1 DEVELOPMENT OF A NOVEL MANAGEMENT METHOD FOR RHIPICEPHALUS SANGUINEU S USING SEMIOCHEMICAL BAITED TRAPS By LUCAS PAUL CARNOHAN A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FU LFILLMENT OF THE REQUIREMENTS FOR TH E DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2013
2 2013 Lucas Paul Carnohan
3 To my brother, Shane Carnohan
4 ACKNOWLEDGMENTS I am extremely grateful to my sou rces of funding for this project; the USDA, NIFA, Pest Management Alternatives Grants Program and the University of Florida have been able to pursue my M.S. degree in ento mology. I appreciate the faculty and staff of the USDA ARS, CMAVE for the generally pleasant and helpful atmosphere they provided during the many hours I spent there. I would like to thank my advisor, Dr. Phillip Kaufman, for supporting and guiding me i n more ways than one. When I was still looking for a degree program, he gave me an opportunity in h is lab, unwavering support that better advisor. He cares about his studen ts and it shows. It would be impossible for me to express enough appreciation for my other committee members, Dr. Sandra Allan and Dr. Emma Weeks. For the first few months of my degree, I shared an office with Dr. Weeks, and so she was easy to find when I needed her expert advice. By the end of my degree, I no longer shared an office with her, but she remained so genuinely involved in my work that I hardly noticed the difference. I will always be inspired by Dr. Allan and her incredible work ethic. I ca n remember multiple occasions when I was in the lab working late to finish up a day of data collections. At times like those I sometimes struggled to keep a positive attitude, but then Dr. Allan would come bursting into the lab like a whirlwind, still goi ng strong. She did not realize it at the time, but she really helped me stay focused through some long days, just by being herself. I would like to thank Dr. Salvador Gezan, for giving me his personal attention to the statistical analysis of my data. Dr. Gezan met with me on several occasions to help
5 strong suit, but he did not lose patience with me on any occasion. I have great respect for his command of statistics. I ex tend my appreciation to Lois Wood as well. When I first arrived in the department, she helped me learn my way around, and she was always there to support me, whether it was purchasing supplies or a shoulder to lean on. And of course, a big thank you to T im Davis, Bo b Aldri d ge, and Dr. Karen Prine for all of the edits and suggestions for my thesis. mates in the department. Amanda Eiden was my first friend in Gainesville. After two years, I have found many more, but she remains one of the best. I owe a debt of gratitude to my good friend Aaron Pomerantz. When he first came to the department a year after I had started my degree, I had just gone through some difficult times and h ad a bit of a pessimistic outlook about what I was doing with my life. Aaron has a passion for entomology that I could not ignore, and it is infectious. Chris Holderman has been a great friend and colleague. He assisted me in any way that he could, and I really appreciate his kindness. Then there is Mike Bentley, a more recent friend but a close friend all the same. I made friends outside of the department from a variety of walks of life, and I wish I could acknowledge them all individually, but that w ould make my thesis Gainesville, I say thank you, and know that you helped me get through this process. I have a massive debt of gratitude to my family back in Washin gton. They may be far from me spatially, but I always feel like they are close. My father, Charles Carnohan, my mother, Lisa Carnohan, and my brother, Shane Carnohan have all been
6 te school, but they were proud of me each and every day. It is hard for me to count the people who have stood by me during my successes, but I only need three fingers to count the ones that stand by me no matter what life brings. I am lucky to have such a wonderful family, and I think about them every day.
7 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 9 LIST OF FIGURES ................................ ................................ ................................ ........ 11 ABSTRACT ................................ ................................ ................................ ................... 12 CHAPTER 1 LITERATURE REVIEW OF THE BROWN DOG TICK, RHIPICEPHALUS SANGUINEUS (LATREILLE) ................................ ................................ .................. 14 Intro duction ................................ ................................ ................................ ............. 14 Biology ................................ ................................ ................................ .................... 14 Description ................................ ................................ ................................ ....... 14 Life Cycle ................................ ................................ ................................ .......... 15 Mating ................................ ................................ ................................ ............... 15 Oviposition ................................ ................................ ................................ ........ 16 Off Host Behavior ................................ ................................ ............................. 16 Host Preference ................................ ................................ ............................... 17 Host Location, Attachment, and Feeding ................................ ......................... 18 Medical and Veterinary Importance ................................ ................................ ........ 19 Tick Chemical Ecology ................................ ................................ ............................ 23 Management ................................ ................................ ................................ ........... 26 Chemical Control ................................ ................................ .............................. 26 Biological C ontrol ................................ ................................ ............................. 28 Semiochemical A ttractants ................................ ................................ ............... 29 Trapping and M o nitoring ................................ ................................ ................... 31 Olfactometers ................................ ................................ ................................ ......... 33 2 BROWN DOG TICK, RHIPICEPHALUS SANGUINEUS (LATREILLE), ATTRACTION TO CO 2 AND OTHER CHEMICALS IDENT IFIED AS ATTRACTANTS IN STUDIES WITH OTHER HEMATOPHAGOUS ARTHROPODS, USING Y TUBE AND STRAIGHT TUBE OLFACTOMETERS .... 35 Introduction ................................ ................................ ................................ ............. 35 Materials and Methods ................................ ................................ ............................ 37 Ticks ................................ ................................ ................................ ................. 37 Y tube Olfactometer Assays ................................ ................................ ............. 39 Straight Tube Olfactometer Video Assays ................................ ........................ 43 Behavioral Analysis ................................ ................................ .......................... 44 Statistical Analysis ................................ ................................ ............................ 45 Y tube olfactometer ................................ ................................ .................... 45
8 Straight tube olfactometer ................................ ................................ .......... 47 Results ................................ ................................ ................................ .................... 48 Y Tube Olfactometer ................................ ................................ ........................ 48 Mean distance from the initial release zone ................................ ............... 48 Mean activation response ................................ ................................ .......... 50 Mean proportion choice response ................................ .............................. 51 Differences between males and females ................................ ................... 53 Straight Tube Olfactometer ................................ ................................ .............. 53 Duration of directional movement ................................ .............................. 53 Time to activation ................................ ................................ ....................... 54 Number of end touches ................................ ................................ .............. 55 Number of direction changes ................................ ................................ ..... 55 Discussion ................................ ................................ ................................ .............. 56 3 EVALUATION OF FOUR BED BUG TRAPS WITH ATTRACTANT AUGMENTATION FOR CAPTURING BROWN DOG TICKS, RHIPICEPHALUS SANGUINEUS (LATREILLE) ................................ ................................ .................. 81 Introduction ................................ ................................ ................................ ............. 81 Materials and Methods ................................ ................................ ............................ 84 Ticks ................................ ................................ ................................ ................. 84 Rooms ................................ ................................ ................................ .............. 85 Traps ................................ ................................ ................................ ................ 87 Evaluation of Trap Model ................................ ................................ .................. 89 Evaluation of Different A ttractants ................................ ................................ .... 90 Statistical Analysis ................................ ................................ ............................ 92 Evaluation of trap model ................................ ................................ ............ 92 Evaluation of attra ctants ................................ ................................ ............ 93 Results ................................ ................................ ................................ .................... 93 Evaluation of Trap Model ................................ ................................ .................. 93 Evaluation of A ttractants ................................ ................................ ................... 95 Discussion ................................ ................................ ................................ .............. 97 4 SUMMARY AND FUTURE DIRECTIONS FOR THE DEVELOPMENT OF NOVEL MANAGEMENT METHODS FOR THE BROWN DOG TI CK, RHIPICEPHALUS SANGUINEUS (LATREILLE), IN RESIDENTIAL ENVIRONMENTS ................................ ................................ ................................ 116 LIST OF REFERENCES ................................ ................................ ............................. 121 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 131
9 LIST OF TABLES Table page 2 1 All chemicals evaluated for adult mixed sex Rhipicephalus sanguineus (Latreille) activation and response in a Y tube olfacto meter ............................... 67 2 2 Mean distance (cm) from an initial release zone where five mixed sex, adult Rhipicephalus sanguineus (Latreille) were recorded. ................................ ......... 68 2 3 Mean proportion of mixed sex, adult Rhipicephalus sanguineus (Latreille) that activated in response to potential attractants. ................................ .............. 70 2 4 Mean proportion of mixed sex adult Rhip icephalus sanguineus (Latreille) that chose the treatment arm subtracted from the mean proportion that chose the control arm. ................................ ................................ ................................ ......... 72 2 5 Summary of statistics for adult mixed sex Rhipicephalus san guineus (Latreille) behaviors including movement, activation, end touch, and change direction in straight tube olfactometers. ................................ .............................. 74 2 6 Movement duration (sec) of a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) exposed to chemicals in a straight tube olfactometer. ..... 75 2 7 The average time to activation at the beginning of each assay for a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) in a straight tube olfactometer. ................................ ................................ ................................ ....... 76 2 8 The total number of times a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) contacted the up wind end of the tube where the chemical originated in a straight tube olfactometer. ................................ ............ 77 2 9 The total number of times a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) change d movement direction in a straight tube olfactometer. ................................ ................................ ................................ ....... 78 3 1 Summary statistics of the ANOVA analyses documenting adult mixed sex Rhipicephalus sanguineus (Latreille) interactions with four CO 2 baited bed bug trap models ................................ ................................ ................................ 107 3 2 Mean (SEM) numbers of 40 mixed sex adult Rhipicephalus sanguineus (Latreille) released into a room and subsequently captured, attracted to, and activated by each of the four CO 2 baited bed bug trap models ........................ 108 3 3 Summary statistics for the ANOVA analyses of attractants on the efficacy of the ClimbUp bed bug trap to capture, attract, and activa te mixed sex adult Rhipicephalus sanguineus (Latreille) ................................ ................................ 109
10 3 4 Mean (SEM) numbers out of 40 mixed sex adult Rhipicephalus sanguineus (Latreille) released into a room and subsequently capture d and activated under eight attractants in evaluations of the ClimbUp bed bug trap. ............... 110 3 5 Summary statistics of the ANOVA analyses evaluating the efficacy of the ClimbUp bed bug trap in ac tivating, attracting, and capturing mixed sex adult Rhipicephalus sanguineus (Latreille). ................................ ...................... 111 3 6 Mean (SEM) numbers out of 40 mixed sex adult Rhipicephalus sanguineus (Latreille) released in to a room and subsequently captured and activated under eight attractants in evaluations of the ClimbUp bed bug trap, adjusted with respect to the covariate average temperature. ................................ .......... 112
11 LIST OF FIGURES Figure page 2 1 Diagrammatic overview of the Y tube olfactometer and air delivery system. ...... 79 2 2 Olfactometer testing station with a 5% CO 2 enhanced air tank on the left, and two Y tube olfactometers with flow rate control devices in the center and surrounded by white cloth to reduce visual stimuli. ................................ ............. 80 3 1 Diagrammatic top down la yout of the Rhipicephalus sanguineus (Latreille) trap evaluation experimental rooms and the ventilation system ...................... 113 3 2 Diagrammatic side view of the Rhipicephalus sanguineus (Latreille) trap evaluation experimental rooms and the ventilation system. ............................. 114 3 3 Four bed bug trap models evaluated for Rhipicephalus sanguineus (Latreille) attraction and capture capabilities. ................................ ................................ ... 115
12 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy DEVELOPMENT OF A NOVEL MANAGEMENT METHOD FOR RHIPICEPHALUS SANGUINEUS USING SEMIOCHEMICAL BAITED TRAPS By Lucas Paul Carnohan August 2013 Chair: Ph illip E. Kaufman Major: Entomology and Nematology The brown dog tick, Rhipicephalus sanguineus is a pest that ca n be f ound worldwide. This tick presents unique difficulties in its management because it can complete its life cycle indoors, resulting in infestations in residential areas and kennels. Acaricide treatments can be costly and have resulted in the develop ment of acaricide resistance. Therefore, there is a demand for alternative control methods and the development of a trapping system using semiochemicals shows promise. In the current study adult R. sanguineus response to semiochemical compounds was eval uated using olfactometers. Both sexes were activated by, and demonstrated significant directional responses to, nine of the 17 semiochemicals tested in a Y tube, and the results of straight tube assays suggested that four chemicals, 1 octen 3 ol, hexanoic acid, methyl salicylate, and benzyl alcohol, resulted in particularly strong responses from R. sanguineus The efficacy of four commercially 2 as an attractant was compa red for R. sanguineus capture. The ClimbUp than the other two trap designs. Thereafter, the ClimbUp trap was evaluated using
13 individual attractant chemicals including 1 octen 3 ol, hexanoic acid, and methyl salicy late, tested with and without CO 2 augmentation. The trapping efficacy for all attractants was significantly higher when CO 2 was included than when the other chemicals were used without CO 2 These results suggest that bed bug traps may be useful in R. san guineus monitoring, and that CO 2 will likely be an important component of a trapping system employed in the future.
14 CHAPTER 1 LITERATURE REVIEW OF THE BROWN DOG TICK, RHIPICEPHALUS SANGUINEUS (LATREILLE) Introduction There are around 900 recognized tick s pecies in the world (Barker and Murrell 2004), and approximately 10% of them are known to vector pathogens (Oliver 1989). The majority of tick species are host specific and occur on wild vertebrates. There are few that feed on domesticated animals or huma ns (Jongejan and Uilenberg 2004). Despite the small percentage of tick species that are vectors of pathogens of medical and veterinary concern, ticks facilitate the transmission of a greater variety of pathogens than any other arthropod vector, including mosquitoes (Oliver 1989, Estrada Pea and Jongejan 1999, Jongejan and Uilenberg 2004). Ticks can transmit these pathogens to humans, as well as domesticated and wild animals (Jongejan and Uilenberg 2004). There are three families of ticks: Argasidae, Nutt alliellidae, and Ixodidae. Argasidae and Ixodidae contain multiple tick genera, whereas Nuttalliellidae currently consists of a single genus (Oliver 1989), Nuttaliella (Horak et al. 2002). Ixodidae encompasses the greatest number of species of the three families, and the majority of the species that are considered to be of medic al or veterinary significance. Biology Description The brown dog tick (BDT), Rhipicephalus sanguineus (Latreille), can be characterized by several features common to all ticks with in the genus Rhipicephalus The BDT has short, broad palps and a basis capituli with a distinctive hexagonal shape (Sonenshine 1991). Both sexes have eyes and festoons, and the males have adanal mall, dark brown in color,
15 and hatch into larval ticks commonly known as seed ticks (Dantas Torres 2008). The larvae are about 0.54 mm long and 0.39 mm wide, and have three pairs of legs. BDT nymphs have four pairs of legs and are reddish brown in color, and measure from 1.14 to 1.3 0 mm in length and 0.57 to 0.66 mm in width. The adults are similar in appearance to the nymphal stage, but larger, and are 2.4 to 2.7 mm long and 1.44 to 1.68 mm wide (Dantas Torres 2008). Life Cycle As reviewed by Dantas Tor res (2008), R. sanguineus as with all Ixodid ticks, has four life stages : egg, larva, nymph, and adult The BDT is considered a 3 host tick, dropping off the host after blood feeding in each mobile developmental stage. Larvae emerge from the eggs after an incubation period of six to 23 days. The larvae locate a host, attach, and blood feed for three to 10 days (Petrova Piontkovskaya 1947). After engorging, the larvae detach and fall off the host, hide in the environment, and undergo a five to 15 day pr e molting period after which they molt into nymphs (Petrova Piontkovskaya 1947). The nymphs locate a host, possibly the same host as was fed on by the larvae, on which they feed for three to 11 days (Petrova Piontkovskaya 1947). After feeding, R. sanguin eus nymphs detach from the host and digest their blood meal for a period of nine to 47 days before molting into adults (Petrova Piontkovskaya 1947). Adults also must locate and feed upon a host. Mating For most Ixodid ticks, including R. sanguineus matin g occurs on the host and has been described in detail by Sonenshine (1991). Aside from ticks in the genus Ixodes a blood meal is required to induce the gonotropic cycle, and mating occurs on the host (Sonenshine 1991). Fed males will detach and seek out attached and partially
16 engorged females using pheromone cues (Sonenshine et al. 1982). The male then to the female in this manner, a spermatophore is exuded from the male genital pore. With the male mouthparts still inserted in the female genital pore, the male will contort its body in a way that facilitates the movement of the spermatophore near the female genital pore. Finally the male will release its mouthparts from the female genital pore, Oviposition Once mated, adult female ticks remain on the host feeding for an additional five to 21 days. Following engorgement, females detach fall from the host and move to a sheltered location to digest their blood meal and prepare for oviposition, which will occur from three to 14 days after detachment (Petrova Piontkovskaya 1947). Females lay 4,000 eggs on average, but the highest quantity of eggs recorded was 7,273 (Koch 1982). The eggs are usually deposited above ground level in cracks and crevices, and often near host resting sites (Dantas Torres 2008). After completing oviposition, the female dies (Dantas Torres 2008). The exact dura tion of each stage of development for R. sanguineus is greatly influenced by humidity, temperature, and host species (Bellato and Daemon 1997), but under ideal environmental conditions this species can complete its life cycle in 63 91 days (Goddard1987, Be chara et al. 1994 Louly et al. 2007). Off H ost Behavior Ticks can survive in the environment without feeding for a number of months, or even years, depending on the temperature and humidity. When off the host, tick metabolism slows significantly, and the re is minimal activity. The only movement during this time is to relocate to an area with improved environmental conditions, or to find an
17 area with an increased chance of encountering a host (Needham and Teel 1991). The greatest difficulty for ticks dur ing off host periods is water regulation. Ticks are susceptible to desiccating conditions (Parola and Raoult 2001) and when they are off of a host, ticks tend to hide in dark and moist locations to stay protected from adverse climatic conditions, as well as to avoid interaction with potential predators (Oliver 1989). To avoid desiccation, ticks secret a hygroscopic substance consisting mostly of sodium and potassium from salivary glands onto the hypostome (Kahl and Knulle 1988). The substance absorbs wat er from the air. Once saturated, the substance is reabsorbed by the tick and the process is repeated. In order for this process to be effective, the relative humidity of the air must be 75% or greater (Rudolf and Knulle 1974; Kahl and Knulle 1988). In ad dition to acquiring moisture from the air during off host periods, many Ixodid ticks will gather together in groups. This behavior is known as assembly, and pheromones, including guanine and other purines, have been indicated in previous studies as the pr imary factors leading to tick assembly (Allan and Sonenshine 2002). This behavior results in groups of ticks coming to rest in microhabitats that can lead to improved off host survival and mating success, and an elevated chance of finding a host (Allan an d Sonenshine 2002). Host P reference Although nymphal and larval stages have been known to feed on small mammals such as rodents, the primary host for R. sanguineus is the domesticated dog, Canis familiaris (L.) (Srivastava and Varma 1964). When dogs are available, large tick populations can establish (Dantas Torres 2008). It is rare for R. sanguineus to parasitize people (Dantas Torres 2008, Raoult and Roux 1997). However, there have
18 been documented cases of R. sanguineus being attached to people through out the world (Brazil, Argentina, Italy, Uruguay, and many states in the U.S.) (Goddard 1987, Carpenter et al. 1990, Manfredi et al. 1990, Guglielmone et al. 1991, Campbell and Bowles 1994, Felz et al. 1996, Harrison et al. 1997, Venzal et al. 2003, Dantas Torres et al. 2006). Historically it is accepted that BDT either do not bite or rarely bite people, but the number of documented cases warrant some concern over the legitimacy of these assumptions. Indeed, R. sanguineus was implicated as a possible vect or of Rickettsia rickettsii to humans in an outbreak of Rocky Mountain Spotted Fever (RMSF) documented in Arizona (Demma et al. 2005). Host Location, Attachment, and F eeding Ticks generally use one of two methods when host seeking. Some ticks use ambush t actics, wherein they wait for a host to contact the substrate that they are questing upon and then grasp onto the host. Rhipicephalus sanguineus is generally accepted as a hunter species, meaning that it actively seeks out hosts by crawling toward them, r ather than waiting for contact (Dantas Torres 2008). Once on a host, Ixodid ticks locate an appropriate site for feeding and cut through the skin using a horizontal motion of the chelicerae (Sonenshine 1991). The hypostome then is inserted into the host as an initial anchor and to provide access to capillaries. Ixodid ticks are telmophages, meaning that they rupture many small capillaries and feed from the resulting pool of blood (Sonenshine 1991). This contrasts with solenophages, such as mosquitoes, w hich feed through direct penetration of a single blood vessel. After hypostome insertion and if the site of penetration is acceptable, Ixodid ticks then secrete a glue throughout engo rgement (Sonenshine 1991). Ticks inject saliva into the host, which
19 the immune system not only assists the tick during feeding, but also increases the to any pathogens that the tick may be harboring (Bowman 1997). Furthermore, tick saliva contains an anesthetic that prevents the host from feeling the lacerations created by the chelicerae (Parola and Raoult 2001). During the feeding process, which takes a number of days in Ixodidae, ticks regularly regurgitate fluids into the host, facilitating the transmission of pathogens (Parola and Raoult 2001). The purpose of regurgitation is for the expulsion of excess ions and water that result from the concentrat ion of the accumulating blood components process is slow because the ticks must prepare the cuticle for rapid expansion (Sonenshine 1991). The actual duration of the feeding process takes a number of days, is highly variable, and depends upon a number of factors, such as host immunity and the location of attachment (Sonenshine 1991). Interestingly, a female tick that has mated can begin to rapidly engorge large volum es of blood over a 12 24 hour period (Sonenshine 1991). Medical and Veterinary Importance Most tick species tend to reside outdoors, but the BDT can be endophilic, r eproducing and surviving within human residences or commercial dog kennels (Dantas Torres 2 008, Jacobs et al. 2001, Louly et al. 2007, Dantas Torres and Otranto 2011). Infestations of kennels may be important sources of ticks for subsequent residential infestations. Indoor development and habitation can lead to high numbers of ticks in residen tial infestations, sometimes to the point where the ticks can be seen climbing up walls or across carpets and furniture (Goddard 1987, Demma et al. 2005,
20 Dantas Torres et al. 2006). Typically R. sanguineus does not feed on humans; however, with high tick populations the likelihood of human parasitism increases. Larval and nymphal ticks may feed on humans and escape notice because of their small size (Harrison et al. 1997). Feeding ticks can impact the host in several ways including bite wounds, allergic r eactions, tick borne paralysis and the transmission of pathogens. As mentioned earlier, ticks are telmophages, meaning they rupture many small capillaries and feed on the resulting pool of blood (Sonenshine 1991). Even after removal of the tick, the host organism is left with a small laceration, which may become infected. In addition to the mechanical damage caused by their bite, brown dog ticks can vector a variety of pathogens. Ticks have been reported to serve as vectors of several Rickettsia species. Rickettsia is a genus of bacteria that contains species that may cause disease in humans and other vertebrates, including a variety of spotted fevers and several types of typhus. Rhipicephalus sanguineus is a vector of several species of Rickettsia mos t of which do not cause disease in humans. However, in many parts of Europe, R. sanguineus commonly carries Rickettsia conorii the causative agent of Mediterranean spotted fever (MSF) (Raoult and Roux 1997, Jongejan and Uilenberg 2004). Although MSF is not found in the United States, it is common in many other parts of the world (Raoult and Roux 1997). The disease is endemic to the Mediterranean region, and symptoms commonly include fever, headaches, rash, an ulcer at the site of the tick bite, and in s ome cases can be fatal depending on the age and underlying health of the patient (Raoult et al. 1986).
