238th ACS National Meeting, Sunday August 16, 2009
Application of Natural Products in Organic Farming
K Chauhan SO Duke
Summary:
Recent Developments in Invertebrate and Vertebrate Repellents
G. E. Paluch, J. R. Coats, and J. Johnston, Organizers
Summary: As the global climate changes, scientists anticipate that the distribution of animal populations and disease vectors will also expand. In the case of arthropods, such efforts hold immense significance as they have the potential to increase human mortality and suffering from arboviruses above current levels. Increasing need for repellent technologies is also necessary for effective management of wildlife populations. Overabundant deer populations offer one such example where there is sufficient need for effective wildlife management strategies for limiting property, agricultural, and natural resource damages, as well as the spread of disease (chronic wasting disease, bovine tuberculosis, cattle tick fever).
Recently, large efforts have been made to understand the role of chemicals in animal behavior and are leading the development of new repellent strategies. The collection of presentations in this symposium represents the field’s current understanding of invertebrate and vertebrate repellent modes of action, along with novel advances in active ingredients and formulation chemistries. Further, challenges in legislation and product registration, including standardization of regulatory issues and establishment of EPA guidelines were addressed. Topics covered multiple fields of study (chemistry, biology, entomology, biochemistry, microbiology, molecular biology, natural product technology, green chemistry, behavioral sciences, chemical ecology, etc.). Professionals from academia, government, and industry working on repellents and other mechanisms of behavior-modification for use in pest management benefited from the findings presented and participation in discussion.
1. Characterization of botanical terpene activity in arthropods. Gretchen E. Paluch, gre@iastate.edu, Joel R. Coats, jcoats@iastate.edu, and Lyric Bartholomay, lyricb@iastate.edu. Department of Entomology, Iowa State University, Ames, IA 50011
Botanicals have a long history of use for protection against biting arthropods and reducing the risk of exposure to arthropod-transmitted disease agents. The aim of these studies was to characterize the activity of the plant derived sequiterpenes and further develop these compounds as long-lasting botanical repellents and insecticides. Studies addressed the utility of sesquiterpene-rich essential oils from Amyris, Amyris balsamifera, and Siam wood, Fokienia hodginsii, and showed spectrum of activity against arthropods including ticks, cockroaches, house flies and mosquitoes. Identification of the most active components of the Amyris and Siam wood essential oils guided the development of quantitative structure-activity relationship (QSAR) models for predicting repellency to the yellow fever mosquito, Aedes aegypti.
2. Discovery of novel mosquito repellents from structure-activity studies. Maia Tsikolia1, Ulrich Bernier1, uli.bernier@ars.usda.gov, Svetoslav Slavov2, C. Dennis Hall2, cdennishall@aol.com, Gary G. Clark1, Kenneth J. Linthicum1, and Alan R. Katritzky3, katritzky@chem.ufl.edu. (1) USDA-Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL 32608, (2) Department of Chemistry, University of Florida, Gainesville FL, (3) Department of Chemistry, University of Florida, Gainesville, FL 32611
The USDA historical archives of repellents and toxicants consists of over 30,000 chemical structures tested over the past 60 years. We have undertaken a collaborative research project to initially target six subsets of these compounds to discover and develop new chemicals for personal protection and control of mosquitoes. The first subset consisted of 68 candidate mosquito repellents comprised of piperidines and carboxamides. Evaluation of two dose rates using a cloth patch assay with human volunteers indicated that the duration of repellency from one of the carboxamides and 28 of the piperidines was greater than that of DEET when repellents were compared at stoichiometric amounts. Some of the piperidines were repellent on cloth for over 50 days at the 25 µm dose, while DEET provided 7 days repellency using "time to 5 bites" out of 500 mosquitoes as the failure threshold (i.e. 1% threshold). Current studies are being extended to evaluate these repellents against other arthropod species, including stable flies (Stomoxys calcitrans) and ticks (Ixodes and Ambylomma).
3. Structure-activity relationship studies on intermedeol and callicarpenal: Two arthropod repellents identified from the Southern folk remedy, Callicarpa americana. Charles L. Cantrell1, clcantr1@olemiss.edu, Jerome A. Klun2, klunj@ba.ars.usda.gov, James Becnel3, james.becnel@ars.usda.gov, and Julia Pridgeon3, julia.pridgeon@ars.usda.gov. (1) NPURU, USDA-Agricultural Research Service, Thad Cochran Research Center, University, MS 38677, (2) Chemicals Affecting Insect Behavior Laboratory, USDA-Agricultural Research Service, Beltsville, MD 20705, (3) Center for Medical, Agricultural, and Veterinary Entomology, USDA-Agricultural Research Service, Gainesville FL 32608
In previous studies on the American beautyberry (Callicarpa americana), it was demonstrated that callicarpenal and intermedeol are responsible for the arthropod repelling ability of this folk remedy. Both compounds showed significant bite-deterring activity against Aedes aegypti and Anopheles stephensi. Callicarpenal and intermedeol were also evaluated in laboratory bioassays for repellent activity against host-seeking nymphs of the blacklegged tick, Ixodes scapularis, a known vector for Lyme disease, and also against Amblyomma americanum, a known vector for erlicheosis. In the present study, structural modifications were performed on both callicarpenal and intermedeol in an effort to understand in part the functional groups necessary for maintaining and/or increasing the activity. Among the modifications to callicarpenal that will be discussed are the oxidation and reduction of the C-12 aldehyde to its corresponding acid or alcohol, complete reduction of the C-3 olefin, epoxidation of the C-3 olefin, and various methyl ester and acetate products. Combinations of the above modifications will also be discussed as well as their effects on both biting-deterrency and toxicity against Ae. aegypti. Additionally, the effects of epoxidations, allylic oxidations, and catalytic hydrogenation to intermedeol will be discussed.
4. Efficacy of the plant-based repellent, BioUD® against mosquitoes and ticks. Brooke W. Bissinger1, Brookellen@yahoo.com, Jiwei Zhu1, jzhu4@ncsu.edu, Charles S. Apperson1, charles_apperson@ncsu.edu, D. Wesley Watson2, wes_watson@ncsu.edu, Daniel E. Sonenshine3, dsonensh@odu.edu, and R. Michael Roe1, michael_roe@ncsu.edu. (1) Department of Entomology, North Carolina State University, Raleigh, NC 27695, (2) Department of Entomology, North Carolina State University, Raleigh, NC 27695, (3) Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529
The wild tomato plant, Lycopersicon hirsutumf.glabratum is covered in glandular trichomes containing chemicals that confer resistance to numerous herbivorous pests that feed on cultivated tomatoes. Two of these chemicals, 2-undecanone and 2-tridecanone, are also repellent to blood-feeding arthropods. BioUD® is a commercially available arthropod repellent that contains 7.75% 2-undecanone and was approved for use by the US EPA in 2007. Efficacy of BioUD® was compared to that of other commercially available repellents against mosquitoes and ticks. In arm-in-cage bioassays, BioUD® was as repellent as 7% and 15% DEET against the mosquitoes Aedes aegypti and Ae. albopictus, respectively.In mosquito field trials, BioUD® was as repellent as 25% DEET in North Carolina and more repellent than 30% DEET in Ontario 6 h after application. BioUD® was more repellent than 98.1% DEET against the ticks Amblyomma americanum and Ixodes scapularis and provided equivalent repellency against Dermacentor variabilis in choice tests on filter paper. On cotton cheesecloth, BioUD® was more repellent than 15% Picaridin and 0.5% permethrin and provided equivalent repellency to 98.1% DEET, 30% oil of lemon eucalyptus, and 19.6% IR3535® against A. americanum and D. variabilis.
5. Essential oil insect repellents: A formulator's challenge. R. Bradbury
Abstract Not Available
24. Plant essential oils as repellents and/or deterrents to agricultural pests Murray B. Isman, murray.isman@ubc.ca, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
The concept of using non-lethal behavior-modifying substances for management of arthropod pests of agricultural crops has been long touted but as yet largely unexploited on a commercial scale. Numerous natural products have demonstrated repellent, antifeedant or oviposition deterrent activities in laboratory bioassays using pest insects, but consistent efficacy under field conditions has seldom been achieved. In part this results from the ability of insects to habituate to deterrent compounds on repeated or continuous exposure. Plant essential oils represent a relatively new class of natural insecticides efficacious against a wide range of pests. While their neurotoxicity to insects and mites is widely recognized, there is strong anecdotal evidence that in some contexts efficacy could be attributed to their actions as behavior modifiers (i.e. as repellents or deterrents). Results of behavioral bioassays that explore the potential of certain essential oils and their constituents as repellents and deterrents to the twospotted spider mite and some other agricultural pests will be presented.
25. Mechanisms of vertebrate herbivore repellency Bruce A. Kimball, bruce.a.kimball@aphis.usda.gov, National Wildlife Research Center, USDA/APHIS/WS, Philadelphia, PA 19104, and Jimmy D Taylor, jimmy.d.taylor@aphis.usda.gov, USDA/APHIS/WS, National Wildlife Research Center, Olympia, WA 98512
Repellents (devices applied to a food source for the purpose of reducing intake) can be categorized into four categories: 1) Stimuli that exploit the herbivore's fear of unfamiliar visual, olfactory, or taste cues; 2) Chemicals that act on the herbivore's trigeminal system; 3) Toxicants that produce negative postingestive consequences and are avoided as a result of conditioning or learning; and 4) Sensory signals that represent perceived consequences, such as those impacting the species on an evolutionary scale. Because the effectiveness of repellents can depend on both the mechanism and the motivation of the individual herbivore, recognition of these mechanisms is needed for proper evaluation and testing of candidate repellents. For example, when alternative foods are available, shiny ribbons (repellent with no consequence) may provide significant protection in localized areas. However, when alternative foods are scarce, repellents that impart actual consequences to the herbivore will be required to effectively reduce browsing.
26. Research on tick repellents: Playing catch up John F. Carroll, john.carroll@ars.usda.gov, Animal Parasitic Diseases Laboratory, USDA-Agricultural Research Service, Beltsville Agricultural Research Center, Bldg. 1040, BARC-East, Beltsville, MD 20705
Historically ticks have received little attention compared to mosquitoes, in the research and development of repellents. With the rise of tick-borne disease during the past two decades, greater attention has focused on repellents as a last line of protection against tick bites. Deet has dominated the repellent market since the 1950s in products for use on human skin while permethrin has become a standard for clothing treatments. However, new products and compounds from natural sources, some of which are discussed in this presentation, are also proving to be effective tick repellents. Two medically important tick species, Ixodes scapularis and Amblyomma americanum, have been shown to detect the repellents deet and SS220 by olfaction, but little is known about the mode of action. Ixodes scapularis and A. americanum differ in their responses to repellents in terms of behavior and efficacy, with implications for repellent testing and development.
27. Mosquito repellents for the tropics: From the lab to the field John Grieco, jgrieco@usuhs.mil, Preventive Medicine and Biometrics, Uniformed Services University, Bethesda, MD
Abstract text not available
28. Research and development of all natural, plant-derived insecticides, pesticides, and repellents for the control of disease-vectoring arthropods of public health importance Marc Dolan, mcd4@cdc.gov, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521
Vector-borne infectious diseases such as tick-transmitted Lyme disease and mosquito-borne West Nile virus and other arboviruses continue to pose a significant public health threat resulting in human and economic loss in the United State and around the globe. Protection against arthropod attack is best achieved by avoiding arthropod infested habitat, application of repellents, and/or the use of synthetic chemical pesticides. While effective, many citizens are hesitant to use them due to concerns about short range toxicity and long range health problems attributed to these chemicals. Laboratory and field trials conducted against ticks, fleas, and mosquitoes using several naturally derived compounds and extracts from forest resources and agricultural residues have been shown to be excellent biocides and repellents. Compound structures and bioactivities will be discussed.
29. Impact of technical, ethical and regulatory developments on registration of repellents Clara Fuentes, fuentes.clara@epa.gov, Biopesticides and Pollution Prevention Division, Environmental protection Agency, Arlington, VA 22202
Technical challenges and ethical requirements impact efficacy evaluation of repellents as required for supporting efficacy claims against public health pests on product labels. Updates in regulatory policies for controlling disease vectors will be addressed as they may affect evaluation and consequently, registration of repellent products. Research needs will be identified, including a summary of proposed strategies for improving communication to consumers.
30. Evaluation of insects repellents from research to consumer protection Daniel Strickman, Veterinary and Medical Entomology, USDA-Agricultural Research Service, GWCC-BLTSVL, 5601 Sunnyside Avenue, Beltsville, MD 20705-5148
Standardized testing and evaluation of insect repellents is a current subject of intense study by US EPA and USDA. The challenges arise from several aspects of these products. First, the mode of action of active ingredients varies, even though we know little about the exact mechanisms. Second, the inherent repellency of an active ingredient is very different from its duration of repellency in a formulated product. Finally, ethical considerations dictate minimization of risk and discomfort during tests, tending to base results on the most exceptional members of an insect population. Some potential solutions are suggested for methods, analysis, and interpretation.
