The genus Amegilla (Hymenoptera, Apidae, Anthophorini) in Australia: A revision of the subgenera Notomegilla and Zonamegilla

Checklist of the bees (Hymenoptera, Apoidea) of New Caledonia

Background

In a world where insects and notably bees are declining, assessing their distribution over time and space is crucial to evaluate species status and highlight conservation priorities. However, this can be a daunting task, especially in areas such as tropical oceanic islands where exhaustive samplings over time have been lacking. This is the case in New Caledonia, an archipelago located in the southwest Pacific. Historical records of bee species are piecemeal and, although contemporary samplings have significantly advanced our knowledge of the bee fauna of New Caledonia, the status of several species remains to be elucidated.

New information

Here, we provide an updated checklist of the 51 bee species recorded for New Caledonia using previous publications and personal samplings. We documented their distribution, origin (i.e. endemic, native or alien) and the year and location of their occurrences. Based on the year of their first capture and the year of their last capture, we determined an occurrence status for each species. Thus, 10 years after the last checklist of the New Caledonian bee fauna, the literature review and recent samplings allowed us to add six new species to the list. Half of them are recently introduced species including one firstly mentioned in this paper (i.e. Hylaeusalbonitens). We consider here that 30 species are effectively present on the territory and the presence of 21 species could not be determined due to a lack of data, which highlights the need to increase sampling efforts across New Caledonia. Given the difficulty of exhaustively sampling the entire archipelago, we would recommend taking, as a starting point, altitude environments and areas where data-deficient species were captured. In a broader perspective, biomolecular analyses are crucial to confirm species identifications. This is also needed to make comparisons between archipelagoes and thus clarify the distribution and status of species at the scale of the southwest Pacific.

Effects of Urbanization on Plant-Pollinator Interactions in the Tropics: An Experimental Approach Using Exotic Plants

Simple Summary

Island environments of the Southwest Pacific, like New Caledonia, generally present poorly diversified bee fauna. Thus, they are particularly prone to the establishment of introduced bee species. These exotic species may compete with native bees for plant resources, disrupt pollination of native plants, and enhance the reproduction of exotic ones. To conserve local plant–pollinator interactions, it is essential to assess the factors favoring the presence and the activity of exotic bees. Here, we focused on the effects of urbanization on plant–pollinator interactions. We set up experimental plant communities composed of four exotic species in two contrasted habitats—a natural environment vs. an urban environment—and observed plant–pollinator interactions. We showed that the urban environment was largely dominated by exotic bees. We also showed that some exotic bee species can interact preferentially with a single exotic ornamental plant species. Overall, our results indicate that Nouméa is an entry point for exotic bees, which should encourage local authorities to maintain biosecurity measures to effectively limit the arrival of exogenous bees. Lastly, the use of exotic horticultural plants in green public spaces should be questioned regarding their potential attractiveness to exotic bees.

Abstract

Land-use changes through urbanization and biological invasions both threaten plant-pollinator networks. Urban areas host modified bee communities and are characterized by high proportions of exotic plants. Exotic species, either animals or plants, may compete with native species and disrupt plant–pollinator interactions. These threats are heightened in insular systems of the Southwest Pacific, where the bee fauna is generally poor and ecological networks are simplified. However, the impacts of these factors have seldom been studied in tropical contexts. To explore those questions, we installed experimental exotic plant communities in urban and natural contexts in New Caledonia, a plant diversity hotspot. For four weeks, we observed plant–pollinator interactions between local pollinators and our experimental exotic plant communities. We found a significantly higher foraging activity of exotic wild bees within the city, together with a strong plant–pollinator association between two exotic species. However, contrary to our expectations, the landscape context (urban vs. natural) had no effect on the activity of native bees. These results raise issues concerning how species introduced in plant–pollinator networks will impact the reproductive success of both native and exotic plants. Furthermore, the urban system could act as a springboard for alien species to disperse in natural systems and even invade them, leading to conservation concerns.

Analysing Sr isotopes in low-Sr samples such as single insects with inductively coupled plasma tandem mass spectrometry using N2 O as a reaction gas for in-line Rb separation

RATIONALE

Strontium isotopes are valuable markers of provenance in a range of disciplines. Limited amounts of Sr in low-mass samples such as insects mean that conventional Sr isotope analysis precludes their use for geographic origins in many ecological studies or in applications such as biosecurity. Here we test the viability of using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with N₂ O as a reaction gas for accurately determining Sr isotopes in insects with Sr < 100 ng.