21 The brown dog tick is a vector of the Rickettsia, Ehrlichia canis, which causes canine ehrlichiosis, a commonly diagnosed disease of dogs (Goddard 1987). German Shepherds and Beagles inoculated with the pathogen intravenously in the laboratory develop symptoms after 10 15 days (Huxsoll et al. 1970). Initial symptoms include anorexia, depression, fever, and a reduction in red and white blood cell counts ( Huxsoll et al. 1970). This febrile period usually lasts from 15 to 25 days, during which time the dogs can undergo extreme weight loss and debilitation, sometimes resulting in death (Huxsoll et al. 1970). In some cases, dogs will survive this period and return to a seemingly healthy and visually normal state. However, surviving dogs are prone to relapses of febrile conditions, and these relapses are more common in German ath within a few days (Huxsoll et al. 1970). Cases of canine ehrlichiosis have been reported throughout t he United States, and it is widely distributed throughout the world (Reviewed by Skotarczak 2003). Although most ehrlichiosis cases have primarily bee n associated with dogs, some human cases have been reported in the southern United States (Goddard 1987). The pathogen that causes human ehrlichiosis is Ehrlichia chaffeensis (Anderson et al. 1991), and is vectored by the lone star tick, Amblyomma america num (L.) (Ewing et al. 1995). Human symptoms of ehrlichiosis include fever, headache, nausea, and rash (Goddard 1987). The pathogenic agent of RMSF, Rickettsia rickettsii can be maintained within a population of Dermacentor variabilis (Say) or Dermacento r andersoni Stiles for many generations because it can be transmitted transovarially (Goddard 1987). Until recently
22 it was not believed to be transmitted by R. sanguineus Demma et al. (2005) reported that R. sanguineus was a possible vector for a foci o f RMSF in Arizona. In this study, 16 probable human cases were identified that all originated close to two towns in Arizona. The most common vectors of the pathogen, D. variabilis and D. andersoni (Schriefer and Azad 1994), were not found at the homes wh ere R. ricketsii was believed to have been contracted, however, R. sanguineus was present in large numbers (Demma et al. 2005). Brown dog tick specimens, collected from homes where R. ricketsii was believed to have been contracted, tested positive for R. ricketsii Although R. sanguineus is not normally associated with transmission of R. rickettsii this study suggested that these ticks may serve as vectors under certain conditions (Demma et al. 2005). Based on the study, one factor that likely contribut ed to the disease outbreak was the large population of dogs heavily infested with R. sanguineus found in close proximity to humans. Another pathogen that R. sanguineus vectors is Babesia canis vogeli which causes canine babesiosis in dogs (Boozer and Mac intire 2003). Canine babesiosis is endemic to Greyhound kennels in the southeastern United States, and it commonly causes anemia in young Greyhounds (Boozer and Macintire 2003). Symptoms of uncomplicated babesiosis infections in dogs include lethargy, fe ver, pallor, icterus, splenomegaly, and haemoglobinuria (Mathe et al. 2006). A variety of additional symptoms also can be observed in infected dogs with complications, such as hepatopathy, pancreatitis, acute renal failure, and disseminated intravascular coagul ation (M ath e et al. 2006). Although babesiosis is primarily a disease of dogs, it can be contracted by humans (Boozer and Macintire 2003).
23 Tick Chemical Ecology Many species of ticks do not have eyes, or have simple eyes (Sonenshine 1991), yet other senses, especially olfaction, are highly developed (Parola and Raoult 2001). Ticks are sensitive to airborne molecules such as CO 2 (Anderson et al. 1998), ammonia (NH 3 ) phenols, and other aromatic compounds (Fourie et al. 1993). Dry ice is commonly use d to attract ticks because it produces CO 2 mimicking the CO 2 production in the breath of a nearby or passing host (Sauer et al. 1974, Perrit t et al. 1993, Demma et al. 2005). Additionally, ticks can sense humidity, temperature, and vibrations (Fourie et al. 1993). Tick sensory organs are found all over the exoskeleton and provide ticks with a variety of information about their external environment (Sonenshine 1991). A sensory f the tarsi of the first pair of legs and contains olfactory and gustatory receptors (Sonenshine 1991). largely be used to detect olfactory chemicals. The organ ha s a small number of sensilla that are each innervated by a large number of neurons, in contrast to insects that usually have many sensilla with few innervating neurons for each sensillum gustatory sensilla, thermosensilla, mechanosensilla, photosensilla and hygrosensilla. As reviewed by Nordlund and Lewis (1976), semiochemicals are compounds that organisms use to interact with each other. These include pheromones and allelochemicals, with pheromones referring to chemicals that organisms use for intraspecific interactions. Allelochemicals are compounds involved with interactions that take place between organisms of different species or between organisms and non living
24 objects (Nordlund and Lewis 1976). There are four recognized categories of allelochemicals including: synomones, allomones, apneumones, and kairomones. Synomones have a positive impact on both the organism that produces them, i.e. the emitter, and the organism that detects th em, i.e. the receiver. Allomones benefit the emitter but have a neutral impact on the receiver. Apneumones are chemicals that are emitted by a non living substance that benefit a receiver and also may negatively affect another living organism. Kairomone s are those chemicals that have a negative effect on the emitter and a positive effect on the receiver (Nordlund and Lewis 1976), such as the ho s t produced compounds that a tick uses for host location. Ticks are known to have pheromones associated with ass embly, aggregation, attachment, and sexual behavior (Oliver 1989). Male Amblyomma spp. secret e an attraction (assembly), aggregation, and attachment pheromone (AAAP) and two components of this pheromone are o nitrophenol and methyl salicylate (Rechav et a l. 1977, No r val et al. 1989, 1996, Maranga et al. 2006, Nchu 2010b). 2,6 Dichlorophenol is an attractant sex pheromone produced by many species of female Ixodidae (Oliver 1989). When feeding on a host, male bont ticks, A. hebraeum Koch, produce an AAAP t hat is highly attractive to female ticks, unfed males, and even nymphs (Rechav et al. 1977). Female A. hebraeum will not attach to a host and feed without the presence of feeding males producing the AAAP (Rechav et al. 1977). Ticks also use kairomones to help them identify and locate hosts. As mentioned above, kairomones are chemicals that benefit the receiver, at the expense of the emitter. Ticks often rely on kairomones coupled with other important host cues such as body heat, visual cues, and sounds ( Sonenshine 2004). Common kairomones that ticks
25 use include CO 2 a component of vertebrate breath, and NH 3 a component of both vertebrate breath and skin secretions (Sonenshine 2004). It is hypothesized that differences in sensitivity to different host k airomone profiles may contribute to tick species abilities to recognize their preferred host (Sonenshine 2004). Carbon dioxide is a kairomone attractive to some tick species and the most common tick traps contain dry ice that serves as a source of CO 2 (Son enshine 1993). Carbon dioxide baited traps have been shown to effectively attract A. americanum (Wilson et al. 1972) and Ixodes ricinus (Linnaeus) (Gray 1985). Although, the effective range of attraction was a much greater distance for A. americanum Fo r A. hebraeum CO 2 only stimulated tick activity, but this tick can be effectively attracted to traps that combine CO 2 with a lure of freshly engorged male ticks, extracts of those ticks, or even a single compound, o nitrophenol, identified from the extrac ts (Norval et al. 1989). Ticks are sensitive to a variety of other compounds in addition to CO 2 Using coupled gas chromatography electrophysiological recordings (GC EL), individual f A. variegatum ( Steullet and Guerin 1994). In these studies, short chain saturated and unsaturated aliphatic aldehydes, furfural, benzaldehyde, methylbenzaldehyde isomers, 2 valerolactone, derived from rabbit and bovine extracts, were shown to A. variegatum Semiochemicals have been identified and used in the development of novel tick control methods for several tick species (Sonenshine 2006). However, semiochemical identification for tick attraction is still in the early stages of development for R. sanguineus control. The kairomones involved with host location and recognition may be
26 complex. Not only do R. sanguineus exhibit a high specificity for domesticated dogs, but there is evidence that they can differen tiate between breeds. Louly et al. (2007) found that the number of R. sanguineus feeding on English Cocker Spaniels was up to 11.5 times higher than the number feeding on mongrel dogs. There is limited knowledge available on BDT pheromones and allelochemi cals. Only a few chemicals known to elicit a response from ticks have been tested on R. sanguineus with squalene invoking the greatest aggregation response (Yoder et al. 2008). Also recently, R. sanguineus excreta, and its main component, guanine, were identified as assembly pheromones for brown dog ticks in Petri dish assays (Yoder et al. 2013). There was not a dose response to varying concentrations of guanine, suggesting that its presence is sufficient to induce a response. However, lowering the rel ative humidity increased the assembly response (Yoder et al. 2013). Haggart and Davis (1980) identified two ammonia sensitive neurons on the first tarsi of the brown dog tick, and subsequently induced questing behavior in response to low levels of the comm on vertebrate breath component in the air. The response of R. sanguineus larvae to two different chemicals, 2,6 dichlorophenol and 1 octen 3 ol, has recently been evaluated (Ranju et al. 2012a, 2012b). Of the total R. sanguineus individuals exposed to 0. 1 M 2,6 dichlorophenol, 71% were attracted (Ranju et al. 2012a). However, R. sanguineus was not a ttracted to 1 octen 3 ol in a separate study (Ranju et al. 2012b). Management Chemical C ontrol Efforts to control tick populations, including R. sanguineus a re heavily reliant on pesticides (Sonenshine 1993). Pesticides that are used to specifically target ticks and
27 mites are known as acaricides. Acaricides may be applied directly to the animal host or to the surrounding environment. Chemical products that can be used on dogs for killing ticks may be available over the counter or following consultation with a veterinarian (Stafford 2007). Chemicals may be applied to the dog in the form of spot ons, collars, sprays, dips, or powders (Stafford 2007). Permeth rin based products, such as K9 Advantix and fipronil based products such as Frontline are commonly applied as spot ons directly onto dogs for tick control (Stafford 2007). Amitraz impregnated tick collars, such as Preventic a lso can be effective for t ick prevention and control (Stafford 2007). When considering effective long term control of the BDT, it is important to consider that 94 1991). The brown dog tick is a gorging fasting org anism, which means it spends a short amount of time acquiring a large amount of blood from a host and then leaves the host and survives in the environment for extended time periods (Needham and Teel 1991). This feeding strategy can result in less than 5% of R. sanguineus populations feeding on a dog at any given time, while the remaining population resides in the environment (Dantas outdoor habitats, in addition to on animal treat ments, are necessary for effective management (Dantas Torres 2008). Overall, people are becoming more concerned with the use of synthetic chemicals in pest control because of the perceived potential to negatively impact human and companion animal health, t he increasing costs of the compounds, and decreasing effectiveness due to pesticide resistance development (Samish et al. 2004).
28 Rhipicephalus sanguineus has the capacity to develop resistance to acaricides (Miller et al. 2001). Miller et al. (2001) foun d moderate to high levels of resistance to pyrethroids and organophosphates in a strain of BDT collected at a U.S. military establishment in Panama. Resistance likely was due to the extensive and exclusive use of a limited number of compounds for many yea rs in a failed effort to control the tick infestation (Miller et al. 2001). The use of acaricides as a stand alone control method for the BDT is common worldwide, which makes the development of resistance a global concern. Integration of the use of acari cides with alternative control methods is necessary to reduce the impact of this tick species on dogs and humans (Dantas Torres 2008). Biological C ontrol Biological control methods for ticks are not widely used. Currently, there are no products marketed o r distributed for commercial or residential use. A variety of potential biological control organisms and methods have been examined for use in integrated control of R. sanguineus including fungal pathogens (Samish et al. 2004, Kirkland et al. 2004), nemat odes (Samish and Glazer 2001), parasitoids (Cole 1965, Knipling and Steelman 2000), and predators (Samish and Alekseev 2001). Visible biological control agents may not be desirable to homeowners with R. sanguineus infestations. Furthermore, some biologic al control agents do not have life histories compatible with surviving indoors, making their use challenging. However, pathogenic fungi may hold the most promise for BDT control in residential environments as they express neither of these undesirable trai ts. Pathogenic fungi could be applied as a spray (Nchu et al. 2010a) or as a component in a self application device i n human inhabited environments in the same way that pesticides are utilized (Maranga et al. 2006, Nchu et al. 2010b.
29 Pathogenic fungi have been shown to effectively kill several species of ticks (Maranga et al. 2006, Nchu et al. 2010b, Bharadwaj and Stafford 2012) and could serve as an anthropogenically desirable alternative to chemical control (Bharadwaj and Stafford 2012). Ixodes scapular is Say demonstrated a high level of susceptibility to Metarhizium brunneum (Petch; previously Metarhizium anisopliae ) in a laboratory study (Bharadwaj and Stafford 2012). Ixodes scapularis were exposed to granular fungal conidia through surface contact us ing emulsifiable concentrates of the fungal conidia applied through dipping and direct spray application. The fungus was highly pathogenic to nymphs and adults, but pathogenicity varied depending on the formulation, application method, exposure duration, and concentration of the conidia (Bharadwaj and Stafford 2012). Although certain species and strains of fungi have shown the capacity to effectively kill R. sanguineus in the laboratory, it is challenging to find a practical method for infecting these tick s in their natural habitat. One potential method is to deliver the fungal spores through an oil suspension and spray the mixture directly on the ticks or on the surfaces that ticks are likely to contact. It has been reported that oil or oil and water mix tures enhanced fungal efficacy by possibly decreasing the rate of water evaporation, giving the spores a sustained hospitable environment for germination (Leemon and Jonsson 2008). Semiochemical A ttractants Semiochemicals can be used to aid in pest control Previously, the use of semiochemical attractants has been helpful in the management of pests in Florida, such as the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Sivinski and Calkins 1986). An artificial sex pheromone known as trimedlure at tracts the males of the
30 species into traps for monitoring purposes. A different lure that mimics the odors produced by protein rich fruits is effective for capturing female flies. Placing traps in strategic locations can provide early detection of small populations, which are more easily controlled and eliminated using other management methods, such as the sterile insect technique (Hendrichs et al. 1995, Papadopoulos et al. 2001). Semiochemicals have potential use with tick monitoring and management progr ams. Using CO 2 as the attractant, A. americanum and Ixodes ricinus can be effectively captured in traps in the field (Wilson et al. 1972, Gray 1985). In both of these studies, traps baited with CO 2 captured more ticks than the traditional flagging method Also, using traps rather than flagging can save time and effort because traps can be placed and left for an extended amount of time, while flagging requires constant labor throughout the collection period. Semiochemicals can be useful in on host tick ma nagement. In a 13 week trial conducted on cattle in Guadeloupe, A. variegatum infestations on cattle were significantly reduced using tags impregnated with pheromones and an acaricide (Allan et al. 1998). The tags were attached either with collars around the neck, or by adhering the tags to tail hair, and were impregnated with o nitrophenol, methyl salicylate, 2,6 dichlorophenol and phenylacetaldehyde to attract the ticks, and an acaricide, such as deltamethrin, to kill the attracted ticks (Allan et al. 1 998). Untreated cattle and cattle with tags that contained only the pheromone experienced increases in tick populations on the animals, while cattle treated with tag s that contained both he pheromone and an acaricide experienced reductions in tick populat ions (Allan et al. 1998). Norval et al. (1996) designed pheromone tag decoys to be attached to the tails of cattle. These tags
31 were impregnated with both an acaricide and synthetic A. hebraeum pheromones, and resulted in greater than 90% tick mortality f or a three month period (Norval et al. 1996). Trapping and M onitoring Home owners who suffer from residential R. sanguineus infestations would likely find it undesirable to spray the interior of the ir house with chemicals or pathogenic fun gi Spraying fun gal formulations in areas where ticks may traverse has potential, but based on previous outdoor studies (Arruda et al. 2005, Leemon and Jonsson 2008, Nchu et al. 201 0a), ticks simply touching a surface treated with a fun gal formulation does not result in a high rate of successful infection The fungal spores are better able to penetrate the tick cuticle when contacting certain body regions, such as leg joints, spiracles, setae, and mouthparts (Arruda et al 2005, Leemon and Jonsson 2008). Therefore, an im proved method is needed that will allow the fungal conidia to contact susceptible tick body components or regions. For several reasons, using an attract and kill device that attracts ticks with semiochem icals to a device where ticks will infect themselves with fungi is potentially a superior method for managing tick populations than spraying a synthetic acaricide or fungal formulation. One advantage is that a smaller amount of the acaricide or fungal formulation would be required in attractant traps than is sprayed with a dispersed application. Instead of spraying large amounts of surface area, the treatment can be concentrated and localized in a small area. A trap provides another advantage through the reduction of human and companion animal contact wit h neurotoxins. It is possible that the efficacy of pathogenic fungi could be enhanced t hrough auto dissemination tend to aggregate in groups in confined spaces near the host (Dantas Torres 2008 Yoder et al. 2013). Auto dissemination of a pathoge n is a
32 concept wherein individuals spread an infection among a conspecific population. The potential for this concept to be useful in pest control was demonstrated by Vickers et al. (2004). In their study, they demonstr ated the use of a sex pheromone bai ted device to attract and infect male diamondback moths, Plutella xylostella L., with a pathogenic fungus, Zoophthora radicans (Brefeld) Batko, under field conditions. These infected males were expected to have the propensity to disperse among the populat ion and distribute the fungus to conspecifics (Vickers et al. 2004). To test the auto dissemination potential, Vickers et al. (2004) used an inoculation chamber to infect adult diamondback moths with Z. radicans These infected adults were caged in the f ield with a group of larvae. Four days after the release of the adult moths, the Z. radicans infection of P. xylostella larvae was 79%, and it was concluded that auto dissemination was a feasible method of P. xylostella control (Vickers et al. 2004). The use of semiochemical baited traps has potential for use in controlling R. sanguineus infestations in dog kennels. Traps baited with CO 2 2,6 dichlorophenol, and a blend of guanine, xanthine, adenine, and hematin, and treated with the acaricide deltamethri n were evaluated in a dog kennel in India (Ranju et al. 2013). The traps attracted 40% of adult male ticks released at a distance of 0.5 m, 34% of ticks released 1.0 m from the traps, and 28% of ticks released 1.5 m from the traps (Ranju et al. 2013). Th e current approach to BDT management using stand alone chemical treatments to eliminate BDT infestations from residential environments has been challenging and is becoming less effective due to BDT acaricide resistance. Another concern includes indoor hum an and companion animal exposure to high levels of acaricides for extended amounts of time. There is a high demand for alternative
33 methods of management for this particular tick species, and a novel trap baited with semiochemicals will provide new options for homeowners with R. sanguineus infestations. A goal of this project was the development of an effective and marketable semiochemical baited trap to aid in the management of brown dog ticks in an indoor residential environment. This device would provi de a mechanism to detect new BDT infestations, monitor for remaining tick populations after other management methods have been employed, and allow for removal of ticks from residences or kennels. A monitoring system that home owners can use would be vastl y superior to waiting until ticks are noticed climbing up the walls and on furniture (Goddard 1987, Demma et al. 2005, Dantas Torres et al. 2006). A monitoring system would also provide homeowners with a better way to verify that tick populations have bee n successfully eradicated from the home, following the implementation of other management methods, such as chemical control. Olfactometers Olfactometers are devices commonly used in behavioral bioassays to evaluate directed movement of an organism to volat ile chemicals (Allan et al. 2010, Weeks et al. 2011). While there are many variations in olfactometer design, including no choice, two choice, and four choice layouts (Rechav et al. 1977, Malonza et al. 1992, Perritt et al. 1993, Yoder 1995, Dautel 2004), organisms are generally placed in a contained area with exposure to a source of one or more volatile chemicals. The general behavior, such as orientation and movement, of the organism is observed and conclusions are for a given compound. Olfactometers can be relatively simple in design, such as a Petri dish or Y tube (Yoder 1995), or they can be
34 more complex, employing tracking systems such as a locomotion compensator (McMahon and Guerin 2002).
35 CHAPTER 2 BROWN DOG T ICK, RHIPICEPHALUS SANGUINEUS (LATREILLE), ATTRACTION TO CO 2 AND OTHER CHEMICALS IDENTIFIED AS ATTRACTANTS IN STUDIES WITH OTHER HEMATOPHAGOUS ARTHROPODS, USING Y TUBE AND STRAIGHT TUBE OLFACTOMETERS Introduction Ticks use two methods to locate hosts. Som e species lay dormant, wait for a host to come near, and are picked up by the host as it passes by. Rhipicephalus sanguineus (Latreille) brown dog ticks, are generally accepted as hunter ticks, meaning that they actively seek their hosts (Dan ta s Torres 2008). Hunter ticks can detect the volatiles, such as CO 2 produced by their host, otherwise known as kairomones (Dantas Torres 2010 ). Hunter ticks use these kairomones as a guide to help them move towards their host (Dantas Torres 2010 ). Rhipicephalus sanguineus may use kairomones to determine host location, but the semiochemicals responsible for R. sanguineus attraction to dogs have not been identified. Some studies have been conducted regarding brown dog tick pheromones (Chow et al. 1975, Louly et al 2008, Yoder et al. 2008, Yoder et al. 2013), but this area is still largely unexplored. Using an olfactometer, chemicals attractive to host seeking brown dog ticks may be determined for potential use in household monitoring traps. The Y tube olfactomete r has simple and straightforward design, and consists of a Y shaped glass tube; a main tube that branches into two arms, with air flow moving from the arms into the main tube. Tested compounds or negative controls are placed at the upwind end of each of t he olfactometer arms, in chem ical release chambers inaccessible to the arthropod (tick). Equivalent levels of air flow are directed into each olfactometer arm, passing over the potential semiochemical(s) as well as the negative control e.g. solvent. The air flow originates from a pressurized air source that is fed into the chemical release chambers
36 where the flow mixes with the volatile s and then moves down the choice arms, to the branch of the arms where the air from the two arms mix into the main tube. The arth ropod experiences the mixed air and can move against the air flow up the main tube from the zone where it was released and make a choice between the different olfactory options in the two arms. Only one arm can be chosen, and through repeated tr ials with be determined (Malonza et al. 1992). Olfactometers have been used successfully with ticks in several studies (Rechav et al. 1977, Malonza et al. 1992, Yun ker et al. 1992, Perrit t et al. 1993), and are widely used to evaluate the role of volatile chemicals in arthropod orientation behavior. The Y tube olfactometer can be further simplified into a straight tube design, wherein the arthrop od is forced to expe rience the volatile containing air flow (Malonza et al. 1992). This type of no in response to a compound by forcing the organism to remain exposed and viewing the subsequent movement Compounds that stimulate specific behaviors are classified as pheromones or kairomones in the literature and little research has been conducted with regard to the pheromones and kairomones of R. sanguineus Chemicals evaluated as attractants by others inc lude host associated chemicals, compounds common in mammalian breath, and compounds that have been shown to elicit responses in a variety of hematophago us insects such as mosquitoes, Tse tse flies, and ticks (Vale and Hall 1985, Yunker et al. 1992, Steulle t and Guerin 1994, Barr et al. 1997, Takken et al.
