scholarly journals Factors affecting virus prevalence in honey bees in the Pacific-Northwest, USA

2021 ◽  
Author(s):  
Vera W Pfeiffer ◽  
David W Crowder
Keyword(s):  
Spatial Autocorrelation ◽  
Pacific Northwest ◽  
Honey Bees ◽  
Management Practices ◽  
Virus Transmission ◽  
Urban Landscapes ◽  
Deformed Wing Virus ◽  
Virus Prevalence ◽  
Julian Date ◽  
The Pacific

Global efforts to assess honey bee health show viruses are major stressors that undermine colony performance. Identifying factors that affect virus incidence, such as management practices and landscape context, could aid in slowing virus transmission. Here we surveyed viruses in honey bees from 86 sites in the Pacific Northwest, USA, and tested effects of regional bee density, movement associated with commercial pollination, julian date, and hive management on virus prevalence. We also explored patterns of virus co-occurrence and spatial autocorrelation to identify whether local transmission was a primary driver of pathogen distribution. Our surveys found widespread prevalence of Deformed wing virus (DWV), Sacbrood virus (SBV), and Black queen cell virus (BQCV). BQCV and SBV were most prolific in commercial apiaries, while Chronic bee paralysis virus (CPBV) was more common in hobbyist apiaries than commercial apiaries. DWV was most common in urban landscapes and was best predicted by mite prevalence and julian date, while the incidence of both SBV and BQCV were best predicted by regional apiary density. We did not find evidence of additional spatial autocorrelation for any viruses, although high co-occurrence suggests parallel transmission patterns. Our results support the importance of mite management in slowing virus spread and suggest that greater bee density increases transmission. Our study provides support that viruses are widespread in honey bees and connects known mechanisms of virus transmission to the distribution of pathogens observed across the Pacific Northwest.

scholarly journals Pupal cannibalism by worker honey bees contributes to the spread of deformed wing virus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Posada-Florez ◽  
Zachary S. Lamas ◽  
David J. Hawthorne ◽  
Yanping Chen ◽  
Jay D. Evans ◽  
...  
Keyword(s):  
Honey Bees ◽  
Control Strategies ◽  
Virus Transmission ◽  
Experimental Conditions ◽  
Colony Losses ◽  
Viral Pathogen ◽  
Deformed Wing Virus ◽  
Hygienic Behaviour ◽  
Pathogen Virulence ◽  
Comprehensive Knowledge

AbstractTransmission routes impact pathogen virulence and genetics, therefore comprehensive knowledge of these routes and their contribution to pathogen circulation is essential for understanding host–pathogen interactions and designing control strategies. Deformed wing virus (DWV), a principal viral pathogen of honey bees associated with increased honey bee mortality and colony losses, became highly virulent with the spread of its vector, the ectoparasitic mite Varroa destructor. Reproduction of Varroa mites occurs in capped brood cells and mite-infested pupae from these cells usually have high levels of DWV. The removal of mite-infested pupae by worker bees, Varroa Sensitive Hygiene (VSH), leads to cannibalization of pupae with high DWV loads, thereby offering an alternative route for virus transmission. We used genetically tagged DWV to investigate virus transmission to and between worker bees following pupal cannibalisation under experimental conditions. We demonstrated that cannibalization of DWV-infected pupae resulted in high levels of this virus in worker bees and that the acquired virus was then transmitted between bees via trophallaxis, allowing circulation of Varroa-vectored DWV variants without the mites. Despite the known benefits of hygienic behaviour, it is possible that higher levels of VSH activity may result in increased transmission of DWV via cannibalism and trophallaxis.

scholarly journals The Effects of Forestry Site Preparation on Mountain Beaver Demographics and Associated Damage to Tree Seedlings

2010 ◽  
Vol 25 (3) ◽  
pp. 127-135
Author(s):  
Wendy Arjo
Keyword(s):  
Pacific Northwest ◽  
Management Practices ◽  
Site Preparation ◽  
Home Ranges ◽  
Tree Seedlings ◽  
Animal Damage ◽  
The Pacific ◽  
Mountain Beaver ◽  
Aplodontia Rufa ◽  
Species Specific

Abstract Timber resources are a vital part of the economy in the Pacific Northwest, yet reforestation efforts are often hampered by animal damage. Understanding the factors that influence seedling damage can assist managers in implementing appropriate techniques to reduce species-specific damage. I radio-collared and monitored mountain beavers (Aplodontia rufa) from preharvest to seedling planting to determine the impacts of forest management practices on demographics. In addition, I monitored Douglas-fir (Pseudotsuga menziesii) seedlings on 28 plots on two harvest units (Vesta and Schoolhouse) to determine the effects of chemical site preparation on mountain beaver foraging and subsequent seedling damage. Mountain beaver densities differed between silvicultural treatments (F3,39 = 3.58, P < 0.02), although reproductive success did not (χ2 = 0.14, df = 1, P = 0.70). Larger mountain beaver home ranges were documented in the mature timber compared with those following harvest. Home ranges were also larger in the chemical site preparation portion of the unit (mean = 3.37 ± 0.9 ha) than in the nontreated portion of the unit (mean = 0.82 ± 0.17 ha) on Vesta. Herbicide treatment did not promote seedling damage on either unit. Vegetation does not appear to be the only factor influencing mountain beaver movements and seedling damage. Availability of water is very important for mountain beavers and may also influence their foraging choice, as well as contributing to their increased movements in mature timber (reduced groundwater) versus clearcut areas. Understanding the effects of vegetation on population demographics and subsequent seedling damage may allow for initiating a nonlethal management method using alternative forage.

