Invertebrate community response to coarse woody debris removal for bioenergy production from intensively managed forests.

Increased market viability of harvest residues as forest bioenergy feedstock may escalate removal of coarse woody debris in managed forests. Meanwhile, many forest invertebrates use coarse woody debris for cover, food, and reproduction. Few studies have explicitly addressed effects of operational-scale woody biomass harvesting on invertebrates following clearcutting. Therefore, we measured invertebrate community response to large-scale harvest residue removal and micro-site manipulations of harvest residue availability in recently clearcut, intensively managed loblolly pine (Pinus taeda) forests in North Carolina (NC; n = 4) and Georgia (GA; n = 4), USA. We captured 39,794 surface-active invertebrates representing 171 taxonomic groups using pitfall traps situated among micro-site locations (i.e., purposefully retained piles of hardwood stems and piles of conifer stems and areas without coarse woody debris in NC; windrows and no windrows in GA). Micro-site locations were located within six, large-scale treatments (7.16-14.3 ha) in clearcuts. Large-scale treatments represented intensive harvest residue removal, 15% and 30% harvest residue retention, and no harvest residue removal. In NC, ground beetles (Coleoptera: Carabidae) and crickets (Orthoptera: Gryllidae) were three times more abundant in treatments with no harvest residue removal than those with the most intensive harvest residue removal and were reduced in treatments that retained 15% or 30% of harvest residues, although not significantly. Invertebrate taxa richness was greater at micro-site locations with retained hardwood and pine (Pinus spp.) harvest residues than those with minimal amounts of coarse woody debris. In both states, relative abundances of several invertebrate taxa, including cave crickets (Orthoptera: Rhaphidophoridae), fungus gnats (Diptera: Mycetophilidae and Sciaridae), millipedes (Diplopoda), and wood roaches (Blattodea: Ectobiidae), were greater at micro-site locations with retained harvest residues than those with minimal coarse woody debris. Intensified woody biomass harvesting without retention of ≥15% of harvest residue volume may reduce invertebrate taxa richness and abundances of some key invertebrate taxa in regenerating stands. Further, harvest residue management during and after woody biomass harvesting may be an important consideration for maintaining invertebrate diversity and conserving invertebrates that are influential in the maintenance of ecosystem function and integrity in young forests.

Integrated vegetation management within electrical transmission landscapes promotes floral resource and flower-visiting insect diversity.

Electrical transmission rights-of-way are ubiquitous and critical infrastructure across the landscape. Active vegetation management of these rights-of-way, a necessity to deliver electricity more safely, maintains these landscape features as stages of early successional habitat, a rarity in many regions, making these areas viable movement corridors for many taxa. The goals of this study were to (i) evaluate the effects of different electrical transmission landscape management practices on flowering plant and flower-visiting insect diversity parameters and (ii) generate conservation management inferences for these landscapes. In this study we tested the impact of three vegetation management levels across 18 electrical transmission sites. We evaluated the effects of treatment on bloom abundance and species richness as well as flower-visiting insect abundance and family richness. We identified 76541 flowers/inflorescences across 456 transects, including 188 species in 56 plant families. Additionally, we obtained data on 11361 flower-visitoring insects representing 33 families from 2376 pan trap sets. High vegetation management favored the reduction of coarse woody debris in the sites and harbored the highest level of abundance and richness of both floral resources and flower-visiting insects. We discuss that we can align social and ecological values of rights-of-way, ensuring their sustainability by applying regular and targeted integrated vegetation management. Thus, we can use rights-of-way landscapes not only as an effective management strategy for the delivery of essential human services, but also to provide conservation benefits for wild pollinators.

Artificial pollination of kiwifruit (Actinidia chinensis Planch. var. chinensis) (Ericales: Actinidiaceae) results in greater fruit set compared to flowers pollinated by managed bees (Apis mellifera L. (Hymenoptera: Apidae) and Bombus impatiens Cresson (Hymenoptera: Apidae)).