37 1997, Geier et al. 19 99, Osterkamp et al. 1999, Donz et al. 2004, Leonovich 2004, Yoder et al. 2008). It has been demonstrated that when a mosquito is attracted to individual host associated chemicals or CO 2 alone, combining CO 2 and the host associated chemicals may have a synergistic effect (Allan et al. 2010). For Amblyomma variegatum CO 2 alone is a fairly effective attractant and has known synergistic effects on other compounds such as methyl salicyl ate, o nitrophenol, nonanoic acid, or pheromones released by freshly engorged male ticks (Barr et al. 1997). Based on the literature, it is possible that CO 2 could enhance the attractiveness of compounds for R. sanguineus as well. Tick trapping devices h ave been successfully implemented in outdoor settings with several Amblyomma species (Wilson et al. 1972, Gray 1985, Norval et al. 1989) and traps placed in dog kennels have resulted in partial success in attracting the b rown dog tick (Ranju et al. 2013 ). The purpose of this study was to identify a select number of attractants that could be used in the development of an indoor trap for the brown dog tick. Therefore, the objectives of this study were to screen numerous previously reported hematophagous art hropod associated pheromones and kairomones for brown dog tick activation and movement responses using a Y tube olfactometer, with subsequent chemical selection refinement and mixture testing using a straight tube olfactometer and behavioral analysis softw are. Materials and Methods Ticks Male and female Rhipicephalus sanguineus adults that were two to four weeks old were used for this study following purchase from Oklahoma State University. All
38 ticks were unfed and aptly described as flat in appearance. A s soon as they were received, they were sorted by sex and stored in glass jars (diam 2.7 cm, ht 3.7 cm). Each jar had 1 mm of Plaster of Paris in the bottom to retain moisture, and plastic lids with 1 cm holes cut in the center. Cloth mesh placed between the lid and the jar allowed for adequate ventilation while preventing escape. The jars were held inside a cabinet (457 x 305 x 305 mm) (Mod. 5317 0180) that contained plastic cups filled with tap water to provide greater than 90% rela tive humidity (RH). The cabinet door was equipped with an airtight rubber seal that maintained chamber humidity. Ticks were moved and sorted by hand with the aid of a fine tipped paintbrush and soft metal forceps. All handling occurred inside a plastic insect cage (92 x 47 x 47 cm) (BugDorm) at 21C and 70 80% relative humidity (RH). Ticks were placed onto a Petri dish (14.5 cm diam) that rested inside a larger plastic dish (23.8 x 23.8 cm). The larger dish was filled with water so that the Petri dish containing the ticks was surrounded by water, preventing tick escape. When ticks were handled, nitrile gloves were worn to prevent the direct contamination of tick sensory organs by human skin volatiles. The responses of ticks to potential attractants we re evaluated in Y tube and straight tube olfactometers, described in detail below. When the ticks were removed from the glass storage jars and placed into the Petri dish surrounded by water, some ticks remained immobile while others crawled around. For e ach trial, only ticks that were active were used. This ensured that all ticks tested were in a similar state and provided an accurate estimate of the attractiveness of the given compound (Posey and
39 Schreck 1981). Individual ticks were evaluated with mult iple chemicals, but never re exposed to the same chemical. Y tube O lfactometer A ssays Glass Y tube olfactometers (Analytical Research Systems, Gainesville, FL, Mod. LFM YT 1018F) with an inner diameter of 2.0 cm and 30 degree angle at the Y branch were use d in these assays (Fig. 2 1). Assays were conducted at the USDA, ARS, CMAVE be tween 8 a.m. and 8 p.m. at 25C and 36% RH. Both atmospheric air from the centrally located pressurized air supply and a commercial blend of air enhanced with 5% carbon dioxide (CO 2 supply was contained in a pressurized tank and had a similar percentage of CO 2 to the 4.5% that is emitted during human expiration (Lehane 2005). In the system, both air flows first passed i nto air delivery systems (Analytical Rese arch Systems, Gainesville, FL, Mod. ADS STD C2FILTER) where each air stream was split into two air streams, resulting in four total outgoing air tubes. The atmospheric air was cleaned by an activated charcoal filte r (Analytical Research Systems, Gainesville, FL) that removed volatile contaminants, and then passed through a flask filled with deionized water that humidified the air to 60 80% RH. The CO 2 enhanced air from the pressurized tank was passed through a simi lar system but was not charcoal filtered in order to retain the increased CO 2 concentration. All streams of air were directed separately through Cole Parmer flow meters (Mod. PMR4 010005), where the flow rates were set to 50 mL /min (Bissinger et al. 2011 ). The air flow rates were verified between each assay using an AALBORG GFM mass flow meter ( Mod. GFM 171). Inert Teflon tubing connected the air delivery systems to the flow meter, and from there to the chemical chambers of the glass Y tube olfactomet ers.
40 The Y tube olfactometer could be configured such that atmospheric or CO 2 enhanced air could be delivered to one or both arms in all potential combinations. In order to reduce the impact of visual stimuli, and to diffuse the fluorescent light coming fr om the ceiling light fixtures (1200 lux), the Y tubes were housed in a rectangular metal frame (1.22 x 1.22 x 0.90 m), which was covered with white cotton sheeting that was clipped to the frame on all sides ( Fig. 2 2). The Y tube olfactometer glassware was cleaned after each sample chemical to ensure that there were no olfactory responses due to residues from other potential attractants. Glassware was hand washed with a brush and Neutrad glassware detergent (Decon Laboratories Inc., King of Prussia, PA), rinsed in deionized water 110C for a minimum of one hour. The 16 tested chemicals were divided into four groups with four chemicals in each group and tested in order of p erceived importance to the brown dog tick based on the scientific literature (Table 2 1). Testing in groups of four was necessary because that was the maximum number of chemicals that could be tested in one day allowing for a complete block design. All c hemicals were purchased from Sigma Aldrich (Milwaukee, WI) and had a level of purity of at least 95%. Potential attractants were tested as liquids absorbed into Whatman ( no. 1; Maidstone, England) filter paper circles that were cut into small disks (diam 1.5 cm) using a paper punch. Pure chemicals were serially diluted in hexane to concentrations of 1.0%, 0.1%, and 0.01%. One of the chemicals tested, benzoic acid, had to be diluted in methanol, because it was insoluble in hexane. Each chemical was test ed in the
41 presence and absence of CO 2 Filter paper disks were placed on flat Teflon coated plastic disks and treated with 30 of a diluted chemical. T he solvent was allowed to evaporate for 30 s (Syed and Leal 2007), and then the disks were placed in the chemical chambers of the Y tube olfactometers. Filter paper disks treated with 30 pure hexane were placed in the contro l arms after a 30 s evaporation period. Chemicals were tested in a randomized complete block design so that one replicate of a set of four chemicals at every concentration was completed each day in the presence of clean air and CO 2 enhanced air. To permit data comparisons among the four groups, two treatments, pure hexane solvent with and without CO 2 enhanced air, were completed in every group of four treatm ent chemicals to act as control treatments Two disks of filter paper were treated with 30 of pure hexane. Treated filter paper disks were allowed 30 s to dry, and were placed in both chemical chambers of the Y tube. The assay was then run as described above. This control was done for three reasons 1) to allow comparison between the treatm ent groups, 2) to verify that the hexane solvent was not an attractant, and 3) to confirm that there was no positional bias in the olfactometer due to lighting o r other environmental factors. All ticks were reused at least once, but they were never used mo re than once with the same chemical in order to eliminate bias from a previous exposure and there was always at least one month between each use. The order that the chemicals were tested each day, sex of ticks used, and the test treatment arm were randomi zed daily to control for potential bias.
42 Five adult ticks of the same sex were placed in the tick release zone via a removable hollow chamber that was inserted into the distal end of the olfactometer tube (Fig. 2 1). Ticks were inserted into the removable chamber, and then the chamber was placed upside down on a smooth surface for one or two min. This technique allowed for acclimatization resulting in reduced tick activity and increased aggregation prior to starting each assay. Chambers containing inact ive ticks were then attached to the release zone of the olfactometer (Fig. 2 1), and left undisturbed for 15 min. The white cloth drape remained closed for the duration of the test period in order to avoid observer presence influencing pote ntial visual st imuli (Fig. 2 2). Scoring was based on the final location of the tick within the Y tube at the end of 15 min. A tick that remained in the tick release zone was scored as having no attraction (Fig. 2 1). Ticks that were located between the release zone a nd the Y branch in the main tube, were scored as having a weak response. If a tick was in the proximal 5 cm of either of the arms, it was recorded as a weak choice, while a tick that had moved to the distal 3 cm of an arm was recorded as having made a st rong choice. The ticks that crawled into a choice zone were recorded as a proportion of the total number of ticks used in the replicate, i.e. one tick in the strong choice zone was recorded as 0.2. Additionally, ticks were scored by the distance (cm) fro m the initial tick release zone to their final location. Those that did not leave the tick release zone were scored as 0 cm. Ruler templates were placed beneath the Y tube so that the distance could be rapidly and accurately assessed. The average distan ce from the release zone was determined for each replicate of five ticks. Each treatment was replicated 10 times.
43 Straight Tube Olfactometer Video A ssays Chemicals that produced significant attraction or activation responses in the Y tube olfactometer we re further evaluated in straight tube olfactometers using video recording to characterize the kinetic responses. Four glass straight tube olfactometers (26.5 cm total L, 21 cm active zone, 2 cm diam) (Analytical Research Systems, Gainesville, FL) were use d with the same air handling equipment as described for the Y tube olfactometer ( Fig. 2 3). Similar to the Y tube, each straight tube had a release zone, but instead of two chemical chambers there was only one. As with the Y tube ticks could not access t he chemical chamber in the straight tubes, and so the active zone for the ticks was confined to the release zone and the straight tube. Responses of ticks in the olfactometers were videotaped for later analysis using an analog Philips camera (LTC 0500/60) an automatic iris lens (1/3 in, 5 55 mm, F 1.4 Rainbow, Irvine, CA), a real time mpeg encoder (Canopus graphics card) and a laptop computer. The camera was mounted above the straight tube olfactometers and was used to visually capture tick movement for the duration of the assays. The same cleaning procedure as described for the Y tube olfactometer was used for cleaning the straight tube olfactometer components. The nine chemicals that induced a tick response in the Y tube assays were evaluated in the straight tube olfactometer. These chemicals were benz yl alcohol, benzaldehyde, 1 octen 3 ol onitrophenol, methyl salicylate, 2,6 dichlorophenol, butyric acid, hexanoic acid, and salicylaldehyde. The responses of ticks were recorded for each individual chemical at concentrations of 1.0%, as well as for three selected mixtures of representatives from the nine compounds. The first mixture consisted of all nine chemicals at total concentrations of 9.0% and 0.9%. The next mixture contained
44 the six chemica ls shown in previous literature to serve as pheromones (benzyl alcohol, benzaldehyde, o nitrophenol, methyl salicylate, salicylaldehyde, and 2,6 dichlorophenol) (Yunker et al. 1992) at total concentrations of 6.0% and 0.6%. The third mixture consisted of the four chemicals shown in previous literature to s erve as tick kairomones (1 octen 3 ol o nitrophenol, butyric acid, and hexanoic acid) (Osterkamp et al. 1999) at total concentrations of 4.0% and 0.4%. Chemicals were prepared in hexane solvent as descr ibed previously. Five adult ticks of mixed sex were placed into the removable release chambers and provided several min to acclimatize and aggregate before placement on one of the four straight tube olfactometer release zones. A filter paper disk (1.5 cm diam) placed on a flat Teflon coated plastic disk was treated with 30 of the test solution and inserted into the removable chamber at the opposite end from the tick release zone. A fine mesh screen separated the region containing the ticks from the re gion containing the filter paper disk so that the ticks could not come in direct contact with the filter paper. Tick activity was recorded for 15 min. Behavioral Analysis Each 15 min video was viewed and specific behavioral events were scored using a be havioral analysis software package (The Observer XT 8.0, Noldus, Wageningen, The Netherlands), which utilized a time stamp for each coded behavior. Defined behavioral events were classified as duration events with a start and stop time. For three during the 15 min assay. A point event, such as changing direction, was recorded for a single point in time, e.g. 3:01 min. Each video was viewed in the software program and when s pecific behaviors were observed, they were manually coded. The following
45 behaviors were scored for duration: walking upwind (towards the odor source), stop walking, and walking downwind (away from the odor source). The following behaviors were scored as point events: direction change, and touching the mesh boundary at the upwind end. These quantifiable data were organized within The Observer XT software into total quantities for each group of five ticks. Four behaviors were statistically analyzed: durati on of directional movement, time to activation, number of end touches, and number of direction changes. The directional movement represented a combination of the time R. sanguineus spent moving upwind and downwind during exposure to a given chemical. The time to activation refers to the number of seconds that ticks took to move outside of the release chamber and to start moving upwind at the start of each assay. The number of end touches refers to how many times the ticks came in contact with the mesh bo undary at the upwind end of the olfactometer where the chemical volatiles were originating. The number of direction changes refers to how many times the ticks stopped moving in one direction and began moving in the opposite direction. Statistical A nalysi s Y tube olfactometer The data were analyzed using a linear mixed model (SAS v.9.2 PROC MIXED) consisting of three factors: test chemical, concentration (0.01 % 0.1 %, 1.0%), and air type (c lean or CO 2 enhanced) and all their interactions including chemical *concentration, concentration*air, chemical*air and chemical*concentration*air. Sex was initially included as a factor but was excluded in the final analysis as there were no significant interactions between sex and the other factors and it was deter mine d biologically irrelevant A linear mixed model was used instead of a three
46 way ANOVA because the control, consisting of hexane solvent without dissolved test chemicals, had only one concentration resulting in an unba lanced design Therefore, the control variable was nested within the factors air and concentration to make the test balanced. The chemical group was considered a random blocking factor while the treatment arm (which ever arm received the test chemical) served as a fixed blocking factor. All models were fitted using PROC MIXED as implemented in SAS v.9.2 using restricted maximum likelihood an alysis and Kenward Rogers correction to calculate the degrees of freedom. The data set was tested for normality, and it was determined that no transforma tions were necessary. Least significant difference ( LSD) tests ( were used to compare th e means of individual treatment combinations Each treatment chemical mean was compared to the hexane solvent control mean using the LSD test. This test also was used to compare clean air to CO 2 enhanced air for each of t he treatments. Three response variables were analyzed in the linear mixed model: mean distance of final location, mean activation response, and mean adjusted choice response. The first variable measured the mean distance ( in cm) R. sanguineus adults were located from the start of the main tube at the conclusion of the 15 min assay. During each 15 min assay, five individuals were allowed to move freely in the Y tube olfactometer. When movement occurred, it was not uncommon for ticks to traverse the olfact ometer in its entirety multiple times (personal observation). After 15 min the final location of each tick was observed and was considered to be representative of the overall strength of the attraction response of each tick.
47 The second variable, mean ac tivation response, was calculated by summing weak response, weak choice, and strong choice proportions (Cook et al. 2011) for each treatment. This variable was used to interpret the proportion of ticks that were activated by each treatment combination. I n other words, ticks that remained in the release zone after 15 min were considered inactive, while ticks that were located anywhere outside of the release zone were considered to have exhibit ed an activation response. The number of ticks activated out of the original five ticks was recorded as a proportion. Adjusted means from the Least Square Means output in SAS were used for improved accuracy, but resulted in some of the strong activation responses showing as a proportion greater than 1.0. The third va riable, mean adjusted choice response, was calculated by subtracting the proportion (Cook et al. 2011) of ticks that chose the treatment arm from the proportion of ticks that chose the control arm (weak choice plus strong choice). After each 15 min trial period, ticks that were located in either the treatment or the control arm of the Y tube olfactometer were considered to have made a choice. The arm of choice was the control arm for all chemicals that induced >70% of the ticks to make a choice. Therefor e, the difference in proportions was a positive value for the chemicals that activated the ticks. Positive adjusted choice proportions indicate that the control arm was chosen by ticks more often than the treatment arm, while negative proportions indicate the treatment arm was chosen more of ten. Larger proportions indicate greater tick preference for the respective arm. Straight tube olfactometer The straight tube data was analyzed by fitting a linear mixed model using restricted maximum likelihood as imp lemented in SAS (v. 9.2) with two effects tested:
48 air (clean or CO 2 enhanced) and chemical, and the interaction term air*chemical. Each variable was tested independently. The four variables tested included the duration of directional movement, the time t o activation, the number of end touches, and number of direction changes A ll were normally distributed e xcept for the time to activation, which was log transformed. Adjusted means were taken from the Least Square Means output in SAS to improve accuracy, and log values for time to activation were back transformed. between individual chemicals were determined using LSD tests for the dependent variables duration of directional movement, time to activation, number of end t ouches, and number of direction changes Results Y T ube Olfactometer Mean distance from the initial release zone Both male and female R. sanguineus demonstrated significant differences in th eir final distance from the release zone at the end of 15 min for 11 of the 16 valerolactone, 1 octen 3 ol, benzaldehyde, benzyl alcohol, hexanal, hexanoic acid, butyric acid, methyl salicylate, o nitrophenol, 2,6 dichlorophenol or salicylaldehyde, resulted in final distances that were significantly greater than the hexane solvent control (F 15,31 = 69.70, P <0.0001; Table 2 2). These chemicals were found to be similarly responsive for the two other variables, activation response and proportion choice respons e. In response to pure hexane solvent, individual ticks were located an average distance of 2.19 ( 0.68) cm from the release chamber in the clean air treatment, and 2.22 ( 0.68) cm from the release chamber in the CO 2 enhance d air treatment. T he chemica l that consistently induced ticks to move the furthest distance from the release zone was 1
49 octen 3 ol. When ticks were exposed to this chemical in the Y tube, they were located on average 21.18 ( 1.44) cm and 22.44 ( 1.44) cm from the release chamber in the presence of clean air and CO 2 enhanced air, respectively. In contrast, aside from the negative control, ticks moved the shortest distance (7.57 1.44 cm) in response to hexanoic acid in the presence of clean air. At the 1% concentration, the final lo = 0.05) than the hexane solvent control (F 15,31 = 69.70, p <0.0001); however, this only occurred in the presence of CO 2 Ticks exposed to these two chemicals in t he presence of CO 2 demonstrated an average final distance of 5.97 ( 1.44) cm for hexanal, and 5.71 ( valerolactone. The mean distance moved by ticks in response to chemicals at the lowest concentration tested, 0.01%, were not significantly d ifferent from the hexane solvent control, and tick responses to 0.1% concentrations were varied. Regardless of air type, ticks exposed to 0.1% concentrations of methyl salicylate, salicylaldehyde, o nitrophenol, butyr ic acid and 2,6 dichlorophenol were lo cated significantly further from the release zone than ticks exposed to the hexane solvent control (Table 2 2). Tick movement when exposed to all other chemicals at a 0.1% concentration did not differ from the hexane solvent control. For some chemicals, the presence of CO 2 significantly increased the final distance from the release zone when compared to trials run in the absence of CO 2 (F 15,946 = 2.23, p = 0.0045). The distance moved 0.05) in the presence of CO 2 at a conce ntration of 0.1%, for methyl salicylate (86%), butyric acid (79.9%) and 2,6 dichlorophenol (70.3%). For butyric acid the distance moved was 5.93
50 ( 1.44) cm in clean air and 10.67 ( 1.44) cm in CO 2 enhanced air. Carbon dioxide enhanced air resulted in inc reases in distance moved when compared to clean air for 1.0% concentrations of hexanoic acid (145%) and hexanal (515%) (F 15,946 = 2.23, p = 0.0045). Mean activation response Tick activation responses were significantly greater than the hexane solvent cont rol for 11 of the 16 chemicals tested at the 1% concentration (F 15,171 = 61.77, p <0.0001; Table 2 3). These chemicals included: o valerolactone, 1 octen 3 ol, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, butyric acid, hexanal, hexanoi c acid, methyl salicylate and salicylaldehyde, in the presence and absence of CO 2 These 11 chemicals demonstrating tick responses are the same chemicals found to be active in the distance from the release zone and the proportio n of choice response analys es. The mean proportion of ticks that demonstrated an activation response to the hexane solvent control was 0.155 ( 0.04) with clean air and 0.130 ( 0.04) with CO 2 enhanced air, with no significant difference between the values (Table 2 3). The mean propo rtion of ticks that demonstrated an activation response to a 1.0% concentration of any chemical ranged from 1.021 ( 0.08) with CO 2 enhanced air for o nitrophenol, to 0.316 ( 0.08) for hexanal, with CO 2 enhanced air. At a 0.1% concentration, in the presenc e and absence of CO 2 o nitrophenol, 2,6 dichlorophenol, methyl salicylate, and salicylaldehyde induced significantly greater tick activation than the hexane control (F 15,171 = 61.77, P <0.0001) (Table 2 3). For example, in the absence and presence of CO 2 enhanced air, the proportion of ticks activated by 0.1% o nitrophenol was 0.701 ( 0.08) and 0.801 ( 0.08), respectively,
51 w hile activation with the hexane solvent was 0.155 ( 0.04) and 0.130 ( 0.04) without and with CO 2 respectively Tick activation wa s significantly greater for butyric acid (0.470 0.08) than the hexane solvent control at a 0.1% concentration, but only in the presence of CO 2 (F 15,171 = 61.77, p <0.0001). The proportions o f ticks activated were significantly lower ( F 2,946 = 424.32, p < 0.0001 ) at the 0.1% concentration when compared to the activation proportions for the 1.0% concentrations and the tick activation responses to 0.01% chemical concentrations were not significantly different from the hexane solvent control for any of the tes ted chemicals. The presence of CO 2 with chemicals resulted in significantly greater activation responses than chemicals without CO 2 enhanced air for 0.1% methyl salicylate, butyric acid and 2,6 dichlorophenol, and for 1.0% benzyl alcohol, hexanal, and hexa noic acid (F 1 ,946 = 5.02, p <0.0253; Table 2 3). At the 0.1% concentration, the proportion of ticks that responded to methyl salicylate in CO 2 enhanced air (0.741 0.08) was 76% higher than the proportion that responded in clean air (0.421 0.08). Simila r responses were observed with hexanoic acid at a concentration of 1.0% where the proportion of ticks activated in CO 2 enhanced air (0.910 0.08) was 133% higher than ticks that activate d in clean air (0.390 0.08). Mean proportion choice response The arm of choice was the control arm for the 10 chemicals that stimulated tick activation when tested both with and without CO 2 at the 1% level (F 15,949 = 86.00, p <0.0001). The mean proportion choice for the hexane solvent control was 0.010 ( 0.027) with clean air and 0.005 ( 0.027) with CO 2 enhanced air, with no significant differences between these values (Table 2 4). At a concentration of 1%, in the presence and absence of CO 2 ticks demonstrated a choice response for o nitrophenol,
52 valerolactone, 1 octen 3 ol, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, butyric acid, hexanoic acid, methyl salicylate, and salicylaldehyde that was significantly greater than the hexane co ntrol (Table 2 4). Numerically, ticks demonstrated the greatest choice response for o nitrophenol at 0.880 ( 0.055) with clean air and 1.00 ( 0.055) with CO 2 enhanced air. In CO 2 enhanced air at 1.0%, tick choice responses were 0.120 ( 0.055) for benzoic acid and 0.280 ( 0.055) for hexanal, which were significantly greater than the control (F 15,949 = 86.00, p <0.0001). At a concentration of 0.1% in the presence and absence of CO 2 tick exposure to methyl salicylate, salicylaldehyde, o nitrophenol, butyric acid and 2,6 dichlorophenol resulted in tick mean choice responses that were significantly greater than the hexane solvent control responses of 0.010 ( 0.027) with clean air and 0.005 ( 0.027) with CO 2 enhanced air (F 15,949 = 86.00, p <0.0001 ; Table 2 4 ) Similar to the response at the 1% concentration, the numerically greatest choice response was observed with o nitrophenol at 0.680 ( 0.055) with clean air and 0.720 ( 0.055) with CO 2 enhanced air. Tick choice response to salicylaldehyde, at the lowest concentration of 0.01% in the presence of CO 2 was 0.120 ( 0.055) which was significantly greater than the response in the control trea tment (F 15,949 = 86.00, p <0.0001). No other chemicals at the lowest concentration resulted in significant tick respons es. Carbon dioxide impacted the mean proportion choice response of R. sanguineus exposed to selected test chemicals (F 15,949 = 1.89, p <0.0206). At a concentration of 1.0%, benzyl alcohol, hexanoic acid and hexanal induced significantly greater choice res ponses by ticks in the presence of CO 2 than in the presence of clean air (Table 2 4). The tick choice response with benzyl alcohol and CO 2 enhanced air (0.700 0.055) was
53 45.8% higher than with clean air (0.480 0.055). The tick choice response with hexa noic acid and CO 2 enhanced air (0.880 0.055) was 144% greater than the hexanoic acid with clean air treatment (0.360 0.055). Tick choices for 0.1% methyl salicylate, butyric acid and 2,6 dichlorophenol were significantly greater in the presence of CO 2 t han with clean air. The greatest differential between responses was observed with methyl salicylate where the response observed with CO 2 enhanced air (0.660 0.055) was 175% greater than with clean air (0.240 0.055). Differences between males and females There was a significant difference between the responses of males and females when comparing the data for distance from the release zone (F 1,946 = 4.44, p = 0.0354) activation response ( F 1,946 = 4.24, p = 0.0397 ) and proportion choice response ( F 1,949 = 4.70, p = 0.0304 ) The mean distance from the release zone for female ticks was 6.40 0.39 cm while the mean distance for males was 5.91 0.39 cm. The mean activation proportion for female ticks was 0.33 0.03 and for males it was 0.30 0.03. The mean c hoice proportion for female ticks was 0.244 0.008 and for males it was 0.220 0.008. Straight Tube O lfactometer Duration of directional movement Adult R. sanguineus actively moved upwind and downwind in the straight tube olfactometer when exposed to the v arious chemicals tested. There were significant differences in the amount of time the ticks spent moving depending on exposure to different chemicals and mixtures of chemicals (F 15,61 = 36.89, p <0.0001) and whether the air flow was clean or CO 2 enhanced for each of the chemical exposures (F 15,61 = 2.24, p = 0.014 0 ) (Table 2 5).
