Origins and implications of apid bees (Hymentopera: Apidae) in French Polynesia

Abstract

Island plant–pollinator networks are typically simpler than their continental counterparts and this can make them less resilient to disturbance from exotic species. French Polynesia has a very low diversity of bees, but their status as either native or introduced species has been largely speculative. We combine previous studies with new DNA sequence data to show that 11 bee species have now been recorded for French Polynesia. Haplotype variation at the ‘barcode’ region of the mitochondrial gene cytochrome c oxidase subunit I (COI) for four of these species, Ceratina dentipes Freise, Xylocopa sonorina Smith, Braunsapis puangensis (Cockerell) and Amegilla pulchra (Smith), indicates that they all represent very recent introductions. Apis mellifera Linnaeus was a purposefully introduced species, and four megachilid species probably arrived due to human‐aided dispersal through maritime activities in the Pacific. The two remaining bee species, an unidentified partial specimen of a halictid bee and the colletid bee Hylaeus (P.) tuamotuensis Michener, are collectively known from only four specimens collected in the 1930s and their provenance is uncertain. French Polynesia therefore comprises a region where recently introduced bee species greatly overwhelm any possible native bee fauna. These introductions are likely to have major ecosystem impacts, including disruptions of existing plant–pollinator networks and facilitating the spread of weedy plant species, as well as positive impacts for agriculture. Future biosecurity initiatives need to consider these potential impacts and the likely routes of dispersal to effectively control any further unintended introductions.

Positive and Negative Impacts of Non-Native Bee Species around the World

“…In the southwest Pacific islands of Fiji, Samoa, and Vanuatu, there is some evidence to indicate that most, if not all, apid and megachilid bees have been introduced by humans [26,64]. A similar situation likely exists in French Polynesia [39]. On the Hawaiian Islands, which likely have only 69 native bee species, there are 14 non-native bee species recorded [9,17].…”

Not all exotic pollinator introductions are bad: an introduced buzz‐pollinating bee Amegilla pulchra (Hymenoptera: Apidae) in Fiji indicates little potential for enhancing the spread of weeds

“…Concerns have been raised that the introduction of the buzzpollinating bee A. pulchra to Fiji may create problems because it could increase seed set in solanaceous weeds with poricidal anthers (Groom et al 2014a(Groom et al , 2017. However, Staines et al (2017) found that an endemic halictine Fijian bee was likely to affect pollination of the major pan-tropical weed, S. torvum, via pollen larceny.…”

“…A recent study (Staines et al 2017) shows that the endemic bee Homalictus fijiensis is not a buzz-pollinator but is able to extract pollen from S. torvum by biting at anther tips and likely effects pollination when crawling over exerted styles, allowing pollen grains stored on metasomal scopae to come into contact with stigmas. Groom et al (2014aGroom et al ( , 2017 argued that the introduction of A. pulchra to Fiji may pose an ecosystem risk by increasing pollination rates of solanaceous weeds. Groom et al (2014aGroom et al ( , 2017 argued that the introduction of A. pulchra to Fiji may pose an ecosystem risk by increasing pollination rates of solanaceous weeds.…”

“…Recent studies have shown a potentially alarming number of exotic bee species introduced into islands in the South West Pacific (SWP) region (Groom et al 2017) which have the potential to disrupt native pollination networks (Davies et al 2013;Groom et al 2014aGroom et al ,b, 2015; see also Goulson 2003). Potential disruption of pollination networks is especially high for Fiji where there are only four described indigenous bee species, all belonging to the genus Homalictus (Halictidae: Halictini), and with only one of these species occurring below 800 m asl (Michener 1979(Michener , 2007Groom et al 2013).…”

“…Another bee unintentionally introduced to Fiji, Amegilla pulchra, is native to Australia and now recorded as an invasive species in the Fijian Islands and French Polynesia (Davies et al 2013;Groom et al 2017). Amegilla pulchra differs strongly from A. mellifera, B. puangensis and the endemic Homalictus species in that it is a buzz pollinator and is able to effect pollination in plants with poricidal anthers (Harder & Barclay 1994), such as tomato plants (Solanaceae) (Hogendoorn et al 2006).…”