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Worldwide declines in critical hymenopteran pollinators, such as bumble bees and honey bees, in recent decades have sparked a surge in research aimed at identifying the factors behind these declines. Among the suspected contributors, infectious diseases have garnered significant attention. In this context, we conduct a comprehensive review of the potential impact of naturalized Palearctic exotic bumble bee species, specifically Bombus terrestris and Bombus ruderatus, on the occurrence of Apicystis bombi in southern South America. Apicystis bombi is a unique apicomplexan protist that belongs to the neogregarines, which as a group exhibit relatively high virulence towards a range of insects. Our review encompasses the available information on its morphology, molecular characteristics, pathology, host range, and geographic distribution. Additionally, we explore three plausible hypotheses, each not necessarily exclusive of the others, in an effort to shed light on the occurrence of A. bombi in South America. These hypotheses include the two classically accepted, but less supported in view of current data (entry via B. terrestris, entry via B. ruderatus), and one postulated for the first time here with arguably better support (pre-existing presence before the introduction of B. terrestris and B. ruderatus, plus the possibility of multiple Apicystis species coexisting). We aim for this review to stimulate interest in this relatively obscure parasitic microbe that affects crucial insect pollinators. [ABSTRACT FROM AUTHOR]

Introduction: Cold-adapted bumblebees are vulnerable to climate change (CC). South American Bombus dahlbomii, the southernmost bumblebee worldwide, has strongly declined since the 1990s and may be particularly susceptible to current and future CC. Aims/methods: We asked (1) whether current CC had a role in the observed decline of this species and (2) how projected CC would affect the future distribution of B. dahlbomii. We used a comprehensive record of occurrences for B. dahlbomii and species distribution models (SDMs) to build maps of (1) predicted current climatic suitability using pre-1990s and post-1990s occurrences, and (2) projected current and future climatic suitability under future (2080–2100) RCP 8.5 scenarios predicted by the 5th IPCC Report. Results and discussion: SDMs did not show changes in species climatic suitability pre-1990 vs. post-1990, suggesting no significant role of CC on the observed decline of the species at this time scale. However, a moderate range reduction of 13% and 14% of the ~ 0.041º grid cells was predicted by 2080–2100 under the 70% and 100% consensus models, respectively. Implications for insect conservation: Identifying the threats to B. dahlbomii allows for prioritizing conservation efforts. Short-term threats imposed by invasive bumblebees deserve urgent attention. The potential synergies between this threat and CC need to be understood to better predict the fate of this species. Binational cooperation should guarantee connectivity between climatically suitable areas in Argentina and Chile. [ABSTRACT FROM AUTHOR]

The invasion of non-native bees to new ecological territories could spread novel pathogens causing emerging infectious diseases (EIDs) in native species. We provide novel information on the prevalence, load, and co-infection network of honey bee viruses, trypanosoma, microsporidia and neogregarinorida pathogens in native Bombus dahlbomii and non-native Bombus terrestris and Bombus ruderatus. Apicystis bombi and Crithidia bombi were highly prevalent (> 78%) in three bumble bee species, with high loads of these pathogens. Nosema bombi was detected only in B. terrestris (37%) and B. ruderatus (15%). Lotmaria passim was detected in low prevalence (< 6%) and low loads in three bumble bee species. Deformed wing virus (genotype A) was detected only in B. terrestris (20%) and B. ruderatus (6%). Black queen cell virus was detected in B. terrestris (34%), B. ruderatus (22%) and B. dahlbomii (23%). Chronic bee paralysis virus, Kashmir bee virus and Acute bee paralysis virus were detected with low prevalence (7%) and titers in the three bumble bee species. The proximity of apiaries and collection sites was not a significant factor in the presence of viruses in bumble bees. The three bumble species were found to be co-infected with Apicystis bombi and C. bombi; a significant positive correlation was found between these two parasites, especially in B. terrestris. Multiple infections with N. bombi, A. bombi, C. bombi and viruses in B. terrestris and B. ruderatus were also detected. This suggests that the invasion and successful establishment of exotic bumble bees in a new area also entails the possible establishment of the pathogens that they carry, which could also be present in native bee species. This finding evidences a potential link between the population decline of B. dahlbomii and the pathogens that were detected with high levels and prevalence. [ABSTRACT FROM AUTHOR]

La crisis mundial de polinización no solo es producida por la pérdida de polinizadores, sino también por su homogeneización, ambos procesos causados por el ser humano. En este documento analizamos los impactos ecológicos que justifican la prohibición de nuevos ingresos del abejorro comercial Bombus terrestris a Chile. Esta especie es altamente invasiva y ha sido prohibida en otros países, pero en Chile se permite su ingreso desde 1997. Miles de colonias y reinas fertilizadas ingresan al país cada año y se expanden por el resto de Sudamérica. En este artículo entregamos once razones para detener los ingresos de B. terrestris a Chile y comenzar a controlarlo. Justificamos estas razones en base al trabajo realizado tanto en el país como fuera de él. Al mismo tiempo, a través de las conclusiones, mencionamos cuáles deberían ser los pasos a seguir respecto a la prohibición de ingreso de B. terrestris a Chile.

