Joshua W. Campbell

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.

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

Abstract 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 <LOD). Within the conditions set forth by our experimental design, our collective data suggest no adverse effects of flupyradifurone on honey bee colonies when following label directions.

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.

Parasitic Beechdrops (Epifagus virginiana): A Possible Ant-Pollinated Plant

Abstract Epifagus virginiana (Beechdrop) is an annual flowering plant that parasitizes Fagus grandifolia (American Beech) roots. The pollination biology of the chasmogamous flowers of E. virginiana is unknown. In September 2011–2012, we observed insect visitors to E. virginiana flowers. Insect visitors included Bombus impatiens, Crematogaster spp., and Prenolepis imparis, but were dominated by P. imparis (over 96% of insect visits). In September 2012, we captured ants (Crematogaster and P. imparis) on E. virginiana flowers in three different areas found in the Coastal Plain and Piedmont physiographic provinces. With the use of 2,5-diphenyl tetrazolium bromide (MTT), we tested E. virginiana pollen from flowers and ant integuments for viability. We observed no significant difference (P > 0.05) between the viability of pollen taken directly from E. virginiana flowers and pollen removed from the ants. Our data suggests that ants can be playing an important role in the pollination of E. virginiana.

Insect Visitors to Flowering Buckwheat, Fagopyrum esculentum (Polygonales: Polygonaceae), in North-Central Florida

Abstract We provide the first extensive documentation of insect visitors to buckwheat (Fagropyrum esculentum Moench; Polygonales: Polygonaceae) in Florida. We visually surveyed eight 2 ha fields of buckwheat in north-central Florida and documented 5,300 visits by Apis mellifera L. (Hymenoptera: Apidae)—the western honey bee—and 3,422 non-Apis insect visits, with the majority of non-Apis visitors being wasps native to Florida or the southeastern United States (81.3%), followed by Diptera (12.5%) and non-Apis bees (5.8%). Sixteen families of insects composed of at least 62 species of flower visitors were observed within the buckwheat fields, with the most common species being the wasp Scolia nobilitata F. (Hymenoptera: Scoliidae). Most of the insect species were parasitoid wasps of various arthropod pests, and many parasitoids may also act as pollinators. Our data suggest that buckwheat attracts a great diversity of beneficial parasitoids, predators, and pollinators; thus, buckwheat possibly could be used as a cover crop to enhance biological control of various pest arthropods within cropping systems or augment local pollinator populations.

Insect community response to switchgrass intercropping and stand age of loblolly pine (Pinus taeda) plantations

Intercropping switchgrass (Panicum virgatum) between rows in managed pine stands is a potential, emerging method for biofuel feedstock production in forestry systems. Switchgrass intercropping likely alters vegetation characteristics within a stand by increasing herbaceous vegetation cover and thus influences insect communities positively. However, its effect may vary with stand age, which often determines canopy closure and vegetation structure within a stand: effects of switchgrass intercropping may be stronger in old pine stands with a closed canopy than in young pine stands with an open canopy. We examined how switchgrass intercropping and stand age, namely 3–4‐year‐old pine (YPine) and 8–9‐year‐old pine (OPine), influenced insect abundance and diversity in loblolly pine (Pinus taeda) stands in Mississippi, U.S.A., during May to August 2013–2014. We captured insects at 36 locations throughout 12 stands (three stands per each of four treatments; intercropping and non‐intercropping treatment in YPine and OPine stands), using pan traps. Abundance and family level richness were greater in YPine stands and Shannon–Wiener diversity and evenness at family level was higher in OPine stands both years. However, insect abundance and diversity did not differ between intercropping and non‐intercropping treatments. Community composition was also influenced by stand age, which explained > 90% of constrained inertia, rather than switchgrass intercropping. Our findings suggest that switchgrass intercropping is unlikely to significantly affect insect communities in managed pine stands, whereas stand age, as well as associated successional changes, can be a main factor affecting insects, as often observed in other animal taxa in managed pine landscapes.