Responding to an Introduced Pathogen: Podosphaera macularis (Hop Powdery Mildew) in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 21 ◽  
Author(s):  
Walter F. Mahaffee ◽  
Carla S. Thomas ◽  
William W. Turechek ◽  
Cynthia M. Ocamb ◽  
Mark E. Nelson ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Management Practices ◽  
Risk Index ◽  
Lessons Learned ◽  
Infection Model ◽  
The Pacific ◽  
Sphaerotheca Macularis ◽  
The Cost ◽  
Podosphaera Macularis

Powdery mildew of hop (Humulus lupus L.), which is caused by Podosphaera macularis (formerly Sphaerotheca macularis) was found in the Yakima Valley, WA in 1996 and subsequently spread to the growing regions in Oregon and northern and southern Idaho. To rapidly assist growers in reducing the cost associated with the preventive fungicide program, the Gubler/Thomas grape powdery mildew risk infection model was adapted for hops. In addition, field surveys were utilized to identify other management practices that impacted disease development. Weather networks were established and utilized to deliver daily regional maps indicating the risk index. These maps were posted to the web for daily access. Lessons learned from this experience will be useful in addressing future pathogen introductions. Accepted for publication 28 March 2003. Published 13 November 2003.

scholarly journals Species-Specific PCR Assays for Differentiating Heterodera filipjevi and H. avenae

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1611-1619 ◽  
Author(s):  
Guiping Yan ◽  
Richard W. Smiley ◽  
Patricia A. Okubara ◽  
Andrea M. Skantar
Keyword(s):  
Pacific Northwest ◽  
Management Practices ◽  
Pcr Amplification ◽  
Nematode Species ◽  
Heterodera Avenae ◽  
Cyst Nematodes ◽  
Specific Pcr ◽  
The Pacific ◽  
Pcr Assays ◽  
Species Specific

Heterodera avenae and H. filipjevi are economically important cyst nematodes that restrict production of cereal crops in the Pacific Northwest United States and elsewhere in the world. Identification of these two species is critical for recommending and implementing effective management practices. Primers were designed from the internal transcribed spacer (ITS) regions of H. avenae and H. filipjevi ribosomal DNA. The primers were highly specific when examined on target isolates but did not amplify DNA from nontarget Heterodera, Globodera, Meloidogyne, Pratylenchus, and other nematode species tested. Polymerase chain reaction (PCR) and amplification conditions were established, and H. avenae and H. filipjevi were clearly distinguished by PCR fragments of 242 and 170 bp, respectively. Robust PCR amplification was achieved with DNA extracted from a single egg or second-stage juvenile (J2) using a laboratory-made worm lysis buffer, and DNA from 0.5 egg or J2 using a commercial kit. The PCR assays were successfully employed for differentiation of H. filipjevi and H. avenae populations collected from eight locations in three Pacific Northwest states. This is the first report of a species-specific ITS PCR assay to detect and identify H. filipjevi. The assays for both species will enhance diagnosis of cereal cyst nematode species in infested fields.

scholarly journals A Comparison of the Costs of Forest Service and Contract Fire Crews in the Pacific Northwest

2005 ◽  
Vol 20 (4) ◽  
pp. 233-239 ◽  
Author(s):  
Geoffrey H. Donovan
Keyword(s):  
Pacific Northwest ◽  
Management Practices ◽  
The United States ◽  
Forest Service ◽  
Fire Season ◽  
Type Ii ◽  
Daily Cost ◽  
The Pacific ◽  
Service Type ◽  
Wildfire Suppression

Abstract Rising wildfire suppression expenditures on public land in the United States have led to increased scrutiny of wildfire management practices. One area that has received particular attention is the Forest Service's increasing reliance on contract fire crews. Because a contract crew rate includes several costs that are not included in the wage costs of a Forest Service crew, it is difficult to determine if this increasing reliance on contract fire crews increases or decreases wildfire suppression costs. The full cost of 33 Forest Service type II fire crews dispatched during the 2003 fire season from five national forests in Oregon and Washington are estimated and compared with the cost of contract crews dispatched in the same region. Results suggest that if sufficient work is available to keep a Forest Service crew productively employed throughout a fire season, then the daily cost of a Forest Service type II crew is lower than the daily cost of a contract crew. West. J. Appl. For. 20(4):233–239.

scholarly journals Pupal Cannibalism byWworker Honey Bees Contributes to the Spread of Deformed Wing Virus.