Bumble bees ( Bombus spp.) are considered one of the most important pollinators of native, non-native, and domesticated plants. Pathogens and parasites, such as the tracheal mite Locustacarus buchneri (Podapolipidae), are harmful to bumble bees. We developed primers based on the mitochondrial CO1 gene for the specific detection of L. buchneri directly from samples of native Bombus dahlbomii and non-native B. terrestris and B. ruderatus. PCR products amplified and sequenced for these primers shared 100 % identity among themselves and around 99-100 % identity with other sequences of L. buchneri reported in Belgium, the Netherlands, and Japan. Bombus terrestris was the most infected species (41 %), followed by B. ruderatus (31 %) and B. dahlbomii (23 %). This is the first report involving L. buchneri in native and non-native bumble bees in Chile. Our described PCR-based detection offers a feasible, specific, and rapid method for the screening of L. buchneri in any bumble bee species. [ABSTRACT FROM AUTHOR]

• Biological invasions are a major driver of biodiversity loss. • Citizen science can provide valuable information to understand invasion processes. • We used citizen science information on two exotic and one native bumblebee species. • Exotic bumblebees mainly visited exotic plants preferring certain colours. • Ornamental exotic plant species may act as steppingstones facilitating invasion. Invasive species are one of the most important drivers of biodiversity loss worldwide. As exotic species invade new ecosystems, they establish ecological interactions with the existing species, which may facilitate their spread. Flower colour is an important trait that influences pollination and pollinator preferences. To determine the role of these variables on the bumblebee preferences, we compared the floral associations of two exotic bumblebee species: Bombus terrestris and B. ruderatus (introduced two decades ago for crop pollination) and the native B. dahlbomii with native and exotic plants in Chile. We analysed 3,019 citizen science records in order to understand bumblebee associations with native and exotic plant species regarding flower colour. We found that the exotic bumblebees were mainly recorded visiting flowers of exotic plants (86% for B. terrestris and 93% for B. ruderatus), while the native B. dahlbomii visited exotic and native plant species in a similar proportion. Also, the exotic bumblebees visited purple and pink flowers more often, while the native bumblebee species frequently visited white, pink, and purple flowers. Although the three species share trichromatic vision, they seem to have different flower colour preferences. The association of B. terrestris and B. ruderatus with exotic non-crop species (i.e., exotic ornamental plants) may be acting as steppingstones from croplands to other habitats, facilitating the bee invasion process. Despite its inherent limitations, citizen science data provide large amounts of valuable information that is difficult to be obtained otherwise, which can be used to improve our understanding of invasion processes, as is the case of exotic Bombus species in southern South America. [ABSTRACT FROM AUTHOR]

Bombus terrestris Linnaeus is an invasive bumblebee in Argentina. Since its first record in March 2006, B. terrestris has rapidly become the most widespread species in the southern Argentina's Patagonia. The explosion of B. terrestris populations has been associated with the rapid decline of the unique native species B. dahlbomii, Guérin-Méneville. However, B. terrestris had never been yet reported farther south than the 50° parallel. We report for the first time the presence of B. terrestris at the southern end of continental Patagonia and discuss its meaning with regards on potential consequences for B. dahlbomii populations. [ABSTRACT FROM AUTHOR]

Since its introduction in Chile, the European Bombus terrestris L. (Hymenoptera: Apidae) has progressively reduced the abundance of the native Patagonian bumblebee, Bombus dahlbomii Guérin. Because an important cause of successful invasion of a species may depend on a potentially advantageous phenotype, we studied morphologies related to flight performance (flight muscle ratio (FMR), wing loading (WL), excess power index (EPI, which integrates FMR and WL) and wing aspect ratio (AR)) in the queens of the two species. Previous empirical studies showed that greater FMR, AR and EPI, and lower WL increase flight performance. In the Patagonian Chilean fjord where the study was carried out, B. dahlbomii was 40% heavier than B. terrestris , a difference theoretically allowing the queens of the native species to take off with heavier loads, despite the fact that the two species have virtually identical FMRs. However, FMR negatively depended on body mass at the intra-specific level. The total wing area was 35% greater in B. dahlbomii , but the difference in forewing length was only of 16%. Once taken into account the effect of body size, WL, was significantly lower in B. terrestris . AR increased with body mass and did not differ between species. EPI was weakly but significantly higher in B. terrestris . Experiments formally linking such parameters with flight performance may help to explain the observed quick and wide spread of this alien species in Patagonia in the last few years. [ABSTRACT FROM AUTHOR]