54 The average total time that a group of five ticks spent moving when exposed to the hexane solvent control was 391 (139) s in clean air, and 201 (139) s in CO 2 enhanced air (Ta ble 2 6). The hexane only exposed tick responses were significantly lower (p < 0.05) than most of the treatments that included tested chemicals or chemical mixtures, with the exception of salicylaldehyde and the 0.4% kairomone blend. Ticks spent the most time moving in the presence of benzyl alcohol (2,444 139 s), the 4% kairomone blend (2,285 170 s), and hexanoic acid (2,142 139 s) in the presence of CO 2 enhanced air. Tick movement in r esponse to these three treatments was not significantly different in the presence of clean air. Tick exposure to methyl salicylate, 1 octen 3 ol, and the 9% all chemical blend also resulted in considerable movement in both types of air, but 0.05) with exposure to benzyl alcohol, the 4% kairomone blend, and hexanoic acid. Time to activation Tick time to activation for clean air was significantly longer than for CO 2 enhanced air, irrespective of the chemical treatment (F 15,61 = 4.72, p = 0.0337; Table 2 5). The time to activation was generally longer for clean air (228 1.0 s) that in was for CO 2 enhanced air (149 1.0 s) There were significant differences (F 15,61 = 13.6, p <0.0001) between chemical treatments in the average time for tick activation at the beginning of each assay (Table 2 7). In the presence of the hexane solvent control, the average total time that a group of five ticks were idle at the beginning of each assay was 3,501 s (Table 2 7). The hexane solvent control had a significantly longer tick activation period t han any of the other chemical treatments except for benzaldehyde (1018 1.7 s). Ticks exhibited the shortest time to activation when exposed to 1 octen 3 ol (15 1.5 s) and the 9% all
55 chemical blend (25 1.5 s) (Table 2 7). Ticks responded ra pidly to sev eral other treatments as well, including methyl salicylate (50 1.5 s), the 4% kairomone blend (50 1.5 s), the 6.0% kairomone blend (64 1.5 s), and butyric acid (76 1.5 s). Ticks exposed to o nitrophenol, 2,6 dichlorophenol, salicylaldehyde, benzyl alc ohol, the 0.9% all chemical blend, hexanoic acid, the 0.6% pheromone blend, and the 0.4% kairomone blend had intermediate reaction times (Table 2 7). Number of end touches There was a significant difference (F 15,61 = 6.29, p = 0.0148) in the number of ti ck end touches for clean air and CO 2 enhanced air, irrespective of the chemical treatment (Table 2 5). In general, ticks touched the upwind end of the olfactometer more often in clean air (7.44 0.37) than in CO 2 enhanced air (6.14 0.36). The groups of 5 ticks in the 4.0% kairomone blend, 1 octen 3 ol and the all chemical blend touched the upwind end of the straight tube an average of 13.33 (1.11), 12.83 (0.99) and 9.17 (0.99) times, respectively, which was significantly more than all other treatments evaluated (F 15,61 = 9.28, p <0.0001; Table 2 8). Ticks touched the upwind end of the olfactometer relatively infrequently for several of the treatments, including benzaldehyde, the hexane solvent control, the 0.4% kairomone blend, the 0.9% all chemical bl end and 2,6 dichlorophenol with the numbers of touches ranging from 1.83 (1.40) to 4.50 (0.99). Number of direction changes There were significant differences in the number of times the ticks changed direction depending on exposure to individual chemical s or the chemical mixtures (F 15,61 = 27.8, p <0.0001) There were also significant differences in the chemical*air (clean or CO 2 enhanced) interaction (F 15,61 = 2.43, p = 0.0076) (Table 2 5).
56 In treatments without CO 2 augmentation, introduction of 1 octe n 3 ol (69.67 5.05) hexanoic acid (61.67 5.05) or the 4% kairomone blend (48.33 5.05) resu lted in significantly more direction changes than exposure to any of th e other treatments (Table 2 9). All treatments that consisted of blends below 1%, both the 6% and .6% pheromone blend s and the 1% blends of o nitrophenol, salicylaldehyde, 2,6 dichlorophenol, and the hexane solvent result ed in the fewest number of direction changes In CO 2 enhanced air, treatments containing the 4.0% kairomone blend (81.50 6 .19) and hexa noic acid (74.00 5.05), caused ticks to change direction significantly more often than the remaining chemical treatments (Table 2 9). Ticks changed direction significantly less often in the presence of several of the chemical treatments, inc luding the hexane solvent control. The average number of times a group of five t icks in these CO 2 enhanced treatments changed direction ranged from 6.6 7 (5.05) to 18.33 (5.05) in the presence of the hexan e solvent control, the 0.9% all chemical blend, t he 0.4% kairomone blend, 2,6 dichlorophenol, salicylaldehyde, and the 6.0% pheromone blend (Table 2 9). Ticks exposed to the CO 2 enhanced 4% kairomone blend treatment changed direction 59.3% more frequently (p<0.05) than ticks exposed to the blend under c lean air conditions (Table 2 9). Discussion In the presence of pure hexane solvent regardless of olfactometer type, groups of ticks rarely moved from the initial release zone. This was in stark contrast to groups of ticks in the presence of one of the sti mulating chemicals, such as 1 octen 3 ol (Table 2 6). The ticks would rapidly leave the initial release zone and actively move throughout the olfactometers, often traversing the entire length of the olfactometer several times
57 before aggregating. Movement from the initial release zone was clear evidence of activation. In the case of the Y tube olfactometer, the distance from the release zone of each tick at the end of each assay was quantifiable, and the olfactory choice of each tick was evidenced by thei r location in either the control or treatment arm. The straigh t tube olfactometer provided a more refined examination of brown dog tick behavior when exposed to the chemicals found to elicit BDT activation in the Y tube. The results of the straight tube study indicated that several of the chemicals were potentially superior BDT activators/attract ants, but did not provide absolute clarity, especially in regard to chemical mixtures. Despite the significant differences in tick activity between many of the ch emicals and control treatments, the Y tube tests did not provide conclusive data regarding directed attraction to chemicals. As is shown in Table 2 4, the tick mean adjusted choice responses to many of the chemicals tested were significantly greater than the choice responses to the hexane solvent control, with ticks consistently stopping movement within the control arm. This phenomenon was consistent for all of the chemicals examined that elicited a response from the ticks. Prior to this observation it w as expected that activated ticks would select the treatment arm more often than the control arm, thus demonstrating attraction. If the chemical was attractive, the logical conclusion would be that the ticks would aggregate in the arm in which the chemical originated. Considering the results obtained, it seems a more explorative explanation for the observed tick responses is needed. Although further studies will be needed for verification, it is hypothesized that the ticks were aggregating in the control a rm of the Y tube olfactometer because that was
58 the only region with a level of stimulating airborne volatiles below the minimal level required to maintain activation. During the 15 min assays, activated ticks had ample time to crawl throughout the testing arena. Eventually most ticks moved into the control arm, where they ceased moving. Given the design of the y tube system, the source arm chemical concentration was twice that of tick release zone. Therefore, once ticks reached the choice portion of the y tube, they were confronted with twice the concentration they had been experiencing. If they entered the no chemical arm, they no longer received the stimulus that the chemical had provided. Alternatively, ticks at the choice portion may have been repe concentration and moved into the control arm in an attempt to escape the high concentration volatiles. An alternative explanation to repellency is that the chemicals tested serve as long range BDT activators and/or a ttractants, but additional close range cues, such as body heat, are necessary for the tick to stop searching for a host. In preliminary studies, ticks were observed entering the high concentration arm, but subsequently leaving it providing support for thi s hypothesis. A previous study demonstrated that CO 2 alone could induce Aedes aegypti (Linnaeus) in a wind tunnel to fly, land, and probe. However, lactic acid or human sweat, when presented alone, largely failed to elicit a response (Eiras and Jepson 19 91). When human sweat or lactic acid was added to the CO 2 enhanced air, an increase in landing and probing behavior occurred. (Eiras and Jepson 1991). In the current study, tick aggregation in the control arm may have been due solely to the lack of chemi cal stimulation and not because the ticks were repelled,
59 and it is possible that some or all of the chemicals that elicited a tick response are attractants, as the literature has shown for other tick species. Regardless of the behaviors observed in the Y t ube olfactometer, it was of considerable interest to determine which of those chemicals that elicited a response in the Y tube, if any, were superior for use in BDT attraction. The Y tube test largely served as a screening for a large number of chemicals identified from the literature, but was only valuable in determining if the chemical activated the ticks. The straight tube olfactometer testing provided improved insight into the differences among the nine activating chemicals identified in the Y tube te sting. Overall, several chemicals emerged as significantly different from the other chemicals and the hexane solvent control. In summary, 1 octen 3 ol, hexanoic acid, methyl salicylate, and benzyl alcohol present ed the greatest potential to serve as attr actants. The response of larval brown dog ticks has recently been evaluated for 2,6 dichlorophenol and 1 octen 3 ol using Petri dish bioassays (Ranju et al. 2012a, 201 2b). In response to 2,6 dichlorophenol exposure at a concentration of 0.1 M, 71% of R. s anguineus larvae were attracted (Ranju et al. 2012a). The se findings support the results of this study, and further evaluations of R. sangu ine us response to 2,6 dichlorophenol are warranted. Interestingly, R. sanguineus larvae were not shown to be attrac ted to 1 octen 3 ol in the Petri dish bioassays performed by Ranju et al. (2012b). In the current study, 1 octen 3 ol emerged as one of the four most efficacious compounds out of the original 17 tested The findings of the two studies may not be as contr adictory as they first seem. Ranju et al. (2012b) used larval ticks whereas the ticks used in this study were adult males and females. This is important to consider because
60 1 octen 3 ol is a host produced kairomone, and the host preferences of ticks are known to change during development. Namely, immature stages tend to be less host specific than adults. With that in mind, it is possible that adult brown dog ticks simply have t are more developed than those found on larval ticks Tick attractants are often complex mixtures of chemicals that must consist of the correct composition, as well as, the correct proportion of each compound. Donz et al. (2004) observed Amblyomma variegatum Fabricius attraction to several components of bovine rumen individually, but not with a combination of butanoic acid, isobutanoic acid, 4 methylphenol and 3 methylindole in a 1:1:1:1 ratio. Increasing the concentration of butanoic acid also failed to induce a tick response. It was only when the ratio of co mpounds was adjusted to reflect the proportions of the chemicals in rumen fluid, 100:10:1:1, that a tick response was observed ( Donz et al. 2004). Osterkamp et al. (1999) demonstrated that a complex mixture of seven chemicals derived from the rumen of bo vine s could induce cattle tick, Rhipicephalus ( Boophilus) microplus, (Canestrini) attraction equal to that observed with pure rumen extract. But, the removal of any one of those seven chemicals resulted in signif icantly lower tick attraction. As such, in order to achieve ideal R. sanguineus attraction, a complex mixture and ratio of chemicals may be required. In the current study, mixtures of the activating compounds were tested in the straight tube olfactometer, as well as the individual compounds. Howe ver, no strong conclusions about the synergistic effects of mixing these compounds could be drawn from the analysis. In some instances the chemi cal blends that were tested were significantly different from the other chemicals, but for each of those instan ces, the blend con tained a chemical that was also tested on its own
61 and was not shown to be significantly different from the blend, making it seem that the individual chemical was responsible for the signifi cant response, and that the blend was therefore n ot an improvement For example, the 4.0% kairomone blend contained hexanoic acid and both of these treatments induced a significantly high duration of tick movement, but the 4.0% blend was not statistically different from hexanoic acid, suggesting that th e blend did not result in appreciable improvements to tick responses (Table 2 6). It is certainly possible that some of these chemicals can work synergistically. Future studies could focus on trying different combinations and alter native ratios of thes e compounds to reveal any synergistic effects. Osterkamp et al. (1999) demonstrated that R microplus exposure to seven chemicals found in bovine breath (pentanoic, hexanoic, benzoic and ethylhexanoic acid, pyruvate, 1 octen 3 ol, and o nitrophenol) result ed in a level of attraction equal to non fractionated bovine breath. It was determined that, of these seven chemicals, 1 oct en 3 ol and o nitrophenol were the most important in tick attraction as removal of either chemical resulted in a greater reduction in tick attraction than re moval of any of the other five chemicals (Osterkamp et al. 1999). The potential for these two chemicals to serve as R. sanguineus attractants was confirmed in the present study, as ticks responded strongly to 1 octen 3 ol and o n itrophenol in the Y tube olfactometer. However, with the inclusion of the findings from the straight tube experiments, it seems that 1 octen 3 ol causes a significantly greater response than o nitrophenol for the brown dog tick. When butyric (butanoic) ac id was presented to tropical bont ticks, A. variegatum they exhib ited a significantly greater percentage attraction and an increase in
62 locomotion when compared to ticks p resented with the control (Donz et al. 2004). The strong responses observed by Donz et al. (2004) suggest that butyric acid could serve as an attractant for R. sanguineus In response to the presence of butyric acid, the BDT became activated and moved to the control arm of the Y tube olfactometer. However in the straight tube study, t hough significantly different from the hexane solvent control, butyric acid elicited relatively moderate responses from the brown dog tick, as compared to some of the other compounds evaluated such as hexanoic acid. In a similar study, a variety of tick p heromones were tested on the bont tick, Amblyomma hebraeum Koch, and the tropical bont tick, A. variegatum using a four choice olfactometer (Yunker et al. 1992). In the study, both species were strongly attracted to benzyl alcohol, nonanoic acid, methyl salicylate, 2,6 dichlorophenol, a commercially produced antiseptic known as TCP (Pfizer), and chlorinated and iodinated phenols (Yunker et al. 1992). Benzyl alcohol, nonanoic acid, methyl salicylate, and 2,6 dichlorophenol, all have been identified in ma le ticks of the aforementioned species (Yunker et al. 1992) and were therefore, included in the current study. In our study, R. sanguineus responded strongly to benzyl alcohol, methyl salicylate and 2,6 dichlorophenol in t he Y tube olfactometer, but did n ot respond to nonanoic acid. Also worth noting, benzyl alcohol induced more movement from R. sanguineus in the straight tube olfactometer than any of the other chemicals or mixtures tested. Brown dog ticks also responded to benzaldehyde, o nitrophenol, an d salicylaldehyde in both olfactometers, all of which were tested on the bont and tropical bont tick with mixed results (Yunker et al. 1992). Even though it was difficult to
63 ascertain whether or not R. sanguineus was attracted to these chemicals, due to i ts unexpected tendency to choose the control arm in the Y tube and unremarkable levels of response in the straight tube, it is likely that these chemicals are attractants based on the correlations between the findings of this study and that of Yunker et al (1992). Rhipicephalus sanguineus previously demonstrated attraction to 2,6 dichlorophenol in two choice, short range olfactory tests (Yoder et al. 2008). All life stages, including separated males and females, were exposed to the chemical at varying con centrations and showed increased attraction as compared to the control. Yoder et al. (2008) also documented responses for 2,6 dichlorophenol at a 0.01% concentration, which contrasts with the Y tube olfactometer results of the current study, wherein R. sa nguineus attraction was demonstrated at 0.1% and 1.0%, but not at 0.01% concentrations. Such incongruence may be attributed to differences in the assays. In particular, the current study incorporated air flow into the assay, which resulted in the movemen t of the airborne chemicals over the ticks and out of the olfactometer. This prevented an accumulation of the chemical around the ticks. There was no forced air movement in the Yoder et al. (2008) study. Therefore, in order to obtain a tick response in t he moving air of the present study, chemical concentrations needed to be higher. Vale and Hall (1985) identified acetone as an important component of ox odor in tsetse fly ( Glossina spp. ) attraction. Acetone is a component of vertebrate breath, much like CO 2 and therefore seemed a likely candidate for R. sanguineus attraction. However, in the current study, acetone failed to elicit a response from the brown dog tick in the Y tube olfactometer. Despite these findings, acetone still could be involved in
64 R sanguineus host attraction, perhaps requiring a synergistic compound. When paired with lactic acid, acetone enhanced Ae. aegypti attraction (Geier et al. 1999). But when tested alone and in the presence of CO 2 acetone was not attractive to this mosqu ito (Geier et al. 1999). It is possible that pairing acetone with lactic acid, or some other compound, could result in a response from R. sanguineus As lactic acid was not evaluated in this study this hypothesis was not tested. Though some mixtures we re tested in this study using the straight tube olfactometer, it would be beneficial in future studies to assess additional mixtures, such as lactic acid with acetone. Both male and female adult brown dog ticks were stimulated to activity by several of the chemicals tested. Adults rather than immature stages were used due to their larger size that provided for improved observation while inside the Y tube olfactometer. There was a significant difference between the responses of males and females when compa ring the data in its entirety, although it is unlikely that these findings are biologically significant. This was evidenced by a preliminary analysis that demonstrated no signifi cant interactions between sex and chemical or air type. For most of the chemi cals, the presence or absence of carbon dioxide did not significantly alter R. sanguineus activation behavior. This was an unexpected observation, as CO 2 has been shown to be an important attractant and/or synergist for many hematophagous arthropods (Vale and Hall 1985, Takken and Kline 1989, Steullet and Guerin 1992 Barr et al. 1997, Takken et al. 1997, Osterkamp et al. 1999, McMahon and Guerin 2002, Syed and Leal 2007, Allan et al. 2010, Carr et al. 2013). In the present study, R. sanguineus did not r espond to a 5% CO 2 concentration when it was presented alone at a flow rate of 50 mL /min. However, Carr et al. (2013)
65 demonstrated that Amblyomma americanum (L.) and Dermacentor variabilis (Say) responded differently to air containing 3% CO 2 depending on the flow rate. Amblyomma americanum responded to 3% CO 2 air at flow rates up to 150 mL /min, but no response was observed at the low flow rate of 25 mL /min (Carr et al. 2013). Dermacentor variabilis responded to 3% CO 2 air at flow rates of 50 and 75 mL /m in, but not at 25 or 100 mL /min (Carr et al. 2013). In regard to the current study, it is possible that R. sanguineus would respond to CO 2 if a flow rate, either higher or lower than 50 mL /min, were tested. An enhanced R. sanguineus response was observed when CO 2 was combined with some of the chemicals tested, namely benzyl alcohol, hexanal, and hexanoic acid at a 1.0% concentration, and 2,6 dichlorophenol, butyric acid, and methyl salicylate at a 0.1% concentration. Interestingly, the synergistic effects were not observed at multiple concentrations for any chemical, suggesting that CO 2 acts synergistically only at certain concentrations of the chemicals. Eiras and Jepson (1991) found similar results with Ae. aegypti responses to CO 2 and lactic acid/human sweat in a wind tunnel experime nt. Synergism was observed after combining CO 2 with either human sweat or lactic acid, but only for a small range of concentrations (Eiras and Jepson 1991). In conclusion, this study revealed several chemicals with potential for use in R. sanguineus attraction. The experiments using the Y tube provided a group of nine chemicals that elicited tick activation. The straight tube experiments allowed for those nine chemicals to be filtered into a smaller subset of particularly i nteresting chemicals, namely 1 octen 3 ol, hexanoic acid, methyl salicylate, and benzyl alcohol, based on a more detailed analysis of tick behavior. The chemicals identified in this study may
66 eventually serve as attractants for use in R. sanguineus manage ment efforts. However, there are still many questions that need to be addressed in more detail. There are a multitude of potential combinations and ratios in which these and other chemicals may be mixed to induce improved tick responses. Additional test ing with CO 2 flow rates is warranted as well. Nevertheless, identifying ideal attractants can be a very complex and sensitive endeavor, and this study has established a base from which to expand our understanding of R. sanguineus attractants.
