Bees play an important role in ecosystems as pollinators, contributing to plant reproduction, agricultural productivity, and biodiversity conservation (Klein et al., 2007; Potts et al., 2010; Ollerton et al., 2011). Due to their sensitivity to environmental change and floral resource availability, they are valuable bioindicators of habitat degradation and land-use change (Odanaka & Rehan, 2019). Despite the increasing global recognition of pollinators' importance, significant knowledge gaps persist regarding their distribution and diversity, particularly in arid and high-altitude ecosystems (Arroyo et al., 1982; Gonzalez & Engel, 2004; Henríquez-Piskulich et al., 2020).

In arid and high-altitude ecosystems, bee diversity and distribution patterns are influenced by extreme environmental conditions such as low temperatures, high solar radiation, and scarce water availability (Abrahamczyk et al., 2011; Orr et al., 2021). These ecosystems tend to support specialized bee communities adapted to harsh climatic conditions, often characterized by a dominance of ground-nesting species and seasonal activity patterns closely linked to the availability of floral resources (Minckley et al., 2000). In addition, the fragmented nature of the vegetation and the presence of endemic plant species contribute to unique plant-bee interactions (Arroyo et al., 1982; Minckley et al., 2000; Henríquez-Piskulich et al., 2018; Luna et al., 2024) that are particularly vulnerable to environmental disturbances, making their conservation a priority (Henríquez-Piskulich et al., 2018; Rodríguez et al., 2021).

In Chile, bee diversity has mainly been studied in the central and southern regions, while the northern high-altitude ecosystems remain underrepresented in the scientific literature (Montalva & Ruz, 2010; Henríquez-Piskulich et al., 2020; López-Aliste et al., 2021; Marshall et al., 2023). The northern region of Chile is characterized by an arid and semi-arid climate, with extreme variations in temperature and solar radiation (Arroyo & Cavieres, 2013; Anthelme et al., 2014; Cavieres et al., 2025). As a result, these areas support an ecosystem that is favorable to diversity and evolution of endemic forms (Orr et al., 2021; Marshall et al., 2023).

The Volcán Isluga National Park, located in the Tarapacá Region, is a protected area characterized by high-altitude desert ecosystems that harbor a rich diversity of native flora and Andean vegetation (CONAF, 1988). This Park has been declared of scientific interest, which restricts mining activities (CHILE, 1983), and natural resource extraction and land use are strictly regulated under a conservation framework that aims to sustain biodiversity and maintain key ecosystem services provided by the local species (Ormazabal, 1993). However, studies on the diversity and ecological interactions of insects in this region remain limited. Bees are the main pollinators of flowering plants (Ollerton et al., 2011), supporting essential ecological processes such as plant reproduction, fruit production, and ecological succession (Klein et al., 2007; Potts et al., 2010). In this sense, this study aims to evaluate the diversity and composition of wild bees and provide a list of plant-bee interactions in Vólcan Isluga National Park. Based on these results, we discuss the relevance of the understanding of bee diversity and their interactions with native plant species as a key component for the conservation of pollination services.

A total of 71 bees representing 19 morphospecies in 13 genera and four families were collected during the sampling periods (Figure 2; Table I). The Apidae family was the most abundant, comprising 35.5 % of the specimens (n= 27 specimens; 7 species), followed by Halictidae (26.3 %; n= 20 individuals; 4 species), Colletidae (17.1 %; n= 13 individuals; 3 species), and Megachilidae (14.5 %; n= 11 individuals; 5 species). No individuals from the family Andrenidae were recorded.