Due to a lack of knowledge on the pollination requirements of kiwifruit cultivars grown within the United States, farmers simultaneously implement multiple pollination methods, like the rental of managed bee species or artificial pollination to achieve high fruit yields. However, implementing multiple pollination methods is costly and possibly an inefficient use of resources. We assessed the contribution of two managed bees (Apis mellifera and Bombus impatiens) to the pollination of kiwifruit by i) determining the relative abundance of kiwifruit pollen collected by foragers of each bee species, and ii) comparing fruit set and fruit quality among insect and artificially pollinated flowers through an insect exclusion experiment. A significant difference was observed between the mean relative abundance of kiwifruit pollen carried in the corbicula of A. mellifera and B. impatiens, with B. impatiens carrying on average 46% more kiwifruit pollen than A. mellifera. Artificially pollinated kiwifruit flowers set significantly greater numbers of fruit per flower at four weeks post-bloom and at harvest compared to insect pollination, wind pollination, and pollen exclusion treatment. Artificial pollination produced fruits of greater weight, size, and seed number compared to insect-pollinated flowers, and few fruits were produced in the pollen exclusion and wind pollination treatments. Kiwifruit producers experiencing similar conditions to ours should focus on artificially pollinating their crops rather than relying on managed or wild insects for kiwifruit pollination. Future research should evaluate other methods of artificial pollination to determine their effectiveness, efficiency, and economics in the pollination of kiwifruit grown within the United States.

CropPol: A dynamic, open and global database on crop 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).

The Pollination and Fruit Quality of Two Kiwifruit Cultivars (Actinidia chinensis var. chinensis 'AU Golden Sunshine' and 'AU Gulf Coast Gold') (Ericales: Actinidiaceae) Grown in the Southeastern United States.

Kiwifruit is a new emerging crop for the southeastern United States that requires cross-pollination to set fruit. However, the pollination requirements for varieties grown in the southeastern United States are unknown. Through insect surveys and a bagging experiment, we assessed the pollination requirements of two female kiwifruit cultivars (Actinidia chinensis var. chinensis 'AU Golden Sunshine' and A. chinensis var. chinensis 'AU Gulf Coast Gold'). For each, fruit quantity (fruit set) and fruit quality (weight, size, seed count, firmness, soluble solid content, and dry matter) were compared among three pollination treatments (wind, insect, and artificial pollination). Low abundances of insects were observed visiting female flowers of both kiwifruit cultivars, and therefore likely minimally influenced kiwifruit pollination. Artificial pollination resulted in the greatest percentages of fruit set and marketable fruits, followed by insect and wind pollination. Artificial pollination resulted in fruits that were greater in weight, size, and contained more seeds, than insect- and wind-pollinated fruits. Firmness and soluble solid content did not vary greatly between pollination treatments, yet were greater in 'AU Golden Sunshine'. Dry matter content did not vary greatly between pollination treatments or between each cultivar. To maximize yields and optimize fruit quality, these results suggest that kiwifruit producers should place more effort into artificial pollination compared to wind and insect pollination. Future research should explore the use of managed bees (e.g., honey bees and bumble bees) within kiwifruit orchards to determine ways to utilize them as a secondary source for pollination needs.

Bees and flowers: How to feed an invasive beetle species.

Invasive species may exploit a wide range of food sources, thereby fostering their success and hampering mitigation, but the actual degree of opportunism is often unknown. The small hive beetle (SHB), Aethina tumida, is a parasite of honeybee colonies endemic to sub-Saharan Africa. SHBs have now spread on all habitable continents and can also infest colonies of other social bees. To date, the possible role of solitary bee nests as alternative hosts is unknown. Similarly, flowers as possible alternative food sources are not well understood. Here, we show that SHBs can complete an entire life cycle in association with nests of solitary bees Megachile rotundata. The data also show that flowers can serve as alternative food sources. These results support the opportunistic nature of this invasive species, thereby generating further obstacles for mitigation efforts in the field. It also suggests that SHB invasions may result in more serious consequences for endemic bee fauna than previously thought. This provides further motivation to slow down the global spread of this pest, and to improve its management in areas, where it is established.

