Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Fathead minnow (FHM) predation on mosquito larvae in laboratory controlled experiments, artificial pools and in a natural aquatic habitat was evaluated. Thirty-three feeding trials with 121 replicates were conducted in the lab. On average, a single FHM consumed 389 (+ 11 SE) 1st and 2nd instar larvae and 236 (+ 18.3) 3rd and 4th instar larvae during a 24 hr feeding period. In feeding trials with mosquito larvae and daphnia (used as alternate prey), larval consumption rates were lower for 1st and 2nd instars but increased by 10% for 3rd and 4th instars. Outdoor feeding trials were conducted in 30 gal wading pools with artificial floral grasses. Vegetation densities were low (9" between plants), moderate (5" between plants) and heavy (1" between plants). Predation rates ranged from 100% in pools with no vegetation (= control) to 91% in pools with heavy vegetation. Thus, plant density did not interfere with the ability of FHM to swim into dense vegetation and consume mosquito larvae. FHM were released in an oxbow southeast of Buffalo, WY in July 2010. Three enclosures were set up along the edge of the oxbow; the areas within these enclosures were designated free of FHM. Between enclosures, three 24' wide plots were set up to which FHM had access. Three hundred FHM (avg. length 2") were released in the oxbow on 12 July 2010. Twenty-five larval dips were taken at 7 - 10 day intervals. The number of larvae per dip, 0.3 to 5.1 from the enclosures and 0.2 to 3.2 from the open plots, was not significantly different. Mosquitoes were assayed for canine heartworm. Heartworm transmission has been reported in Montana although very little is known regarding the vector(s), prevalence of the parasite or enzootic foci. The primary vector appears to differ geographically. We are interested in identifying potential vector(s) in MT to assist in arresting local transmission. Mosquitoes collected in 2005 and 2007 with CO2-baited light traps were decapitated and placed in vials @ 20 heads per vial for PCR assays. Approximately 40,000 mosquitoes collected in 2007 were tested and all were negative for D. immitis. Collections from 2005 are currently be assayed. The difficulty in finding positive mosquitoes reflects the relatively low transmission rate recorded in the state but does not reflect the importance of the parasite to domestic canids. Insecticide ear tags and IGR loose mineral and tubs were evaluated for horn fly and face fly control. Ear tags evaluated were chosen on their chemistry and newness to the market. Warrior and Corathon tags provided excellent fly control while the newer tag, CyGuard, was less effective and will not be recommended for producer use. The IGR loose mineral and mineral tubs were effective in preventing fly emergence from manure pats but had no effect on adult flies. We recorded flies on treated animals that were likely migrating from untreated cattle. PARTICIPANTS: The fathead minnow project involved Wyoming Game and Fish Department and the Northeast Wyoming Sage-Grouse Working Group. Canine heartworm studies involved professors and students from Carroll College (Helena, MT) and students from Montana State University. MSU students worked on cattle ectoparasite studies. TARGET AUDIENCES: Livestock producers were the primary target audience for cattle ectoparasite control. Veterinarians and companion animal owners for the canine heartworm survey. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The Fathead minnow study demonstrates that FHM readily consumes immature mosquitoes; that the 24 hr predation rate was relatively high when compared to other species in the literature; and that high densities of vegetation did not reduce accessibility or interfere with FHM predation. Although results from the 2010 field release study were equivocal, the demonstrated ability of FHM to readily feed on mosquito larvae in the lab suggests it is an efficient predator and will compliment other mosquito control strategies in CBNG impoundments. The results of the canine heartworm survey indicate that mosquito infection rates are low and difficult to find. However, there is evidence indicating that transmission does occur in the state. Thus, while the risk of infection is low, companion animal owners are advised to take preventative measures. A degree-day model is being developed to determine areas of high risk in the state. Ectoparasite control studies enable cattle producers to make informed decisions on selecting appropriate control tactics to manage economically important livestock pests. The results from IGR studies demonstrated that while immature stages of horn fly and face fly are readily controlled in the manure, it has no effect on migrating adult flies. Hence cattle fed IGR plus mineral will still be infested with horn flies and face flies.