Among the collected specimens, Apidae exhibited the highest species richness and abundance, with notable species including Alloscirtetica weyrauchi Michener, LaBerge & Moure, 1955, Anthophora arequipensis Bréthes, 1920, and multiple Centris species (C. buchholzi Herbst, 1918, C. escomeli Cockerell, 1926, C. sacsayhuaman Vivallo, 2020, and C. miluni Vivallo, 2020), as well as Xylocopa viridigastra Lepeletier, 1841 (Fig. 3). The most abundant species were A. arequipensis (n= 12 specimens, 16.9 %), Caenohalictus cuprellus (Vachal, 1903) (n= 10 specimens, 14.1 %, Table I). Bee species exhibited distinct social behaviors, including solitary, cleptoparasitic and variations of social patterns behaviour (Table I).

Table I Table I List of bee morphospecies collected in Volcán Isluga National Park, including their ecology and records of floral interactions Table I List of bee morphospecies collected in Volcán Isluga National Park, including their ecology and records of floral interactions Notes

Classification of bee species by body size: S= small (5-8 mm), M= medium (9-16 mm), G= large (> 17 mm), based on body width

Figure 3.

The vertical columns represent bee species, while each horizontal row corresponds to a plant species. The color intensity of the heatmap reflects the number of observed floral visits, with darker shades indicating higher interaction frequencies

Regarding the sampling method, only one specimen of Lasioglossum sp. 1 (Halictidae) was collected using yellow pan traps, while the remaining individuals were recorded using the active sweep net method (Table I). Bees were recorded interacting with 18 plant species belonging to 9 botanical families. Fabaceae (n= 7 species; 18 specimens) and Asteraceae (n= 5 species; 18 specimens) showed the highest number of plants species, while Malvaceae, represented by one single species, was the most abundant family (27 specimens). The remaining families, Calceolariaceae, Caryophyllaceae, Francoaceae, Lamiaceae, Loasaceae, Solanaceae, and Vivianiaceae, were each represented by a single species (Fig. 3).

Among the 19 bees morphospecies recorded in our study, 12 had previously documented distributions for the Tarapacá region. Notably, our survey recorded Centris miluni and Centris sacsayhuaman, two species that were only recently described (Vivallo et al., 2020), as well as Caupolicana albiventris, Xeromelissa wilmattae, and Nothanthidium bizonatum, which were previously documented only by Toro (1986). Another relevant record, Anthidium funereum, had only been documented previously for the Arica region (Toro, 1986).

Our findings highlight the diversity and abundance of wild bees in Volcán Isluga National Park, the first assessment of plant-bee interactions in this high-altitude desert ecosystem in this region. Our exploration of plant–bee interactions revealed that 19 bee species interacted with 18 native plant species, primarily from the Fabaceae and Asteraceae families. These results suggest that the local flora may play a key role in supporting solitary bees, particularly within the Apidae and Halictidae families.

According to López-Aliste et al. (2021), the study region has a low frequency of documented bee records. In their most recent survey of the Tarapacá region, 26 bee species were reported, ten of which were also observed in our study (See Table I). The presence of Centris miluni, Centris sacsayhuaman, Caupolicana albiventris, Xeromelissa wilmattae, and Nothanthidium bizonatum in our survey underscores the Tarapacá region's understudied bee diversity. Several of these species have been recently described or were previously documented only in distant locations (Vivallo et al., 2020; Toro, 1986), which suggests that their geographic ranges are likely broader than currently recognized. It is also important to highlight that the identification of some morphospecies was limited to the genus level due to outdated or incomplete taxonomic references for certain groups (e.g., Lasioglossum). This limitation reflects the taxonomic challenges documented in recent literature, particularly for morphologically difficult and cryptic taxa such as Lasioglossum (Halictidae) (Landaverde-González et al., 2017).

Studies in arid desert ecosystems have revealed high bee diversity of interest (Argueta-Guzmán et al., 2022; Thapa‐Magar et al., 2022). The species share adaptations that allow them to survive in arid, high-altitude conditions where climatic extremes (Sakagami & Munakata, 1972; Eickwort et al., 1996; Purcell et al., 2015). These adaptations include specific body traits such as increased hair density for thermoregulation (Turnley et al., 2025) and predominantly solitary behaviour (Moss & While, 2021; Ostwald et al., 2024). In addition to arid conditions, the availability of floral resources, both spatially and temporally (Snyder et al., 2006; Pueyo et al., 2008), appear to play an important role in determining bee richness and occurrence in these ecosystems (Rodríguez et al., 2021).