The Health of Commercial Bombus impatiens (Hymenoptera: Apidae) Colonies After Foraging in Florida Watermelon and Blueberry.

Bumble bees are commonly used to provide pollination services within crop fields and greenhouses, with Bombus impatiens Cresson; Hymenoptera: Apidae, a bee native to the eastern United States, being the only managed bumble bee available commercially in the United States. Although many researchers have explored managed bumble bees' ability to pollinate various crops and the potential spread of pathogens by managed bumble bees, scant research is available on how managed bumble bee colony health is affected after foraging within crop fields. We measured 10 B. impatiens colony health parameters: 1) colony weight; number of 2) honey/pollen pots, 3) workers, 4) queens, 5) drones, 6) immatures, 7) eggs; and weight of 8) workers, 9) drones, and 10) queens from colonies that foraged within blueberry or watermelon fields, and compared them to control colonies that were purchased and immediately frozen upon receipt. Bees that foraged within blueberry increased in colony weight and in the number of immatures and eggs during the bloom period compared to control colonies. In contrast, bee colonies placed within watermelon decreased in colony weight, number of workers and immature bees, and individual bee weight compared to control colonies. Blueberry appeared to provide bees with sufficient nectar and pollen, whereas watermelon may not have provided adequate resources for the bees. Bees foraging within watermelon were probably forced to search for other sources of pollen and nectar, resulting in colony health parameter declines. Our data suggest that some crops (e.g., blueberry) can support managed B. impatiens, potentially adding to localized bumble bee populations, while others (e.g., watermelon) cannot.

Fruit Set and Single Visit Stigma Pollen Deposition by Managed Bumble Bees and Wild Bees in Citrullus lanatus (Cucurbitales: Cucurbitaceae).

Pollinators provide essential services for watermelon, Citrullus lanatus (Thunb.; Cucurbitales: Cucurbitaceae). Managed bumble bees, Bombus impatiens (Cresson; Hymenoptera: Apidae), have been shown to be a useful watermelon pollinator in some areas. However, the exact contribution bumble bees make to watermelon pollination and how their contribution compares to that of other bees is unclear. We used large cages (5.4 × 2.5 × 2.4 m) to confine bumble bee hives to watermelon plants and compared fruit set in those cages to cages containing watermelons but no pollinators, and to open areas of field next to cages (allows all pollinators). We also collected data on single visit pollen deposition onto watermelon stigmas by managed bumble bees, honey bees, and wild bees. Overall, more fruit formed within the open cages than in cages of the other two treatment groups. B. impatiens and Melissodes spp. deposited the most pollen onto watermelon stigmas per visit, but all bee species observed visiting watermelon flowers were capable of depositing ample pollen to watermelon stigmas. Although B. impatiens did deposit large quantities of pollen to stigmas, they were not common within the field (i.e., outside the cages) as they were readily drawn to flowering plants outside of the watermelon field. Overall, bumble bees can successfully pollinate watermelon, but may be useful in greenhouses or high tunnels where watermelon flowers have no competition from other flowering plants that could draw bumble bees away from watermelon.

Trap Nesting Wasps and Bees in Agriculture: A Comparison of Sown Wildflower and Fallow Plots in Florida.

Wildflower strip plantings in intensive agricultural systems have become a widespread tool for promoting pollination services and biological conservation because of their use by wasps and bees. Many of the trap-nesting wasps are important predators of common crop pests, and cavity-nesting bees that utilize trap-nests are important pollinators for native plants and many crops. The impact of wildflower strips on the nesting frequency of trap-nesting wasps or bees within localized areas has not been thoroughly investigated. Trap-nests made of bamboo reeds (Bambusa sp.) were placed adjacent to eight 0.1 ha wildflower plots and paired fallow areas (control plots) to determine if wildflower strips encourage the nesting of wasps and bees. From August 2014 to November 2015, occupied reeds were gathered and adults were collected as they emerged from the trap-nests. Treatment (wildflower or fallow plots) did not impact the number of occupied reeds or species richness of trap-nesting wasps using the occupied reeds. The wasps Pachodynerus erynnis, Euodynerus megaera, Parancistrocerus pedestris, and Isodontia spp. were the most common trap-nesting species collected. Less than 2% of the occupied reeds contained bees, and all were from the genus Megachile. The nesting wasp and bee species demonstrated preferences for reeds with certain inside diameters (IDs). The narrow range of ID preferences exhibited by each bee/wasp may provide opportunities to take advantage of their natural histories for biological control and/or pollination purposes.

