Geology topics

Elaine Evans

Publications and source records attributed to Elaine Evans.

4 recordsLinked to original sources

USGS2025

Estimating occupancy of focal bee species

Current bee monitoring efforts have a limited capacity for understanding factors affecting wild bee population changes, including the effects of management. To improve the effectiveness of wild bee monitoring, we first discuss principles of biological monitoring and provide a framework to design monitoring projects to estimate species occupancy, where occupancy is defined as the probability that a Sampling Unit or site is occupied by the focal species. Monitoring practitioners should first define the desired goal or question of monitoring and secondly select the appropriate state variable for monitoring ( e.g ., species richness, occupancy, abundance). These represent two critical, yet often overlooked, steps in the development of wild bee monitoring projects. As with all forms of demographic monitoring, practitioners who are interested in estimating species occupancy will need to develop a sampling scheme tailored to meet their monitoring objectives. Defining key sampling terms will provide the architecture of their scheme, including the Area of Interest, Sampling Unit, Season, and Replicate Survey. We also highlight data standards, including core data fields that must be collected during Surveys for bee occupancy data and additional, recommended data fields . We illustrate how these monitoring concepts are being applied to the design of a real-world monitoring project for the federally endangered rusty patched bumble bee ( Bombus affinis Cresson). This framework was developed in association with the U.S. National Native Bee Monitoring Network.

Journal of Melittology↗

USGS2025

Answering key bumble bee conservation questions by studying discovered wild nests: A Bombus affinis case study

The nesting ecology of wild bumble bees is not well resolved, but information learned from discovered nests can be of great conservation value. Data collected at nests on foraging patterns, caste-specific behaviour and health (e.g., pathogens) are invaluable for understanding bumble bee behaviour and ecology, but difficult to decipher solely from foraging observations away from the nest. Post-senescence nest excavation allows the estimation of colony size, caste numbers, documents pest incidence and provides opportunities to examine nest material for stressors (e.g., pesticides) and to use nest material for training purposes (e.g., conservation dogs). Wild nests are often found opportunistically, and there is an absence of standardised guidance on data collection. We provide an action plan to ensure the data collection is comparable across studies. This framework includes key conservation questions and methodological guidelines for both for in situ and post-season nest data collection and is ordered by increasing complexity of data collection methods. To illustrate our framework, we provide an example with recently discovered Bombus affinis (rusty patched bumble bee) nests. Through observations at B. affinis nests, we discovered novel patterns of activity, changing activity levels over time, the timing of male and gyne production, variable timing in nest senescence, and associations of nests with past rodent activity. Although individual nest discoveries may be of limited value in forwarding conservation strategies, the aggregate collections of many similar datasets can be of critical importance for species of conservation concern.

Insect Conservation and Diversity↗

USGS2024

Range-wide genetic analysis of an endangered bumble bee (Bombus affinis, Hymenoptera: Apidae) reveals population structure, isolation by distance, and low colony abundance

Declines in bumble bee species range and abundances are documented across multiple continents and have prompted the need for research to aid species recovery and conservation. The rusty patched bumble bee ( Bombus affinis ) is the first federally listed bumble bee species in North America. We conducted a range-wide population genetics study of B. affinis from across all extant conservation units to inform conservation efforts. To understand the species’ vulnerability and help establish recovery targets, we examined population structure, patterns of genetic diversity, and population differentiation. Additionally, we conducted a site-level analysis of colony abundance to inform prioritizing areas for conservation, translocation, and other recovery actions. We find substantial evidence of population structuring along an east-to-west gradient. Putative populations show evidence of isolation by distance, high inbreeding coefficients, and a range-wide male diploidy rate of ~15%. Our results suggest the Appalachians represent a genetically distinct cluster with high levels of private alleles and substantial differentiation from the rest of the extant range. Site-level analyses suggest low colony abundance estimates for B. affinis compared to similar datasets of stable, co-occurring species. These results lend genetic support to trends from observational studies, suggesting that B. affinis has undergone a recent decline and exhibit substantial spatial structure. The low colony abundances observed here suggest caution in overinterpreting the stability of populations even where B. affinis is reliably detected interannually. These results help delineate informed management units, provide context for the potential risks of translocation programs, and help set clear recovery targets for this and other threatened bumble bee species.

Iowa, Illinois, Indiana, Kentucky, Michigan, Minne↗

USGS2024

Floral Composition of Pollen Collected from a Rusty Patched Bumble Bee (Bombus affinis, Cresson) Nest in Southeastern Minnesota

Understanding the forage diets of imperiled bumble bees can improve conservation planning and habitat restoration efforts. In this study, we describe the taxonomic composition of bee-collected pollen from 2 Rusty Patched Bumble Bee ( Bombus affinis , Cresson) nests located in southeastern Minnesota. This is the first published reporting of pollen collected from active B. affinis nests. We also compared pollen identification via traditional palynological light microscopy with genetic identification via ITS metabarcoding. Among the 49 pollen samples analyzed, we detected 41 and 56 distinct taxa via light microscopy and metabarcoding, respectively. Furthermore, 27 of 47 total genera overlapped between the 2 methods. Bittersweet Nightshade ( Solanum dulcamara , Linnaeus) was the most detected species for both metabarcoding and microscopy identification for pollen prevalence. Pollen volume from the microscopy data showed that Lesser Burdock ( Arctium minus , Bernhardi), Alfalfa ( Medicago sativa , Linnaeus), Bittersweet Nightshade ( Solanum dulcamara , Linnaeus), Plumeless Thistle ( Carduus acanthoides , Linnaeus), and Red Clover ( Trifolium pratense , Linnaeus) together comprised more than half of the total volume of pollen. Light microscopy and metabarcoding revealed compositionally distinct plant communities when analyzed at the species level. Methodological concordance improved when analyzing pollen data at genus level, but both methods still reveal marginally distinct groupings. Our study highlights specific plant taxa that are important components of B. affinis pollen diets and provides actionable research for conservation efforts in urban systems. Our study also supports that B. affinis is a generalist forager and will collect pollen from a variety of native and non-native host plants.

Minnesota↗