67 Table 2 1. All chemicals evaluated for adult mixed sex Rhipicephalus sanguineus (Latreille) activation and response in a Y t ube olfactometer, with random assignment to group number Group 1 Group 2 Group 3 Group 4 Acetone 3 Pentanone Benzoic acid Salicylaldehyde Be nzaldehyde Methyl salicylate Butyric acid Hexanal Benzyl alcohol o Nitrophenol Hexanoic acid 2,6 Dichlorophenol 1 Octen 3 ol Valerolactone Nonanoic acid Squalene All chemicals were tested at three concentrations (0.01%, 0.10%, 1.00%) and with two dif ferent air supplies (clean and 5% CO 2 enhanced) Hexane control tested in each group n = 10
68 Table 2 2. Mean distance (cm) from a n initial release zone where five mixed sex, adult Rhipicephalus sanguineus (Latreille) were recorded following a 15 min exposure to individual chemicals. Test Chemical % Distance a Effect of CO 2 Clean air CO 2 enhanced air p value b o Nitrophenol 0.01 2.37 1.33 0.526 0.1 15.19*** 16.55*** 0.407 1.0 19.69*** 21.75*** 0.210 Valerolactone 0.01 1.47 0.75 0.661 0.1 1.47 1.77 0.855 1.0 5.01 5.71* 0.670 1 Octen 3 ol 0.01 2.72 1.26 0.374 0.1 2.28 1.26 0.534 1.0 21.18*** 22.44*** 0.433 2,6 Dichlorophenol 0.01 2.31 2.27 0.981 0.1 10.35*** 17.63*** <0.001 1 .0 15.25*** 17.93*** 0.103 3 Pentanone 0.01 2.89 0.67 0.176 0.1 2.09 0.81 0.435 1.0 2.61 1.35 0.443 Acetone 0.01 0.58 2.02 0.380 0.1 1.78 1.44 0.836 1.0 1.18 1.84 0.688 Benzaldehyde 0.01 2.64 2.68 0.981 0.1 2.54 1.84 0.670 1.0 18.68*** 17.82*** 0.600 Benzoic Acid 0.01 1.39 2.97 0.336 0.1 1.95 1.35 0.715 1.0 4.07 3.07 0.542 Benzyl Alcohol 0.01 2.66 1.96 0.670 0.1 1.16 2.74 0.336 1.0 11.74*** 16.90*** 0.002 Butyric Acid 0.01 2.47 2.13 0.836 0.1 5 .93* 10.67*** 0.004 1.0 19.03*** 20.27*** 0.450
69 Table 2 2. Continued Test Chemical % Distance a Effect of CO 2 Clean air CO 2 enhanced air p value b Hexanal 0.01 3.47 1.69 0.278 0.1 2.47 0.93 0.348 1.0 0.97 5.97* 0.002 Hexane Solvent (Co ntrol) 2.19 2.22 0.971 Hexanoic Acid 0.01 3.03 0.97 0.210 0.1 1.65 2.03 0.817 1.0 7.57* 18.57*** <0.001 Methyl Salicylate 0.01 3.99 2.61 0.400 0.1 8.03*** 14.95*** <0.001 1.0 21.75*** 20.59*** 0.480 Nonanoic Acid 0.01 4.69 1.8 5 0.084 0.1 2.73 2.05 0.679 1.0 1.69 0.69 0.542 Salicylaldehyde 0.01 1.89 4.01 0.197 0.1 11.85*** 12.89*** 0.526 1.0 20.67*** 20.11*** 0.733 Squalene 0.01 1.91 2.09 0.913 0.1 0.75 1.81 0.518 1.0 1.53 1.95 0.798 Exposure occurred in a Y tube olfactometer with an airflow rate of 50 mL /min in each arm and all concentrations of treatment chemicals tested were dissolved in hexane There were 10 replicates with 5 ticks per replicate Complete data set analyzed with a linear mixed model us ed to determine a difference between chemicals (F15,31 = 69.70, p <0.0001) and air types (F1,946 = 8.75, p = 0.0032) SEM for all means was 1.44 cm for all treatments, except the hexane control, which was 0.68 cm a Within a column, adjusted means were com pared to hexane solvent control using Least Significant Difference (LSD) tests (* = p <0.05; ** = p <0.01; *** = p < 0.001) b Within a row, p values calculated using LSD tests showing the probability of a significant difference between the chemical tested i n clean air and CO 2 enhanced air.
70 Table 2 3. Mean proportion of mixed sex, adult Rhipicephalus sanguineus (Latreille) that activated in resp onse to potential attractants. Test Chemical % Proportion Activated a Effect of CO 2 Clean air CO 2 enhanced air p value b o Nitrophenol 0.01 0.121 0.141 0.814 0.1 0.701*** 0.801*** 0.240 1.0 0.921*** 1.021*** 0.240 Valerolactone 0.01 0.121 0.061 0.481 0.1 0.101 0.121 0.814 1.0 0.281 0.341** 0.481 1 Octen 3 ol 0.01 0.193 0.093 0.240 0.1 0.153 0.093 0.481 1.0 1.013*** 1.033*** 0.814 2,6 Dichlorophenol 0.01 0.116 0.156 0.638 0.1 0.496*** 0.856* ** <0.001 1.0 0.816*** 0.896*** 0.347 3 Pentanone 0.01 0.161 0.061 0.240 0.1 0.141 0.081 0.481 1.0 0.161 0.101 0.481 Acetone 0.01 0.053 0.133 0.347 0.1 0.113 0.093 0.814 1.0 0.093 0.153 0.480 Benzaldehyde 0.01 0.193 0.153 0.6 38 0.1 0.153 0.133 0.814 1.0 0.933*** 0.813*** 0.158 Benzoic Acid 0.01 0.090 0.190 0.240 0.1 0.090 0.110 0.814 1.0 0.230 0.130 0.240 Benzyl Alcohol 0.01 0.193 0.113 0.347 0.1 0.093 0.173 0.347 1.0 0.613*** 0.873*** 0.002 Bu tyric Acid 0.01 0.170 0.110 0.481 0.1 0.270 0.470*** 0.019 1.0 0.890*** 0.930*** 0.638
71 Table 2 3. Continued Test Chemical % Proportion Activated a Effect of CO 2 Clean air CO 2 enhanced air p value b Hexanal 0.01 0.196 0.076 0.158 0.1 0.156 0.0 36 0.158 1.0 0.036 0.316* 0.001 Hexane Solvent (Control) 0.155 0.130 0.557 Hexanoic Acid 0.01 0.170 0.070 0.240 0.1 0.070 0.090 0.814 1.0 0.390** 0.910*** <0.001 Methyl Salicylate 0.01 0.221 0.141 0.347 0.1 0.421*** 0.741*** < 0.001 1.0 1.021*** 0.981*** 0.638 Nonanoic Acid 0.01 0.290 0.070 0.010 0.1 0.110 0.090 0.814 1.0 0.070 0.030 0.638 Salicylaldehyde 0.01 0.076 0.236 0.060 0.1 0.656*** 0.616*** 0.638 1.0 0.956*** 0.956*** 1.000 Squalene 0.01 0 .136 0.116 0.814 0.1 0.056 0.096 0.638 1.0 0.056 0.076 0.814 Exposure occurred in a Y tube olfactometer with an airflow rate of 50 mL /min in each arm and all concentrations of treatment chemicals tested were dissolved in hexane There were 10 replicate s with 5 ticks per replicate Complete data set analyzed with a linear mixed model used to determine a difference between chemicals (F15,171 = 61.77, p <0.0001) and air types (F1,946 = 5.02, p = 0.0253) SEM for all means was 0.07 for all treatments except the hexane control, which was 0.04 a Within a column, adjusted means were compared to hexane solvent control using Least Significant Difference (LSD) tests (* = p <0.05; ** = p <0.01; *** = p < 0.001) b Within a row, p values calculated using LSD tests sh owing the probability of a significant difference between the chemical tested in clean air and CO 2 enhanced air.
72 Table 2 4. Mean proportion of mixed sex adult Rhipicephalus sanguineus (Latreille) that chose the treatment arm subtracted from the mean propo rti on that chose the control arm. Test Chemical % Adjusted Choice Proportion a Effect of CO 2 Clean air CO 2 enhanced air p value b o Nitrophenol 0.01 0.100 0.060 0.606 0.1 0.680*** 0.720*** 0.606 1.0 0.880*** 1.000*** 0.122 Valerolactone 0.01 0.020 0.020 1.000 0.1 0.020 0.040 0.796 1.0 0.180** 0.240*** 0.439 1 Octen 3 ol 0.01 0.040 0.040 1.000 0.1 0.000 0.020 0.796 1.0 0.960*** 0.980*** 0.796 2,6 Dichlorophenol 0.01 0.080 0.060 0.796 0.1 0.480*** 0.7 20*** 0.002 1.0 0.560*** 0.700*** 0.071 3 Pentanone 0.01 0.060 0.020 0.606 0.1 0.020 0.020 0.606 1.0 0.020 0.020 0.606 Acetone 0.01 0.000 0.060 0.439 0.1 0.020 0.000 0.796 1.0 0.020 0.000 0.796 Benzaldehyde 0.01 0.060 0.060 1.000 0.1 0.080 0.040 0.606 1.0 0.800*** 0.760*** 0.606 Benzoic Acid 0.01 0.040 0.020 0.439 0.1 0.020 0.040 0.796 1.0 0.060 0.120* 0.439 Benzyl Alcohol 0.01 0.080 0.060 0.796 0.1 0.000 0.100 0.197 1.0 0.480*** 0.700*** 0.005 Butyric Acid 0.01 0.120* 0.100 0.796 0.1 0.220*** 0.500*** <0.001 1.0 0.920*** 0.960*** 0.606
73 Table 2 4. Continued Test Chemical % Adjusted Choice Proportion a Effect of CO 2 Clean air CO 2 enhanced air p value b Hexanal 0.01 0.080 0.040 0. 606 0.1 0.080 0.020 0.439 1.0 0.060 0.280*** 0.005 Hexane Solvent (Control) 0.010 0.005 0.897 Hexanoic Acid 0.01 0.080 0.060 0.796 0.1 0.020 0.100 0.302 1.0 0.360*** 0.880*** <0.001 Methyl Salicylate 0.01 0.060 0.000 0.439 0.1 0.240*** 0.660*** <0.001 1.0 0.980*** 0.960*** 0.796 Nonanoic Acid 0.01 0.120 0.060 0.020 0.1 0.060 0.060 1.000 1.0 0.060 0.000 0.439 Salicylaldehyde 0.01 0.100 0.120* 0.796 0.1 0.440*** 0.520*** 0.302 1.0 0.940*** 0.880*** 0.439 Squalene 0.01 0.060 0.020 0.606 0.1 0.060 0.080 0.796 1.0 0.000 0.020 0.796 Exposure occurred in a Y tube olfactometer with an airflow rate of 50 mL /min in each arm and all concentrations of treatment chemicals tested were dissolved in h exane There were 10 replicates with 5 ticks per replicate Complete data set analyzed with a linear mixed model used to determine a difference between chemicals (F15,949 = 86.00, p <0.0001) and air types (F1,949 = 17.41, p <0.0001) SEM for all means was 0 .055 for all treatments except the hexane control, which was 0.027 a Within a column, adjusted means were compared to hexane solvent control using Least Significant Difference (LSD) tests (* = p <0.05; ** = p <0.01; *** = p < 0.001) b Within a row, p value s calculated using LSD tests showing the probability of a significant difference between the chemical tested in clean air and CO 2 enhanced air.
74 Table 2 5. Summary of statistics for adult mixed sex Rhipicephalus sanguineus (Latreille) behaviors including m ovement, activation, end touch, and change direction in response to exposure to chemicals, with and without the presence of CO 2 enhanced air in straight tube olfactometers. Effect Movement (s) Activation (s) End Touch Change Direction Num DF p Num DF p N um DF p Num DF p Air 1 0.2986 1 0.0337 1 0.0148 1 0.3243 Chemical 15 < 0 .0001 15 < 0 .0001 15 < 0 .0001 15 < 0 .0001 Air*Chemical 15 0.014 0 15 0.1851 15 0.1476 15 0.0076 Air = CO 2 enhanced or Clean n = 3
75 Table 2 6. Movement duration (sec) of a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) exposed to chemicals in a straight tube olfactometer. Test chemical Movement in s (SEM) a Effect of CO 2 Clean air CO 2 enhanced air p value b Benzyl alcohol 1,824 (139)abc 2,444 (139)a 0.391 4% Kairo mone blend 1,979 (139)ab 2,285 (170)a 0.168 Hexanoic acid 2,032 (139)a 2,142 (139)a 0.579 Methyl salicylate 1,481 (139)cd 1,743 (139)b 0.186 1 octen 3 ol 1,844 (139)abc 1,640 (139)b 0.303 9% All chemical blend 1,613 (139)bcd 1,521 (139)bc 0.6 39 o Nitrophenol 1,323 (139)de 1,232 (139)cd 0.645 Benzaldehyde 1,371 (240)cde 1,132 (139)cde 0.391 Butyric acid 1,695 (139)abcd 1,093 (139)de 0.003 0.6% Pheromone blend 677 (139)fg 936 (139)def 0.191 6% Pheromone blend 818 (139)ef 772 (139) efg 0.817 2,6 Dichlorophenol 769 (139)fg 614 (139)fg 0.432 0.9% All chemical blend 865 (139)ef 597 (139)fg 0.175 Salicylaldehyde 721 (139)fg 518 (139)gh 0.304 0.4% Kairomone blend 751 (139)fg 432 (139)gh 0.109 Hexane solvent control 391 (139) g 201 (139)h 0.335 Each chemical had three replicates of both air types with five ticks per replicate, and group totals of replicates were averaged Exposure occurred for 15 min with an airflow rate of 50 mL /min, and all single chemicals were tested at a 1.0% concentration Kairomone blend 1 octen 3 ol, o nitrophenol, butryric acid, and hexanoic acid Pheromone blend methyl salicylate, salicylaldehyde, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, and o nitrophenol a Letters a e following means within a column indicate significant differences (p < 0.05) calculated using Least Significant Difference (LSD) tests b Within a row, P values calculated using LSD tests showing the probability of a significant difference between the chemical tested with and witho ut CO 2
76 Table 2 7. The average time to activation at the beginning of each assay for a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) in a straight tube olfactometer. Test c hemical Adjusted mean (LSM) in s ( SEM) 1 Octen 3 ol 15 (1.5) a 9.0% All chemical blend 25 (1.5)ab Methyl salicylate 50 (1.5)bc 4.0% Kairomone blend 50 (1.5)bc 6.0% Pheromone blend 64 (1.5)bcd Butyric acid 76 (1.5)cd o Nitrophenol 168 (1.5)de 2,6 Dichlorophenol 182 (1.5)de Salicylaldehyde 233 (1.5)ef Benzyl alcohol 283 (1.5)efg 0.9% All chemical blend 336 (1.5)efg Hexanoic acid 426 (1.5)efg 0.6% Pheromone blend 567 (1.5)fg 0.4% Kairomone blend 660 (1.5)fg Benzaldehyde 1018 (1.7)gh Hexane solvent control 3501 (1.5)h Replicates of both air types were combined giving a total of six replicates for each chemical with five ticks per replicate, and group totals of replicates were averaged Exposure occurred for 15 min with an airflow rate of 50 mL /min, and all single chemicals were tested at a 1. 0% concentration Kairomone blend 1 octen 3 ol, o nitrophenol, butryric acid, and hexanoic acid Pheromone blend methyl salicylate, salicylaldehyde, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, and o nitrophenol Letters a h following means within a co lumn indicate sig nificant differences (p < 0.05) calculated using Least Significant Difference tests
77 Table 2 8. The total number of times a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) contacted the upwind end of the tube where the ch emical originated during chemical exposure in a straight tube olfactometer. Chemical Adjusted mean (LSM) ( SEM) Benzaldehyde 1.83 (1.40)a Hexane solvent control 3.00 (0.99)ab 0.4% Kairomone blend 3.83 (0.99)ab 0.9% All chemical blend 4.17 (0.99)ab 2,6 Dichlorophenol 4.50 (0.99)ab 0.6% Pheromone blend 5.33 (0.99)b 6.0% Pheromone blend 5.50 (0.99)bc Salicylaldehyde 6.17 (0.99)bc Benzyl alcohol 6.67 (0.99)bcd o Nitrophenol 7.00 (0.99)cd Butyric acid 7.83 (0.99)d Methyl salicylate 8.67 ( 0.99)de Hexanoic acid 8.83 (0.99)e 9.0% All chemical blend 9.17 (0.99)f 1 Octen 3 ol 12.83 (0.99)f 4.0% Kairomone blend 13.33 (1.11)f Replicates of both air types were combined giving a total of six replicates for each chemical with five ticks pe r replicate, and group totals of replicates were averaged Exposure occurred for 15 min with an airflow rate of 50 mL /min, and all single chemicals were tested at a 1.0% concentration Kairomone blend 1 octen 3 ol, o nitrophenol, butryric acid, and hexanoic acid Pheromone blend methyl salicylate, salicylaldehyde, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, and o nitrophenol Letters a f following means within a column indica te significant differences (p < 0.05) calculated using Least Significant Differe nce tests
78 Table 2 9. The total number of times a group of five adult mixed sex Rhipicephalus sanguineus (Latreille) changed movement direction during chemical exposure in a straight tube olfactometer. Test chemical No. of Direction Changes (SEM) a Effect of CO 2 Clean air CO 2 enhanced air p value b 4% Kairomone blend 48.33 (5.05)bc 81.50 (6.19)a <0.001 Hexanoic acid 61.67 (5.05)ab 74.00 (5.05)a 0.090 1 Octen 3 ol 69.67 (5.05)a 58.00 (5.05)b 0.1078 Benzyl alcohol 36.33 (5.05)cd 50.33 (5.05)bc 0 .0548 9% All chemical blend 29.67 (5.05)def 39.00 (5.05)cd 0.1966 Methyl Salicylate 36 .00 (5.05)cde 30.00 (5.05)de 0.4046 Benzaldehyde 23 .00 (8.76)defgh 27.33 (5.05)def 0.6697 Butyric acid 32 .00 (5.05)de 25.33 (5.05)defg 0.3547 0.6% Pheromone blend 15 .00 (5.05)gh 22.67 (5.05)efgh 0.2877 o Nitrophenol 23.33 (5.05)defgh 21.67 (5.05)efgh 0.8164 6% Pheromone blend 17.67 (5.05)fgh 18.33 (5.05)efghi 0.926 Salicylaldehyde 15 .00 (5.05)gh 15.67 (5.05)fghi 0.926 2,6 Dichlorophenol 15.33 (5.0 5)gh 15.00 (5.05)fghi 0.963 0.4% Kairomone blend 24.67 (5.05)defg 12.33 (5.05)ghi 0.0895 0.9% All chemical blend 22 .00 (5.05)efgh 10.67 (5.05)hi 0.118 Hexane solvent control 9.33 (5.05)h 6.67 (5.05)i 0.7104 Each chemical had three replicates of both air types with five ticks per replicate, and group totals of replicates were averaged Exposure occurred for 15 min with an airflow rate of 50 mL /min, and all single chemicals were tested at a 1.0% concentration Kairomone blend 1 octen 3 ol, o nitroph enol, butryric acid, and hexanoic acid Pheromone blend methyl salicylate, salicylaldehyde, 2,6 dichlorophenol, benzaldehyde, benzyl alcohol, and o nitrophenol a Letters a e following means within a column indica te significant differences (p < 0.05) calcula ted using Least Significant Difference tests b P Within a row, values calculated using LSD tests showing the probability of a significant difference between the chemical tested with and without CO 2
79 Figure 2 1. Diagrammatic overview of the Y tube olfactom eter and air delivery system. All measurements are lengths (cm).
80 Figure 2 2. Olfactometer testing station with a 5% CO 2 enhanced air t ank on the left, and two Y tube olfactometers with flow r ate control devices in the center and surrounded by white clo th to reduce visual stimuli.
81 CHAPTER 3 EVALUATION OF FOUR BED BUG TRAPS WITH ATTRACTANT AUGMENTATION FOR CAPTURING BROWN DOG TICKS, RHIPICEPHALUS SANGUINEUS (LATREILLE) Introduction During the 1970s and 1980 s it was widely recognized that the chemical pes ticides being used could result in human health risks, environmental damage, and the development of pesticide resistance in the target pests (Heuskin et al. 2011). The adverse effects of chemical pesticides stimulated the development of integrated pest ma nagement (IPM) strategies (Heuskin et al. 2011). Integrated pest management relies on the use of several management strategies that together achieve acceptable pest population levels (Heuskin et al. 2011). Currently the brown dog tick, Rhipicephalus sang uineus (Latrielle) is a particularly difficult pest to control due to acaricide resistance development as well as difficulties in treating all of the residential locations where this tick takes refuge (Miller et al. 2001). As currently practiced, brown d og tick IPM programs rely heavily on animal and premise acaricide use and cultural controls and thus, are in need of additional tools to improve their success Traps are commonly used as monitoring tools for indoor pest insect populations, s uch as cockroac hes and bed bugs, Cimex lectularius L. (Ballard and Gold 1982, Sever et al. 2007, Shahraki et al. 2011, Wang et al. 2011). Bed bug traps that contain attractive lures and traps placed under furniture legs can be used to detect low level bed bug infestation s. These traps also can be used to check the effectiveness of treatments for bed bug control f ollowing the use of other control methods After an
82 initial insecticide application, traps could be used to captur e the few remaining bed bugs, thus reducing the need for further insecticide applications (Wang et al. 2011). Over the years, various volatile chemicals have been used to attract ticks to localized areas, either to kill them with a contained acaricide, or to trap them. The use of CO 2 as a standalone a ttractant can be effective for trapping ticks, although all studies to date have evaluated trapping in outdoor environments and dog kennels. The lone star tick, Amblyomma americanum (L.) (Wilson et al. 1972) and Ixodes ricinus (L.) (Gray 1985), can be suc cessfully attracted and captured in a CO 2 augmented trap. Wilson et al. (1972) found that CO 2 baited traps were capable of capturing 50 adult A. americanum for every one adult that was captured using the flagging method. Gray (1985) also found CO 2 baited traps captured more adult I. ricinus than did flagging. The tropical bont tick, Amblyomma variegatum Fabricius, and the bont tick, Amblyomma hebraeum Koch, have been successfully attracted to semiochemical baited traps outdoors (Norval et al. 1989, Marang a et al. 2006, Nchu et al. 2010 b ). Norval et al. (1989) demonstrated that a lure consisting of blood fed adult male A. hebraeum ticks in combination with CO 2 attracted more ticks than an extract from fed males with CO 2 or o nitrophenol with CO 2 Maranga et al. (2006) and Nchu et al. (2010 b ) both successfully lured A. variegatum to traps using synthetic attraction aggregation attachment pheromone (AAAP). These studies demonstrated that A. variegatum and A. hebraeum can be attracted to traps using semioc hemicals and CO 2 Another Amblyomma spp., Amblyomma maculatum Koch, also has a pheromone that is similar in function to the bont ticks (Gladney et al. 1974).
83 Attract and kill field trials were conducted recently on R. sanguineus in a dog kennel in India ( Ranju et al. 2013). Carbon dioxide and 2,6 dichlorophenol were evaluated as attractants with the killing agent deltamethrin added to the mixture. In this study, 50 brown dog ticks were released at distances of 0.5, 1.0, and 1.5 m from a platform holding the attractants and acaricide Ticks attracted to the platform by the volatile chemicals would die when they contacted deltamethrin At the 0.5 m distance, 40% of the ticks released were attracted, whereas 34% were attracted at a distance of 1.0 m, and 2 8% were attracted at a distance of 1.5 m (Ranju et al. 2013). This study demonstrated that brown dog ticks could be drawn to a localized area using olfactory attractants and that distance influenced attraction There are several commercial bed bug traps t hat are available for use in population monitoring (Weeks et al. 2011). These traps may be interceptive or baited. Interceptive traps capture or kill bed bugs as they attempt to leave or access the bed. Baited traps utilize constituents such as heat, ch emical lures, or a combination of the two, to attract the bed bugs (Weeks et al 2011). Wang et al. (2011 ) constructed a simple bed bug trap out of an inverted plastic cat feeder and an insulated jug filled with dry ice to dispense CO 2 The bed bugs, attr acted by CO 2 crawled up the side of the cat feeder, and fell into the talcum powder coated lip that acted as a moat where they remained trapped. Bed bugs and brown dog ticks are both endophilic pests that hide in the cracks and crevices of homes and come out to host seek. Due to the behavioral and habitat similarities between bed bugs and R. sanguineus some of the commercially available bed bug traps may be useful in residential R. sanguineus monitoring.
