Michigan’s lakeplain prairie and prairie fen natural communities contain refugia for many at-risk species of insects, including species that are listed at the federal and state level. Wild bees are a group of insects crucial for maintaining robust plant-pollinator communities. Numerous species of bees are presumed to be in decline. However, baseline community surveys are lacking and needed to document the status of species occupying these natural communities. In 2021, Michigan Natural Features Inventory completed wild bee surveys in lakeplain prairie (lakeplain wet-mesic prairie and lakeplain wet prairie) and prairie fens in Michigan using a combination of aerial netting and bowl trapping. A total of 1,118 wild bees, representing 104 unique species or morphospecies, were collected during these surveys, including new state records for Dufourea marginata (Cresson, 1878) and Sphecodes nigricorpus Mitchell, 1956. The baseline inventory of wild bees in 2021 provides valuable information on species presence at these locations and suggests that they may act as refuges for rare species of native bees in the state. Continued management of lakeplain prairie and prairie fen natural communities should take into consideration wild bee communities and strive to ensure populations maintain stable numbers.

Urbanization is commonly associated with biodiversity loss and habitat fragmentation. However, urban environments often have greenspaces that can support wildlife populations, including rare species. The challenge for conservation planners working in these systems is identifying priority habitats and corridors for protection before they are lost. In a rapidly changing urban environment, this requires prompt decisions informed by accurate spatial information. Here, we combine several approaches to map habitat and assess connectivity for a diverse set of rare species in seven urban study areas across southern Michigan, USA. We incorporated multiple connectivity tools for a comprehensive appraisal of species-habitat patterns across these urban landscapes. We observed distinct differences in connectivity by taxonomic group and site. The three turtle species (Blanding's, Eastern Box, and Spotted) consistently had more habitat predicted to be suitable per site than other evaluated species. This is promising for this at-risk taxonomic group and allows conservation efforts to focus on mitigating threats such as road mortality. Grassland and prairie-associated species (American Bumble Bee, Black and Gold Bumble Bee, and Henslow's Sparrow) had the least amount of habitat on a site-by-site basis. Kalamazoo and the northern Detroit sites had the highest levels of multi-species connectivity across the entire study area based on the least cost paths. These connectivity results have direct applications in urban planning. Kalamazoo, one of the focal urban regions, has implemented a Natural Features Protection (NFP) plan to bolster natural area protections within the city. We compared our connectivity results to the NFP area and show where this plan will have an immediate positive impact and additional areas for potential consideration in future expansions of the protection network. Our results show that conservation opportunities exist within each of the assessed urban areas for maintaining rare species, a key benefit of this multi-species and multi-site approach. We combined several approaches to map habitat and assess connectivity for a diverse set of rare species in seven urban study areas across southern Michigan, USA. Our results show that conservation opportunities exist within each of the assessed urban areas for maintaining rare species, a key benefit of this multi-species and multi-site approach.image

Ongoing declines of bees and other pollinators are driven in part by the loss of critical floral resources and nesting substrates. Most conservation/restoration efforts for bees aim to enhance floral abundance and continuity but often assume the same actions will bolster nesting opportunities. Recent research suggests that habitat plantings may not always provide both forage and nesting resources. We evaluated wildflower plantings designed to augment floral resources to determine their ability to enhance nesting by soil-nesting bees over 3 study years in Northern California agricultural landscapes. We established wildflower plantings along borders of annual row crops and paired each with an unplanted control border. We used soil emergence traps to assess nest densities and species richness of soil-nesting bees from spring through late summer at paired field borders planted with wildflowers or maintained conventionally as bare or sparsely vegetated areas, as is typical for the region. We also quantified soil-surface characteristics and flower resources among borders. Wildflower plantings significantly increased nest densities and the richness of bee species using them. Such benefits occurred within the first year of planting and persisted up to 4 years post establishment. The composition of nesting bee communities also differed between wildflower and unenhanced borders. Wildflower plantings differed from controls in multiple characteristics of the soil surface, including vegetation cover, surface microtopography and hardness. Surprisingly, only vegetation cover significantly affected nest densities and species richness. Wildflower plantings are a widespread habitat action with the potential to support wild bees. The demonstrated benefit wildflower plantings had for increasing the nesting of soil-nesting bees greatly augments their relevance for the conservation of wild bee communities in agricultural and other landscapes. Identifying soil-surface characteristics that are important for nesting provides critical information to guide the implementation and management of habitats for bees.

