Progress 09/01/09 to 08/31/13
Outputs
Target Audience: Researchers, extension personnel, and producers interested in fly control on cattle. Changes/Problems: The laboratory assays proved to be more demanding than anticipated, but we powered through all of them in CA, and the survival assays in NC. What opportunities for training and professional development has the project provided? Two graduate students and 5 undergraduate students helped significantly with these studies in CA, and several others in NC. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Three summers' of study were devoted to field testing repellents and gauging the population-level responses of horn flies to those treatments. The field tests were only the beginning, however, and were followed by laborious, year-round processing of the flies collected. Livestock settings in CA and NC required different arrangements and experimental approaches, which still were synchronized as well as possible. In NC sufficient cattle herds existed to test both repellents against an untreated control simultaneously. In CA we had only 2 groups of cattle, so we tested the repellents consecutively on somewhat larger herd groups, comparing them against an untreated control. Geraniol tended to repel horn flies for 24-48 h, but did not kill them. The C8910 (fatty acid combination), on the other hand, did kill flies if it hit them directly. It repelled horn flies for 1-3 days. In CA it was possible to imbed untreated individual cattle (identified by ear tags), in order to gauge the repellent versus killing effects. The geraniol resulted in relatively more flies moving from treated to untreated animals (imbedded control counts rose post-treatment). After C8910 tretament, however, counts on all cattle dropped (including imbedded controls. This probably reflected direct mortality, but also may have been caused by a spatial repellent effect. Defensive cattle behaviors (against flies) reflected horn fly numbers, and probably will be helpful in determining actual biting (vs mere fly presence on animals). The laboratory assays will assess blood ingestion by flies, mating success, egg production, and adult fly survival. The CA laboratory fly processing has been completed, and the NC assays measuring survival have been done. These data sets are extremely dense, so analysis will take some more time. However, this is without question the most thorough assessment of horn fly field population biology. When the repellent testing is superimposed, and coupled with the cattle defensive behavior, iit will be a uniquely deep and useful study. The laboratory assays showed that the repellents reduced lab horn fly feeding by > 80% after trt, declining with time post-trt. Electroantennagrams showed fly responses to both repellents. Persistence appeared better for C8910 than for geraniol. The top priority now is to complete the analysis and writing up of these studies.
Publications
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Progress 09/01/12 to 08/31/13
Outputs
Target Audience: Researchers, producers interested in control of pest flies on cattle using repellents. Changes/Problems: The laboratory assays required more time and effort than anticipated, but we accomplished the goals. In the last summer, a pinkeye outbreak in the cattle required the producer to treat all of the animals. This stopped us from being able to test one of the two main repellents, but only in the 3rd year. What opportunities for training and professional development has the project provided? Several undergraduate students have helped a lot with this project, including assisting with field fly and cow behavior counts, applicaitons of repellents, and many assays in the laboratory to support that. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? Enphasis now is on analyzing an absolutely huge data set and writing it up for publication.
Impacts
What was accomplished under these goals?
We accomplished almost all of the goals, pending some additional assays for blood feeding and mating/fecundity of horn flies in North Carolina. Currently we are analyzing the data for manuscript preparation.
Publications
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Progress 09/01/11 to 08/31/12
Outputs
OUTPUTS: This is by far the most intensive population biology yet done with the horn fly. Processing the samples has required an immense effort that is still ongoing, but good progress has been made. We expect horn fly survival to lessen under pressure from the test repellents, and have seen some intriguing shifts in sex ratios with the treatments. Both repellents will reduce horn fly adult numbers on cattle acutely and over time. The geraniol seems to be a true repellent, while the fatty acids will also kill flies that are hit by a spray. We added manure pat sampling and have investigated the relationship between manure pat mass and relative numbers of face flies and horn flies emerging from the pats. PARTICIPANTS: Principal participants included Drs. Bradley Mullens (UC Riverside Entomology) and D. Wes Watson (NC State Entomology). Partners included Cal Poly Pomona (particularly Dr. Broc Sandelin, Animal Science) and the Goldsboro Ag. Center (Goldsboro, NC). Technical assistance was provided by D. Soto, D. Rawls, A. Diniz, C. Martin, F. Fowler, I. Esquivel, P. Montez and A. Murillo. TARGET AUDIENCES: Veterinary entomologists, pastured beef and dairy cattle researchers or producers. PROJECT MODIFICATIONS: The intensity of data processing and analysis has taken more time than anticipated, but should be worth it once the results are available.
Impacts
Both repellents have promise in organic production. They might be very amenable to use in automated spray equipment to treat cattle leaving a milking barn, for example. Once data analysis is complete, we should be able to determine exactly how severely the repellents may interfere with vital fly activities such as blood feeding, mating, and survival. Those factors have been very little studied with horn flies. This information thus is relevant to any efforts to control the pest, regardless of material used.