84 ug B commercially available bed bug traps for use in monitoring infestations as well as have been evaluated for bed bug capturing efficacy with varying result s (Wang et al. 2009, 2011). Based on a previous study, it is likely that the efficacy of these traps for capturing bed bugs is related to the amount of CO 2 that they produce, where traps that produce more CO 2 capture greater numbers of bed bugs than traps with lower CO 2 production ( Wang et al. 2011). Evaluating bed bug traps for their efficacy in capturing brown dog ticks would provide much needed data for the development of effective brown dog tick monitoring or control devices. The objective of this study was to evaluate four comm ercially available bed bug traps in a semi field setting for their efficacy in capturing brown dog ticks. Traps were either evaluated as provided by the manufacturer, with a few modifications, as well as with the addition of suspected attractive semiochem icals. Materials and Methods Ticks Male and female R. sanguineus adults that were two to four weeks old were used for this study following purchase from Oklahoma State University. All ticks were unfed and aptly described as flat in appearance. As soon as they were received, they were sorted by sex and stored in glass jars (diam 2.7 cm, ht 3.7 cm). Each jar had 1 mm of Plaster of Paris in the bottom to retain moisture, and plastic lids with 1 cm holes cut in the center. Cloth mesh placed between the lid and the jar allowed for adequate cabinet (45 7 x 305 x 305 mm) (Mod. 5317 0180) that contained plastic cups filled with
85 tap water to provide greater than 90% relative humi dity (RH). The cabinet door was equipped with an airtight rubber seal that maintained room humidity. The temperature of the cabinet was not controlled and so the ticks experienced a standard room temperature of 21C, and room lighting was automated to a 14:10 LD cycle. Ticks were moved and sorted by hand with the aid of a fine tipped paintbrush and soft metal forceps. All handling occurred inside a plastic insect cage (92 x 47 x 47 cm; BugDorm) at 21C and 70 80% relative humidity (RH). Ticks were place d onto a Petri dish (14.5 cm diam) that rested inside a larger plastic dish (23.8 x 23.8 cm). The larger dish was filled with water so that the Petri dish containing the ticks was surrounded by water, preventing tick escape. When ticks were handled, nitr ile gloves were worn to prevent direct contact of ticks with human skin volatiles. For the first experiment, ticks were released into specially designed rooms to evaluate the efficacy of four commercial trap models. For the second experiment, one of the f our trap models from the first experiment was selected for additional study based on tick capture efficacy as well as the potential for daily use by stakeholders. The selected trap model was used in conjunction with the chemicals selected and conclusions drawn from the olfactometer experiments from Chapter 2. Rooms Two rooms w ere constructed within a building located at the USDA, ARS, CMAVE in Gainesville, FL. Each room was 2.159 m high, 1.918 m wide, with a length of 2.057 m. The upper boundaries of th e rooms were sealed with fine mesh screen (8 squares per cm) to prevent tick escape but allow air exchange. The doors were spring loaded to ensure that they stayed securely closed by default, and were made of clear polyacrylate so that the interior of the rooms could be observed without opening the
86 doors. To prevent tick escape through small cracks around the door seals or when the doors were opened on conclusion of the assay, a perimeter of fly paper (Atlantic paste and Glue Corporation, Brooklyn, NY, EP A # 057296 WI 001) coated with 32 UVR soft glue was taped around each door. Any small cracks or depressions found on the walls or floors of each room were filled with white caulk (DAP Alex Ultra 230), and the entire room was sealed with two coats of whi gloss 19910 White). The caulk and paint combination helped prevent tick escape, and made tick monitoring and relocation more efficient due to the contrast between the white room and the brown ticks. Both rooms were fitted with an a ir ventilation system receiving fresh air from a fan drawing from outdoors, and air was removed from the rooms by a second fan drawing from the rooms with outdoor deposition (Fig 3 1 3 2 ). Both fans (Home Ventilating Institute, Phoenix AZ) were connecte d to the rooms using aluminum foil tubing (10.16 cm diam ; incoming air was introduced through a connection in the top of the wall, and the outgoing air was vented through four points (10.16 cm) around the base of the walls. All air entry and exit points were sealed using the same mesh that was used to tick proof the ceiling. In order to achieve at least two complete air exchanges per hour, each of the four vents in each room was adjusted to ve n t air at a rate of 9.144 m /min. The incoming air was dra wn from an air conditioned room located between both rooms, through a humidifier (Essick Air Mod. H12 300, Little Rock, AR) that was positioned underneath the fan so that the air being introduced in to the rooms maintained a relative humidity greater than 60%. The air entering the humidifier was charcoal filtered (AIR
87 HANDLER Activated Carbon Air Filter hem # SW095 CCL4 Activity 0.6; 6.35 mm thick) to remove impurities. The temperature within the roo ms was controlled as much as possible using wall mounted air conditioning units. The temperatures and RH for each room were recorded at the beginning and end of each assay as well as the overall minimum and maximum temperatures and RH for the six hour tes ting period using AcuRite weather thermometers with outdoor sensors (Chaney Instrument Co., Lake Geneva, WI). The average temperature during the morning (a.m.) evaluation period was 24.85C with a range of 21.11 28.89C. The average temperature during t he afternoon (p.m.) evaluation period was 26.54C w ith a range of 22.78 29.44C. There were two fluorescent light bulbs (Cool White Exolux Watt Miser, 34W, GE, U.S.A.) in each room that were kept on for the duration of each evaluation period. Traps Four models of commercial bed bug traps were evaluated for their efficacy in capturing brown dog ticks. Three of the traps are commercially available as baited Philadelphia, PA), Bed Bu commercially available as an interceptive trap, ClimbUp (Susan McKnight Inc., Memphis, TN). All four of the traps had pitfalls designed for the capture of bed bugs (Fig 3 3). In preliminary trials, only the ClimbUp was able to contain ticks in its pitfall trap as designed, due to the presence of a thin layer of talcum powder that coated the inner surfaces of the pitfall. Therefore, odorless talcum powder (Trident ) was applied to the inner pitfall surf aces of the other three bed bug traps using a watercolor paintbrush to facilitate tick containment in all traps.
88 The ClimbUp trap was modified for use in this stu dy with the addition of a 1.89 L ) filled completely with pelleted dry ice to produce CO 2 as an activator and attractant. The thermos was placed upside down in the center of the ClimbUp trap, and had a 1.2 cm hole drilled in the bottom to allow the CO 2 ad an automated electronic system, producing CO 2 at a rate of 161 mL /min from a 567 g canister of compressed gas (Wang et al. 2011), and also emitting heat (44.7C) from a section of its surface with the intention of mimicking the warmth produced by a home otherm. The manufactured CO 2 booster packs that contained an unmixed collection of propriety compounds which, when mixed, produced low levels of CO 2 for a 2 production kit much like be mixed with water to activate. Carbon dioxide levels (ppm) were measured using a carbon dioxide transmitter (Vaisala Type: GMT222 CON1BOC1AOB Serial No: H3330057) Measurements were taken from the anti chamber at the start of each assay to determine the ambient CO 2 levels indoors (705 ppm), whereas the outdoor ambient CO 2 levels were approximately 400 ppm. To determine initial CO 2 levels within each room after tr ap placement, a probe attached to the CO 2 transmitter was placed inside the room, approximately equidistant from the trap and the wall. This measurement was repeated at the end of each assay to determine the CO 2 ppm levels within the room following trap u se. The mean change s in CO 2 levels were calculated by averaging eight individual recordings for each trap.
89 Evaluation of Trap M odel Morning assays were initiated daily between 6:00 and 7:00 a.m. EST and afternoon assays were initiated between 2:00 and 3:0 0 p.m EST Nitrile gloves (Fisher Scientific Inc.) and shoe guards (Trimaco, Morrisville, NC) were worn when entering the rooms. The gloves prevented potential skin oils from being transferred to ticks, traps, and room surfaces. The shoe guards reduced the amount of debris that was transferred into the rooms. Ten ticks, of mixed sex were released in each of the four corners of both rooms, at least 15 cm from the wal ls. Therefore, a total of 40 ticks were released in each room, with a total of 160 ticks used per day. Once released, ticks were allowed a one hour acclimatization period before t raps were introduced. Following the acclimatization period, one trap was placed in the center of each room approximately 1 m from the walls the door was sealed and the rooms were left undisturbed for a period of six hours. One replicate consisted the combined morning and afternoon (a.m. and p.m.) placements for each day, so that all four traps were evaluated once per day. At the end of the six hour capture period, the positions of the ticks within the rooms and on traps were recorded. The number of ticks captured, attracted, and activated were recorded for each room. Only ticks recovered in the pitfall of the trap were considered captured. The sum of the ticks co unted both on the trap and in the pitfall of the tr ap were classified as attracted. The combination sum of the ticks co unted on the trap and in the pitfall of the trap and on the floor of the room were considered to be activated. Final CO 2 levels were de termined, all ticks were re collected from the room, and the traps were removed. New groups of 40 ticks were released into the rooms and
90 allowed one hour to acclimatize. A high powered fan was run during the first 15 minutes of tick acclimatization to he lp return the room CO 2 levels to near the inside background level of 705 ppm After tick acclimatization, the remaining two traps were placed in the rooms and the second assay was run for a six hour period. Procedures as described previously were conduct ed. The rooms were then left vacant overnight with the regular ventilation fans running in preparation for assays the following day. Assays were conducted for a period of eight days. To adjust for possible discrepancy in tick behavior due to time of day effects, differences between the two rooms, and the traps impacting each other when paired together, modifications to the study design were made. Over eight days each of the 4 traps was tested 8 times with 40 ticks per test (n = 8). Traps were randomized to room and time of day (a.m. or p.m.) ensuring that all combinations were equally represented. Evaluation of Different A ttractants For this experiment eight treatments were evaluated. A single trap model was utilized in combination with one of three che micals with and without dry ice as a CO 2 source, as well as heat without chemicals or dry ice and dry ice without heat or chemicals. Based on the findings of the trap comparison using only CO 2 as an attractant, and the relative ease of use and practicalit y observed among the traps tested, the ClimbUp trap was selected for use in the chemical combinations experiment. Three chemicals were selected for use based on the findings of the experiments completed in Chapter 2 Briefly, chemic als were selected bas ed on R. sanguineus responses to chemicals that were significantly different in from responses to a hexane solvent control, as well as tick responses to chemicals that were significant ly
91 greater than tick responses to other attractant candidates. The chem icals evaluated were 1 octen 3 ol, hexanoic acid, and methyl salicylate (Sigma Aldrich, Milwaukee, WI). Assays were conducted in th e same manner as described previously for the trap comparis on study with a few modifications. The high powered fan was run for 30 min at the end of each assay, with all of the room doors open, to return the room CO 2 levels to background levels of 705 ppm as well as to remove remaining chemical volatiles. This was done before the placement of new ticks. This air purging meth od was used in place of the procedure described for the trap comparison study for two reasons: it ensured that the new ticks were not affected by the high powered fan during acclimatization, and it was more effective in returning the CO 2 to indoor backgrou nd levels. As before, groups of 40 ticks were placed into each room prior to trap placement, however instead of allowing the ticks one hour to acclimatize, they were left undisturbed for 30 min. The acclimatization time given to the ticks was shortened b ased on observations during the previously described trap comparison study wherein the ticks finished aggregating w ithin 30 min For each assay, two ClimbUp traps were prepared with chemicals, chemicals with CO 2 CO 2 alone, or a heat source. Aliquots (50 0 ) of pure, undiluted (100% v:v) chemicals were used for each assay. Preliminary studies verified that 500 of pure chemical easily lasted for a six hour duration, volatilizing throughout the time period. Each 500 aliquot was pipetted into a clear glass vial with a hole in the lid (5 mm diam), and an 8 cm piece of pipe cleaner was folded in half and inserted into the lid of the vial to facilitate diffusion of the chemical volatiles. For combinations that did not utilize CO 2 the chemical primed lu res were placed in the ClimbUp trap on top of a
92 folded piece of paper towel to prevent chemicals in the vial from contaminating the trap surfaces. For combinations that required CO 2 the vials were attached to the top of the dry ice containing thermos, a pproximately 2 cm from the hole where the CO 2 gas was released from the thermos, the vial was secured in position using double sided Scotch tape (3M, U.S.A.). For the heat only treatment, an air activated Hot Hands hand warmer (HeatMax Inc., Dalton, GA) was placed in the center of the ClimbUp trap with an average temperature of 44.1C and 45.1C at the beginning and end of each assay, respectively. As with the trap comparison test, the number of ticks on the floor of the room, on the trap, and the numbe hr evaluation period. The ticks found in the pitfall trap were considered to be captured ticks. The number of ticks observed in the pitfall of the trap plus the ticks found els ewhere on t he trap, but not in the pitfall, were considered to be attracte d to the trap. The sum of the number of ticks observed in the trap pitfall, on the trap, and on the floor of the room were considered to be activated. The temperature and humidity conditions were recorded as previously described. Statistical A nalysis Evaluation of trap model The data were analyzed using a one way analysis of variance (SAS v.9.2 PROC MIXED) with the blocking factor s of room (one or two) and time of day (a.m. or p.m.). The test factor for this analysis was trap model ( ). The three variables analyzed were the average number of ticks captured, attracted, and activated within an individual experimental unit. Each analysis was chec ked for normality, and it was determined that no transformations were
93 necessary. Means from the statistical analysis were used for the presentation of the data, and Least Significant Difference tests were used to compare the means of the differ ent traps tested. Evaluation of attractants Experimental data from the attractant combinations were analyzed using a one way analysis of variance (SAS v.9.2 PROC MIXED) with the blocking factors of room (one or two) and time (a.m. or p.m.). The test fac tor for this analysis was attractant (1 octen 3 ol, hexanoic acid, and methyl salicylate with and without CO 2 CO 2 alone, and heat alone). The three variables analyzed were the average number of ticks captured, attracted, and activated, with definitions a s previously described. Each analysis was checked for normality, and it was determined that no transformations were necessary. Least Square Means were used for data presentation, and Least Significant Difference tests were used to compare the means of th e different attractant combinations tested. Following the initial analysis, the ANOVA was repeated with the addition of covariates including average temperature and average relative humidity for each of the variables activated, attracted, and captured. Eac h covariate that was significant incorporated into the model to obtain a maximal model. Any covariates that were not >0.05) were removed resulting in a minimal (parsimonious) model. Results Evaluation of T rap M odel The mean increase in room CO 2 level for each trap, was 1 023.75 (111.15), 1 082.5 (117.97), 1 118.75 (81.71), and 4 130 (3.78) ppm for the Bed Bug respectively. The mean numbers of
94 ticks captured, attracted and activated were out of a group of 40 ticks released at the beginning of each evaluation period. Significantly fewer (F 1,26 = 6.85, p = 0.0146) ticks were attracted to traps tested in the morning (a.m.) evaluations (5.94 0.61) as compared to ticks attracted to traps placed in afternoon (p.m.) evaluations (8.1 0.61; Table 3 1). There also was a significant difference (F 1,26 = 5.40, p = 0.0282) in the mean number of ticks captured between the two rooms (5.31 0.67 in room one versus 3.13 0.6 7 in room two ; Table 3 1). There were significant differences between trap models in the number of R. sanguineus captured (F 3,26 = 10.44, p = 0.0001), attracted(F 3,26 = 24.41, p <0.0001), and activated (F 3,26 = 12.06, p <0.0001; Table 3 1). The mean numbe r of ticks captured with the ClimbUp bed bug trap was the greatest, at 6.63 (0.94), but was not tch any ticks during any of the evalua = 0.05) than all other traps tested. The ClimbUp raps attracted the greatest number of ticks, with 11.63 (0.86) and 9.25 (0.86) ticks, respectively. The number of ticks attract ed by the ClimbUp = (Table 3 2). Continuing the trend, the ClimbUp trap also had the greatest mean number of activated ticks, wit = 0.05) than all three of the other traps tested. The Bed Bug Beacon activated the fewest number of ticks, 4.88 (1.25).
95 Evaluation of A ttractants There were significant differences in the mean number o f ticks captured (F 1,27.6 = 4.95, p = 0.0344), attracted (F 1,46 = 32.64, p <0.0001), and activated (F 1,46 = 17.52, p = 0.0001) in the morning (a.m.) and afternoon (p.m.) evaluation periods (Table 3 3). Out of a group of 40 released ticks, the mean number of ticks captured was higher for the afternoon evaluations, with 2.01 (0.66) and 4.14 (0.66) ticks captured in the morning and afternoon, respectively. The mean number of ticks attracted was 7.60 (0.80) and 14.33 (0.80) in the morning and afternoon, r espectively, while, the mean number of ticks activated was 12.42 (0.89) and 17.90 (0.89) in the morning and afternoon, respectively. The mean number of ticks attracted (F 1,46 = 8.11, p <0.0065) and activated (F 1,46 = 7.03, p = 0.0110) were significantly different between the two evaluation rooms. The mean number of ticks attracted to the ClimbUp trap was 9.39 (0.78) in room one, and 12.53 (0.78) in room two. The mean number of ticks activated by the ClimbUp trap was 13.54 (0.86) in room one, and 16 .78 (0.86) in room two. There were significant differences bet ween the attractants presented in the ClimbUp trap for the number of ticks captured (F 7,31.8 = 6.36, p = 0.0001) and activated (F 7,46 = 3.19, p = 0.0077) (Table 3 3). The mean number of ticks captured was highest with the 1 octen 3 ol and CO 2 combination, with 5.86 (1.00) ticks captured (Table 3 4). However, the mean number of ticks captured in the ClimbUp trap using the 1 octen 3 ol and CO 2 attractant combination was not significantly diff = 0.05) from any of the remaining treatments that included CO 2 Heat, hexanoic acid and 1 octen 3 ol without the inclusion of CO 2 resulted in mean capture numbers that were significantly = 0.05) than treatments that included CO 2 ranging from 0.24 (0.99) for 1
96 octen 3 ol to 1.20 (0.99) for heat alone. Although numeric alignment between capture and activation responses were not congruent, trends were similar. All CO 2 containing treatments generated the greatest activation response s ra nging from 14.94 (1.74) to 19.69 ( 1.74) and were statistically equivalent = 0.05; Table 3 4). There were no significant differences between the attractants for the number of ticks attracted. The mean number of ticks attrac ted to the different treatments ranged from 7.89 (19.72%) to 13.81 (34.53%). Due to the significant diff erences observed betwe en morning and afternoon assays, e.g. higher temperatures in the afternoon, attempts were made to determine the cause through covariate analysis. Average temperature and relative humidity were added to the model individually to determ ine their relationship with ticks caught, attracted and activated. There was a significant effect of the mean temperature (F 1,23.3 = 28.74, p <0.0001) on the number of ticks captured (Table 3 5) but no significant effects on the numbers of ticks attracte d and activated A one degree Celsius increase in temperature translated into 0.75 more ticks captured (taken from the solution estimate for average temperature). Analysis of the data, with the mean relative humidity (RH) values that were collected for e ach evaluation period included as a covariate, generated a restructured output for the variable captured, but mean RH was not relevant for the variables attracted and activated (Table 3 5). There was a significant effect of mean RH (F 1,22.8 = 13.84, p = 0 .0011) on the number of ticks captured (Table 3 5). A one percent increase in RH resulted in 0.20 fewer ticks captured. When the two significant covariates, i.e. average RH and average temp, were combined into a maximal model only average temperature rem ained significant (F 1,24 = 11.2, p =
97 0.0027) Therefore, average RH was removed and only average temp remained in the minimal model. Using the minimal model with the blocking factors time and room and the covariate averag e temperature for the variable c ap tured the significance of the effect of time (a.m. or p.m.) was reduced so that the difference between morning and afternoon evaluation periods was no longer significant ( Table 3 5). The mean number of ticks captured in the ClimbUp trap was significantl y different (F 7,40.9 = 7.65, p <0.0001) for the attractant combinations evaluated, with mean temperature included as a covariate (Table 3 5). Ticks captured following exposure to the eight treatment groups separated into two discrete and significantly dif = 0.05) groups (Table 3 6). The treatments that included CO 2 resulted in significantly greater numbers of ticks captured than treatments that did not include CO 2 Although the numerical response of tick activation appeared to generally mirror t hat of the capture data and significant = 0.05) were observed between treatment groups, the overlap in the means separation made data interpretation more ambiguous (Table 3 6). Discussion During both the trap comparison and the a ttractant ev aluation studies, a large proportion of the ticks attracted to the traps were found somewhere on the trap, but not in the containment area of the trap. For example, the mean number of ticks captured in the ClimbUp pitfall trap in the trap evaluation test was 6.63 (16.58%) while the mean number of ticks on various surfaces of the trap plus the number captured in the pitfall was 11.63 (29.08%). Personal observations revealed that the ticks were often content to crawl onto the initial vertical surfaces of t he trap and then aggregate, either on the vertical side of the trap or on the highest edge prior to the pitfall, as though they
98 preferred not to move downwards. Indeed, the brown dog tick has a high affinity for crawling upward (Goddard 1987). It therefo re stood to reason that the number of ticks captured was not necessarily an accurate representation of the attractiveness of the trap. Observing this behavior in preliminary evaluations prompted the counting of not only the ticks caught in the pitfall, bu t also the ticks found crawling on the sides of the trap an d the ticks found on the floor. Inclusion of ticks on the floor was utilized as most ticks crawled up the wall in the absence of a trap placed in the room In trap model comparisons, the ClimbUp bed bug trap equipped with dry ice proved to be the most efficacious trap in all areas evaluated. Although the trap, the ClimbUp is considered more practical for consumer use based on challe nges with CO 2 canister acquisition and initial investment expense. Specifically, the cost of supplying each of the traps with CO 2 filling a thermos with dry ice for the ClimbUp The refill c osts are relatively similar, but refilling canisters can be challenging in some locations, while dry ice is more readily at $350.00 was not comparable to the relatively inex pensive plastic dish design of the ClimbUp which costs from $10.00 to $ 40.00 depending on size Therefore, the ClimbUp trap was designated for further study with potential chemical attractants. The results of this study suggested that the efficacy of t he trap s as tick monitoring devices were directly related to the amount of CO 2 produced by each trap. Based on the mean CO 2 levels that were recorded for each trap at the end of the six hour evaluation period higher CO 2 production resulted in higher trap efficacy. The dry
99 ice used in the ClimbUp trap generated the highest CO 2 concentrations (ppm) within he second highest concentration albeit substantially lower than the ClimbUp These two traps were also the most efficacious. This relationship is similar to the findings of Wang et al. (2011), where traps with the highest CO 2 output caught the most bed bugs. In fact, Wang et al. (2011) found the most effective trap to be a homemade device consisting of an inverted cat feeder baited with a dry ice filled thermos. This trap used by Wang et al. (2011) is very similar to the dry ice baited ClimbUp trap used in the current study. However, it is hile the other three traps Furthermore, there is still room for speculation regarding the relationship between CO 2 output and the efficacy of the traps. Carr et al. (2013) d etermined that the highest CO 2 flow rates did not induce the greatest tick attraction when examining A. americanum and Dermacentor variabilis (Say) responses to different CO 2 rates in a Y tube olfactometer using variable flow rates. With air that containe d 3% CO 2 A. americanum demonstrated the greatest attraction at a flow rate of 100 mL /min, with a significant reduction in attraction at 150 mL /min (Carr et al. 2013). Similarly, D. variabilis were most attracted to the CO 2 enhanced air at a flow rate of 75 mL /min, but at 100 mL /min, there was no significant difference in attraction between the CO 2 enhanced air and clean air (Carr et al. 2013). Clearly there is an upper limit to the amount of CO 2 that will enhance tick attraction, and increasing CO 2 level s beyond it can decrease tick responsiveness.
