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Both the identity and prevalence of parasitoid dipterans associated with bumble bees (Bombus spp.) in southern South America are little known. Between 2009 and 2017, a total of 2978 bumble bees were individually collected in 63 localities from 11 provinces of the country. After dissections, the presence of parasitoids was observed in the native bumble bees Bombus pauloensis, B. bellicosus, B. opifex, and B. brasiliensis, plus in the exotic invasive species B. terrestris. A combination of both morphological and molecular analysis based on the COI gene allowed the isolation of two species of Physocephala (Conopidae) and one of Helicobia (Sarcophagidae), expanding their host range and geographic distribution. The second instar larva of Helicobia aurescens is described. [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]

While feeding, foragers can alter their environment. Such alteration constitutes ecological niche construction (ENC) if it enables future benefits for the constructor and conspecific individuals. The environmental modification may also affect non‐constructing, bystander species, especially if they share resources with constructor species. If so, ENC could confer the constructor species a competitive advantage by both enhancing its foraging returns and reducing those of bystander species.Expectations – (E1) ENC frequency should vary positively with the recent and current density of the constructor species, and (E2) constructors should use modifications disproportionately. In contrast, bystanders should (E3) experience intensified competition for the affected resource, and (E4) exhibit diverse, possibly mitigating, responses to ENC, depending on opportunity and relative benefits.We investigated these expectations in Argentina for competition for Fuchsia magellanica nectar between an invasive bumble bee Bombus terrestris (terr: putative constructor), which often bites holes at the bases of floral tubes to rob nectar, and native B. dahlbomii (dahl: bystander), which normally accesses Fuchsia nectar through the flower mouth (front visits). Robbing holes constitute ENC, as they persist until the 7‐day flowers wilt. The dynamics of the incidence of robbed flowers, abundance of both bees and the number and types of their flower visits (front or robbing) were characterised by alternate‐day surveys of plants during 2.5 months.After initially accessing Fuchsia nectar via front visits, terr switched to robbing and its abundance on Fuchsia increased 20‐fold within 10 days (E2). Correspondingly, the incidence of robbed flowers varied positively with recent and past terr abundance (E1). In contrast, dahl abundance remained low and varied negatively with the incidence of robbed flowers (E3). When terr ceased visiting Fuchsia, dahl abundance increased sixfold within 10 days (E3), possibly because many dahl previously had avoided competition with terr by feeding on other plant species (E4). While terr was present, dahl on Fuchsia used front visits (tolerance) or used existing robbing holes (adoption: E4). The diverse dahl responses suggest partial compensation for competition with terr.ENC alters competitive asymmetry, favouring constructor species. However, bystander responses can partially offset this advantage, perhaps facilitating coexistence. [ABSTRACT FROM AUTHOR]

Chronic bee paralysis virus (CBPV) is a positive single-stranded RNA virus that exhibits a worldwide distribution. Although the effects of this virus on honeybees' health are well known, its presence in other bee species has not been fully studied. In this work, CBPV was detected in several native bees from Argentina, including Bombus pauloensis, Halictillus amplilobus, Peponapis fervens, and members of the genus Xylocopa. Here, we report for the first time the presence of CBPV in native bees from South America. [ABSTRACT FROM AUTHOR]

Understanding how bees use resources at a landscape scale is essential for developing meaningful management plans that sustain populations and the pollination services they provide. Bumblebees are important pollinators for many wild and cultivated plants, and have experienced steep population declines worldwide. Bee foraging behavior can be influenced by resource availability and bees' lifecycle stage. To better understand these relationships, we studied the habitat selection of Bombus pauloensis by tracking 17 queen bumblebees with radio telemetry in blueberry fields in Entre Ríos province, Argentina. To evaluate land use and floral resources used by bumblebees, we tracked bees before and after nest establishment and estimated home ranges using minimum convex polygons and kernel density methods. We also classified the pollen on their bodies to identify the floral resources they used from the floral species available at that time. We characterized land use for each bee as the relative proportion of GPS points inside of each land use. Bumblebees differed markedly in their movement behavior in relation to pre and post nest establishment. Bees moved over larger areas, and mostly within blueberry fields, before nest establishment. In contrast, after establishing the nest, the bees preferred the edges near forest plantations and they changed the nutritional resources to prefer wild floral species. Our study is the first to track queen bumblebee movements in an agricultural setting and relate movement changes across time and space with pollen resource availability. This study provides insight into the way bumblebee queens use different habitat elements at crucial periods in their lifecycle, showing the importance of mass flowering crops like blueberry in the first stages of queen's lifecycle, and how diversified landscapes help support bee populations as their needs changes during different phases of their lifecycle. [ABSTRACT FROM AUTHOR]

