Patricia R. Knight

Distribution of Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in Mississippi

Abstract An extensive monitoring and survey program in Mississippi was conducted from 2000 to 2004 to investigate the distribution of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Seventy-two towns from 22 counties in southern Mississippi were monitored with a total of 3914 traps that catch alates during the swarming season. In addition, 259 licensed pest management professionals in Mississippi were surveyed to determine the locations of termite infestations treated. The alates of C. formosanus were recovered in 12 counties with light traps, and termite infestations were documented in an additional 13 from data collected in the termite survey. Infestations of C. formosanus have been documented in urban, urban cluster, rural, and forested areas of Mississippi. However, the distribution in mean total capture of alates for 4 yr differed significantly among the four ecological areas with the highest percentage in forested areas (31%) and the lowest percentage in urban cluster areas (17%). Most of the infestations of C. formosanus were geographically distributed along the coastal areas of southern Mississippi from Gulfport to Pascagoula. The greatest total number of alates captured in light traps was documented in Pearl River County. Mass swarming of C. formosanus occurred primarily in May or June, depending on weather conditions. The number of documented counties with the evidence of large and widely dispersed swarms of C. formosanus in different ecological areas, and the increase in total annual alate captures from 2000 to 2003, suggest that this invasive termite species is now firmly established in Mississippi.

Powdered sugar shake to monitor and oxalic acid treatments to control varroa mites (Varroa destructor Anderson and Trueman) in honey bee (Apis mellifera) colonies

A practical method to control the destructive varroa mite, Varroa destructor Anderson and Trueman in honey bee colonies consisted of monitoring with powdered sugar and treatment with oxalic acid (OA). We tested mite populations within 28 honey bee colonies on adult bees by a using a powdered sugar shake method. Subsequently, the same colonies were treated with 2.9% oxalic acid and 31.9% sucrose-in-water solution (w/w) four times, with a final varroa treatment using Apistan strips. On average 66.10 ± 35.23% and 94.64 ± 9.56% mites were detected using this simple sugar shake method in August and October, 2015. Furthermore, positive correlations were found between relative number of infested honey bees detected by powdered sugar shake and washing bees with alcohol plus soapy water (r = 0.90 and r = 0.62). Temperature and humidity seems to be crucial in determining the effectiveness of the powdered sugar shake method. For control of the mites, four consecutive OA treatments performed during the winter months in colonies containing capped brood had an average of 228 ± 226.93, 167 ± 313.79, 92 ± 160.50, and 27 ± 42.19 varroa mortality, respectively. Combination of four successive OA applications by trickling onto adult bees between combs in situ, during warm temperate winter conditions ensured a cumulative efficacy of 98%. Based on this level of mortality, it can be concluded that using the powdered sugar shake method to establish adult bee infestation levels in colonies along with an OA treatment may provide adequate varroa control in certain situations.

Brood removal or queen caging combined with oxalic acid treatment to control varroa mites (Varroa destructor) in honey bee colonies (Apis mellifera)

Few studies of honey bee colonies exist where varroa mite control is achieved by integrating broodless conditions, through either total brood removal or queen caging, in combination with oxalic acid (OA) applications. We observed significant varroa mortality after total brood removal or caging the queens and OA applications in broodless colonies, as well as in colonies with brood that received four consecutive OA applications. In laboratory tests, we recorded higher mortality of caged bees exposed to Apistan® compared to oxalic acid or untreated control bees. However, this mortality is not believed to negatively impact the colony. We therefore recommend combining OA applications with artificial broodless colony conditions achieved either by brood removal or queen caging as an effective management strategy for varroa mites.

Effects of coumaphos and imidacloprid on honey bee (Hymenoptera: Apidae) lifespan and antioxidant gene regulations in laboratory experiments

The main objective of this study was to test comparatively the effects of two common insecticides on honey bee Apis mellifera worker’s lifespan, food consumption, mortality, and expression of antioxidant genes. Newly emerged worker bees were exposed to organophosphate insecticide coumaphos, a neonicotinoid imidacloprid, and their mixtures. Toxicity tests were conducted along with bee midgut immunohistological TUNEL analyses. RT-qPCR assessed the regulation of 10 bee antioxidant genes linked to pesticide toxicity. We tested coumaphos at 92,600 ppb concentration, in combination with 5 and 20 ppb imidacloprid. Coumaphos induced significantly higher bee mortality, which was associated with down regulation of catalase compared to coumaphos and imidacloprid (5/20 ppb) mixtures, whereas, both imidacloprid concentrations independently had no effect on bee mortality. Mixture of coumaphos and imidacloprid reduced daily bee consumption of a control food patty to 10 mg from a coumaphos intake of 14.3 mg and 18.4 and 13.7 mg for imidacloprid (5 and 20) ppb, respectively. While coumaphos and imidacloprid mixtures induced down-regulation of antioxidant genes with noticeable midgut tissue damage, imidacloprid induced intensive gene up-regulations with less midgut apoptosis.

Toxicity of Selected Acaricides to Honey Bees (Apis mellifera) and Varroa (Varroa destructor Anderson and Trueman) and Their Use in Controlling Varroa within Honey Bee Colonies

The efficacies of various acaricides in order to control a parasitic mite, the Varroa mite, Varroa destructor, of honey bees, were measured in two different settings, namely, in laboratory caged honey bees and in queen-right honey bee colonies. The Varroa infestation levels before, during, and after the acaricide treatments were determined in two ways, namely: (1) using the sugar shake protocol to count mites on bees and (2) directly counting the dead mites on the hive bottom inserts. The acaricides that were evaluated were coumaphos, tau-fluvalinate, amitraz, thymol, and natural plant compounds (hop acids), which were the active ingredients. The acaricide efficacies in the colonies were evaluated in conjunction with the final coumaphos applications. All of the tested acaricides significantly increased the overall Varroa mortality in the laboratory experiment. Their highest efficiencies were recorded at 6 h post-treatment, except for coumaphos and thymol, which exhibited longer and more consistent activity. In the honey bee colonies, a higher Varroa mortality was recorded in all of the treatments, compared with the natural Varroa mortality during the pretreatment period. The acaricide toxicity to the Varroa mites was consistent in both the caged adult honey bees and workers in the queen-right colonies, although, two of these acaricides, coumaphos at the highest doses and hop acids, were comparatively more toxic to the worker bees.

Species and Media Effects on Soil Carbon Dynamics in the Landscape.

Three woody shrub species [cleyera (Ternstroemia gymnanthera Thunb. ‘Conthery’), Indian hawthorn (Rhaphiolepis indica L.) and loropetalum (Loropetalum chinensis Oliv.‘Ruby’)] were container-grown for one growing season in 2008 using either pinebark (industry standard), clean chip residual or WholeTree (derived by-products from the forestry industry) as potting substrates and then transplanted into the landscape in 2008. An Automated Carbon Efflux System was used to continually monitor soil CO2 efflux from December 2010 through November 2011 in each species and substrate combination. Changes in soil carbon (C) levels as a result of potting substrate were assessed through soil sampling in 2009 and 2011 and plant biomass was determined at study conclusion. Results showed that soil CO2-C efflux was similar among all species and substrates, with few main effects of species or substrate observed throughout the study. Soil analysis showed that plots with pinebark contained higher levels of soil C in both 2009 and 2011, suggesting that pinebark decomposes slower than clean chip residual or WholeTree and consequently has greater C storage potential than the two alternative substrates. Results showed a net C gain for all species and substrate combinations; however, plants grown in pinebark had greater C sequestration potential.