100 The results of the experiment with different attractants suggest that the brown dog tick can be consistently lured to a trap baited with CO 2 The importance of CO 2 in tick activation and attraction has been de monstrated many times, either as a standalone attractant (Wilson et al. 1972, Gray 1985), or in combination with other semiochemicals (Norval et al. 1989, Maranga et al. 2006, Nchu et al. 2010 b Ranju et al 2013). In the current study, R. sanguineus were significantly more activated and significantly more ticks were captured in the ClimbUp trap when the attractant combination included CO 2 indicating that, as with other species of ticks, CO 2 is an important component in tick attraction, and thus should b e considered for inclusion in a brown dog tick trap. However, previous studies have indicated that for some ticks, the presence of CO 2 alone is not enough to attract the ticks but merely activates them. Norval et al. (1989) reported that the bont tick, A. hebraeum did not move towards CO 2 sourc es in the field unless the sources were synergized with AAAP through the use of fed adult males, extracts thereof, or o nitroph enol In the current study, 1 octen 3 ol, hexan oic acid, or methyl salicylate, selected base d on conclusions from Chapter 2, did not significantly increase the mean number of ticks activated, attracted or captured by the ClimbUp trap. This could indicate that CO 2 alone is sufficient to use as bait in brown dog tick traps, as demonstrated w ith A. americanum (Wilson et al. 1972) and I. ricinus (Gray 1985). In both studies, CO 2 baited traps were shown to be more effective in capturing ticks than the flagging method. In the case of A. americanum 50 ticks were captured in traps for every sing le tick that was captured flagging (Wilson et al. 1972). On the contrary, it could be that the three chemicals tested in the current study were simply not appropriate and additional semiochemicals need to be evaluated. The three
101 chemicals in this study w ere used without being diluted, and so rates of volatilization were only limited by surface area and the properties of each chemical. Therefore, it may be that the chemicals were too strong to invoke a natural attraction response from R. sanguineus The chemicals tested were selected for this study because they demonstrated the greatest significant differences from the hexane control in straight tube experiments (Chapter 2). Determining the correct semiochemicals and semiochemical mixtures is an area tha t demands further study for brown dog tick management. In a similar study, traps were baited with CO 2 2,6 dichlorophenol and a blend of guanine, xanthine, adenine, and hematin, and treated with the acaricide deltamethrin (Ranju et al. 2013). The ratio of the purines was 12:1:1:1. These traps were evaluated in a dog kennel in India (Ranju et al. 2013), where they attracted 40% of adult male ticks released at a distance of 0.5 m, 34% of ticks released 1.0 m from the traps, and 28% of ticks released 1.5 m f rom the traps (Ranju et al. 2013). It was concluded that CO 2 together with the aforementioned semiochemicals provided the tick attraction observed. In the current study, the highest percent of ticks attracted was with CO 2 and 1 octen 3 ol in combination (42.68%) and CO 2 alone (48.55%; Table 3 6). Alt hough not significantly different, CO 2 alone attracted more ticks than CO 2 in combination with 1 octen 3 ol. The percentages attracted in this study are similar, if slightly higher, than the percentages repo rted by Ranju et al. (2013). However, in the previous study, CO 2 was not tested as a standalone attractant as it was in the current study. Therefore, it may be that CO 2 would have attracted just as many ticks without the presence of 2,6 dichlorophenol an d the purine blend. Additional studies comparing the efficacy of traps
102 baited with CO 2 alone, to traps baited as described by Ranju et al. (2013) would provide much needed clarity on this issue. In this study, the traps were intended to capture and contai n the ticks, but this is only one potential use for a baited trap. Maranga et al (2006) and Nchu et al. (2010 b ) used traps baited with semiochemicals and CO 2 to attract A. variegatum but not to permanently contain the ticks. Instead the traps were desi gned to expose attracted ticks to pathogenic fungi, after which they could leave the trap and return to their natural habitat. In both experiments, inoculation with the fungi significantly reduced tick populations when compared to control treatments (Mara nga et al 2006 and Nchu et al. 2010 b ). One common problem with trying to use pathogenic fungus in pest control is the difficulty in retaining spore viability while under field conditions, such as sunlight. Using semiochemical and CO 2 baited traps treate d with pathogenic fungi could be more effective with brown dog ticks, because they are indoor pests, and so the fungi may remain viable for longer periods of time as the fungal spores would be protected from the outdoor environment. The mean number of tick s activated by the attractant combinations did not align directly with the mean numbers captured (Table 3 4). For example, the combination that activated the numerically largest number of ticks was CO 2 alone, with 49.23% of ticks activated. The combinati on that resulted in the most ticks captured, was 1 octen 3 ol plus CO 2 capturing 42.48% of the ticks released. Overall, there was a considerable overlap in the confidence intervals between attractant combinations for the mean number of ticks activated, b ut in general, the combinations that included CO 2 activated more ticks than the combinations without CO 2 ( Table 3 4). The lack of
103 significant differences between attractants for the variable activated indicates that there is likely more error associated w ith in this variable in comparison to the variable captured. Ticks were co nsidered activated if found captured in the trap, observed on the trap, or observed on the floor of the room and excluded if aggregated on the walls. In some cases, ticks on the flo or of the room were likely not activated, but only located on the floor at the end of the 6 hr evaluation by chance. In a related study conducted by Ranju et al. (2013), varying the tick starting distance from traps impacted the percentages of ticks that w ere attracted. Ticks placed farther from the traps were less likely to be attracted than ticks that were placed closer to the traps. Of the ticks that were placed a distance of 1 m from the traps, 34% were attracted (Ranju et al. 2013). In the current s tudy, ticks were placed about 1 m from the ClimbUp trap, which is comparable to the 1 m distance tested in the study conducted by Ranju et al. (2013). Th e percentage of ticks that were attracted at 1 m in the study by Ranju et al. (2013) is similar to th e highest percentage of ticks that were attracted to the ClimbUp trap baited in the current study, which was 34.53%. The mean temperature during the morning evaluation period was lower than the mean temperature during the afternoon evaluation period. C ovariate analysis revealed that mean temperature significantly influenced the mean number of ticks captured for the attractant combination experiment. Subsequently, more ticks were caught in traps in the afternoon evaluations, when tick testing rooms were warmer (26.54C), than in the morning evaluations (24.85C). These findings suggest that slight differences in temperature play an important role in R. sanguineus behavior, and activity increases in temperatures slightly higher than standard temperature conditions (22 C ) Gray (1985)
104 suggested that temperature may have affected the rate of capture of I. ricinus in the field using a CO 2 baited trap Temperatures were recorded for each day of trapping, and ranged from 14 C to 21C. Higher temperatures co incided with greater numbers of captured ticks (Gray 1985). There are undoubtedly temperature extremes both hot and cold, that reduce R. sanguineus activity, as it has been shown that excessively cold temperatures slow down R. sanguineus egg development. Dantas Torres et al. (2010) exposed eggs to environments at 8C for various amounts of time and reported slower development, a lower hatch percentage, and larvae that did hatch demonstrated reduced longevity compared to eggs held at 26C. Thus, finding t he ideal temperature at which brown dog ticks reach peak activity would be helpful in developing an effective management and monitoring program for this pestiferou s tic k because it would allow for the optimization of trap performance While temperatures we re lower during the morning assays and higher during the afternoon assays, relative humidity was inversely related. During the morning assays relative humidity was higher than it was during the afternoon assays. Covariate analysis suggested that higher r elative humidity reduced the number of ticks caught. However, covariate analysis using temperature and relative humidity together caused relative humidity to lose significance. The most likely explanation is that temperature is the true explanatory varia ble, while relative humidity inversely mirrored the temperature differences between the morning and afternoon assays. The number of ticks captured in these studies was much lower than the number found in the general vicinity of the traps. Therefore, to im prove the tick capture rate, a
105 different method of capture such as immo bilizing the ticks seems necessary. Perhaps a sticky, flat surface, similar to the one used by Gray (1985) to effectively capture I. ricinus could be used in place of the p itfalls. As mentioned before, R. sanguineus have an affinity for crawling upwards (Goddard 1987), and that seems to reduce the efficacy of pitfall traps due to their design. In order to become trapped in a pitfall, the ticks must crawl downwards. A hori zontal sticky surface would probably be more effective, because the ticks would contact the surface and become immobilized without the requirement of downward movement. There was a significant difference between the rooms in the number of ticks caught for the trap comparison and the number of ticks attracted and activated for the attractant evaluation studies. For the number of ticks caught in the trap comparison study, room one caught more ticks than room two. For the number of ticks attracted and activa ted in the attractant evaluation study, room two had significantly greater numbers than room one. The significantly superior room was different for each study, and the significant differences between the rooms was unexpected. Therefore the differences be tween the rooms were likely not biologically significant. In conclusion, the use of traps baited with semiochemicals and/or CO 2 has great potential to aid in brown dog tick management efforts. The results of this study demonstrated that bed bug traps ha ve potential to serve as traps for brown dog ticks, perhaps with modifications, such as sticky trap surfaces rather than smooth walled pitfalls. Specifically, our data suggest that CO 2 was the most influential attractant evaluated for the brown dog tick. We established baseline data on three semiochemicals, their combinations with CO 2 and heat, upon which further research
106 can build to identify brown dog tick specific chemicals and chemical mixtures to improve tick capt ure rates Furthermore, the results of this study indicate that tick capture can be significantly increased by raising the indoor temperature slightly above standard room temperature (22C). Overall, these findings will assist future research in the development of effective trapping system s for R. sanguineus
107 Table 3 1. Summary statistics of the ANOVA analyses documenting adult mixed sex Rhipicephalus sanguineus (Latreille) interactions with four CO 2 baited bed bug trap models including the mean numbers of ticks captured, attracted, and ac tivated at the conclusion of a 6 hr evaluatio n period Captured a Attracted b Activated c Effect F value p F value p F value p Trap model 10.44 0.0001 24.41 <0.0001 12.06 <0.0001 Time (a.m. or p.m.) 3.21 0.0847 6.85 0.0146 2.39 0.1345 Room (1 or 2) 5.4 0 0.0282 0.53 0.4736 0.02 0.8823 ClimbUp (Susan McKnight Inc., Memphis, TN) n = 8 Time = period o f the day when study was initiated (a.m. or p.m.) Room = the two rooms where the traps were placed a Mean number of ticks captured in the pitfall of the trap b Mean number of ticks captured in the pitfall of the trap and observed on the trap c Mean number of ticks captured in the pitfall of the trap, observed on the trap, and observed on the floor of the room
108 Table 3 2. Mean (SEM) numbers of 40 mixed sex adult Rhipicephalus sanguineus (Latreille) released into a room and subsequently captured, attracted to, and activated by each of the four CO 2 baited bed bug trap models evaluated over a 6 h r period Trap model a Captured b Attracted c Activated d 0.00 (0.94)a 2.00 (0.86)a 4.88 (1.25)a 4.00 (0.94)b 5.38 (0.86)b 9.00 (1.25)b 6.25 (0.94)b 9.25 (0.86)c 10.88 (1.25)b ClimbUp 6.63 (0.94)b 11.63 (0.86)c 15.38 (1.25)c ANOVA used to determine a difference between traps for each of the followi ng measurement variables: Captured ( F 3,26 = 10.44, p = 0.0001 ), Attracte d ( F 3,26 = 24.41, p <0.0001), and Activated (F 3,26 = 12.06, p <0.0001) Letters following means within a column indica te significant differences (p < 0.05) calculated using Le ast Significant Difference tests n = 8 a ClimbUp (Susan McKnight Inc., Memphis, TN) b Mean number of ticks captured in the pitfall of the trap c Mean number of ticks captured in the pitfall of the trap and observed on the trap d Mean number of ticks captured in the pitfall of the trap, observed on the trap, and observed on the floor of the room
109 Table 3 3. Summary statistics for the ANOVA analyses of attractants on the efficacy of the ClimbUp bed bug trap to capture, attract, and activate mixed sex adult Rhipicephalus sanguineus (Latreille) at the conclusion of a 6 hr evaluatio n period Captured a Attracted b Activated c Effect F value p F value p F value p Time (a.m. or p.m.) 4 .95 0.0344 32.64 <0.0001 17.52 0.0001 Room (1 or 2) 0.69 0.4146 8.11 0.0065 7.03 0.0110 Attractants 6.36 0.0001 1.98 0.0782 3.19 0.0077 ClimbUp (Susan McKnight Inc., Memphis, TN) Time = period of the day when study was initiated (a.m. or p.m.) Room = t he two rooms where the traps were placed n = 7 Attractants included individual presentation of 1 octen 3 ol, hexanoic acid, or methyl salicylate with and without CO 2 augmentation, and heat without CO 2 augmentation or chemicals, and CO 2 augmentation without chemicals or heat. a Mean number of ticks captured in the pitfall of the trap b Mean number of ticks captured in the pitfall of the trap and observed somewhere on the trap c Mean number of ticks captured in the pitfall of the trap, observed somewhere on t he trap, and observed on the floor of the room
110 Table 3 4. Mean (SEM) numbers out of 40 mixed sex adult Rhipicephalus sanguineus (Latreill e) released into a room and subsequently captured and activated under eight attractants in evaluations of the ClimbUp bed bug trap Attractants Captured a Activated b 1 Octen 3 ol + CO 2 5.86 (1.00)a 16.99 (1.78)abc CO 2 5.25 (1.00)a 19.69 (1.74)a Methyl salicylate + CO 2 5.24 (0.99)a 18.52 (1.72)ab Hexanoic acid + CO 2 4.46 (1.00)ab 14.94 (1.74)abcd Methyl salic ylate 1.90 (0.99)bc 12.09 (1.72)cd Heat 1.20 (1.00)c 14.23 (1.74)bcd Hexanoic acid 0.42 (0.99)c 10.84 (1.72)d 1 Octen 3 ol 0.24 (0.99)c 13.98 (1.72)bcd ClimbUp (Susan McKnight Inc., Memphis, TN) ANOVA used to determine a difference between att ractants for each of the response variables Captured ( F 7,31.8 = 6.36, p = 0.0001 ) and A ctivated (F 7,46 = 3.19, p = 0.0077) Letters following means within a column indicate significant diff erences (p < 0.05) calculated using Least Significant Difference test s n = 7 a Mean number of ticks captured in the pitfall of the trap b Mean number of ticks captured in the pitfall of the trap, observed on the trap, and observed on the floor of the room
111 Table 3 5. Summary statistics of the ANOVA analyses evaluating the efficacy of the ClimbUp bed bug trap in activating, attracting, and capturing mixed sex adult Rhipicephalus sanguineus (Latreille) at the conclusion of a 6 hr evaluation period using several att ractants Captured a Attracted b Activated c Covariate Effec t F value p F value p F value p Mean RH Mean RH 13.84 0.0011 1.00 0.3229 3.78 0.0581 Time (a.m. or p.m.) 0.38 0.5418 21.07 <0.0001 8.47 0.0056 Room (1 or 2) 0.77 0.3903 8.11 0.0066 7.44 0.0091 Attractants 6.93 <0.0001 1.99 0.0770 3.43 0.0050 Mean T emperature Mean temperature 28.74 <0.0001 3.17 0.0817 2.40 0.1282 Time (a.m. or p.m.) 0.04 0.8527 15.77 0.0003 7.56 0.0086 Room (1 or 2) 0.80 0.3796 8.43 0.0057 7.19 0.0102 Attractants 7.65 <0.0001 1.82 0.1074 3.02 0.0109 ClimbUp (Susan McKnight In c., Memphis, TN) Time = period of the day when study was initiated (a.m. or p.m.) Room = the two rooms where the traps were placed n = 7 Attractant s included individual presentation of 1 octen 3 ol, hexanoic acid, or methyl salicylate with and without CO 2 augmentation, and heat without CO 2 augmentation or chemicals, and CO 2 augmentation without chemicals or heat. ANOVA was performed for each of the response variables captured, attracted, and activated, considering the covariate s mean temperature and mean re lative humidity a Mean number of ticks captured in the pitfall of the trap b Mean number of ticks captured in the pitfall of the trap and observed on the trap c Mean number of ticks captured in the pitfall of the trap, observed on the trap, and observed on the floor of the room
112 Table 3 6. Mean (SEM) numbers out of 40 mixed sex adult Rhipicephalus sanguineus (Latreille) released into a room and subsequently captured and activated under eigh t attractants in evaluations of the ClimbUp bed bug trap, adjusted with respect to the covariate average temper ature Attractants Captured a Activated b 1 Octen 3 ol + CO 2 5.97 (0.88)a 17.07 (1.75)abc CO 2 5.22 (0.87)a 19.42 (1.72)a Methyl salicylate + CO 2 4.87 (0.86)a 18.41 (1.69)ab Hexanoic acid + CO 2 4.74 (0.8 7)a 15.21 (1.72)abcd Methyl salicylate 2.10 (0.86)b 12.40 (1.7)cd Hexanoic acid 0.64 (0.86)b 10.97 (1.69)d Heat 0.60 (0.87)b 13.93 (1.72)bcd 1 Octen 3 ol 0.42 (0.86)b 13.88 (1.69)bcd ClimbUp (Susan McKnight Inc., Memphis, TN) Us ing the covar iate mean temperature ANOVA was used to determine a difference between attractants for each of the response variables Caught ( F 7,40.9 = 7.65, p <0.0001 ) and Activated (F 7,45 = 3.02, p = 0.0109) Letters following means within a column indica te significant differences (p < 0.05) calculated using Least Significant Difference tests n = 7 a Mean number of ticks captured in the pitfall of the trap b Mean number of ticks captured in the pitfall of the trap, observed on the trap, and observed on the floor of the ro om
113 Figure 3 1. Diagrammatic top dow n layout of the Rhipicephalus sanguineus (Latreille) trap evaluation experimental rooms and the ventilation system. Ventilation tubing was equidistant for both rooms.
114 Figure 3 2. Diagrammatic side view of the Rhip icephalus sanguineus (Latreille) trap evaluation experimental rooms and the ventilation system.
115 Figure 3 3. Four bed bug trap models eval uated for Rhipicephalus sanguineus (Latreille) attraction and capture capabilitie baited with heated sides and intermittent CO 2 production originating from a 2 production kit contained internally. C) CO 2 producing liquid mixture. D) The ClimbUp bed bug trap pri med with a chemical lure alone and E) t he ClimbUp bed bug trap primed with a CO 2 producing thermos and a chemical lure. A B C D E
116 CHAPTER 4 SUMMARY AND FUTURE DIRECTIONS FOR THE DEVELOPMENT OF NOVEL M ANAGEMENT METHODS FOR THE BROWN DOG TICK, RHIPICEPHALUS SANGUINEUS (LATREILLE), IN RESIDENTIAL ENVIRONMENTS The use of acaricides in the treatment of brown dog tick, Rhipicephalus sanguineus (Latreille), infestations needs to be supplemented with new manag ement strategies. Acaricide use alone can lead to acaricide resistance within populations of R. sanguineus (Miller et al. 2001), which can eventually lead to the acaricides becoming less effective for control purposes. Due to the fact that R. sanguineus infestations often occur within human inhabited areas, such as houses, the use of acaricides is also unde sirable because of the potential toxin e xposure that home owners and their pets may experience. An integrated pest management (IPM) program that uses multiple methods to achieve control of the brown dog tick would reduce the severity of the negative impacts that currently result from complete reliance on acaricides. My research has identified much needed tick attractant information that will provide s a foundation for the futu re development of semiochemical baited traps Such traps would be useful for R. sanguineus early infestation detection, post treatment monitoring and, perhaps, population elimination in residential environments. My Y tube olfactomet er study provided the first comprehensive screening for the behavioral reaction of brown dog ticks to 17 chemicals suspected of being either pheromones or kairomones. Following this screening, nine chemicals were identified that invoke d an activation and movement response from R. sanguineus Clear activation and movement was demonstrated with a 1% hexane solution of 1 octen 3 ol, benzaldehyde, benzyl alcohol, hexanoic acid, butyric acid, methyl salicylate, o nitrophenol, 2,6 dichlorophenol and salicylalde hyde. Previous R. sanguineus studies
117 have been conducted to identify potential semiochemicals (Chow et al. 1975, Haggart and Davis 1980, Louly et al. 2008, Yoder et al. 2008, Ranju et al. 2012a, 2012b, Yoder et al. 2013), but none have included this many chemicals for a comprehensive comparison, and for the specific purpose of identifying activators and attractants. My follow up study using straight tube olfactometers allowed for the differentiation of the nine activating chemicals based on real time tick behavior during each chemical exposure. This approach also provided an opportunity to include basic mixtures of representatives from the nine chemicals to characterize possible synergistic effects. The amount of time ticks spent moving, the time to act ivation, the number of times they changed direction, and the number of times they approached the source of the semiochemical volatiles were all behavioral responses that were quantified and used as an indication of the relative efficacy of potential chemic al attractants. Upon analyzing the data from the straight tube study, three of the nine chemicals were particularly interesting, because they were consistently among those demonstrating the greatest response among all of the behavioral variables tested. C hemicals in this group were 1 octen 3 ol, hexanoic acid, methyl salicylate, and benzyl alcohol. Of these four chemicals, only methyl salicylate has been positively identified as a brown dog tick attractant (Yoder et al. 2008). Two of the remaining three had not been evaluated with the brown dog tick (hexanoic acid and benzyl alchohol), and 1 octen 3 ol was shown to have no attractant properties for R. sanguineus (Ranju et al. 2012b). At the concentrations and ratios tested, t he chemical mixtures were not significantly different from their single chemical components in regard to R. sanguineus attraction, based on the results of this study.