The alarming loss of pollinator diversity world‐wide can reduce the productivity of pollinator‐dependent crops, which could have economic impacts. However, it is unclear to what extent the loss of a key native pollinator species affects crop production and farmer's profits.By experimentally manipulating the presence of colonies of a native bumblebee species Bombus pauloensis in eight apple orchards in South Argentina, we evaluated the impact of losing natural populations of a key native pollinator group on (a) crop yield, (b) pollination quality, and (c) farmer's profit. To do so, we performed a factorial experiment of pollinator exclusion (yes/no) and hand pollination (yes/no).Our results showed that biotic pollination increased ripe fruit set by 13% when compared to non‐biotic pollination. Additionally, fruit set and the number of fruits per apple tree was reduced by less than a half in those orchards where bumblebees were absent, even when honeybees were present at high densities. Consequently, farmer's profit was 2.4‐fold lower in farms lacking bumblebees than in farms hosting both pollinator species. The pollination experiment further suggested that the benefits of bumblebees could be mediated by improved pollen quality rather than quantity.Synthesis and applications. This study highlights the pervasive consequences of losing key pollinator functional groups, such as bumblebees, for apple production and local economies. Adopting pollinator‐friendly practices such as minimizing the use of synthetic inputs or restoring/maintaining semi‐natural habitats at farm and landscape scales, will have the double advantage of promoting biodiversity conservation, and increasing crop productivity and profitability for local farmers. Yet because the implementation of these practices can take time to deliver results, the management of native pollinator species can be a provisional complementary strategy to increase economic profitability of apple growers in the short term. [ABSTRACT FROM AUTHOR]

Apis mellifera filamentous virus (AmFV) is a large double stranded DNA virus of honey bees and its prevalence and relationship with other parasites is poorly known. Samples consisted of fifty-one adult bees belonging to eight native species collected using entomological nets in six provinces of Argentina, from 2009 to 2018. Total genomic DNA was extracted from individual bees and a 551 bp fragment of the Bro-N gene of AmFV was amplified by qPCR. In the present work we have reported for the first time both the presence and the wide geographic distribution of AmFV in Argentinian species of native bees. This is the first report of the presence of this virus associated with Xylocopa atamisquensis, X. augusti, X. frontalis, X. spendidula, Bombus pauloensis and Peponapis fervens. Detecting pathogens that could threaten native bee health is of outmost importance to generate both conservation and management strategies. [ABSTRACT FROM AUTHOR]

Pollinators such as Apidae bees are vital for ecosystems and food security. Unfortunately, their populations have declined due to several factors including pesticide use. Among them, the organophosphate insecticide chlorpyrifos, poses a global threat, while legacy compounds like organochlorine pesticides (OCPs) easily bioaccumulate, increasing the concern. Bombus pauloensis, a widely distributed native bee in Argentina, is used for commercial pollination; however, information regarding their health status is scarce. This study assessed chlorpyrifos and OCP levels in B. pauloensis (workers and males) and related environmental matrices living from three different land uses schemes, by means of GC-ECD and GC-MS. The ornamental horticulture field (OP) showed the highest total pesticide concentrations in workers (13.1 ng/g), flowers and soils, whereas the organic agriculture field (OA) exhibited the lowest. Chlorpyrifos was the most abundant compound, accounting for at least 20 % of pesticide load across all matrices. The food production horticulture field (FH) had the highest chlorpyrifos concentration in workers, males and soils (5.0, 4.4 and 3.3 ng/g, respectively), suggesting a local greater usage, whereas OA showed the lowest. Regarding OCPs groups, Drins and DDTs were predominant in most matrices, with FH males registering the highest levels (4.0 and 2.5 ng/g, respectively), closely followed by OP. However, metabolites' contribution indicated historical use and atmospheric inputs in all sites. Multivariate analyses confirmed the significance of site and bumblebee sex to explain pesticide composition. Males from all sites exhibited higher chlorpyrifos levels than workers and this trend was similar for some OCP groups. Overall, OA differed from FH and OP, indicating a correlation between production modes and pesticide profiles. This study demonstrates the value of B. pauloensis as a pesticide biomonitor but also offers insights into its populations' health in the area. In this sense, this information could be useful towards the preservation of this crucial pollinator., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Bumblebees are economically important insects which perform essential pollination tasks in natural and managed ecosystems. Recent research studying Neotropical bumblebee species in Brazil showed a clear decrease in genetic diversity over time in Bombus pauloensis. A new temporal assessment of genetic diversity is needed to know whether this was a location-specific result, or a more general phenomenon. This knowledge is essential to be able to prioritize conservation and management needs. Here, the genetic variability of B. pauloensis populations in Argentina was investigated over time using museum collection specimens from 1933 to 2016, and compared with reanalyzed data from Brazilian populations. Furthermore, specific time series were made for two Argentinean locations, Candelaria and La Plata, and compared with the time series of Porto Alegre (Brazil). All collected specimens were genotyped with 16 microsatellite loci to estimate genetic diversity parameters. Our results showed no drop in either allelic richness or expected heterozygosity over all Argentinean populations. However, a clear drop in genetic diversity was observed in two out of three location-specific time series. This loss of diversity will have negative impacts on population survival, especially over longer periods of time. Furthermore, the use and release of mass-reared specimens of B. pauloensis, which may be inbred and specifically selected for certain commercial but non-adaptive traits, could further diminish the genetic pool. Thus, our result implies the urgent need for regional conservation policies of B. pauloensis in South Brazil and North Argentina. [ABSTRACT FROM AUTHOR]