METHODS

Strontium isotopes were determined in solution mode using ICP-MS/MS with 0.14 L/min N₂ O as a reaction gas to convert Sr⁺ into SrO⁺ for in-line separation of ⁸⁷ Sr from ⁸⁷ Rb. The Sr isotope reference standards NIST SRM 987, NIST SRM 1570a and NIST SRM 1547 were used to assess accuracy and reproducibility. Ten insect species collected from the wild as a proof-of-principle application were analysed for Sr concentration and Sr isotopes.

RESULTS

Using ICP-MS/MS we show for the first time that internal mass bias correction of ⁸⁷ Sr¹⁶ O/⁸⁶ Sr¹⁶ O based on ⁸⁸ Sr¹⁶ O/⁸⁶ Sr¹⁶ O works to give for NIST SRM 987 a ⁸⁷ Sr/⁸⁶ Sr ratio of 0.7101 ± 0.012 (RSD = 0.17%) and for NIST SRM 1570a a ⁸⁷ Sr/⁸⁶ Sr ratio of 0.7100 ± 0.009 (RSD = 0.12%), which are within error of the accepted values. The first ⁸⁷ Sr/⁸⁶ Sr ratio of NIST SRM 1547 is 0.7596 ± 0.0014. Strontium analyses were run on 0.8 mL of 0.25-0.5 ppb Sr, which equates to 2-4 ng of Sr. Strontium isotope analysis with a precision of >99.8% can be achieved with in-line separation of ⁸⁷ Sr from ⁸⁷ Rb at least up to solutions with 25 ppb Rb.

CONCLUSIONS

A minimum of 5 mg of insect tissue is required for Sr isotope analysis. This new ICP-MS/MS method enables Sr isotope analysis in single insects, allowing population-scale studies to be feasible and making possible applications with time-critical uses such as biosecurity.

A method to generate multilocus barcodes of pinned insect specimens using MiSeq

For molecular insect identification, amplicon sequencing methods are recommended because they offer a cost-effective approach for targeting small sets of informative genes from multiple samples. In this context, high-throughput multilocus amplicon sequencing has been achieved using the MiSeq Illumina sequencing platform. However, this approach generates short gene fragments of <500 bp, which then have to be overlapped using bioinformatics to achieve longer sequence lengths. This increases the risk of generating chimeric sequences or leads to the formation of incomplete loci. Here, we propose a modified nested amplicon sequencing method for targeting multiple loci from pinned insect specimens using the MiSeq Illumina platform. The modification exists in using a three-step nested PCR approach targeting near full-length loci in the initial PCR and subsequently amplifying short fragments of between 300 and 350 bp for high-throughput sequencing using Illumina chemistry. Using this method, we generated 407 sequences of three loci from 86% of all the specimens sequenced. Out of 103 pinned bee specimens of replicated species, 71% passed the 95% sequence similarity threshold between species replicates. This method worked best for pinned specimens aged between 0 and 5 years, with a limit of 10 years for pinned and 14 years for ethanol-preserved specimens. Hence, our method overcomes some of the challenges of amplicon sequencing using short read next generation sequencing and improves the possibility of creating high-quality multilocus barcodes from insect collections.

The genus Amegilla (Hymenoptera, Apidae, Anthophorini) in Australia: a revision of the subgenus Asaropoda

The species in the subgenus Amegilla (Asaropoda) are revised. Species delineation was decided based on diagnostic morphological characters as well as an incomplete phylogeny based on mitochondrial cytochrome oxidase 1 sequence data. Strong support was obtained for separating the Australian species of Amegilla into the three subgenera previously proposed on the basis of morphology. The subgenus Asaropoda was found to comprise 21 species, including ten new species: A.albiclypeata Leijs, sp. nov., A.aurantia Leijs, sp. nov., A.batleyi Leijs, sp. nov., A.crenata Leijs, sp. nov., A.griseocincta Leijs, sp. nov., A.incognita Leijs, sp. nov., A.nitidiventris Leijs, sp. nov., A.scoparia Leijs, sp. nov., A.xylocopoides Leijs, sp. nov., and A.youngi Leijs, sp. nov. The subspecies A.preissifrogatti is raised to species level, and 16 new synonymies are proposed. Keys to the species of both sexes and descriptions or redescriptions are provided. Distribution maps, data on flower visitation and phenology are given.