2020 ◽  
Author(s):  
Francisco Posada-Florez ◽  
Zachary Lamas ◽  
David Hawthorne ◽  
Yanping Chen ◽  
Jay Evans ◽  
...  
Keyword(s):  
Honey Bees ◽  
Control Strategies ◽  
Virus Transmission ◽  
Experimental Conditions ◽  
Colony Losses ◽  
Viral Pathogen ◽  
Deformed Wing Virus ◽  
Hygienic Behaviour ◽  
Pathogen Virulence ◽  
Comprehensive Knowledge

Abstract Transmission routes impact pathogen virulence and genetics, therefore comprehensive knowledge of these routes and their contribution to pathogen circulation is essential for understanding host-pathogen interactions and designing control strategies. Deformed wing virus (DWV), a principal viral pathogen of honey bees associated with increased honey bee mortality and colony losses, became highly virulent with the spread of its vector, the ectoparasitic mite Varroa destructor. Reproduction of Varroa mites occurs in capped brood cells and mite-infested pupae from these cells usually have high levels of DWV. The removal of mite-infested pupae by worker bees, Varroa Sensitive Hygiene (VSH), leads to cannibalization of pupae with high DWV loads, thereby offering an alternative route for virus transmission. We used genetically tagged DWV to investigate virus transmission to and between worker bees following pupal cannibalisation under experimental conditions. We demonstrated that cannibalization of DWV-infected pupae resulted in high levels of this virus in worker bees and that the acquired virus was then transmitted between bees via trophallaxis, allowing circulation of Varroa-vectored DWV variants without the mites. Despite the known benefits of hygienic behaviour, it is possible that higher levels of VSH activity may result in increased transmission of DWV via cannibalism and trophallaxis.

scholarly journals Rapid Quantitative Assessment of Rhizoctonia Resistance in Roots of Selected Wheat and Barley Genotypes

Plant Disease ◽  
2016 ◽  
Vol 100 (3) ◽  
pp. 640-644
Author(s):  
Patricia A. Okubara ◽  
Natalie Leston ◽  
Ute Micknass ◽  
Karl-Heinz Kogel ◽  
Jafargholi Imani
Keyword(s):  
Pacific Northwest ◽  
Management Practices ◽  
Production Systems ◽  
Low Cost ◽  
Genetic Resistance ◽  
Bare Patch ◽  
Rhizoctonia Root Rot ◽  
The Pacific ◽  
Wide Range ◽  
Barley Genotypes

Rhizoctonia solani AG8, causal agent of Rhizoctonia root rot and bare patch in dryland cereal production systems of the Pacific Northwest United States and Australia, reduces yields in a wide range of crops. Disease is not consistently controlled by available management practices, so genetic resistance would be a desirable resource for growers. In this report, we describe three rapid and low-cost assays for R. solani AG8 resistance in wheat and barley, with the view of facilitating screens for genetic resistance in these hosts. The first assay uses 50-ml conical centrifuge tubes containing soil infested with R. solani AG8 on a substrate of ground oats. The second assay uses roots of 3-day-old seedlings directly coated with infested ground oats, followed by incubation in plastic dishes. The third assay, suitable for barley, uses whole infested oat kernels in 50-ml tubes. Symptoms are quantified on the bases of root fresh weight and total root length at 7 and 3 days for the tube and coating assays, respectively. Each of the assays show the same disease differential between susceptible and partially resistant wheat genotypes. The assays can be conducted in the laboratory, growth chamber, or greenhouse.

scholarly journals Possible Spillover of Pathogens between Bee Communities Foraging on the Same Floral Resource

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 122
Author(s):  
Anne Dalmon ◽  
Virgine Diévart ◽  
Maxime Thomasson ◽  
Romain Fouque ◽  
Bernard E. Vaissière ◽  
...  
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Population Decline ◽  
Virus Transmission ◽  
Wild Bees ◽  
Deformed Wing Virus ◽  
Wild Bee ◽  
Pollinator Community ◽  
Floral Resource ◽  
Paralysis Virus

Viruses are known to contribute to bee population decline. Possible spillover is suspected from the co-occurrence of viruses in wild bees and honey bees. In order to study the risk of virus transmission between wild and managed bee species sharing the same floral resource, we tried to maximize the possible cross-infections using Phacelia tanacetifolia, which is highly attractive to honey bees and a broad range of wild bee species. Virus prevalence was compared over two years in Southern France. A total of 1137 wild bees from 29 wild bee species (based on COI barcoding) and 920 honey bees (Apis mellifera) were checked for the seven most common honey bee RNA viruses. Halictid bees were the most abundant. Co-infections were frequent, and Sacbrood virus (SBV), Black queen cell virus (BQCV), Acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were widespread in the hymenopteran pollinator community. Conversely, Deformed wing virus (DWV) was detected at low levels in wild bees, whereas it was highly prevalent in honey bees (78.3% of the samples). Both wild bee and honey bee virus isolates were sequenced to look for possible host-specificity or geographical structuring. ABPV phylogeny suggested a specific cluster for Eucera bees, while isolates of DWV from bumble bees (Bombus spp.) clustered together with honey bee isolates, suggesting a possible spillover.

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