Mites have been observed on the bumblebee's body and inside their nest for over 150 years, and parasitic relationships between them have occasionally been reported. One of the most interesting animal associations between mites and bees is phoresy. At present, no study has evaluated the distribution patterns of phoretic mites on bumblebees nor the factors that might be influencing such association. The main goal of this research was to determine whether an aggregation of external mites on bumblebees is influenced by (a) the phoretic mite load per bee, (b) the host species, (c) the caste of bumblebee, (d) the interaction between mite load and bee species, and (e) the presence of a suitable physical place for the mites to accommodate on the bee body. The following mite species were recorded on Bombus atratus and Bombus opifex: Kuzinia laevis, Kuzinia americana, Kuzinia affinis, Kuzinia sp., Pneumolaelaps longanalis, Pneumolaelaps longipilus, Scutacarus acarorum, and Tyrophagus putrescentiae. Our results indicate that Kuzinia mites have a strong preference for a particular region on the propodeum, which has shorter hairs than on most areas of the body. In addition, generalized linear model analysis demonstrated that mite aggregation was influenced by the caste and host species. [ABSTRACT FROM AUTHOR]

Summary The neogregarine Apicystis bombi is considered a low prevalence parasite of Bombus spp. Before our work it has only once been detected in one single specimen of the Western honeybee Apis mellifera. This contribution reports the presence of A. bombi parasitizing both A. mellifera and Bombus terrestris at a site in Northwestern Argentine Patagonia (Bariloche, close to the border with Chile) and analyses its possible absence in the Pampas region, the most important beekeeping region of the country. In Bariloche, prevalence of A. bombi in A. mellifera was 7.6% in 2009, and 13.6% in 2010, whereas in B. terrestris it was 12.1%. Infections were not detected in 302 bee hives periodically prospected along 3 years (almost 400 000 honeybee specimens) in the Pampas. Analysis with the probability program FreeCalc2 suggested a possible absence of A. bombi in this area. Because of high virulence showed in several species of Bombus in the Northern hemisphere, A. bombi should be closely monitored in A. mellifera and in native Bombus species or other Apidae. [ABSTRACT FROM AUTHOR]

Abstract: The flagellate Crithidia bombi and the neogregarine Apicystis bombi have been found in individuals of Bombus terrestris, a Palaearctic species of bumble bee commercially reared and shipped worldwide for pollination services. B. terrestris has recently entered into the northwestern Patagonia region of Argentina from Chile, where it was introduced in 1998. Prevalence was 21.6% for C. bombi and 3.6% for A. bombi (n =111). The pathogens were not detected in 441 bumble bees belonging to five of the eight known Argentine native species (Bombus atratus, Bombus morio, Bombus bellicosus, Bombus opifex, Bombus tucumanus) collected elsewhere in the country. Although the absence of natural occurrence of C. bombi and A. bombi in Argentine native bumble bees cannot be ascertained at present due to the limited surveys performed, it is important to report their detection in invasive B. terrestris. The invasion event is relatively recent and the accompanying pathogens are not species specific within the genus Bombus. [Copyright &y& Elsevier]

Invasive social bees can alter plant-pollinator interactions with detrimental effects on both partners. However, most studies have focused on one invasive bee species, while the interactions among two or more species remain poorly understood. Also, many study sites had a history of invasive bees, being hard to find sites with historical low abundances. In Patagonia, Bombus ruderatus (F.) invasion begun in 1993 and B. terrestris (L.) in 2006. Though honey bees (Apis mellifera L.) introduction started in 1859, their density is still low in some parts. By experimentally increasing honey bee densities, we evaluated the effect of honey bees and bumblebees floral visitation on native pollinator floral visitation, pollen deposition, and reproductive success of three plant species in mixed Nothofagus antarctica forests of northern Patagonia: Oxalis valdiviensis, Mutisia spinosa and Cirsium vulgare. Our results show that exotic bees became the main floral visitors. No negative association was found between invasive bee and native pollinator visitation rates, but there was evidence of potential competition between honey bees and bumblebees. Floral neighborhood diversity played an important role in pollinator behavior. Conspecific pollen deposition was high for all species, while deposition of heterospecific pollen was very high in M. spinosa and C. vulgare. Not as expected, honey bees visitation rate had a negative effect on heterospecific pollen deposition in C. vulgare. For O. valdiviensis, exotic visitation rates increased conspecific pollen deposition, which was positively related to reproductive success. Although exotic bees became main floral visitors, their contribution to reproductive success was only clear for one species.