Publications
- No publications reported this period
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: The first year of this 3-year project was just completed, so there are no written or formal scientific outputs as yet. We are, however, sharing the information as we get it with our collaborators in North Carolina and at our two field sites- Cal Poly Pomona and Sonora High School. PARTICIPANTS: California studies are being done with assistance from A. Gerry (UC Cooperative Extension), B. Sandelin (Cal Poly Pomona assoc. prof.), D. Soto and R. Stumpp (UCR technicians), D. Tenney (Cal Poly Pomona undergraduate), C. Martin (UCR graduate student) and M. Reynoso (UCR undergraduate student). Similar studies are being done in North Carolina (field studies in Goldsboro) under the direction of D. W. Watson (NC State Univ., Raleigh). Laboratory support work is being done under the direction of J. Zhu (USDA-ARS, Lincoln). TARGET AUDIENCES: Agricultural research scientists, cooperative extension, industry, and actual beef/dairy producers. PROJECT MODIFICATIONS: In California, two sites (rather than the original 4 planned) are being used, and studies are therefore being spread over a broader period of time. The two sites have superb collaboration and extremely tame cattle, making them highly desirable. The repellent comparisons with a control (site 1) are being done consecutively in a larger beef herd at the treatment site (site 2). Treatment periods are 2 weeks (pretreatment, treatment, posttreatment) with 4 samples taken during each time period. Thus we have two 6-week cycles, rather than one 9 week cycle).
Impacts
The two repellents for horn flies, geraniol and the fatty acid mixture, both provide a high level of short term suppression (1-2 days) of fly numbers on cattle. The cattle fly defensive behaviors support the idea that repellents are dramatically reducing biting pressure. The fatty acids seem to kill the flies with direct contact, while the geraniol temporarily incapacitates them but is not fatal as often, even if the flies are hit directly with the spray. Imbedded, untreated control cattle in a treated herd show increases in fly numbers when the herd is treated with geraniol. That is, there is evidence that we are concentrating the flies in a pasture on untreated hosts. Fatty acid treatments tend to reduce flies somewhat even on untreated, imbedded control cattle and may reflect some spatial repellency. We are currently processing large numbers of flies for blood feeding success using a Drabkins reagent assay (colorimetric assay based on reaction with hemoglobin). This is necessary due to the small and frequent blood meals, which are hard to gauge visually. The other aspects (mating assays, age via pterin accumulation in the heads, stages of egg development and numbers of active ovarioles) are proceeding as planned.
Publications
- No publications reported this period
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Progress 09/01/09 to 08/31/10
Outputs
OUTPUTS: The study is perfectly on-track. Last winter (Jan. 2010) Wes Watson visited UC Riverside. We discussed research methods, laboratory assays, and visited the California field sites. Also last winter and spring horn fly pupae were obtained from Dr. Kim Lohmeyer at the USDA-ARS laboratory in Kerrville, TX. These flies were allowed to emerge from pupae and were held at 30 degrees C for set periods of time to calibrate the pterin age-grading assay at UC Riverside. These flies (separately for males and females) have been processed, but data analysis is pending. The field study was launched in both states (CA and NC) in July 2010. The NC work is occurring in Goldsboro, NC. Cattle groups (untreated control, mineral oil control, permethrin, 15% C8-9-10 fatty acid mixture in mineral oil, and 2% geraniol in mineral oil) were held in a single large pasture and treatments were assessed for effects on horn fly numbers over time (2 weeks pretrt, 2 weeks trt at 2x/week, 2 weeks postrt). This was a head-to-head fly numbers assay. The more involved repellent tests (untreated, geraniol, fatty acid groups) to assess population-level effects were done using 3 physically-separated cattle herds in the southern portion of the Goldsboro experimental farm (same pretrt, trt, and postrt periods as above). The NC field work ended in late September. In California the population-level field tests were done at two locations (very isolated cattle herds) separated by 16 km. The larger location (Cal Poly Pomona) had two cattle groups separated by 1.6 km; the smaller cattle group (10 animals) ultimately was used as an untreated control, while the larger group (34 animals) received each repellent in sequence as above (6 weeks for the fatty acid trial and 6 weeks for the geraniol trial), with 4 imbedded untreated cattle. The smaller cattle group was moved among pastures erratically, and we are unsure how those movements will impact the fly population structure. The second site (Sonora High School FFA herd) therefore was used as an additional untreated control location. Those studies will end in mid-October. In Nebraska laboratory feeding assays using the fatty acids separately against horn flies confirmed activity (80% antifeedancy) for C8 and C9, while the C10 antifeedant effect was >99%. This fall-spring the laboratory assays and counting flies in photographs will occur. PARTICIPANTS: The main investigators are B. A. Mullens, Professor, Dept. of Entomology, UC Riverside; A. C. Gerry, Associate Extension Specialist, Dept. of Entomology, UC Riverside; D. W. Watson, Professor, Department of Entomology, NC State Univ.; and J. Zhu, Research Scientist, USDA-ARS. Numerous collaborators are helping with the project. TARGET AUDIENCES: Beef and dairy cattle producers and associated research/extension scientists. PROJECT MODIFICATIONS: We added the head-to-head fly count comparison assays in NC and ran the CA tests in sequence rather than simultaneously. We also superimposed a teat examination score to determine if horn fly test materials were influencing teat damage in NC. We did not use permethrin as a positive control in CA this year due to doubts about the effects of cattle movement in one of the herds on fly population performance. We may be able to add this trt back next year in CA pending examination of the field fly data.
Impacts
This is the first detailed population-level assessment of effects of chemicals on horn fly abundance, age structure (survival), and blood-feeding and mating success in the field. It further is designed to evaluate mechanisms of horn fly perception of repellents in the laboratory. The 3-year study will provide new, in-depth insights on how this key cattle pest functions in the field and responds to the two repellents being screened as a substitute for traditional pesticides or adjunct for field suppression (e.g. in organic settings).
Publications
- No publications reported this period
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