Perennial wildflower plantings are commonly used to support pollinators and other beneficial insects, but their establishment can be costly, and few studies have directly compared the effectiveness of different management strategies for wildflower establishment. To determine the relative importance of pre‐seeding weed control, seed density, and post‐seeding management on seed mix establishment, we developed a multifactorial field experiment in a grass‐dominated weed community. Pre‐seeding management treatments (mowing, herbicide, or soybean cover crops) did not affect the stem density of sown plants, or the percent of ground covered by sown plants. However, the percent of ground covered by weeds was significantly influenced by pre‐seeding treatments, with infrequent mowing resulting in significantly less weedy ground cover than the herbicide or soybean pre‐seeding treatments. Plots with a higher seeding rate had a significantly greater density of sown wildflower species and a higher percent cover of these species after 3 years. Plots that received no post‐seeding management had higher stem density, a greater percent ground cover of sown forbs, and higher species richness compared to those that were intensively managed (mow or mow + herbicide). The total number of bee visits (honey bees, bumble bees, and other wild bees) increased with higher forb species richness, higher ground cover of sown forbs, and higher sown species richness. Doubling the density of seeds resulted in a 24.3% increase in the number of wild bees observed. When establishing wildflower habitat for pollinators, investment in ground preparation and seeding density has the greatest impact on sown species establishment.

Mason bees (Megachilidae: Osmia) are alternative managed pollinators with the potential to supplement pollination by honey bees in many crops. However, challenges for their management in orchards still remain. If nesting conditions are not optimal, females can show high dispersion rates, which decrease their economic viability at commercial scales. One way to improve female retention is by offering attractive nesting substrates. We tested the effect of several combinations of substrate materials and shelter types, as well as an attractant compound, on the retention and performance of Osmia lignaria and O. cornifrons females. We compared nesting in three types of shelter (blue and white plastic totes and brown pine plywood), with cardboard tubes of four different diameters (5–8 mm), reeds, and wood blocks as substrates at an experimental farm orchard. In a separate experiment with plywood shelters and 7‐mm cardboard tubes, we tested an attractant spray based on decanoic acid (patent number US 9301521B2), a compound isolated from O. lignaria cocoons and expected to encourage females to nest in artificial cavities. In both experiments, O. cornifrons showed higher female retention than O. lignaria. The combination of plywood shelters with reeds had the highest nesting for both species, although O. cornifrons also readily used cardboard tubes of 5–6 mm diameter. The attractant spray increased nesting by O. cornifrons, but not by O. lignaria. We also found a significant interaction between the effect of the attractant and the year of the experiment, indicating that weather and other environmental variables could affect the efficacy of the attractant. Together, our results suggest that using the right combination of shelters and substrates, as well as the attractant spray, is an effective strategy to increase Osmia female retention for orchard pollination.

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open, and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e., berry mass, number of fruits, and fruit density [kg/ha], among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), North America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-2005 (21 studies), 2006-2010 (40), 2011-2015 (88), and 2016-2020 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA).

Designing wildflower habitats to support beneficial insects providing pollination and pest control services is important for supporting sustainable crop production. It is often desirable to support both groups of insects, making the selection of resource plants for insect conservation programs more challenging. Moreover, the process of selecting resource plants is complicated by the array of possible options in each region, and the need to provide resources over the entire growing season. Identifying traits shared by resource plants that are attractive to both bees and natural enemies can reduce the need to evaluate new plants in each region, by providing a guide for the types of plants expected to be rewarding to these insects. Using insect visitation data collected from replicated common garden plantings of native wildflower and shrub species from the Great Lakes region of the United States, we found a high degree of correlation between the abundance of bees and natural enemies visiting native plant species. These results were used to identify a set of 15 plant species that can provide resources for these insects throughout the summer. Across all tested species, pollen quantity per flower and the week of bloom were positively correlated with some, but not all, taxonomic groupings of beneficial insects. In contrast, floral area was consistently positively associated with visitation of both natural enemies and wild bees. This trait is easy to document and can allow for efficient local testing of potential resource plants, providing a faster path to implementing insect conservation in working landscapes.