In Volcán Isluga, most of the recorded species were solitary and visited especially native plants, such as Tarasa operculata (Malvaceae), Grindelia tarapacana (Asteraceae) and Lupinus oreophilus (Fabaceae). These species are typically found in the herbaceous and shrubby vegetation of the desert Matorral system, which occurs on the dry western slopes of the Andes. Some species, such as Tarasa operculata, are adapted to higher altitudes (ranging from 1,600 to 2,300 m) and to conditions with limited water availability (Chicalla-Rios, 2021). Native bees were observed collecting pollen and other floral resources, indicating that the presence of these plant species in the desert landscape may serves as key resources for sustaining bee communities and maintaining ecosystem stability.

Furthermore, our study presents limitations that may affect the generalizability of its findings. Although it provides an initial insight into plant-bees interaction, we did not quantify the influence of plant abundance and diversity across spatial heterogeneity gradients on plant-bee interactions. The availability and distribution of floral resources can directly impact bee foraging behavior (Escobedo-Kenefic et al., 2020), resource partitioning, and the overall structure of pollination networks (generalist or specialist) (Bendel et al., 2019). Although we combined different collection methods, our study was conducted in a limited time period, which restricts our ability to capture seasonal variations in bee activity and floral resource availability. Since the composition and level of specialization of plant-bee interactions are strongly influenced by phenological cycles (Oertli et al., 2005), future studies should incorporate multiseasonal sampling to adequately characterize community dynamics and assess the effect of temporal variability on pollination networks in high-altitude desert ecosystems (Bendel et al., 2019).

Combining active and passive sampling methods provides a more comprehensive assessment of bee diversity and plant-bee interactions (Wilson et al., 2016). However, the success of each type of method can vary depending on climatic conditions, seasonality, suitable habitat, trap color and insect body size (Prendergast et al., 2020). In our study, the effectiveness of passive collection methods, such as pan traps, was notably lower, recording only a single bee species. This result probably reflects the limitations of trap color selection, and the small number of samples taken, which may have reduced the ability to capture the full diversity of bee species present in the study area. To overcome these limitations, some studies have employed multi-colored pan traps combined with standardized active surveys, which improves the representativeness of bee community overviews in terms of both diversity and abundance (Vereecken et al., 2021; Hutchinson et al., 2022; Xie et al., 2024). However, these combined approaches also increase the logistical effort and financial cost of sampling and monitoring, which can limit their feasibility in remote or resource-constrained environments (Bell et al., 2023).

Despite these limitations, our study provides an important baseline characterization of plant-bee interactions in a high-altitude desert ecosystem in northern Chile. Many of the recorded interactions occur within legally protected areas, such as national parks, which help safeguard these ecological relationships. However, on a regional scale, the park is located in a zone of potential conflict due to the proximity of mining activities to protected areas (Toledo et al., 2017). Our findings underscore the importance of ongoing monitoring and conservation efforts in the region and highlight the value of Isluga Volcano as a refuge for pollinator communities and other forms of biodiversity.

Overall, our finding suggests that bee diversity in the region is underestimated and likely higher than previously reported. The presence of previously unrecorded species further underscores the importance of documenting plant-bee interactions. These interactions can provide valuable insights into local ecological processes such as pollination and ecosystem resilience. Future research should focus on analyzing plant-bee networks, including their temporal and spatial dynamics, as well as assessing the effectiveness of bees as pollinators. Incorporating measures of pollination effectiveness, beyond simple floral visitation, will allow a better understanding of the distinct roles that different floral visitors play within the community and inform conservation strategies in these high-altitude desert ecosystems (Santiago‐Hernández et al., 2019).