Theodore B. Mitchell

The Mojave and Sonoran Deserts, recognized as a global hotspot for bee biodiversity, are experiencing habitat degradation from urbanization, utility‐scale solar energy (USSE) development, and climate change. In this study, we evaluated the current and future distribution of bee diversity, assessed how protected areas safeguard bee species richness, and predicted how global change may affect bees across the region. Using Joint Species Distribution Models (JSDMs) of 148 bee species, we project changes in species distributions, occurrence area, and richness under four global change scenarios between 1971 and 2050. We evaluated the threat posed by USSE development and predicted how climate change will affect the suitability of protected areas for conservation. Our findings indicate that changes in temperature and precipitation do not uniformly affect bee richness. Lower elevation protected areas are projected to experience mean losses of up to 5.8 species, whereas protected areas at higher elevations and transition zones may gain up to 7.8 species. Areas prioritized for future USSE development have an average species richness of 4.2 species higher than the study area average, and lower priority “variance” areas have 8.2 more species. USSE zones are expected to experience declines of up to 8.0 species by 2050 due to climate change alone. Despite the importance of solitary bees for pollination, their diversity is often overlooked in land management decisions. Our results show the utility of JSDMs for leveraging existing collection records to ease the inclusion of data‐limited insect species in land management decision‐making.

AbstractBees (Hymenoptera: Apoidea) are vital components of global ecosystems, yet knowledge of their distribution is limited in many regions. Washington state is located in an ecologically diverse part of North America and encompasses habitat types and plant communities known for high bee species richness. To establish a baseline for future studies on bee communities in the state, we used published and unpublished datasets to develop a preliminary annotated checklist of bees occurring in Washington state. We document, with high confidence, 565 species of bees in Washington and identify an additional 102 species likely to occur in the state. We anticipate future research survey efforts, such as the newly initiated Washington Bee Atlas, will discover several species that have the potential to occur in Washington and provide new data for 84 species which have not been recorded in more than 50 years.

The first record of Xenoglossa (Cemolobus) ipomoeae (Robertson, 1891) (Apidae: Eucerini) for the state of Mississippi, USA is reported. This species is a rarely encountered specialist bee that is known to forage on Ipomoea pandurata (L.) G.F.W. Mey (Convolvulaceae), potentially along with other closely related plants in the genus Ipomoea. A single female was collected in Bolivar County during 2017 that a represents a significant southwestern range expansion for this bee species.

The solitary oil-collecting bees of the tribes Centridini, Tapinotaspidini, and Tetrapediini inhabit areas from the southern part of the Nearctic Region through the Patagonian in southern South America, including the Caribbean. These bees are morphologically and behaviorally specialized in collecting oils as a reward from specialized floral glandular structures present in oil-producer plants. Oil-producer plants and oil-collecting bees have a mutualistic relationship in which the latter potentially pollinate the formers while collecting oils from their flowers. The main objective of this work is to infer the species richness and the key areas for conservation, research, and sustainable use of oil-collecting bees of the tribes Centridini, Tapinotaspidini, and Tetrapediini in the Americas. We collected occurrence records for 528 species of oil-collecting bees and estimated the species richness for each tribe and genus. In total, we estimated 664 species across the three mentioned tribes. With that baseline information, we created models of the richness and rarity patterns of the entire group of species and each tribe as a criterion to highlight key areas, along with richness and rarity centers for the American oil-collecting bees. We identified several critical areas that can be prioritized for conservation and research projects, including territories in Panama, Costa Rica, the Central and Northern Andes, the Amazon basin, and the biogeographic provinces of Cerrado, Atlantic Forest, Pampean, and Chacoan. Here we provide crucial information on key diversity areas for oil-collecting bees across the Americas. This information can be used for the conservation, research, and sustainable use of this important group of insect pollinators.

We analysed the wild bee community sampled from 1921 to 2018 at a nature preserve in southern Michigan, USA, to study long-term community shifts in a protected area. During an intensive survey in 1972 and 1973, Francis C. Evans detected 135 bee species. In the most recent intensive surveys conducted in 2017 and 2018, we recorded 90 species. Only 58 species were recorded in both sampling periods, indicating a significant shift in the bee community. We found that the bee community diversity, species richness and evenness were all lower in recent samples. Additionally, 64% of the more common species exhibited a more than 30% decline in relative abundance. Neural network analysis of species traits revealed that extirpation from the reserve was most likely for oligolectic ground-nesting bees and kleptoparasitic bees, whereas polylectic cavity-nesting bees were more likely to persist. Having longer phenological ranges also increased the chance of persistence in polylectic species. Further analysis suggests a climate response as bees in the contemporary sampling period had a more southerly overall distribution compared to the historic community. Results exhibit the utility of both long-term data and machine learning in disentangling complex indicators of bee population trajectories.

Updated records related to coexisting species, the presence of invasive species, and the presence or absence of Threatened, Endangered, or Species of Greatest Conservation Need are a necessary component of wildlife conservation. Here, we compile a list of historically documented fish species found in San Felipe Creek and report updated occurrence from recent sampling events. Of the anticipated 49 species within San Felipe Creek, we documented 16 between 2019 and 2022. We observed Devils River minnow (Dionda diaboli), a federally Threatened species, during all sampling events. Additionally, we confirmed the presence of three state Threatened species and one Species of Greatest Conservation Need. We also document continued presence of the invasive suckermouth catfish (Hypostomus plecostomus) and blue tilapia (Oreochromis aureus). Researchers may use species occurrence data provided by these efforts to assess future assemblage changes within the San Felipe Creek system.

