Native + + ASTERACEAE Carduus pycnocephalus L Introduced + Centaurea solstitialis L Introduced + Cirsium vulgare Savi Introduced + + + Cynara cardunculus L. Introduced + + Chrysanthemum sp. Introduced + Chuquiraga oppositifolia D. Native + Nassauvia pungens Phil. Native + Senecio bustillosianus Remy. Native + Senecio erucaeformis Remy. Native + Senecio sp. Native + Taraxacum officinale Weber Introduced + + BERBERIDACEAE Berberis buxifolia Native + Berberis darwinii Hook. Native + Berberis microphylla G. Forst. Nativa + BIGNONIACEAE Campsidium valdivianum (Phil.) Skottsb Native + Jacaranda mimosifolia D. Don Introduced + + BORAGINACEAE Echium vulgare L. Introduced + + + Borago officinalis Introduced + + BRASSICACEAE Brassica campestris L. Introduced + + Brassica sp Introduced + Raphanus sativus L. Introduced + CAESALPINACEAE Senna birostris (Vogel) H. S. Irwin & Barneby Native + CARYOPHYLLACEAE Cerastium arvense L. Introduced + CONVOLVULACEAE Lavatera arborea L. Introduced + Calystegia sepium (L.) R. Br. Introduced + + CUNONIACEAE Caldcluvia paniculata (Cav.) D. Don Native + DESFONTAINEACEAE Desfontainia spinosa Ruiz & Pavon. Native + Table 1. Bombus species present in Chile (Bombus dahlbomii, B.d.; Bombus funebris, B.f.; Bombus ruderatus, B.r.; and Bombus terrestris, B.t.) and the associated flora grouped according to family. 15 Bombus and their associated flora in Chile Table 1. Cont. Associated plant species Plant Type Bombus species B.d. B.f B.r B.t ELAEOCARPACEAE Aristotelia chilensis (Mol.) Stunz. Native + Crinodendron patagua Mol. Native + + Crinodendron hookerianum Gay. Native + + ERICACEAE Gaultheria phillyreafolia (Pers.) Sleumer Native + ESCALLONIACEAE Escallonia pulverulenta (R et P) Pers. Native + + EUCRYPHIACEAE Eucryphia cordifolia Cav. Native + FABACEAE Cytisus striatus (Hill) Rothm. Introduced + Galega officinalis L. Introduced + + Lotus uliginosus (Schkuhr) Native + Lupinus arboreus Sims Introduced + Lupinus luteus L. Introduced + Otholobium glandulosum L. Native + + Parkinsonia aculeata L. Introduced + Senna candolleana (Vogel) Irw. & Barn Native + Sophora microphylla Aito Native + + Teline monspessulana (L.) K. Koch Introduced + Trifolium pratense L. Introduced + + + Trifolium striatum L. Introduced + Ulex europaeus L. Introduced + Vicia faba L. Introduced + Vicia nigricans Hook. & Arn. Native + FUMARIACEAE Fumaria capreolata L. Introduced + + GENTIANACEAE Gentianella ottonis (Phil.) Muñoz Native + + GERANIACEAE Geranium sp Introduced + GESNERIACEAE Asteranthera ovata (Cav.) Hanst. Native + Mitraria coccinea Cav. Native + Sarmienta repens Ruiz & Pavón. Native + HYDRANGEACEAE Hydrangea serratifolia (H. & A.) F. Phil. Native + HYDROPHYLLACEAE Phacelia secunda J. F. Gmel. Native + LAMIACEAE Lavandula sp. Introduced + + Lavandula officinalis L. Introduced + Mentha aquatica Ehrh Introduced + + Mentha pulegium L. Introduced + Salvia leucantha cav Introduced + Stachys albicaulis Lindl. Native + Stachys arvensis L. Introduced + 16 Montalva, Dudley, Arroyo, Retamales, Abrahamovich Table 1. Cont. Associated plant species Plant Type Bombus species B.d. B.f B.r B.t LILIACEAE Luzuriaga radicans Ruiz & Pav. Native + Luzuriaga polyphylla (Hook.) J.F. Macbr. Native + LOASACEAE Caiphora coronata (Gillies ex Arn.) Hook. & Arn Native + Caiophora peduncularis (K.Presl) Weigend & M.Ack. Native + Loasa caespitosa Phil. Native + Loasa heterophylla Hook. & Arn. Native + LOBELIACEAE Lobelia bridgesii Hook. & Arn. Native + LORANTHACEAE Desmaria mutabilis (P. et E.) Van Tiegh. ex Jacks Native + MIMOSACEAE Acacia dealbata Link Introduced + + MUTISIACEAE Mutisia decurrens Cav. Native + Mutisia sinuata Cav. Native + MYRTACEAE Amomyrtus luma (Mol.) Legr. & Kaus. Native + Amomyrtus meli Legr. & Kaus. Native + Eucalyptus globulus Labill Introduced + Luma apiculata (DC.) Burret Native + Myrceugenia ovata (Hook. & Arn.) Berg. Native + Myrceugenia parvifolia (DC.) Kausel Native + Myrceugenia planipes.