An official website of the United States government.
We propose to evaluate and help develop the first insect repellents for the livestock industry reliant on naturally occurring compounds. Our preliminary laboratory and field studies suggest that medium chain length saturated fatty acids and the plant-derived compound geraniol may effectively prevent the horn fly from attacking cattle. Rather than relying solely on numbers of horn flies on cattle as a measure of pest intensity (as all past studies have done), we will utilize changes in fly population age structure, survivorship data, fecundity, and blood feeding rates, and for the first time incorporate fly defensive behaviors of cattle as a measure of irritation. The repellents will be evaluated against both a negative (nothing) and a positive (permethrin) control in studies of small cattle herds over 9-week intervals with 3 discrete time periods: pretreatment, treatment, and posttreatment. Small groups of untreated animals in each herd will serve both as a sink (refuge) and a potential source of flies. Adjunct laboratory studies will help determine the relative importance of contact versus spatial repellency (bioassays and electroantennagrams) as a function of dose and time. The studies will allow us to examine treatment-related fly movement relevant to the eventual development of a push-pull strategy (PPS). Used in integrated cropping systems, the PPS relies on the manipulation of the pest by inducing behavioral changes that result in less damage to the crop. Application of PPS has utility in the management of pests in animal agriculture by providing alternative pasture fly management technologies, reducing pesticide use and contributing to a more sustainable production system. We anticipate that these technologies and methods will contribute significantly to improved management of the horn fly, Haematobia irritans, a key pest for pastured cattle nationally. Further, it will serve as a model for future evaluation of other livestock fly pests.
<p>NON-TECHNICAL SUMMARY:<br/> Insecticide resistance and reregistration issues, and societal environmental and food safety concerns, are becoming quite serious in the developed world. They threaten to greatly reduce or eliminate traditional chemical control options for the horn fly, a severe pest of pastured cattle (beef and dairy) that reduces weight gains, milk production and feed conversion efficiency. Very little is known about how pesticides or repellents actually affect horn fly populations (beyond simply reducing numbers). Two new and environmentally-friendly repellents have been screened and show great promise for horn fly management. One is the plant-derived repellent geraniol, and the other is a mixture of fatty acids, which are normal constituents of food and are found on animal skin. We will evaluate these in a series of field and laboratory tests to learn
exactly how severely the repellents interfere with horn fly survival, feeding, and reproduction. The cattle themselves will help us assess this through changes in their fly defensive behavior, which essentially tells us how badly they are being bitten. We will compare how the repellents perform over 3 years relative to a standard insecticide, permethrin, and an untreated check. Field studies will be done in North Carolina and California, with supporting laboratory evaluations (to determine exactly how the flies perceive the chemicals) in Nebraska. Our goal is to develop these repellents for animal protection and to define methods for similar development of other repellents against other fly pests of animals. Repellents eventually should be useful in what are called "push-pull" approaches to pest management. These ""push"" a pest away from valuable animals or crops using a repellent and
simultaneously using an attractant to ""pull"" them toward other animals (e.g. a smaller number treated with insecticides), or toward traps which can capture and kill the pests.
APPROACH: Four discrete field sites (cattle with horn fly populations) will be utilized in CA and NC. In each of 3 years the field sites will be subjected to one of the following treatment regimes: negative control (untreated), positive control (permethrin), geraniol, or a fatty acid mixture (C8, C9, C10). Treatment periods of 3 weeks each will include a pretreatment interval, treatment interval, and posttreatment interval. Each site will house 12-24 cattle. One fourth of those cattle at a site will not be treated, to serve as both a fly source and a sink (i.e. a possible harborage for flies repelled from treated cattle). The remaining cattle will be exposed to 2x/week treatments with one of the repellents, or weekly treatment with permethrin. Cattle fly defensive behaviors will be monitored weekly to help interpret the degree of fly biting they are sustaining. Horn
fly populations will be visually estimated (digital pictures) and then sampled weekly using a sweep net from the untreated and treated cattle at each site. Flies will be tested for pterin accumulation in the head (an indicator of age). The abdomens will be dissected to determine proportion and degree of blood feeding, parity (proportion that have laid eggs), insemination (mating success), and the stage of egg development. The data will tell us how well the flies are surviving, how much they are feeding, and how the population is performing under pressure from repellents versus a toxicant. We expect to be able to document reductions in blood feeding, survival,and possibly mating success in conjunction with the treatments, and the age structure and changes in relative numbers on treated and untreated cattle will tell us about fly movement among cattle.<p>
PROGRESS: <br/>2012/09 TO 2013/08 <br/>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.</p><p>
PROGRESS: <br/>2011/09/01 TO 2012/08/31 <br/>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.<br/>
PROGRESS: <br/>2010/09/01 TO 2011/08/31 <br/>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).<br/>
PROGRESS: <br/>2009/09/01 TO 2010/08/31 <br/>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.</p>