Publications
- No publications reported this period
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: This investigation was conducted near Buffalo, WY to determine if the fathead minnow would penetrate vegetation and actively search and consume mosquito larvae. Field experiments utilizing enclosures were unsuccessful due to the presence of tiger salamanders that killed and consumed fish in 6' x 6' enclosures. We then used 40 gal wading pools lined with varying densities of artificial grasses. Based on replicated feeding trials, it was determined that FHM will penetrate vegetation regardless of density and prey on immature mosquitoes. Additional field studies are planned for 2010. Additional lab studies were conducted to determine the 24-h satiation point (think hotdog eating contest) of fathead minnows using 1st - 2nd and 3rd - 4th instar mosquito larvae. Maximum consumption was >300 1st - 2nd instar larvae; the satiation point was not determined. Average consumption for 3rd - 4th instars was 235 larvae in a 24 hr period. This rate of consumption is further evidence supporting the suitability of FHM for integration into a mosquito management program. PARTICIPANTS: Wyoming Game and Fish Department were contacts on this project. TARGET AUDIENCES: Target audiences include landowners, petroleum industry, mosquito abatement districts, and Bureau of Land Management. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
FHM appear to be a suitable species for integration into a mosquito management program. It will readily feed on immature mosquitoes; it is widely distributed in NE Wyoming; it will tolerate a variety of conditions (low O2, high salinity, warm temperatures); is commercially available; and is polyphagous so it won't starve if mosquitoes aren't present.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/09
Outputs
OUTPUTS: Fathead minnow (FHM) predation on mosquito larvae in laboratory controlled experiments, artificial pools and in a natural aquatic habitat was evaluated. Thirty-three feeding trials with 121 replicates were conducted in the lab. On average, a single FHM consumed 389 (+ 11 SE) 1st and 2nd instar larvae and 236 (+ 18.3) 3rd and 4th instar larvae during a 24 hr feeding period. In feeding trials with mosquito larvae and daphnia (used as alternate prey), larval consumption rates were lower for 1st and 2nd instars but increased by 10% for 3rd and 4th instars. Outdoor feeding trials were conducted in 30 gal wading pools with artificial floral grasses. Vegetation densities were low (9" between plants), moderate (5" between plants) and heavy (1" between plants). Predation rates ranged from 100% in pools with no vegetation (= control) to 91% in pools with heavy vegetation. Thus, plant density did not interfere with the ability of FHM to swim into dense vegetation and consume mosquito larvae. FHM were released in an oxbow southeast of Buffalo, WY in July 2010. Three enclosures were set up along the edge of the oxbow; the areas within these enclosures were designated free of FHM. Between enclosures, three 24' wide plots were set up to which FHM had access. Three hundred FHM (avg. length 2") were released in the oxbow on 12 July 2010. Twenty-five larval dips were taken at 7 - 10 day intervals. The number of larvae per dip, 0.3 to 5.1 from the enclosures and 0.2 to 3.2 from the open plots, was not significantly different. Mosquitoes were assayed for canine heartworm. Heartworm transmission has been reported in Montana although very little is known regarding the vector(s), prevalence of the parasite or enzootic foci. The primary vector appears to differ geographically. We are interested in identifying potential vector(s) in MT to assist in arresting local transmission. Mosquitoes collected in 2005 and 2007 with CO2-baited light traps were decapitated and placed in vials @ 20 heads per vial for PCR assays. Approximately 40,000 mosquitoes collected in 2007 were tested and all were negative for D. immitis. Collections from 2005 are currently be assayed. The difficulty in finding positive mosquitoes reflects the relatively low transmission rate recorded in the state but does not reflect the importance of the parasite to domestic canids. Insecticide ear tags and IGR loose mineral and tubs were evaluated for horn fly and face fly control. Ear tags evaluated were chosen on their chemistry and newness to the market. Warrior and Corathon tags provided excellent fly control while the newer tag, CyGuard, was less effective and will not be recommended for producer use. The IGR loose mineral and mineral tubs were effective in preventing fly emergence from manure pats but had no effect on adult flies. We recorded flies on treated animals that were likely migrating from untreated cattle. PARTICIPANTS: The fathead minnow project involved Wyoming Game and Fish Department and the Northeast Wyoming Sage-Grouse Working Group. Canine heartworm studies involved professors and students from Carroll College (Helena, MT) and students from Montana State University. MSU students worked on cattle ectoparasite studies. TARGET AUDIENCES: Livestock producers were the primary target audience for cattle ectoparasite control. Veterinarians and companion animal owners for the canine heartworm survey. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The Fathead minnow study demonstrates that FHM readily consumes immature mosquitoes; that the 24 hr predation rate was relatively high when compared to other species in the literature; and that high densities of vegetation did not reduce accessibility or interfere with FHM predation. Although results from the 2010 field release study were equivocal, the demonstrated ability of FHM to readily feed on mosquito larvae in the lab suggests it is an efficient predator and will compliment other mosquito control strategies in CBNG impoundments. The results of the canine heartworm survey indicate that mosquito infection rates are low and difficult to find. However, there is evidence indicating that transmission does occur in the state. Thus, while the risk of infection is low, companion animal owners are advised to take preventative measures. A degree-day model is being developed to determine areas of high risk in the state. Ectoparasite control studies enable cattle producers to make informed decisions on selecting appropriate control tactics to manage economically important livestock pests. The results from IGR studies demonstrated that while immature stages of horn fly and face fly are readily controlled in the manure, it has no effect on migrating adult flies. Hence cattle fed IGR plus mineral will still be infested with horn flies and face flies.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Mosquito trapping and West Nile virus surveillance occurred in 15 counties in 2008. Of these counties, 9 were located east of the Continental Divide (Blaine, Custer, Gallatin, Hill, Lewis & Clark, Pondera, Sheridan, Valley, Yellowstone) and 6 were located west of the Divide (Deer Lodge, Flathead, Lake, Missoula, Powell, Ravalli). There were 23 trap sites where surveillance occurred - 15 sites east of the Continental Divide and 8 sites west of the Continental Divide. Cooperators for these surveillance efforts included MSU county extension agents, MT Fish Wildlife and Parks personnel, reservation college instructors, private citizens, mosquito district personnel, county maintenance personnel, and commercial pesticide applicators. Biting midge populations were monitored from nine trap sites located near Hardin, Billings, Miles City, Malta and Jordan to facilitate detection and early warning of biting midge population increases and the presence of bluetongue virus. Trap collections and assay results were communicated in a timely manner to cooperators, producers and the Montana Department of Livestock personnel. Cool summer temperatures suppressed midge development and virus transmission activity, and was the probable reason a repeat of the 2007 epizootic did not occur. We evaluated several insecticides at the UW Sheep Research Facility in Laramie as sprays, pour-ons and ear tags for biting midge control Mortality of pre-fledged pelicans in pelican colonies in the northern Great Plains has increased 7 to 8 fold following the arrival of WNV into the region. We determined that West Nile virus was responsible for increased mortality in juvenile pelicans at Medicine Lake National Wildlife Refuge. The effects of WNV infection among American white pelican colonies are alarming from a wildlife conservation standpoint and also from a human health perspective. We calculated an odds ratio and found the probability of human West Nile neuroinvasive disease (WNDD), a more serious form of West Nile virus infection, had increased 5-fold when WNV-associated mortality occurred among the nesting pelicans in that county. We also found that WNV-related pelican deaths occurred approximately 12 days before onset of human WNND. Field and laboratory necropsy found that feather pulp and skin were the most consistently infected tissues among WNV-infected pelicans. These tissues meet criteria for a low-resource approach to dead bird surveillance: samples require a minimal amount of time for field collection, dissection of the carcass is not required, exposure of laboratory personnel to infected carcasses is avoided, samples can be easily transported and shipped, and laboratory processing costs can be kept to a minimum. PARTICIPANTS: Dr. Jack Lloyd, University of Wyoming Dr. Will Reeves, USDA ARS ABADRL Dr. Nicholas Komar, CDC Dr. Nicole Nemeth, CDC TARGET AUDIENCES: Education and PSA's of general public for WNV protection. Livestock producers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Summer climatic conditions play a huge role in mosquito production, extrinsic incubation times and transmission activity. For example, July 2007 was unusually hot and was the hottest July on record for the state as a whole. Significant numbers of Cx. tarsalis, the primary vector of West Nile virus, were