The introduction of bees for agricultural production in distinct parts of the world and poor management have led to invasion processes that affect biodiversity, significantly impacting native species. Different Bombus species with invasive potential have been recorded spreading in different regions worldwide, generating ecological and economic losses. We applied environmental niche and potential distribution analyses to four species of the genus Bombus to evaluate the similarities and differences between their native and invaded ranges. We found that B. impatiens has an extended environmental niche, going from dry environmental conditions in the native range to warmer and wetter conditions in the invaded range. Bombus ruderatus also exhibited an extended environmental niche with drier and warmer conditions in the invaded range than in its native range. Bombus subterraneus expanded its environmental niche from cooler and wetter conditions in the native range to drier and warmer conditions in the invaded range. Finally, B. terrestris showed the most significant variation in the environmental niche, extending to areas with similar and different environmental conditions from its native range. The distribution models agreed with the known distributions for the four Bombus species, presenting geographic areas known to be occupied by each species in different regions worldwide. The niche analysis indicate shifts in the niches from the native to the invaded distribution area of the bee species. Still, niche similarities were observed in the areas of greatest suitability in the potential distribution for B. ruderatus, B. subterraneus, and B. terrestris, and to a lesser degree in the same areas with B. impatiens. These species require similar environmental conditions as in their native ranges to be established in their introduced ranges. Still, they can adapt to changes in temperature and humidity, allowing them to expand their ranges into new climatic conditions.

This paper presents an exploratory study on the taxonomic diversity of pre-Hispanic archaeofaunas in the South-Central Andes (SCA; western South America) from the Pleistocene-Holocene boundary to the Late-Holocene. The SCA is a complex of diverse environments and has undergone distinct climate events for the last 13,000 years, such as the occurrence of warmer and drier conditions in the Middle-Holocene. The South-Central Andean area was part of the larger Andes interaction area, which was a primary center for animal and plant domestication and the emergence of agro-pastoralist economies. Since subsistence was key to these processes, the SCA provides a relevant case study on the interactions among environment, foodways and sociocultural evolution. Taxonomic diversity was used here as a proxy for diet breadth. A total of 268 archaeofaunal assemblages were sampled from the zooarchaeological literature. Reviewed variables included the cultural chronology and spatial coordinates of the assemblages, as well as the presence and abundance of taxa at the family rank. Taxonomic diversity covered two dimensions: composition (families present in each assemblage) and structure (quantitative relationships among taxa), which was measured through richness (NTAXA), ubiquity and relative abundance (NISP based rank-order). Despite the uneven distribution of samples, the analyses revealed the following trends: (1) a moderate relationship between NTAXA and distance from coastline for most of the Holocene; (2) a potential decrease in assemblage richness for coastal ecoregions during the Late-Holocene; and (3) a generalized increase in the relative abundance of Camelidae.

Globally, insects have been impacted by climate change, with bumble bees in particular showing range shifts and declining species diversity with global warming. This suggests heat tolerance is a likely factor limiting the distribution and success of these bees. Studies have shown high intraspecific variance in bumble bee thermal tolerance, suggesting biological and environmental factors may be impacting heat resilience. Understanding these factors is important for assessing vulnerability and finding environmental solutions to mitigate effects of climate change. In this study, we assess whether geographic range variation in bumble bees in the eastern United States is associated with heat tolerance and further dissect which other biological and environmental factors explain variation in heat sensitivity in these bees. We examine heat tolerance by caste, sex, and rearing condition (wild/lab) across six eastern US bumble bee species, and assess the role of age, reproductive status, body size, and interactive effects of humidity and temperature on thermal tolerance in Bombus impatiens. We found marked differences in heat tolerance by species that correlate with each species' latitudinal range, habitat, and climatic niche, and we found significant variation in thermal sensitivity by caste and sex. Queens had considerably lower heat tolerance than workers and males, with greater tolerance when queens would first be leaving their natal nest, and lower tolerance after ovary activation. Wild bees tended to have higher heat tolerance than lab reared bees, and body size was associated with heat tolerance only in wild‐caught foragers. Humidity showed a strong interaction with heat effects, pointing to the need to regulate relative humidity in thermal assays and consider its role in nature. Altogether, we found most tested biological conditions impact thermal tolerance and highlight the stages of these bees that will be most sensitive to future climate change.

The subgenus Megachile (Chrysosarus) is known for the lack of cutting edges in the female mandible. Nevertheless, a small cutting edge on the lower margin of the third tooth is present in a few species, all described from Brazil. This contribution calls attention to the presence of this condition in several species occuring in Argentina, Chile, and Uruguay. Four new species are described: M. basimacula, M. platensis, M. sancticlaudii, and M. simpliciclypeata. The identity of two species described over a century ago is clarified: M. interjecta Vachal, and M. cubiceps Friese. Megachile uncinata González, Griswold & Engel is a junior synonym of M. cubiceps Friese. Species of M. (Chrysosarus) with a small cutting edge in the female mandible form an heterogeneous as- semblage, and seem to be related to species that completely lack cutting edges, and not to each other. A probable exception is the group formed by the four species M. basimacula, M. cubiceps, M. euzona, and M. tetrazona, which share a number of common features, and are included as the M. euzona species group. Descriptions, illustrations, and distributional data are presented for all treated species.