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Funded Project |
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Funding Program:
Enhancement Grants - Special Projects |
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Project Title:
Detection and quantification of insect repellents in bovine milk |
Project Directors (PDs):
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Lead State: NC Lead Organization: North Carolina State University |
| Undesignated Funding: $24,868 |
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Start Date: Jul-09-2007 End Date: Jul-08-2008 |
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Summary:
Geraniol is a naturally occurring monoterpene that functions as part of a plant's defense mechanism to ward off attack by insects. Geraniol is a common component of lemongrass, geranium, tomato and alfalfa and is usually associated with glandular tissues on the leaf and stem. When concentrations of geraniol are low, insects may be attracted to the plant but at high concentrations the insect is repelled. North Carolina State University has been exploring stimula deterrent (push-pull) strategies for the management of flies in the pasture ecosystem, most importantly the horn fly, Haematobia irritans. The push pull concept has been successfully used in a variety of cropping systems but to the best of our knowledge has never been used in animal agriculture. In a NC pilot project we used the naturally occurring plant oil geraniol to repel the horn flies from the treated animals. Horn flies, seeking alternative hosts, were attracted to other animals treated with a non-repellent parasiticide. Data described in this proposal demonstrates this strategy has utility for the reduction of pesticides in the environment and in our foods. We propose to gather preliminary data for a larger multistate project being developed between the states of NC, Florida and Arkansas. Obtaining funding for this multistate project hinges on the concern that the selected natural repellent might flavor cows' milk. Our goal herein is to gather data on the presence or absence of the geraniol in milk harvested from the topically treated animals. Geraniol concentrations in raw and pasteurized whole milks will be evaluated using solid phase microextraction and gas chromatography/mass spectrometry. The possible sensory impact of geraniol in milk will be addressed by the use of threshold analysis and difference and/or consumer acceptance tests.
Objectives: 1. Evaluate and quantify monoterpene flavors in milk following topical application of geraniol to cattle for as an insect repellent. Subobjective 1a. Quantitative analysis of geraniol in milk samples. Subobjective 1b. Evaluate the sensory impact of geraniol in milk using a taste panel. |
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Final Report: |
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Project Type: IPM Seed Grant or IPM Capstone Grant This IPM Seed Grant was instrumental in developing the use of repellent strategies for the management of pasture flies on dairy cattle. Key to the success of such integrated strategies was proof that the essential oil, geraniol, when used as a fly repellent did not alter the flavors of milk. |
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Introduction The horn fly is an obligate blood-sucking parasite of cattle and is considered the most important pest of pastured cattle in the United States. Horn fly feeding habits cause cattle annoyance, alteration of grazing habits, and decrease both milk production and weight gains. Losses as a result of horn fly blood feeding can cause a 15% decrease in milk production or weight loss. Horn fly management is largely accomplished using broad-spectrum pesticides. Treatments are made through several application techniques including pour-on, insecticide-impregnated ear tags, backrubbers and feed through for insecticides while anthelmintics are applied as a pour-on, injectible or bolus. Dairy farmers reported using insecticides two to three times per month to manage flies on pastured cattle. Push-pull strategies (PPS) to manage of arthropod pests have been successfully used in onions and cotton. When reduced to practice PPS is the manipulation of the pest by applied pressures causing behavioral changes that result in less crop damage. Conceptually a variety of compounds, including repellents, oviposition deterrents, and antifeedants are used to push the pest away from the crop. Other agents pull the pests toward a trap crop using lures such as pheromones, attractants, and feeding stimulants. Insect repellents to protect humans from disease vectors, biting flies, mosquitoes and ticks are relatively common but rarely used with livestock. Natural product repellents have great appeal for those wishing to reduce pesticide applications. Geraniol, a monoterpene, is listed among 31 minimal risk active ingredients exempt from the registration requirements of the Federal Insecticide, Fungicide and Rodenticide Act. We explored the potential for geraniol to relieve cattle from biting fly pressure. Horn flies were repelled from cattle treated with 30% geraniol mixed in mineral or soybean oil and did not return for at least 24 hours. We observed that abandoning horn flies were attracted to untreated cattle housed close-by and that fly populations could be controlled by treating a small portion of the herd with an insecticide and the majority with geraniol. We recognize that the potential benefits of plant oils as insect repellents for livestock would provide needed relief to animals from the persistent attack of biting flies, and reduce pesticides applied to food producing animals. However the commercial viability of geraniol based products could not proceed without needed studies to determine if geraniol, when applied to dairy animals, flavored the milk or milk products. Forages, including alfalfa containing high amounts of monoterpenes impart a flavor to milk fat monoterpenes. The presence of monoterpenes in milk may lead to learned taste aversion to milk following ingestion. In this study we evaluated bovine milk flavors following topical application of geraniol at rates sufficient to repell biting flies. Sensory evaluation required the use of a taste panel. Panelists were identified and asked to score products on a scale of 1 to 9 with 1 being no off flavor, 5 being off flavor and 9 being extremely flavored. A split plot design was used for the sensory evaluation analysis. |
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Outcomes Detection of Geraniol in Milk Samples. The limit of detection was determined for geraniol using headspace analysis with solid phase microextraction followed by gas chromatography and mass spectrometry. The instrumental detection limit for geraniol was 125 ppb in samples to which geraniol was added. Milk samples taken from cattle treated with 60, 120 and 180cc of 30% geraniol in soybean oil were negative for the presence of geraniol. No geraniol was detected in any of the commercially available milks tested. Threshold Determination of Geraniol Odors in Milk The orthonasal (detectable odor) determination of serially diluted geraniol added to water, skim milk and whole milk was quantified using an ascending forced choice scale. The group best estimate threshold (BET) was 147.0, 137.9 and 332.5 ppb for water, skim milk and whole milk, respectively. The threshold determination for geraniol in skim milk and water were similar. In contrast, the threshold for geraniol in whole milk was significantly higher, presumably because geraniol bound with lipids was less detectable. Descriptive Analysis of Geraniol in Milk The dairy lexicon describes seven milk flavors, cooked, sweet aromatic, sweet taste, astringency, salty milk fat and grassy. Trained panel flavor profiles of milk from geraniol treated cows were not different from milk from control cows. There was no differences between milk gathered from cattle treated with 60, 120 and 180 cc of 30% geraniol. This information was presented at two conferences, American Dairy Science Assoc in 2008 and the Livestock Insect Workers Conference in 2007. Watson, D. M., J. P. Evans, R. E. Miracle, M. A. Drake, S. P. Washburn, and D. W. Watson. 2008. Presence of geraniol in bovine milk following topical application as a natural insecticide. J. Dairy Sci. 91, E - Suppl. 1: 216 (Abstr.) http://adsa.asas.org/meetings/2008/abstracts/0215.PDF Watson, D. W., MaryAnne Drake, Steve Washburn, and Jerry Butler. 2007. Detection and quantification of an insect repellent in bovine milk. LIWC ISEP Meeting Lexington, KY. June 10-14. |
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Non-technical summary Geraniol is a plant derived compound found naturally in many plants with demonstrated insect repellency properties. Geraniol is listed as a minimal risk active ingredient exempt from the Federal registration requirements and this generally recognized as safe (GRAS) repellent could benefit organic or other producers wishing to reduce or eliminate reliance on insecticides. However, before acceptance of geraniol as an insect repellent it was necessary to know if geraniol affected milk flavors. This study was conducted to determine if topical application of geraniol influenced milk flavor. Tests performed on Dairy cows at the Center for Environmental Farming Systems in Goldsboro, NC indicate geraniol applied to cattle to repel flies was not detectable in milk harvested from treated animals. Results of this study proved that geraniol fly repellent could be included in an integrated pest management strategy to control pasture flies without risk of causing off flavors in milk. |
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Impacts Impacts of this study are three fold. 1)Instrumental analysis may be a viable quality assurance step to quantify the presence of geraniol in milks at levels below human sensibilities. 2) Geraniol applied topically to dairy cows did not result in detectable levels in milk either by sensory panel or by descriptive analysis. 3) Lack of detectable residues in milk allows geraniol to be considered as a promising natural insect repellent, potentially applicable to organic dairy herds. Results of this study directly lead to the first geraniol product to be registered by the Organic Materials Review Institute (OMRI) for use on organic cattle as a fly repellent. The description of Meadowland Natural Fly Repellent can be see at the following link. http://www.omri.org/simple-opl-search/results/meadowland |
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Appendices http://adsa.asas.org/meetings/2008/abstracts/0215.PDF |
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