collected beginning early in the season (June/July) suggesting that we were on the threshold of an epidemic. Early detection (July 10) of WNV in mosquito pools further supported concerns relative to an epidemic particularly in areas previously identified as high risk areas (major river drainages - Yellowstone River, Milk River, Missouri River). Montana experienced a WNV epidemic in 2007 with 202 human cases reported and four fatalities. In 2008 June the weather was both cooler and wetter than normal, July had near normal temperatures and August had alternating hot and cool spells. While high temperatures accelerate WNV epidemiology, cool summer temperatures suppress mosquito development and virus transmission activity. This is reflected in the reduced light trap catches of Cx. tarsalis and virus infection rates in mosquitoes; five human cases of WNV were reported from Montana for 2008. An insecticide (Permectrin WS) containing permethrin and piperonyl butoxide (p.b.o.) when applied as a low volume spray to the belly effectively reduce blood-feeding by C. sonorensis. In addition, an insecticide-impregnated ear tag, PYthon, containing zetacypermethrin and p.b.o. when attached at the rate of one per animal was also effective as a repellent. Based on this work, the companies prepared supplemental labeling for these products and they are now available for producers to use in Wyoming and Montana on sheep for biting fly protection and bluetongue transmission reduction. Continued surveillance of individual American white pelican colonies is important relative to assessing the long-term impact of WNV on individual colonies as well as populations in the northern plains and upper Midwest. Coordination between wildlife and public health sectors to monitor these colonies for WNV activity could potentially be important for presaging human WNV infection and related mosquito-borne diseases.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: In 2007 mosquito and West Nile virus surveillance activities occurred in 20 counties in Montana. Of these counties, 10 were located east of the Continental Divide (Big Horn, Blaine, Broadwater, Custer, Gallatin, Hill, Lewis & Clark, Sheridan, Valley, Yellowstone), and 10 were located west of the Divide (Deer Lodge, Flathead, Granite, Lake, Lincoln, Missoula, Powell, Ravalli, Sanders, Silver Bow). There were 43 trap sites where surveillance occurred - 20 sites east of the Continental Divide and 23 sites west of the Continental Divide. Cooperators for these surveillance efforts included MSU county extension agents, Environmental health specialists, reservation college instructors, private citizens, mosquito district personnel, county maintenance personnel, and commercial pesticide applicators. An alarming number of vector mosquitoes were captured in several localities early in the summer (especially along the Yellowstone River and its tributaries and the Milk River in northern
Montana) and these numbers were higher than the catches we recorded in 2003 - the first West Nile virus epidemic in Montana. Accompanying these catches were high WNV infection rates in the mosquitoes. We calculated infection rates up to 13 per 1000 mosquitoes; values >4 are generally considered a potential public health threat. This intensity of WNV activity in the state was in part due to the elevated temperatures occurring during the summer which accelerated mosquito development and WNV amplification. These surveillance data provided ample time to inform residents, tourists, and mosquito control districts of the occurrence of virus activity in certain areas of the state via radio and TV PSAs, and feature news articles. Although our communication efforts extended statewide, 201 humans were diagnosed with WNV and there were four deaths. It is difficult to predict virus transmission activity, thus the importance of mosquito and virus surveillance. It is generally agreed by researchers
and epidemiologists that WNV is here to stay, and that we will experience periodic epidemics in Montana and surrounding states.
PARTICIPANTS: Participants included MSU county extension agents, Marni Rolston, Kristina Hale, and Anya Jackson. Partner organizations included Montana Department of Health and Human Services and Montana Public Helath Laboratory.
TARGET AUDIENCES: General public.
PROJECT MODIFICATIONS: No modifications are planned.
Impacts
The results form the mosquito and WNV surveillance program prompted early warnings to the general public, county agents, cooperators, DPHHS personnel and the news media relative to a potential WNV outbreak. These early warnings, triggered by mosquito light trap collections, were justified with the ensuing WNV outbreak. Throughout the summer, weekly updates and were provided to personnel with county and state agencies and the general public through various media outlets.
Publications
- Hale, K. M. 2007. Investigations of the West Nile virus transmission cycle at Medicine Lake National Wildlife REfuge, Montana. MS Thesis. 74p.