Managed Bumble Bees (Bombus impatiens) (Hymenoptera: Apidae) Caged With Blueberry Bushes at High Density Did Not Increase Fruit Set or Fruit Weight Compared to Open Pollination

Abstract Highbush blueberry (Vaccinium corymbosum L.) is an important crop grown throughout Florida. Currently, most blueberry growers use honey bees (Apis mellifera L.) to provide pollination services for highbush blueberries even though bumble bees (Bombus spp.) have been shown to be more efficient at pollinating blueberries on a per bee basis. In general, contribution of bumble bees to the pollination of commercial highbush blueberries in Florida is unknown. Herein, we determined if managed bumble bees could contribute to highbush blueberry pollination. There were four treatments in this study: two treatments of caged commercial bumble bee (Bombus impatiens Cresson) colonies (low and high weight hives), a treatment excluding all pollinators, and a final treatment which allowed all pollinators (managed and wild pollinators) in the area have access to the plot. All treatments were located within a highbush blueberry field containing two cultivars of blooming plants, ‘Emerald’ and ‘Millennia’, with each cage containing 16 mature blueberry plants. We gathered data on fruit set, berry weight, and number of seeds produced per berry. When pollinators were excluded, fruit set was significantly lower in both cultivars (<8%) compared to that in all of the other treatments (>58%). Berry weight was not significantly different among the treatments, and the number of seeds per berry did not show a clear response. This study emphasizes the importance of bumble bees as an effective pollinator of blueberries and the potential beneficial implications of the addition of bumble bees in commercial blueberry greenhouses or high tunnels.

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.

Managed and Wild Bee Flower Visitors and Their Potential Contribution to Pollination Services of Low-Chill Highbush Blueberry (Vaccinium corymbosum L.; Ericales: Ericaceae)

Abstract Highbush blueberry (Vaccinium corymbosum L.; Ericales: Ericaceae) is an important crop grown throughout the eastern United States and Canada. Cross-pollination by insects greatly enhances pollination and fruit set in highbush blueberry. In Florida, low-chill cultivars that flower during the winter when most bees are dormant are used, thus, making it difficult to utilize and depend on unmanaged bees. We investigated flower visitation rates by managed and wild bees and the subsequent berry formation, berry weight, and number of seeds/berry in highbush blueberry fields in north-central Florida. Additionally, we tested three pollinator treatments: 1) pollinator-excluded flowers, 2) open-pollinated treatments that were available to managed and wild bees, and 3) flowers that were hand pollinated. Overall, we found seven native bee species that contribute to highbush blueberry pollination in Florida, but managed honey bees and bumble bees were the main flower visitors. Additionally, 14.5 times more blueberries formed in the open treatments than in the pollinator exclusion treatments, thus illustrating the economic impact bees have on blueberry pollination. Most of the wild bees observed visiting blueberry flowers were ground-nesting species that need uncultivated areas for nesting sites.Therefore, leaving field edges uncultivated and some undisturbed habitat may increase native bee numbers within blueberry farms over time.

The Introduction and Establishment of Campsomeris dorsata (Hymenoptera: Scoliidae) in Florida

Summary Campsomeris dorsata is a hymenopteran scoliid that is endemic to South America, Central America, and parts of the West Indies. It has been used as a biological control agent in the past in Puerto Rico, Mauritius, and Florida to aid in reducing coleopteran pests in sugar cane agricultural systems. The status of C. dorsatas establishment in Florida has been unknown since intentional introductions to sugar cane fields occurring during the 1930s. We surveyed primarily coastal sites throughout the state of Florida and captured 91 females ranging from Osceola County to Miami-Dade County (north vs south) and from Broward County to Collier County (east vs west). The results from this study show that C. dorsata is well established in these areas of Florida, and might still be an important biological control agent of white grubs in sugar cane as well as turf production and maintenance.