The alteration and transformation of the areas surrounding native forests due to anthropogenic disturbance can result in differences near this newly created boundary, termed 'edge effects'., Our study describes the consequences of edge creation over two successive stages in the life cycle of a hemi-parasitic mistletoe ( Tristerix corymbosus), which determine its reproductive success, in temperate austral forests., We assessed how flower production and pollinator visits change with distance to the nearest forest edge and how these changes affect fruit set, fruit and seed size, and fruit removal by seed dispersers., Edge effects were dominated by fruit removal, which increased with the distance to the edge, height in the canopy and fruit availability. As a result, plant reproduction (in terms of seeds produced and fruits removed, which putatively leads to higher seed dispersal) decreased strongly near to forest edges. In contrast, visitation rates of the main pollinator (the hummingbird) were unaffected by edges, and their strong effects on fruit set (including the alleviation of quality pollen limitation arising in the forest interior) might be mitigating the decrease in bumblebee visitation near to forest edges., Synthesis. Our study shows clearly how secondary and tertiary responses to forest edges acted in opposite directions (increasing or decreasing plant reproductive performance), highlighting the need to study several successive processes that impact upon plant fitness under disturbance. Preserving relatively large patches of old-growth forest with low perimeter/area ratios would be key to the habitat requirements of the main disperser and pollinator and thus for mistletoe reproductive performance. [ABSTRACT FROM AUTHOR]

The worldwide trade in bumblebees can lead to the spread of diseases, which in turn has been claimed as a factor in bumblebee decline. Populations of the introduced Bombus terrestris, which invaded NW Patagonia, Argentina, in 2006, harbor the highly pathogenic protozoan Apicystis bombi. We asked whether A. bombi had been co-introduced with B. terrestris, and if so, whether spillover occurred to the two resident bumblebee species in the region: the introduced European Bombus ruderatus and the native Bombus dahlbomii. We searched for A. bombi by means of PCR in samples of B. ruderatus and B. dahlbomii collected before and after the invasion of B. terrestris and in samples of the latter. We found no A. bombi in samples of B. ruderatus and B. dahlbomii collected before B. terrestris invasion, whereas post invasion, A. bombi was present in all 3 species. The identity of the parasite was established by sequencing the 18S region, which was identical for the three bumblebee species and also matched the European sequence, confirming it to be A. bombi. This is the first report of A. bombi in B. ruderatus and B. dahlbomii. Moreover, our results suggest that Patagonia had been free of A. bombi until this parasite was co-introduced with B. terrestris, and spilled over in situ to these two previously resident species. Finally, our findings provide indirect circumstantial evidence of a potential link between the population collapse and geographic retraction of B. dahlbomii and the introduction of this novel parasite. [ABSTRACT FROM AUTHOR]

Biological invasions might constitute a major threat to mutualisms. Introduced pollinators might competitively displace their native counterparts, which in turn affects the pollination of native plants, if native and alien visitors differ in pollinator effectiveness. Since its invasion in 1994 into south-west Argentina, the introduced European bumblebee Bombus ruderatus has continuously increased in abundance, along with a simultaneous decrease in the abundance of the native Bombus dahlbomii. The latter is the only native bumblebee species of the temperate forests of southern South America, and the main pollinator of the endemic herb Alstroemeria aurea. In order to evaluate the impact of the ongoing displacement of the native by the alien bumblebee, we compared the pollinator effectiveness (i.e., the combination of pollinator efficiency per visit and visitation frequency) between both bumblebee species, as well as related pollinator traits that might account for potential differences in pollinator efficiency. Native Bombus dahlbomii, which has a larger body and spent more time per flower, was the more efficient pollinator compared to Bombus ruderatus, both in terms of quantity and quality of pollen deposited per visit. However, Bombus ruderatus was a much more frequent flower visitor than Bombus dahlbomii. As a consequence, Bombus ruderatus is nowadays a more effective pollinator of A. aurea than its native congener. Despite the lack of evidence of an increase in seed set at the population level, comparisons with historical records of Bombus dahlbomii abundances prior to Bombus ruderatus’ invasion suggest that the overall pollination intensity of A. aurea might in fact have risen as a consequence of this invasion. Field experiments like these, that incorporate the natural variation in abundance of native and alien species, are powerful means to demonstrate that the consequences of invasions are more complex than previous manipulated and controlled experiments have suggested. [ABSTRACT FROM AUTHOR]