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Progress 01/01/06 to 12/31/06
Outputs
The Bluetongue project has been completed and manuscripts are in preparation. A joint paper is being prepared that estimates vectorial capacity of C. sonorensis in southern Alberta and Montana. The data in this manuscript explains why C. sonorensis is, for the most part, an incompetent vector of bluetongue virus in Montana and Alberta. A second paper is planned on the species composition and seasonal abundance of biting midges in Montana. West Nile virus surveillance in Montana has determined that enzootic foci occur along major river drainages in the state including the Milk River, Yellowstone River and Missouri River. The use of mosquito pools and sentinel chickens for virus detection has shown that virus is first detected in mosqutioes before seroconversion occurs in sentinel birds. WNV human cases were reported from western Montana for the first time in 2006. Despite a severe drought in northeast Montana which significantly reduced mosquito production, a WNV
epizootic was recorded in juvenile American white pelicans at Medicine Lake National Wildlife Refuge. This outbreak has prompted investigations into non-mosquito WNV transmission among pelicans. Insect pest control studies were conducted on horn flies on cattle and the sheep ked and African blue louse on sheep. Insecticide impregnated ear tags provided about 8 weeks control of horn flies on rangeland cattle which was less than the manufacturers' claim of 4 months control. Horn fly populations reached more than 1,100 flies per animal in the untreated control. Reports on the Arican blue louse are becoming more frequent in Montana mainly due to the lack of an effective, registered insecticide. Currently, a product is being evaluated for both sheep ked and lice control.
Impacts
The bluetongue study has demonstrated that bluetongue transmission in Montana and Alberta is not an issue and should not be subject to trade regulations. WNV surveillance work ahs shown that testing mosquito pools for virus is the most useful prognostic tool for informing residents that WNV transmission activity is occurring. Control of livestock pests will improve animal health and economics.
Publications
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Progress 01/01/05 to 12/31/05
Outputs
Research activities focused on characterizing a WNV enzootic focus at Medicine Lake, Montana and determining the importance of coal bed methane ponds in northeast Wyoming in contributing to mosquito vector production. Research has thus far determined that the primary vector of WNV at Medicine Lake is Culex tarsalis which preferentially feeds on mourning doves. Coal bed methane ponds produce more putative WNV vectors than natural water and agricultural sources.
Impacts
West Nile virus work has thus far demonstrated that humans and equines in the Powder River Valley are at an increased risk to WNV because of the proliferation of coal bed methane ponds.
Publications
- Johnson, G.D. 2005. Mosquito and West Nile virus surveillance in Montana. Technical Report. 26p.
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Progress 01/01/04 to 12/31/04
Outputs
Oral infectivity studies indicated that Culicoides sonorensis is refractory to bluetongue virus and thus a poor vector of bluetongue. Wild caught flies were fed a blood + virus suspension and held for 12 days @ 20C to allow amplification of the virus inside the insect. Following the 12-day incubation period, flies were assayed using a Vero cell placque system and found to be negative for the virus. Flies assayed immediately after feeding were positive indicating the feeding system delivered viable virus. These data suggest that the northern population of C. sonorensis is an incompetent vector.
Impacts
Data suggest that C. sonorensis is a poor vector of BT virus in Montana. These data also suggest that cattle shipped to Canada present a negligible risk to infection of Canadian cattle.
Publications
- Bionomics of Culicoides sonorensis: a vector of bluetongue in Montana? 2004. Proceedings 48th Annual Livestock Insect Workers' Conference. 2 pp.
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Progress 01/01/03 to 12/31/03
Outputs
In 2003 biting midges were trapped from 19 different sites in Montana. Eight Culicoides species were identified with the most abundant being C. sonorensis, the vector of bluetongue and EHD viruses. Fourteen of the 19 sites were positive for sonorensis. Trapping data showed three generations are produced with the highest density recorded during mid-summer and there appears to be an elevational response (i.e.>4500 ft no midges were captured). A serology survey indicated 1/600 spring-born calves positive for BT virus. Viral assays of flies orally infected with BT-11 found no positive flies after an incubation period of 12 days at 20 C.
Impacts
Data suggest that C. sonorensis is a poor vector of BT virus in Montana. These data also suggest that cattle shipped to Canada present a negligible risk to infection of Canadian cattle.
Publications
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