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Results for “Journal of Applied Entomology”

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6 recordsLinked to original sources
USGS2018

Distance models as a tool for modelling detection probability and density of native bumblebees

Effective monitoring of native bee populations requires accurate estimates of population size and relative abundance among habitats. Current bee survey methods, such as netting or pan trapping, may be adequate for a variety of study objectives but are limited by a failure to account for imperfect detection. Biases due to imperfect detection could result in inaccurate abundance estimates or erroneous insights about the response of bees to different environments. To gauge the potential biases of currently employed survey methods, we compared abundance estimates of bumblebees ( Bombus spp.) derived from hierarchical distance sampling models (HDS) to bumblebee counts collected from fixed‐area net surveys (“net counts”) and fixed‐width transect counts (“transect counts”) at 47 early‐successional forest patches in Pennsylvania. Our HDS models indicated that detection probabilities of Bombus spp. were imperfect and varied with survey‐ and site‐covariates. Despite being conspicuous, Bombus spp. were not reliably detected beyond 5 m. Habitat associations of Bombus spp. density were similar across methods, but the strength of association with shrub cover differed between HDS and net counts. Additionally, net counts suggested sites with more grass hosted higher Bombus spp. densities whereas HDS suggested that grass cover was associated with higher detection probability but not Bombus spp. density. Density estimates generated from net counts and transect counts were 80%–89% lower than estimates generated from distance sampling. Our findings suggest that distance modelling provides a reliable method to assess Bombus spp. density and habitat associations, while accounting for imperfect detection caused by distance from observer, vegetation structure, and survey covariates. However, detection/non‐detection data collected via point‐counts, line‐transects and distance sampling for Bombus spp. are unlikely to yield species‐specific density estimates unless individuals can be identified by sight, without capture. Our results will be useful for informing the design of monitoring programs for Bombus spp. and other pollinators.

Pennsylvania↗
USGS2017

Acquisition of Borrelia burgdorferi infection by larval Ixodes scapularis (Acari: Ixodidae) associated with engorgement measures

Measuring rates of acquisition of the Lyme disease pathogen, Borrelia burgdorferi sensu lato Johnson, Schmid, Hyde, Steigerwalt & Brenner, by the larval stage of Ixodes scapularis Say is a useful tool for xenodiagnoses of B. burgdorferi in vertebrate hosts. In the nymphal and adult stages of I. scapularis , the duration of attachment to hosts has been shown to predict both body engorgement during blood feeding and the timing of infection with B. burgdorferi . However, these relationships have not been established for the larval stage of I. scapularis . We sought to establish the relationship between body size during engorgement of larval I. scapularis placed on B. burgdorferi- infected, white-footed mice ( Peromyscus leucopus Rafinesque) and the presence or absence of infection in larvae sampled from hosts over time. Body size, time, and their interaction were the best predictors of larval infection with B. burgdorferi . We found that infected larvae showed significantly greater engorgement than uninfected larvae as early as 24 h after placement on a host. These findings may suggest that infection with B. burgdorferi affects the larval feeding process. Alternatively, larvae that engorge more rapidly on hosts may acquire infections faster. Knowledge of these relationships can be applied to improve effective xenodiagnosis of B. burgdorferi in white-footed mice. Further, these findings shed light on vector–pathogen–host interactions during an understudied part of the Lyme disease transmission cycle.

Journal of Medical Entomology↗
USGS2008

Dispersal of Culex quinquefasciatus (Diptera: Culicidae) in a Hawaiian rain forest

Introduced mosquito-borne pathogens avian malaria (Plasmodium relictum Grassi and Feletti) and avian pox virus (Avipoxvirus) have been implicated in the past extinctions and declines of Hawaiian avifauna and remain significant obstacles to the recovery and restoration of endemic Hawaiian birds. Effective management of avian disease will require extensive mosquito control efforts that are guided by the local ecology of the vector Culex quinquefasciatus Say (Diptera: Culicidae). During October and November 1997 and September through November 1998 five mark-release-recapture experiments with laboratory-reared Cx. quinquefasciatus were conducted in a native rain forest on Hawaii Island. Of the overall 66,047 fluorescent dye-marked and released females, 1,192 (1.8%) were recaptured in 43-52 CO2-baited traps operated for 10-12-d trapping periods. Recaptured mosquitoes were trapped in all directions and at distances up to 3 km from the release site. The cumulative mean distance traveled (MDTs) over the trapping period ranged from a high of 1.89 km after 11 d (September 1998) to a low of 0.81 km after 11 d (November 1998). Released mosquitoes moved predominately in a downwind direction and they seemed to use forestry roads as dispersal corridors. Applying an estimated MDT of 1.6 km to a geographical information system-generated map of the Hakalau Forest National Wildlife Refuge clearly demonstrated that the effective refuge area could be reduced 60% by mosquitoes infiltrating into managed refuge lands. These findings should have significant implications for the design of future refuges and development of effective mosquito-borne avian disease control strategies.