Plant-pollinator interactions are partially driven by the expression of plant traits that signal and attract bees to the nutritional resources within flowers. Although multiple physical and chemical floral traits are known to influence the visitation patterns of bees, how distinct bee groups vary in their responses to floral traits has yet to be elucidated. In this study, we used a common garden experiment to test for morphological floral traits associated with pollen quantity at the plant species level, and examined how the visitation patterns of taxonomically and functionally distinct bee groups are related to flower trait characteristics of 39 wildflower species. We also determined how floral traits influence the structure of wild bee communities visiting plants and whether this varies among geographic localities. Our results suggest that floral area is the primary morphological floral trait related to bee visitation of several distinct bee groups, but that wild bee families and functionally distinct bee groups have unique responses to floral trait expression. The composition of the wild bee communities visiting different plants was most strongly associated with variability in floral area, flower height, and the quantity of pollen retained in flowers. Our results inform wildflower habitat management for bees by demonstrating that the visitation patterns of distinct bee taxa can be predicted by floral traits, and highlight that variability in these traits should be considered when selecting plants to support pollinators.

Many landscapes throughout the Great Lakes region have experienced reductions in floral and nesting resources for bees. Identifying the resources used by bees in the family Megachilidae can be used to inform conservation programs that aim to support this group. In this study, we identified the preferred nesting substrate and size, as well as the proportion of distinct pollen types used for offspring provisioning by Megachile species. A total of 39 completed artificial nesting tubes were collected between July 25 and August 30, 2016. A majority of completed nests were in 4 mm diameter tubes. However, more 6 mm and 7 mm diameter nests were occupied later in the season. A total of 98 cells from 20 nests were analyzed for the composition of the pollen provisions. Nesting females gathered pollen primarily from Trifolium repens-type (70.2% of total pollen) and the majority of collection of this species occurred between July 25 and August 10. There was also frequent pollen collection from Centaurea stoebe (L.) (9.0%), Rudbeckia-type (8.4%), and Cirsium spp. (8.3%) with the majority of collection from these species occurring after August 10. Our results show that Megachile species at our mid-Michigan site exhibited strong preferences for specific nest hole sizes, and they primarily collected pollen from non-native plants. This information can inform efforts to build local populations of these summer-active bees using combined nesting and foraging resources.

Epeoloides pilosulus (Cresson 1878) (Hymenoptera: Apidae) is one of the rarest bees in North America with only a handful of records since 1960.Epeoloides pilosulus is a brood parasite of Macropis bees, which until recently had not been collected in Michigan since 1944.Bee surveys in Midland County, Michigan have led to the rediscovery of E. pilosulus in this state -the first record in 74 years.Michigan becomes the fourth state where E. pilosulus has been rediscovered after Connecticut in 2006, New York in 2014 and Maine in 2016, and the sixth region in North America after Nova Scotia in 2002 and Alberta in 2010.State-wide bee surveys have also shown that the principal host, Macropis nuda (Provancher 1882), remains widespread in Michigan, and that Macropis patellata Patton 1880 is newly recorded for the state.

Abstract Arthropods provide a variety of critical ecosystem services in agricultural landscapes; however, agricultural intensification can reduce insect abundance and diversity. Designing and managing habitats to enhance beneficial insects requires the identification of effective insectary plants that attract natural enemies and provide floral resources. We tested the attractiveness of 54 plant species with tolerance to dry soils, contrasting perennial forbs and shrubs native to the Great Lakes region to selected non-native species in three common garden experiments in Michigan during 2015–2016. Overall, we found 32 species that attracted significantly more natural enemies than associated controls. Among these, Achillea millefolium and Solidago juncea were consistently among the most attractive plants at all three sites, followed by Solidago speciosa, Coreopsis tripteris, Solidago nemoralis, Pycnanthemum pilosum, and Symphyotrichum oolantangiense. Species which attracted significantly more natural enemies at two sites included: Asclepias syriaca, Asclepias tuberosa, Monarda fistulosa, Oligoneuron rigidum, Pycnanthemum virginianum, Dasiphora fruticosa, Ratibida pinnata, Asclepias verticillata, Monarda punctata, Echinacea purpurea, Helianthus occidentalis, Silphium integrifolium, Silphium terebinthinaceum, Helianthus strumosus, and Symphyotrichum sericeum. Two non-native species, Lotus corniculatus, and Centaurea stoebe, were also attractive at multiple sites but less so than co-blooming native species. Parasitic Hymenoptera were the most abundant natural enemies, followed by predatory Coleoptera and Hemiptera, while Hemiptera (Aphidae, Miridae, and Tingidae) were the most abundant herbivores. Collectively, these plant species can provide floral resources over the entire growing season and should be considered as potential insectary plants in future habitat management efforts.