(Hook. & Arn.) Berg. Native + Tepualia stipularis (Hook. & Arn.) Griseb. Native + Ugni candollei (Barnéoud) O. Berg Native + Ugni molinae Turcz. Native + ONAGRACEAE Fuchsia lycioides Andrews Native + + Fuchsia magellanica Lam. Native + OXALIDACEAE Oxalis compacta Gillies ex Hook. & Arn. Native + PHILESIACEAE Lapageria rosea Ruiz & Pav. Native + Philesia magellanica Gmel. Native + POLIGONACEAE Polygonum persicaria L. Introduced + PROTEACEAE Embothrium coccineum J.R. & G. Foster Native + + Gevuina avellana Mol. Native + RHAMNACEAE Colletia spinosissima Gmel Native + Retanilla trinervia Miers Native + ROSACEAE Quillaja saponaria Mol. Native + + Rubus ulmifolius Schott Introduced + + + Rosa rubiginosa L. Introduced + Distribution: Regions IV to X including Chiloé island (Fig. 2). B. terrestris was introduced to Chile during 1997-1998, from colonies reared in Belgium and Israel, as a pollinator for greenhouse tomatoes. They were introduced in several localities: Arica, Copiapó, Ovalle, San Felipe, Quillota, Limache, Santiago y Los Ángeles. Currently, this species is naturalized from the IV to IX Regions (Fig. 2). All known populations appear to have high frequency of individuals and range across habitat types, including urban situations. In 2006, specimens of this species were collected in the province of Neuquén, Argentina. This finding represents a first evidence that B. terrestris has emigrated from Chile to Argentina. Associated flora: B. terrestris is associated with 48 plant species, 20 native, and 28 introduced species, which belong to 24 families (Table 1):Asteraceae (6), Fabaceae (6), Scrophulariaceae (4), Tropaeolaceae (4), Lamiaceae (3), Anacardiaceae (2), Boraginaceae (2),Elaeocarpaceae (2), Rhamnaceae (2), Rosaceae (2), Agapanthaceae (1), Apiaceae 17 Bombus and their associated flora in Chile (1), Bignoniaceae (1), Brassicaceae (1), Convolvulaceae (1), Escalloniaceae (1), Fumariaceae (1), Gentianaceae (1), Geraniaceae (1), Myrtaceae (1), Onagraceae (1), Poligonaceae (1), Solanaceae (1), Violaceae (1), and Winteraceae (1). Collective summary Description: The four species are generally of similar size and morphology. B. terrestris has a shorter tongue compared to the other three species. Colour patterns are quite varied across species, ranging from black to orange-yellows tones. Nesting: Three species build their nests early in the growing season with queens overwintering. Nest construction is also similar with the three using abandoned rodent galleries. Information is lacking for B. funebris. Table 1. Cont. Associated plant species Plant Type Bombus species B.d. B.f B.r B.t SAPOTACEAE Pouteria splendens (A. DC.) O.K. Native + SAXIFRAGACEAE Francoa appendiculata Cav. Native + SCROPHULARIACEAE Alonsoa meridionalis L.F Native + Digitalis purpurea L. Introduced + + + Mimulus luteus L. Native + + Verbascum virgatum Stockes Introduced + SOLANACEAE Datura sp. Native + Schizanthus hookeri Gillies ex gram. Native + + Solanum sp Native + THYMELAEACEAE Ovidia pillopillo (Gay) Meisn. Native + TROPAEOLACEAE Lonicera japonica Thunb. Introduced + + Tropaeolum azureum Bert. ex Colla Native + Tropaeolum majus L. Introduced + + Tropaeolum tricolor Sweet Native + VERBENACEAE Rhaphithamnus spinosus (Juss.) Moldenke Native + VIOLACEAE Viola arvensis Murria Introduced + Viola portalesia Gay Native + Winteraceae Drimys winteri J.R. et Forster Native + Distribution: Only one species has a limited, non-overlapping distribution, B. funebris; whereas, the other three have overlapping distributions in central Chile. Floral associations: Bombus spp. were found to visit a total of 160 plant species 94 of which were native and 66 of which were introduced (Table 1). We found a significant non-random plant association among introduced bumble bee species and introduced plant species (χ2 22.151 p < 0.0001) (Table 2, Fig. 3). Further notes: Two additional species mentioned for Chile, Bombus (Fervidobombus) opifex and B. (Pyrobombus) impatiens (Ruz, 2002; Milliron, 1973; Toro, 1986) bear mentioning here. Similarly to the early example of B. funebris, B. opifex was mistakenly cited for Coquimbo. In this case, seven workers were deposited in the collection of Kansas with labels indicating the locality of Las Vacas, but unlike B. funebris, the species was never present in Chile (Peña, 1986). Bombus impatiens is native along the Atlantic coast of North America and during the late nineties some queens were imported to Chile to pollinate greenhouse tomatoes; however, its current status in the country is unknown. 