Journal of Medical Entomology↗
USGS2005

Reservoir competence of native North American birds for the Lyme disease spirochete, Borrelia burgdorferi

Reservoir competence for the Lyme disease spirochete, Borrelia burgdorferi , was tested for six species of native North American birds: American robin, gray catbird, brown thrasher, eastern towhee, song sparrow, and northern cardinal. Wild birds collected by mist netting on Fire Island, NY, were held in a field laboratory in cages over water and locally collected larval ticks were placed on the birds, harvested from the water after engorgement, and tested for infection by direct fluorescent-antibody staining after molting to the nymphal stage. American robins were competent reservoirs, infecting 16.1% of larvae applied to wild-caught birds, compared with 0% of control ticks placed on uninfected laboratory mice. Robins that were previously infected in the laboratory by nymphal feeding infected 81.8% of applied larvae. Wild-caught song sparrows infected 4.8% of applied larvae and 21.1% when infected by nymphal feeding. Results suggest moderate levels of reservoir competence for northern cardinals, lower levels for gray catbirds, and little evidence of reservoir competence for eastern towhees or brown thrashers. Lower infection rates in larvae applied to wild-caught birds compared with birds infected in the laboratory suggest that infected birds display temporal variability in infectiousness to larval ticks. Engorged larvae drop from birds abundantly during daylight, so the abundance of these bird species in the peridomestic environment suggests that they might contribute infected ticks to lawns and gardens.

Journal of Medical Entomology↗
USGS1969

Toxicity of Zectran insecticide to several wildlife species

Zectran® (4-dimethylamino-3,5-xylyl methycarbamate), all insecticide proposed for control of spruce budworm, Choristoneura fumiferana (Clemens), was tested against 16 species of pen-reared or captivity-acclimated animals to determine its toxicity and potential hazard to wildlife. The acute oral LD 60 values in mg/kg were: lesser sandhill crane, Grus canadensis canadensis L.., 1.0-4.5; Canada goose, Branta canadensis L.., 2.64; mourning dove, Zenaidura macroura L.., 2.83; mallard duck, Anas platyrhyndura L.., 3.0; coturnix quail, Coturnix coturnix japonica (Teminck & Schlep get), 3.21; mallard duckling 4.2; ring-necked pheasant, Phasianus colchicus L.., 4.5; house finch, Garpodacus mexicanus (Müller), 4.76; chukar partridge, Alectoris graeca (Meisner), 5.24; domestic pigeon, Columba livia (Gmelin), 6.47; sharp-tailed grouse, Pedioecetes phasianellus L.., 10.0; albino Sprague-Dawley rat, Rattus noruegicis (Fischer), 14.1; domestic goat, Capra aegagnzs L., 15.0-30.0; mule deer, Odocoileus hemionus (Rafinesque), 20.0-30.0; house (English) sparrow, Passer domesticus 1.., 50.4; and bullfrog, Rana catesbeiana (Shaw), 283.0-800.0. In general, birds were more susceptible to single oral doses than mammals and reacted more quickly to intoxication and were more quickly affected. In both groups, the first easily recognized symptom of Zectran poisoning was an increase in the respiratory rate. Deaths appeared to occur from respiratory failure following tachypnea and Cheyne-Stokes respiration. Zectran did not show any marked cumulative effect in subacute oral tests with mallards, chukars, and mule deer. The animals were able to tolerate up to about 40% of a single oral LD 50 dose per day for 30 days, and there was some evidence of a low degree of acquired resistance. Zectran applied dermally to albino New Zealand rabbits, Oryctolagus cuniculus (Lilljeborg), at 2000 mg/kg produced no discernible effects. The reproduction of chukars surviving repeated daily doses of Zectran was similar to that of controls. Low application rates, rapid degradation, low dermal toxicity, and the low degree of cumulative toxic action indicate that little hazard to wildlife should result under field conditions, even though Zectran is highly toxic in acute oral tests.

Journal of Economic Entomology↗
USGS2021

Field-level exposure of bumble bees to fungicides applied to a commercial cherry orchard

Bumble bees, Bombus spp. (Apidae), are important native pollinators; however, populations of some species are declining in North America and agricultural chemicals are a potential cause. Fungicides are generally not highly toxic to bees, but little is known about sublethal or synergistic effects. This study evaluates bumble bee exposure to fungicides by quantifying concentrations of boscalid and pyraclostrobin in nectar and pollen collected by colonies of Bombus huntii Greene, 1860 (Hunt bumble bee) deployed in a commercial cherry Prunus avium L. orchard in the spring of 2016. Seven colonies were placed adjacent to an orchard block that was sprayed with a fungicide mixture of boscalid and pyraclostrobin and a control group of seven colonies was placed next to an unsprayed block of orchard 400 m away from the treated block. Nectar and pollen were collected daily, beginning 1 d before spray application and continuing for a total of 12 d, and analyzed for both fungicides. Fungicide concentrations varied spatially by colony and temporally by day. The highest concentrations in nectar occurred 1 and 3 d after spraying: up to 440 ng/g boscalid and 240 ng/g pyraclostrobin. Six days after application, pollen from cherry flowers contained the highest concentrations of the fungicides: up to 60,500 ng/g boscalid and 32,000 ng/g pyraclostrobin. These data can help to determine field-level fungicide concentrations in nectar and pollen and direct future work on understanding the effects of these compounds, including their interactions with important bumble bee pathogenic and beneficial symbionts.

Journal of Economic Entomology↗