118 Future studies aimed at identi fying chemical mixtures attractive to R. sanguineus will undoubtedly improve the efficac y of attractants for these ticks. One of the best known tick semiochemical attractant complexes, the attraction, aggregation, and attachment pheromone (AAAP) produced by fed male bont ticks, has been identified and successfully used to attract and trap th e bont tick, Amblyomma hebraeum Koch, and the tropical bont tick, Amblyomma variegatum Fabricius (Rechav et al. 1977, Schni et al. 1984). The mixture of chemicals and the ratio of the chemicals relative to each other are important aspects of the AAAP. F or example, the components of the AAAP for A. variegatum are o nitrophenol, methyl salicylate, and nonanoic acid. The quantity and ratio of these chemicals in a single fed male tick is 2:1: 8 x 10 6 g ( Schni et al. 1984). A synthetic blend of these chemi cals in the aforementioned ratio will attract conspecific ticks in a manner similar to a fed male naturally producing the pheromone, whereas o nitro phenol presented alone will invoke a response but to a lesser degree. M ethyl salicylate or nonanoic acid p resented alone do not attract A. variegatum conspecifics ( Schni et al. 1984). This phenomenon most likely applies to the brown dog tick as well, and therefore future studies involving gas chromatography mass spectrometry of host volatiles similar to the study conducted by Schni et al. (1984), will likely clarify some of the questions that have been raised by my olfactometer based studies. The results of my bed bug trap comparison study pertaining to their efficacy for brown dog ticks indicated that some but not all of the commercially available traps may be useful with brown dog ticks. Of the fou r traps tested, only two (ClimbUp and R. sanguineus One of these
119 two traps, the ClimbUp was a pitfa ll trap equipped with a thermos filled with dry ice to provide CO 2 as an attractant. This design was very similar to a homemade trap that was found to be the most efficacious in a trap comparison study with bed bugs, Cimex lectularis Linnaeus (Wang et al. 2011). It was suggested by Wang et al. (2011) that the amount of CO 2 produced by the bed bug traps determined how well each trap performed, so that traps producing more CO 2 captured more bed bugs than traps producing less CO 2 I identified a similar tre nd with brown dog ticks in the trap comparison study. The ClimbUp produced the most CO 2 followed distantly by the R. sanguineus have an extremely high affinity for grippi ng and climbing smooth, vertical surfaces. The efficacy of future brown dog tick traps coul d be enhanced greatly by altering the capture mechanism found in bed bug traps from a pitfall design to some form of sticky surface, such as the one described by Wi lson et al. (1972). My chemical combination studies further supported the notion that CO 2 is important in brown dog tick activation and attraction. ClimbUp traps equipped with CO 2 tended to capture and activate significantly greater numbers of brown dog ticks than traps without CO 2 Unfortunately, no significant differences were observed based on the presence or absence of 1 octen 3 ol, hexanoic acid, or methyl salicylate. These findings may indicate that CO 2 alone is sufficient for use in BDT traps (Wi lson et al. 1972, Gray 1985), but it seems more likely that the proper mixture and ratio of chemicals simply has yet to be determined. Nonetheless, this study verified that large quantity of CO 2 produced b y dry ice is at effective as an attractant in brow n dog tick traps.
120 As pesticide resistance continues to become increasingly common in human attempts to control pests the development of IPM strategies will progressively become more important. The impact of the semiochemical and trap development research herein provides the foundation for improved tick management using reduced risk methodologies that fit an IPM program. It is critical for the success of a future brown dog tick IPM program that an efficacious trap be developed that will allow for monitorin g and population reduction. Such a device could be used for population reduction through an attract treat and release program that could have a devastating impact within a localized region Conceptually, an autodissemination device could utilize pathogen ic fungi as the killing agent A device baited with semiochemical attractants and used for the autodissemination of fung i already has been demonstrated to have potential with other tick species in an outdoor environment (Maranga et al. 2006, Nchu et al. 2 010b). A dditionally, a brown dog tick trap will provide a much needed monitoring method, so that homeowners can identify infestations before they reach high populations and ticks are seen crawling up the walls (Goddard 1987, Demma et al. 2005, Dantas Torr es et al. 2006). Such a device could be used to determine which rooms in a residence are infested, reducing treatment costs and exposures. Finally, h omeowners and pest control companies will be able to monitor for ticks following the implementation of ot her control methods, to verify tick eradication was successful.
121 LIST OF REFERENCES Allan, S. A., and D. E. Sonenshine. 2002. Evidence of an assembly pheromone in the black legged deer tick Ixodes scapularis. L. J. Chem. Ecol. 28: 15 27. Allan, S. A., N. B arr D. E. Sonenshine, and M. J. Burridge. 1998. Efficacy of tags impregnated with pheromone and acaricide for control of Amblyomma variegatum Med. Vet. Entomol. 12: 141 150. Allan, S. A., U. R. Bernier, and D. L. Kline. 2010. Laboratory evaluation of la ctic acid on attraction of Culex spp. (Diptera: Culicidae). J. Vector Ecol. 35: 318 324. Anderson, R. B., G. J. Scrimgeour, and K. Reuben. 1998. Responses of the ixodid tick, Amblyomma hebraeum (Acari: Ixodidae), to carbon dioxide. Exp. Appl. Acarol. 22: 6 67 681 Anderson, B. E., J. E. Dawson, D. C. Jones, and K. H. Wilson. 1991. Ehrlichia chaffeensis a new species associated with human ehrlichiosis. J. Clin. Microbiol. 29: 2838 2842. Arruda, W I. Lu beck, A. Schrank, and M. A. Vainstein. 2005. Morphologi cal alterations of Metarhizium anisopliae during penetration of Boophilus microplus Exp. Appl. Acarol. 37: 231 244 Ballard, J. B., and R. E. Gold. 1982. The effect of selected baits on the efficacy of a sticky trap in the evaluation of German cockroach p opulations. J. Kans. Entomol. Soc. 55: 86 90. Barker, S. C., and A. Murrell. 2004. Systematics and evolution of ticks with a list of valid gen us and species names. Parasitology. 129: S15 S36. Barr, N., G. I. Garris, and O. Lorvelec. 1997. Field sampling o f the tick Amblyomma variegatum (Acari: Ixodidae) on pastures in Guadeloupe; attraction of CO 2 and/or tick pheromones and conditions of use. Exp. Appl. Acarol. 21: 95 108. Bechara, G. H., M. P. Szabo, L. S. Mukai, and P. C. Rosa. 1994. Immunization of dogs hamsters and guinea pigs against Rhipicephalus sanguineus using crude unfed adult tick extracts. Vet. Parasitol. 52: 79 90. Bellato, V., and E. Daemon. 1997. Efeitos de tres temperaturas sobre a fase nao parasitaria de Rhipicephalus sanguineus (Latreille 1806) (Acari: Ixodidae). Rev. Bras. Parasitol. Vet. 6: 21 27. Bharadwaj, A., and K. C. Stafford. 2012. Susceptibility of Ixodes scapularis (Acari: Ixodidae) to Metarhizium brunneum F52 (Hypocreales: Clavicipitaceae) using three exposure assays in the lab oratory. J. Econ. Entomol. 105: 222 231.
122 Bissinger, B. W., C. S. Apperson, D. W. Watson, C. Arellano, D. E. Sonenshine, and R. M. Roe. 2011. Novel field assays and the comparative repellency of BioUD, DEET and permethrin against Amblyomma americanum Med. Vet. Entomol. 25: 217 226. Boozer, A. L., and D. K. Macintire. 2003. Canine babesiosis. Vet. Clin. Small Anim. 33: 885 904. Bowman, A. S., L. B. Coons, G. R. Needham, and J. R. Sauer. 1997. Tick saliva: R ecent advances and implications for vector competen ce. Me d. Vet. Entomol. 11: 277 285. Campbell, B. S., and D. E. Bowles. 1994. Human tick bite records in a United States Air Force population, 1989 1992: Implications for tick borne disease risk. J. Wild. Med. 5: 405 412. Carr, A. L., R. M. Roe, C. Arellano D. E. Sonenshine, C. Schal, and C. S Apperson. 2013 Responses of Amblyomma americanum and Dermacentor variabilis to odorants that attract haematophagous insects. Med. Vet. Entomol. 27: 86 95. Carpenter, T. L., M. C. McMeans, and C. P. McHugh. 1990. Add itional instances of human parasitism by the brown dog tick (Acari: Ixodidae). J. Med. Entomol. 27: 1065 1066. Chow, Y. S., C. B. Wang, and L. C. Lin. 1975. Identification of a sex pheromone of the female brown dog tick, Rhipicephalus sanguineus Ann. Ento mol. Soc. Am. 68: 485 488. Cole, M. M. 1965. Biological control of ticks by the use of hymenopterous parasites a review. W.H.O. Publ. 65: 1 12. Cook, J. I., S. Majeed, R. Ignell, J. A. Pickett, M. A. Birkett, and J. G. Logan. 2011. Enantiomeric selectivit y in behavioural and electrophysiological responses of Aedes aegypti and Culex quinquefasciatus mosquitoes. Bull. Entomol. Res. 101: 541 550. Dantas Torres, F. 2010 Biology and ecology of the brown dog tick, Rhipicephalus sanguineus Parasit. Vectors 3: 2 6. Dantas Torres, F. 2008. The brown dog tick, Rhipicephalus sanguineus (Latreille, 1806) (Acar i: Ixodidae): F rom taxonomy to control. Vet. Parasitol. 152: 173 185. Dantas Torres, F., and D. Otranto. 2011. Rhipicephalus sanguineus on dogs: relationships be tween attachment sites and tick developmental stages Exp. Appl. Acarol. 53: 389 397
123 Dantas Torres, F., A. Giannelli, L. A. Figueredo, and D. Otranto. 2010 Effects of prolonged exposure to low temperature on eggs of the brown dog tick, Rhipicephalus san guineus (Latreille, 1806) (A cari: Ixodidae). Vet. Parasitol. 171: 327 3 30. Dantas Torres, F., L. A. Figueredo, and S. P. Brando Filho. 2006. Rhipicephalus sanguineus (Acari: Ixodidae), the brown dog tick, parasitizing humans in Brazil. Rev. Soc. Bras. Med Trop. 39: 64 67. Dautel, H. 2004. Test systems for tick repellen ts. Int. J. Med. Microbiol. 293: 182 188. Demma, L. J., M. S. Traeger, W. L. Nicholson, C. D. Paddock, D. M. Blau, M. E. Eremeeva, G. A. Dasch, M. L. Levin, J. Singleton Jr., S. R. Zaki, J. E. Cheek, D. L. Swerdlow, and J. H. McQuiston. 2005. Rocky Mountain spotted fever from an unexpected tick vector in Arizona. New Engl. J. Med. 353: 587 594. Donz, G., C. McMahon, and P. M. Guerin. 2004. Rumen metabolites serve ticks to exploit large mamma ls. J. E xp Biol. 207: 4283 4289. Eiras, A. E., and P. C. Jepson. 1991. Host location by Aedes aegypti (Diptera: Culicidae): a wind tunnel study of chemical cues. Bul. Entomol. Res. 81: 151 160. Estrada Pea, A., and F. Jongejan. 1999. Ticks feeding on hum ans: a review of records on human biting Ixodidae with special reference to pathogen transmission. Exp. Appl. Acarol. 23: 685 715. Ewing, S. A., J. E. Dawson, A. A. Kocan, R. W. Barker, C. K. Warner, R. J. Panciera, J. C. Fox, K. M. Kocan, and E. F. Blouin 1995. Experimental transmission of Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) among white tailed deer by Amblyomma americanum (Acari: Ixodidae). J. Med. Entomol. 32: 368 374. Felz, M. W., L. A. Durden, and J. H. Oliver Jr. 1996. Ticks parasitizin g humans in Georgia and South Carolina. J. Parasitol. 82: 505 508. Fourie, L. J., A. Snyman, D. J. Kok, I. G. Horak, and J. M. Van Zyl. 1993. The appetence behaviour of two South African paralysis inducing ixodid ticks. Exp. Appl. Acarol. 17: 921 930. Geie r, M., O. J. Bosch, and J. Boeckh. 1999. Ammonia as an attractive component of host odour for the yellow fever mosquito, Aedes aegypti Chem. Senses. 24: 647 653. Gladney, W. J., R. R. Grabbe, S. E. Ernst, and D. D. Oehler. 1974 The Gulf Coast tick: evide nce of a pheromone produced by males. J Med Entomol 11: 303 306. Goddard, J. 1987. Ticks of medical importance occurring in the Western Hemisphere. Texas: USAF School of Aerospace Medicine, pp. 1 139.
124 Gray, J. S. 1985. A carbon dioxide trap for prolong ed sampling of Ixodes ricinus L. populations. Exp. Appl. Acarol. 1: 35 44. Guglielmone, A. A., A. J. Mangold, and A. E. Vinabal. 1991. Ticks (Ixodidae) parasitizing humans in four provinces of north western Argentina. Ann. Trop. Med. Parasitol. 85: 539 542 Haggart, D. A., and E. E. Davis. 1980. Ammonia sensitive neurones on the first tarsi of the tick, Rhipicephalus sanguineus J. Insect Physiol. 26: 517 523. Harrison, B. A., B. R. Engber, and C. S. Apperson. 1997. Ticks (Acari: Ixodida) uncommonly found b iting humans in North Carolina. J. Vector Ecol. 22: 6 12. Hendrichs, J., G. Franz, and P. Rendon. 1995. Increased effectiveness and ap plicability of the sterile insect t echnique through male only releases for control of Mediterranean fruit flies during fru iting seasons. J. Appl. Entomol. 119: 371 377. Heuskin, S., F. J. Verheggen, E. Haubruge, J. Wathelet, and G. Lognay. 2011. The use of semiochemical slow release devices in integrated pest management strategies. Biotechnol. Agron. Soc. Environ. 15: 459 470 Horak, I. G., J. Camicas, and J. E. Keirans. 2002. The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida): a world list of valid tick names. Exp. App. Acarol. 28: 27 54. Huxsoll, D. L., P. K. Hildebrandt, R. M. Nims, H. L. Amyx, and J. A. Ferguson. 1970. Epizootiology of tropical canine pancytopenia. J. Wildl. Dis. 6: 220 225. Jacobs, P. A. H., L. J. Fourie, D. J. Kok, and I. G. Horak. 2001. Diversity, seasonality and sites of attachment of adult ixodid ticks on dogs in the central region of the Fre e State Province, South Africa. Ond erstepoort J. Vet. Res. 68: 281 290 Jongejan, F. 1999. Integrated control of ticks and tick borne diseases. Parassitologia 41: 51 58. Jongejan, F., and G. Uilenberg. 2004. The global i mportance of ticks. Parasitol olgy 1 29: 3 14. Kahl, 0., and W. Knu lle. 1988. Water vapour uptake from subsaturated atmospheres by engorged immature ixodid ticks. Exp. App. Acarol. 4: 73 83. Kirkland, B. H., S. W. Greg, and O. K. Nemat. 2004. Pathogenicity of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae to Ixodidae tick species Dermacentor variabilis Rhipicephalus sanguineus and Ixodes scapularis J. Med. Entomol. 41: 705 711. Knipling, E. F., and C. D. Steelman. 2000. Feasibility of controlling Ixodes scapularis tick s (Acari: Ixodidae), the vector of Lyme disease, by parasitoid augmentation. J. Med. Entomol. 37: 645 652.
125 Koch, H. G. 1982. Oviposition of the brown dog tick (Acari: Ixodidae) in the laboratory. Ann. Entomol. Soc. Am. 75: 583 586. Leemon, D. M., and N. N. Jonsson. 2008. Laboratory studies on Australian isolates of Metarhizium anisopliae as a biopesticide for the cattle tick Boophilus microplus J. Invertebr. Pathol. 97: 40 49. Lehane, M. J. 2005. The biology of blood sucking insects, 2 nd ed. Cambridge Univ ersity Press, Cambridge, UK., pp. 33. Leonovich, S. 2004. organ in Ixodes ricinus ticks and their possible role in host perception. Exp. Appl. Acarol. 32: 89 102. Louly, C. C. B., I. N. Fo nseca, V. F. Oliveira, G. F. C. Linhares, L. B. Menezes, and L. M. F. Borges. 2007. Seasonal dynamics of Rhipicephalus sanguineus (Acari: Ixodidae) in dogs from a police unit in Goiania, Goias, Brazil. Cienc. Rural 37: 464 469. Louly, C. C. Braz, D. N. Sil veira, S. F. Soares, P. H. Ferri, A. C. C. Melo, and L. M. F. Borges. 2008. More about the role of 2, 6 dichlorophenol in tick courtship: identification and olfactometer bioassay in Amblyomma cajennense and Rhipicephalus sanguineus Mem. Inst. Oswaldo Cruz 103: 60 65. Malonza, M. M., O. O. Dipeolu, A. O. Amoo, and S. M. Hassan. 1992. Laboratory and field observations on anti tick properties of the plant Gynandropsis gynandra (L.) Brig. Vet. Parasitol. 42: 123 136. Manfredi, M. T., V. Dini, S. Piacenza, and C. Genchi. 1990. Tick species parasitizing people in an area endemic for tick borne diseases in north western Italy. Parassitologia. 41: 555 560. Maranga, R. O., A. Hassanali, G. P Kaaya, and J. M. Mueke. 2006. Performance of a prototype baited trap in a ttracting and infecting the tick Amblyomma variegatum (Acari: Ixodidae) in field experiments. Exp. Appl. Acarol. 38: 211 218. Mathe, A., K. Voros, L. Papp, and J. Reiczigel. 2006. Clinical manifestations of canine babesiosis in Hungary (63 cases). Acta Vet Hung. 54: 367 385. McMahon, C., and P. M. Guerin. 2002. Attraction of the tropical bont tick, Amblyomma variegatum to human breath and to the breath components acetone, NO and CO 2 Naturwissenschaften 89: 311 315. Miller, R. J., J. E. George, F. Guerrer o, L. Carpenter, and J. B. Welch. 2001. Characterization of acaricide resistance in Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) collected from the Corozal Army Veterinary Quarantine Center, Panama. J. Med. Entomol. 38: 298 302.
126 Nchu, F., N. K. M aniania, A. Hassanali, and K. N. Eloff. 2010a. Optimizing modes of inoculation of Rhipicephalus ticks (Acari: Ixodidae) with a mitosporic entomopathogenic fungus in the laboratory. Exp. App. Acarol. 51: 373 382. Nchu, F., N. K. Maniania, A. Hassanali, and J. N. Eloff. 2010b. Performance of a Metarhizium anisopliae treated semiochemical baited trap in reducing Amblyomma variegatum populations in the field. Vet. Parasitol. 169: 367 372. Needham, G. R., and P. D. Teel. 1991. Off host physiological ecology of ixodid ticks. Annu. Rev. Entomol. 36: 659 681. Nordlund, D. A., and W. J. Lewis. 1976. Terminology of chemical releasing stimuli in intraspecific and interspecific interactions. J. Chem. Ecol. 2: 211 220. Norval, R. A. I., J. F. Butler, and C. E. Yunker. 1 989. Use of carbon dioxide and natural or synthetic aggregation attachment pheromone of the bont tick, Amblyomma hebraeum to attract and trap unfed adults in the field. Exp. Appl. Acarol. 7: 171 180. Norval R. A. I., D. E. Sonenshine, S. A. Allan, and M. J. Burridge. 1996. Efficacy of pheromone acaricide impregnated tail tag decoys for control of bont ticks, Amblyomma hebraeum on cattle in Zimbabwe. Exp. Appl. Acarol. 20: 31 46. Oliver Jr., J. H. 1989. Biology and systematics of ticks (Acari: Ixodida). A nnu. Rev. Ecol. Syst. 20: 397 430. Osterkamp, J., U. Wahl, G. Schmalfuss, and W. Haas. 1999. Host odour recognition in two tick species is coded in a blend of vertebrate volatiles J. Comp. Physiol 185: 59 67. Parola, P., and D. Raoult. 2001. Ticks and ti ckborne bacterial diseases in humans: an emerging infectious thr eat. Clin. Infect. Dis. 32: 897 928 Papadopoulos, N. T., B. I. Katsoyannos, N. A. Kouloussis, J. Hendrichs, J. R. Carey, and R. R. Heath. 2001. Early detection and population monitoring of Ce ratitis capitata (Diptera: Tephritidae) in a mixed fruit orchard in northern Greece. J. Econ. Entomol. 94: 971 978. Perritt, D., G. Couger, and R. W. Barker. 1993. Computer controlled olfactometer system for studying behavior responses of ticks to carbon d ioxide. J. Med. Entomol. 30: 571 578. Petrova Piontkovskaya, S. P. 1947. Comparative data on the biology of Rhipicephalus sanguineus Latr. and Rhipicephalus turanicus Pom. under laboratory conditions. Zool. Zh. 25: 173 176. Posey, K. H., and C. E. Schreck. 1981. An air flow apparatus for selecting female mosquitos for use in repellent and attraction studies. Mosq. News. 41: 566 568.
127 Ranju, R. S., B. R. Latha, V. Leela, and S. A. Basith. 2012a. Effect of attractant sex pheromone on immature larval stages of ixodid tick species. J. Parasit. Dis. 36: 155 158. Ranju, R. S., B. R. Latha, V. Leela, and S. A. Basith. 2012b. Effect of 1 octen 3 ol, the ruminant kairomone on ixodid tick larvae Veterinarski Arhiv. 82: 609 615. Ranju, R. S., B. R. Latha, V. Leela, and S. A. Basith. 2013. Field trials to attract questing stages of brown dog tick, Rhipicephalus sanguineus using tick pheromone acaricide complex. J. Parasit. Dis. 37: 84 87. Raoult, D., P. J. Weiller, A. Chagnon, H. Chaudet, H. Gallais, and P. Casanova. 198 6. Mediterranean spotted fever: clinical, laboratory and epidemiological features of 199 cases. Am. J. Trop. Med. Hyg. 35: 845 850. Raoult, D., and V. Roux. 1997. Rickettsioses as paradigms of new or emerging infectious diseases. Clin. Microbiol. Rev. 10: 694 719. Rechav, Y., H. Pardis, G. B. Whitehead, and M. M. Knight. 1977. Evidence for an assembly pheromone(s) produced by males of the bont tick, Amblyomma hebraeum (Acarina: Ixodidae). J. Med. Entomol. 14: 71 78. Rudolph, D., and W. Knulle. 1974. Site and mechanism of water vapour uptake from the atmosphere of ixodid ticks. Nature. 249: 84 85 Samish, M., and E. A. Alekseev. 2001. Arthropods as predators of ticks (Ixodoidea). J. Med. Entomol. 38: 1 11. Samish, M., and I. Glazer. 2001. Entomopathoge nic nematodes for the biocontrol of ticks. Trends Parasitol. 17: 368 371. Samish, M., H. Ginsberg, and I. Glazer. 2004. Biologica l control of ticks. Parasitol ogy 129: 389 403. Sauer, J. R., J. A. Hair, M. S. Houts. 1974. Chemo attraction in the lone star tick (Acari: Ixodidae). 2. Responses to various concentrations of CO 2 Ann. Entomol. Soc. Am. 67: 150 152 Schni, R., E. H ess, W. Blum, and K. Ramstein. 1984. The aggregation attachment pheromon e of the tropical bont tick Amblyomma variegatum Fabricius (A cari, Ixodidae): Isolation, identificatio n and action of its components. J. Insect Physiol. 30: 613 618 Schriefer, M. E., and A. F. Azad. 1994. Changing ecology of Rocky Mountain spotted fever, In D. E. Sonenshine and T. N. Mather (eds), Ecological dynami cs of tick borne zoonoses. Oxford University Press, NY. pp. 314 326.
128 Sever, M. L., S. J. Arbes Jr., J. C. Gore, R. G. Santangelo, B. Vaughn, H. