Agricultural Science Commons^™

Hessian Fly, Jeffrey J. Stuart, Ming-Shun Chen, Marion O. Harris

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The Hessian fly (Mayetiola destructor) is a gall-forming insect (Harris et al. 2006) with several attributes that make it suitable for genetic analysis: a short life cycle (30 days), a small genome (158 Mb) (Johnston et al. 2004), and polytene chromosomes. The reproductive biology and behavior of the insect also make it an attractive model (Harris and Rose 1989,1990; Bergh et al. 1990; Kanno and Harris 2000; Morris et al. 2000; Harris et al. 2001). Compared to most plant-feeding insects, Hessian flies can be reared in a small space. Unlike gall-forming aphid species, the Hessian fly is always …

Uncertainty In Environmental Decision Making: Issues, Challenges And Future Directions, H. R. Maier, J. C. Ascough, M. Wattenbach, C. S. Renschler, W. B. Labiosa, J. K. Ravalico

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

There has been an increase in the use of formal approaches to environmental management. Jakeman and Letcher (2003) and Jakeman et al. (2006) have demonstrated the importance of integrated models as a means of assessing the response of environmental systems to proposed enlargement options. Gunderson and Holling (2000), Cowie and Borrett (2005), Curtis et al. (2005) and Pahl-Wostl (2005) have highlighted the need for the incorporation of social and institutional aspects into decision-making processes.

Effects Of Atmospheric Co2 Enrichment On Crop Nutrient Dynamics Under No-Till Conditions, Stephen A. Prior, G. Brett Runion, Hugo H. Rogers, H. Allen Torbert

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Increasing atmospheric CO₂ concentration could increase crop productivity and alter crop nutrient dynamics. This study was conducted (3 yrs) with two crops ([Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench.]) grown under two CO₂ levels (ambient and twice ambient) using open top field chambers on a Blanton loamy sand under no-tillage. Macronutrient and micronutrient concentrations and contents were determined for grain, stover, and roots. Although elevated CO₂ tended to reduce nutrient concentrations, high CO₂ consistently increased nutrient content especially in grain tissue; this response pattern was more notable with macronutrients. The …

Good Vibrations? Structure And Function Of The Cloacal Tip Of Male Australian Maluridae, Melissah Rowe, Murray R. Bakst, Stephen Pruett-Jones

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

When females mate multiply, sperm competition can generate strong selection for traits that provide males with a fertilisation advantage. This study examined the cloacal tip, a unique morphological structure of males that appears to be associated with sperm competition in Australian Maluridae. Species in this group appear to experience a range of sperm competition intensities and exhibit a diversity of associated reproductive adaptations and behaviours. A prominent cloacal tip was present in the striated grasswren Amytornis striatus striatus, and superb Malurus cyaneus cyanochlamys, splendid M. splendens melanotus, red-backed M. melanocephalus and white winged fairy-wrens M. leucopterus leuconotus …

General Introduction To Areawide Pest Management, Robert M. Faust

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Welcome to the realm of areawide pest management (AWPM). This book represents one of the first comprehensive 'treatises' on the AWPM concept and approach, and should be of interest and use to many types of readers, from research scientists in government, university and industry to pest control advisors and extension personnel, growers, pest control and integrated pest management (IPM) practitioners, students, teachers, natural resource managers and others interested in environmentally sound pest control. There is a range of topics included in the subject area. The book is grouped into three parts. Chapters 2-8 discuss the foundation of areawide pest management; …

Establishing Inter-Agency, Multidisciplinary Areawide Pest Management Programmes, Robert M. Nowierski, Hendrik J. Meyer

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Pest management today usually comprises multiple complex tactics that transcend disciplines, geographical regions, climatic zones, production/management systems, production scales and economic strata. Solutions to priority problems involve research, education and extension professionals. But, equally important to project success are the users of the knowledge generated and the end-users of the 'products'. Setting a direction for the future goals, IPM has been an important activity for the 'community' of constituents who share concerns for future pest management.

Under the leadership of the USDA and land grant universities, a road map for IPM has been developed with extensive participation of diverse stakeholders. …

Social And Economic Aspects Of Areawide Pest Management, Sean P. Keenan, Paul A. Burgener

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

This chapter explores demonstration elements from the United States Department of Agriculture, Agricultural Research Service's demonstration programme for cereal aphid AWPM. We explore elements of the demonstration programme as agricultural innovations. We discuss potential adoption of these elements by wheat producers on the Great Plains and implications of the programme outcomes for other wheat-growing regions of the world. We begin with a history of research on the adoption of agricultural innovations, which provides the context for evaluating the cereal aphid programme from the perspective of farmer adoption. Chapter 19, this volume, by Kristopher Giles et al. provides a summary and …

The Role Of Databases In Areawide Pest Management, Vasile Catana, Norman Elliott, Kris Giles, Mustafa Mirik, David Porter, Gary L. Hein, Frank Peairs, Jerry Michels

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The simplest definition of the term 'database' is given in Webster's dictionary as 'a comprehensive collection of related data organized for convenient access, generally in a computer' (Random House, 1996). This term appeared in the late 1960s because of the evolution of computer software and the need to distinguish the specialized computer systems for the storage and manipulation of data, called database management systems (DBMS) (Neufeld and Cornog, 1986). Today, the acronym 'DBMS' is universally understood within Information Technology (IT), just like the acronym 'Bt' for 'Bacillus thuringiensis' is in the field of biological pest control. …

Corn Rootworm Areawide Pest Management In The Midwestern Usa, Laurence D. Chandler, James R. Coppedge, C. Richard Edwards, Jon J. Tollefson, Gerald R. Wilde, Robert M. Faust

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

For many maize (Zea mays) producers across the Midwestern USA, as well as in parts of the northern and southern plains, the corn rootworm complex (Diabrotica spp.; Coleoptera: Chrysomelidae) has represented one of the greatest challenges to efficient, quality maize-grain production over the past 50-60 years. Three species of corn rootworm are particularly troublesome: the western corn rootworm, Diabrotica virgifera virgifera, the northern corn rootworm, D. barberi and the Mexican corn rootworm, D. virgifera zeae; all have consistently been important economic pests of maize (Metcalf, 1986b). Prior to the introduction of transgenic maize varieties designed …

Turkey Sperm Reside In The Tubular Glands In The Urodeum Following Artificial Insemination, M. R. Bakst, V. Akuffo

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A turkey hen in egg production requires 48 h after the last insemination to maximize the number of sperm in the uterovaginal junction sperm-storage tubules. Where the sperm that continue to fill the oviductal spermstorage sites during this 48-h period reside remains unknown. Histological sections of the juncture of the vagina with the urodeum, the central compartment of the cloaca, revealed deep tubular glands containing periodic acid- Schiff-positive secretory material. When examined 36 h after the last artificial insemination, sperm were observed in the lumen of the tubular glands associated with the urodeum. We suggest that sperm reside in the …

Central And Peripheral Administration Of Kisspeptin Activates Gonadotropin But Not Somatotropin Secretion In Prepubertal Gilts, Clay A. Lents, Neely L. Heidorn, C. Richard Barb, J. Joe Ford

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

It is well established that kisspeptin signaling is necessary for the onset of puberty in laboratory animals. However, the role that kisspeptin may have in regulating puberty in large domestic animals is unknown.We tested the hypothesis that either central or peripheral infusion of kisspeptin would stimulate gonadotropin and GH secretion in prepubertal gilts. In experiment 1, prepubertal gilts were fitted with i.c.v. cannula and indwelling jugular catheters. Animals were randomly assigned to receive 0, 10, or 100 μg kisspeptin in saline. In experiment 2, prepubertal gilts, fitted with indwelling jugular catheters, randomly received 0, 1, 2.5, or 5 mg kisspeptin …

Parentage-Based Dna Traceback In Beef And Dairy Cattle, Mike Heaton

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Why is animal ID needed?

Ways to physically label individual cattle

Disputes arise even when animal identification systems are in place

The dispute

The resolution

DNA is the label never removed from beef

A chromosome has genes and other DNA

Genes are encoded by sequences of DNA

What are SNPs?

Properties of SNPs

Ways to use DNA for traceback

Sometimes parentage testing is the last resort for DNA-based traceback

Using SNP markers for parentage

Accurate sire determination requires many DNA markers

Comparing the calf to the sire: elimination

Comparing the calf to a possible sire

The ideal parentage SNP markers …

Genetic Profiling To Determine Potential Origins Of Boll Weevils (Coleoptera: Curculionidae) Captured In A Texas Eradication Zone: Endemicity, Immigration, Or Sabotage?, Kyung Seok Kim, Thomas W. Sappington, Charles T. Allen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Thirty-seven boll weevils, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), were captured in pheromone traps near Lubbock, TX, in the Southern High Plains/Caprock eradication zone during August-October 2006. No boll weevils had been captured in this zone or neighboring zones to the north earlier in the year, and only very low numbers had been captured in neighboring zones to the south and east. Therefore, the captures near Lubbock were unexpected. Five of the weevils captured the last week of August were preserved and genotyped at 10 microsatellite loci for comparison with a database of genotypes for 22 boll weevil populations sampled …

Improvement Of Perennial Forage Species As Feedstock For Bioenergy, William Anderson, Michael Casler, Brian S. Baldwin

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Both native and non-native forage species other than switchgrass are less commonly considered as potential lignocellulosic feedstocks for bioenergy in the United States. These species hold potential as bioenergy feedstocks because of the experience and infrastructure that is already in place for management and harvest, and in certain areas of the country they have greater yield potential than switchgrass or other feedstocks. The forage grasses consist of temperate cool-season (most commonly C3) grasses as well as tropical or sub-tropical warm-season (C4) grasses. Some legume species may also play a significant role in supplying useful bioenergy feedstocks. Most have been researched …

The Artiodactyl Apobec3 Innate Immune Repertoire Shows Evidence For A Multi-Functional Domain Organization That Existed In The Ancestor Of Placental Mammals, Rebecca Larue, Stefán Jónsson, Kevin Silverstein, Mathieu Lajoie, Denis Bertrand, Nadia El-Mabrouk, Isidro Hötzel, Valgerdur Andrésdóttir, Timothy Smith, Reuben Harris

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Background: APOBEC3 (A3) proteins deaminate DNA cytosines and block the replication of retroviruses and retrotransposons. Each A3 gene encodes a protein with one or two conserved zinccoordinating
motifs (Z1, Z2 or Z3). The presence of one A3 gene in mice (Z2–Z3) and seven in humans, A3A-H (Z1a, Z2a-Z1b, Z2b, Z2c-Z2d, Z2e-Z2f, Z2g-Z1c, Z3), suggests extraordinary evolutionary flexibility. To gain insights into the mechanism and timing of A3 gene expansion and into the functional modularity of these genes, we analyzed the genomic sequences, expressed cDNAs and activities of the full A3 repertoire of three artiodactyl lineages: sheep, cattle and pigs.
Results: …

Chapter 17. Nitrogen Management Modeling Techniques: Assessing Cropping Systems/Landscape Combinations, J. A. Delgado, M. J. Shaffer

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Nitrogen use efficiency (NUE) in production agriculture is often low, which results in losses of excess N to groundwater as NO₃-N, to gaseous emissions of NH₃ and N₂O, and to N losses in surface runoff and erosion. Best management practices (BMPs) are needed to improve efficiency levels while maintaining proper nutrition for crops. Field studies designed to investigate potential BMPs are both time consuming and costly, and cannot cover all scenarios. Application of simulation models with N cycling components in conjunction with associated field investigations offers methodology that can help identify BMPs that show promise …

Genotype By Environment Interaction Due To Heat Stress, J. Bohmanova, University Of Georgia Misztal, S. Tsuruta, H. D. Norman, T. J. Lawlor

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Heat stress was evaluated as a factor in differences between regional evaluations for milk yield in the United States. The national data set (NA) consisted of 56 million first-parity, test-day milk yields on 6 million Holsteins. The Northeastern subset (NE) included 12.5 million records on 1.3 million first-calved heifers from 8 states, and the Southeastern subset (SE) included 3.5 million records on 0.4 million heifers from 11 states. Climatic data were available from 202 public weather stations. Each herd was assigned to the nearest weather station. Average daily temperature-humidity index (meanTHI) 3 d before test date was used as an …

Susceptibility Of Eggs And Adult Fecundity Of The Lesser Grain Borer, Rhyzopertha Dominica, Exposed To Methoprene, Y. Chanbang, F. H. Arthur, G. E. Wilde, J. E. Throne, Bh. Subramanyam

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A series of tests were conducted to determine the susceptibility of eggs and neonates of the lesser grain borer Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae = Bostrychidae), exposed to the insect growth regulator, methoprene, on filter paper and on rough rice. In the first test, the hatch rate of eggs exposed on filter paper treated with methoprene at the label rate of 0.003 mg [AI] /cm² when used as a surface treatment in structures was 52.0 ± 7.3% compared to 93.0 ± 3.3% on untreated controls. In the second test, eggs were exposed to a dose-response series of 0.00003 to …

Building A Community Modelling And Information Sharing Culture, A. Voinov, R. R. Hood, J. D. Daues, H. Assaf, R. Stewart

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Much of human creativity is geared towards moving energy and materials rather than information, even though information has become another crucial component of human welfare and livelihood. Information, unlike energy and materials, is not subject to conservation laws. By copying information from sources and distributing it to new destinations we do not lose information at the sources. This is what is known as non-rival goods in ecological economics (Daly and Farley, 2003). As with gravity, by using information we do not decrease the ability of others to use it. Nevertheless, exchange of information is restricted by patent law, as well …

Comparison Of Field Measured Soil Absorption Field Loading Rates And Loading Rates Estimated From Soil Morphologic Properties, Kelli S. Hart, Brad D. Lee, Philip J. Schoeneberger, Donald P. Franzmeier, Phillip R. Owens, Douglas R. Smith

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Concerns from local health departments regarding premature septic system failure (less than 1 year from installation) has led to an investigation of septic system soil absorption field design parameters in northeast Indiana. The objective of this study was to compare the loading rate based on field measured saturated hydraulic conductivity (LR_m) across a toposequence to the estimated allowable loading rate (LR_e) based on soil morphological properties. Saturated hydraulic conductivity measurements were determined by a compact constant-head permeameter at five landscape positions, at four depths (surface horizon, upper argillic horizon, transition zone between the argillic horizon and …

Modeling Trench Sidewall And Bottom Flow In On-Site Wastewater Systems, S. D. Finch, D. E. Radcliffe, L. T. West

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Little is known about how much wastewater infiltrates the soil via the trench sidewall versus the trench bottom in on-site wastewater systems. Our objectives were to develop a method of simulating trench bottom and sidewall flow using a two-dimensional numerical computer model that would include the trench within the model space and determine how much sidewall flow would occur under steady-state conditions. We used HYDRUS-2D to simulate water flow in a two-dimensional cross section of a conventional gravel-filled trench and the surrounding drainfield.

Numerical Modeling Of Bank Instability By Seepage Erosion Undercutting Of Layered Streambanks, M. L. Chu-Agor, G. V. Wilson, G. A. Fox

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Undercutting, primarily considered due to fluvial mechanisms, has been reported to have a major impact on slope failure. Predicting bank collapse specifically due to seepage erosion undercutting by particle mobilization on layered streambanks has not been fully studied or modeled, even though its role in streambank erosion may be important. The limitation originates from the limited field measurements or laboratory experiments as well as the unavailability of discrete element models that can effectively simulate seepage particle mobilization, undercutting, and the corresponding mass wasting. The objective of this research was to demonstrate a procedure for incorporating seepage undercutting into bank stability …

Genomic Analysis Of Fusarium Verticillioides, D. W. Brown, R. A.E. Butchko, R. H. Proctor

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Fusarium verticillioides (teleomorph Gibberella moniliformis) can be either an endophyte of maize, causing no visible disease, or a pathogen-causing disease of ears, stalks, roots and seedlings. At any stage, this fungus can synthesize fumonisins, a family of mycotoxins structurally similar to the sphingolipid sphinganine. Ingestion of fumonisin-contaminated maize has been associated with a number of animal diseases, including cancer in rodents, and exposure has been correlated with human oesophageal cancer in some regions of the world, and some evidence suggests that fumonisins are a risk factor for neural tube defects. A primary goal of the authors’ laboratory is to …

Soil Properties And Macro Cations Status Impacted By Long-Term Applied Poultry Litter, Zhongqi He, Irenus A. Tazisong, Zachary N. Senwo, Donglin Zhang

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Most ethnic populations worldwide consume poultry products. Whereas poultry litter (PL) is a traditionally inexpensive and effective fertilizer to improve soil quality and agricultural productivity, overapplication to soils has raised concerns because excess nutrients in runoff could accelerate the eutrophication of fresh bodies of water. A long-term field experiment of land application of PL to soils used for pasture growth has been maintained for nearly two decades in the Sand Mountain region of north Alabama, USA. In this work, several soil parameters impacted by the long-term applied litter were characterized. The findings clearly support previous general observations that long-term applied …

Registration Of ‘Darrell’ Wheat, A. M. H. Ibrahim, S. D. Haley, P. S. Baenziger, Y. Jin, M. A. C. Langham, J. Rickertsen, S. Kalsbeck, R. Little, J. Ingemansen, O. K. Chung, B. W. Seabourn, G. H. Bai, Ming-Shun Chen, D. V. Mcvey

Department of Agronomy and Horticulture: Faculty Publications

‘Darrell’ (Reg. No. CV-1024, PI 644224) hard red winter wheat (Triticum aestivum L.) was developed by the South Dakota State University–Agricultural Experiment Station and released in 2006 to seed producers by the South Dakota State University–Agricultural Experiment Station and the University of Nebraska Agricultural Experiment Station. Darrell was selected from the cross 2076-W12-11/‘Karl 92’ (PI 564245)//NE89526. NE89526 is an experimental line from the University of Nebraska with the pedigree ‘Lancota’ (CI 17389) selection/’Siouxland’ (PI 483469)//TX792729. 2076-W12-11 is an unreleased experimental line that originated from a population with an unidentified pedigree. Darrell was selected as an F3:4 line in 1998 …

Comparison Of Nitrogen Fertilization Methods And Rates For Subsurface Drip Irrigated Corn In The Semi-Arid Great Plains, D. D. Tarkalson, J. O. Payero

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In semi‐arid areas such as western Nebraska, interest in subsurface drip irrigation (SDI) for corn is increasing due to restricted irrigation allocations. However, crop response quantification to nitrogen (N) applications with SDI and the environmental benefits of multiple in‐season (IS) SDI N applications instead of a single early‐season (ES) surface application are lacking. The study was conducted in 2004, 2005, and 2006 at the University of Nebraska‐Lincoln West Central Research and Extension Center in North Platte, Nebraska, comparing two N application methods (IS and ES) and three N rates (128, 186, and 278 kg N ha^-1) using a …

Using The Solvent Retention Capacity Test When Breeding Wheat For Diverse Production Environments, Carl Walker, Kimberly A. Garland-Campbell, Brady Carter, Kimberlee Kidwell

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The solvent retention capacity (SRC) test is used to predict commercial baking performance of soft wheat (Triticum aestivum L.) by measuring the capacity of flour to retain each of four solvents— water, Na₂CO₃, sucrose, and lactic acid— to assess overall absorption capacity, starch damage, pentosan and gliadin content, and glutenin quality, respectively. Our objectives were to determine sources of variation in the test, repeatability, and optimum scale and resource allocation needed to maximize efficiency. Duplicate SRC tests were conducted for each solvent using two flour sample sizes (5 and 0.2 g) from two field replications …

Winter Cover Crops And Vinegar For Early-Season Weed Control In Sustainable Cotton, P. J. Moran, S. M. Greenberg

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Weeds may be suppressed by winter cover crops and the use of organic herbicides such as vinegar. Black oat (Avena strigosa) and hairy vetch (Vicia villosa) winter cover crops were planted for 2 years as part of a sustainable production system for cotton in the Lower Rio Grande Valley of Texas, and were till-killed each spring prior to cotton planting. Palmer amaranth (Amaranthus palmeri), common purslane (Portulaca oleracea), and sunflower (Helianthus annuus) were frequently-encountered winter and spring weeds. Both cover crops controlled winter weeds as well as did winter tillage …

A Landscape Perspective In Managing Vegetation For Beneficial Plant-Pestnatural Enemy Interactions: A Foundation For Areawide Pest Management, Michael J. Brewer, Takuji Noma, Norman C. Elliott

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In the USA, Europe and increasingly in other regions, cropping systems designed for high production output are significant features of the landscape. Deployment of mechanized and high-input cropping systems over the last 50 years has resulted in substantial transformation and fragmentation of major grassland, shrubland and woodland systems throughout the world. These cropping systems are typically less diverse in species composition, structure and ecological functioning than those found in the original plant community (Altieri, 2004). Decreases in plant diversity of agroecosystems (i.e. the crops themselves and surrounding remnants of the original plant system) have negatively affected ecosystem functions (Freemark, 2005). …

Synthesis And Bioassay Of Improved Mosquito Repellents Predicted From Chemical Structure, Alan R. Katritzky, Zuoquan Wang, Svetoslav Slavov, Maia Tsikolia, Dimitar Dobchev, Novruz G. Akhmedov, C. Dennis Hall, Ulrich R. Bernier, Gary G. Clark, Kenneth Linthicum

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Mosquito repellency data on acylpiperidines derived from the United States Department of Agriculture archives were modeled by using molecular descriptors calculated by CODESSA PRO software. An artificial neural network model was developed for the correlation of these archival results and used to predict the repellent activity of novel compounds of similar structures. A series of 34 promising N-acylpiperidine mosquito repellent candidates (4a–4q’) were synthesized by reactions of acylbenzotriazoles 2a–2p with piperidines 3a–3f. Compounds (4a–4q’) were screened as topically applied mosquito repellents by measuring the duration of repellency after application to cloth patches worn on the arms of human volunteers. Some …