18 Discussion The four Bombus species belong to four different subgenera: B. dahlbomii to Fervidobombus, B. Funebris to Funebribombus, B. ruderatus to Megabombus and B. terrestris to Bombus s. str. (Williams, 1998). Coloration patterns are distinct between native species, making them easily distinguishable. In contrast, the introduced species have similar patterns and colours. The small tongue of B. terrestris distinguishes it from the other three species. Due to this feature, it may have a more restricted nectar resource base, being blocked from ingesting tubular flower nectar unless ‘robbing’ it by biting the corollas for access (Montalva et al., 2008). Bombus spp behave similarly with respect to nest construction. In Japan, B. terrestris competes with native bumble bees for nest sites (Inoue and Yokoyama, 2010). Little work has been done in Chile, investigating possible competition for nest sites. Some information is known in regards to B. terrestris, which indicates no specific requirements in source of material or location of sites for nest building. There are examples of the species using abandoned rodents burrows, building walls, house attics, and leaf litter cavities (Arroyo, pers. comm.; Morales, 2007; Montalva et al., 2008). Three of the four species have similar phenologies; B. funebris is unknown. Of the four species only the native B. funebris was found to have a unique distribution restricted to one locality in northern Chile (Fig. 2). The two introduced species overlap extensively with the native B. dahlbomii in several regions of the country. Because of the distributional overlap between B. dahlbomii with the two introduced bee species, it is likely that B. dahlbomii interacts with these introduced bees. We found that native bumble bees preferred to visit native plants while introduced bumble bees preferred to visit introduced plants similar to other studies (Fig. 3) (Telleria, 1993; Morales and Aizen, 2002; Goulson, 2003; Goulson and Hanley, 2004). Our data suggest that introduced bees may facilitate the invasion potential of Montalva, Dudley, Arroyo, Retamales, Abrahamovich Table 2. Contingency table for the association between Bombus species and type of plant, native or non-native. Values obtained from Table 1. N DF -LogLike RSquare (U) 160 1 11.075390 0.1018 Contingency Table BEE By Flower Tests Test ChiSquare Prob>ChiSq Likelihood Ratio 22.151 <.0001 Pearson 21.857 <.0001 Fl ow er 0.00 0.25 0.50 0.75 1.00 native nonnative BEE native nonnative Fig. 3. Mosaic plot of the proportion of occurrences for which introduced and native bees are associated with introduced and native plants. Grey tiles indicate introduced status and black tiles native status Native bumble bee Introduced bumble bee Total Native plant Count Total % Col % Row % 69 43.13 74.19 73.40 25 15.63 37.31 26.60 94 58.75 Introduced plant Count Total % Col % Row % 24 15.00 25.81 36.36 42 26.25 62.69 63.64 66 41.25 Total Count Total % 93 58.13 67 41.88 160 introduced plants through pollination service (Stout and Goulson, 2002; Hingston, 2006). Potential negative affects of sympatry among bees such as resource competition may be partially ameliorated due to the association between introduced bees with introduced plant species. Nevertheless, Hingston (2005) found introduced bumble bees foraging indiscriminately on native and introduced plant species. Additionally, although we found a strong association between introduced bumble bee and introduced plants, it is important to mention that it was also common for introduced bees to be associated with native plants (25 out of 67 plant associations). We recommend monitoring introduced species in Chile, mainly their dispersal, settlement and competition with native species to provide baseline information for planning of future conservation strategies for native Chilean Bombus. This is particularly vital given the global decline in bumble bee abundance and diversity (Colla and Packer, 2008; Williams et al., 2009; Williams and Osborne, 2009). Acknowledgements Thanks to Gabriela Luna, CEPAVE, Universidad Nacional de La Plata, for your comments and suggestions on the manuscript. JM. also acknowledge the Master of Science’s scholarship (Project ICM, P05-002). 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