In response to growing concerns surrounding pollinator health, there have been increased efforts to incorporate wildflower habitat into land management programs, particularly in agricultural systems dependent on bee-mediated pollination. While recommended plant lists abound, there is limited research on which plant species support the greatest bee abundance and diversity. In many farm settings, drought-tolerant plant species adapted to well-drained sandy soils are needed, since wildflower plantings are typically not irrigated. We used a common garden experimental design to evaluate 51 drought-tolerant native perennial plant species, and 2 non-native plant species in three regions of Michigan for their ability to support honey bees (Apis mellifera L. (Hymenoptera: Apidae)) and wild bees. 1,996 honey bees and 2,496 wild bees were recorded visiting study plants. The wild bee community visiting plant species was dominated by Bombus spp. (Hymenoptera: Apidae) (25%), Halictus spp. (Hymenoptera: Halictidae) (23%), and Lasioglossum spp. (Hymenoptera: Halictidae) (16%). The number of honey bees and wild bees visiting study plants varied considerably, suggesting that bee groups have distinct preferences for plant species. Of the plant species assessed, Asclepias syriaca L. (Gentianales: Apocynaceae) (early season), Monarda fistulosa L. (Lamiales: Lamiaceae) (middle season), and Solidago speciosa Nutt. (Asterales: Asteraceae) (late season) were the three most attractive plant species to the entire bee community. Many other plants consistently attracted a high abundance of wild bees, honey bees, or both. Our results inform plant selection to support managed and wild bees as part of pollinator conservation programs in the Great Lakes region of the United States.

Running title: Monarch alternative migration: We collected 434 adult monarchs and surveyed milkweeds for immature monarchs in southwest Michigan, USA in order to test the hypothesis that monarchs are temporally variable, sequential partial migrants rather than partial migrants that may be spatially separated. Adult size, wing wear, female egg counts, fat content and sequestered chemical defenses were measured in monarchs across an entire season from spring migrant arrival, through breeding, until autumn migrant departure. We predicted that a population characterized by starting from all migrants and no residents, through breeding residents, to all migrants and no residents should show life history measures consistent with changes in these proportions. Results show that female monarch spring migrants arrive with chorionated eggs and high wing loads in both intact and fat-extracted adults. Wing loads of both males and females decrease during the summer and increase again immediately before autumn departure, when the fat content of all adults increases markedly. The high fat content of spring arrivals is also characteristic of migrants. Cardenolide content of adults showed a similar pattern of high content in spring arrivals, a decrease in the summer and then an accumulation of cardenolide defenses in adults in late summer just before migratory departure. We conclude that these results are consistent with temporally variable, sequential partial migration in a short-lived insect that contrasts with spatially variable partial migration in longer-lived vertebrates.

The timing of events in the life history of temperate insects is most typically primarily cued by one of two drivers: photoperiod or temperature accumulation over the growing season. However, an insect’s phenology can also be moderated by other drivers like rainfall or the phenology of its host plants. When multiple drivers of phenology interact, there is greater potential for phenological asynchronies to arise between an organism and those with which it interacts. We examined the phenological patterns of a highly seasonal group of fireflies ( Photinus spp , predominantly P. pyralis ) over a 12-year period (2004–2015) across 10 plant communities to determine if interacting drivers could explain the variability observed in the adult flight activity density ( i.e. mating season) of this species. We found that temperature accumulation was the primary driver of phenology, with activity peaks usually occurring at a temperature accumulation of ~800 degree days (base 10°C), however, our model found this peak varied by nearly 180 degree day units among years. This variation could be explained by a quadratic relationship with the accumulation of precipitation in the growing season; in years with either high and low precipitation extremes at our study site, flight activity was delayed. More fireflies were captured in general in herbaceous plant communities with minimal soil disturbance (alfalfa and no-till field crop rotations), but only weak interactions occurred between within-season responses to climatic variables and plant community. The interaction we observed between temperature and precipitation accumulation suggests that, although climate warming has potential to disrupt phenology of many organisms, changes to regional precipitation patterns can magnify these disruptions.