Switchgrass (Panicum virgatum) Intercropping within Managed Loblolly Pine (Pinus taeda) Does Not Affect Wild Bee Communities.

Intensively-managed pine (Pinus spp.) have been shown to support diverse vertebrate communities, but their ability to support invertebrate communities, such as wild bees, has not been well-studied. Recently, researchers have examined intercropping switchgrass (Panicum virgatum), a native perennial, within intensively managed loblolly pine (P. taeda) plantations as a potential source for cellulosic biofuels. To better understand potential effects of intercropping on bee communities, we investigated visitation of bees within three replicates of four treatments of loblolly pine in Mississippi, U.S.A.: 3-4 year old pine plantations and 9-10 year old pine plantations with and without intercropped switchgrass. We used colored pan traps to capture bees during the growing seasons of 2013 and 2014. We captured 2507 bees comprised of 18 different genera during the two-year study, with Lasioglossum and Ceratina being the most common genera captured. Overall, bee abundances were dependent on plantation age and not presence of intercropping. Our data suggests that switchgrass does not negatively impact or promote bee communities within intensively-managed loblolly pine plantations.

An Evaluation of the Honey Bee (Hymenoptera: Apidae) Safety Profile of a New Systemic Insecticide, Flupyradifurone, Under Field Conditions in Florida.

Flupyradifurone (Sivanto) is a novel systemic insecticide from the butenolide class developed by Bayer. Based on available data (USEPA 2014), this insecticide appears to have a favorable safety profile for honey bee colonies. As a result, the label permits the product to be applied during prebloom and bloom in various crops, including citrus, except when mixed with azole fungicides during the blooming period. We placed 24 honey bee (Apis mellifera L.) colonies adjacent to eight flowering buckwheat (Fagopyrum esculentum Moench) fields that either had been sprayed with the maximum label rate of flupyradifurone or with water only (control fields), with three colonies placed adjacent to each field. We conducted colony strength assessments during which the number of adult bees, eggs, uncapped brood cells, capped brood cells, food storage cells, and weights of honey supers and brood chambers were determined prior to, during, and after the flowering period. We also analyzed bee-collected pollen and nectar for flupyradifurone residues. Overall, there were no differences in any colony strength parameter for colonies placed at control and flupyradifurone-treated buckwheat fields. Residue analyses showed that pollen (x = 565.8 ppb) and nectar (x = 259.4 ppb) gathered by bees on fields treated with flupyradifurone contained significantly higher flupyradifurone residues than did bee bread and unprocessed nectar collected by bees from control fields (75% of samples

Heavy metal and selenium concentrations in liver tissue from wild American alligator (Alligator mississippiensis) livers near Charleston, South Carolina.

Liver samples from 33 wild American alligators (Alligator mississippiensis) livers from the Charleston, South Carolina, area were analyzed for arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), nickel (Ni), lead (Pb), and selenium (Se) concentrations. Alligators are top predators and are considered a good biomonitoring species for various toxins, including heavy metals. Alligators from other areas in the US have shown high concentrations of mercury and other heavy metals, but the Charleston area, which is highly industrialized, has not been investigated. We found wide variation in hepatic heavy metal and selenium concentrations among alligators. Length and sex did not show a strong relationship with any metal based on statistical analysis. However, cluster analysis revealed three groupings of alligators based on liver metal concentrations. Alligators with low Se:Hg ratios also had high concentrations of Hg. Due to the wide variation in metal concentrations among individual alligators, we postulate that individual diet and microhabitat usage could be the cause for this variation.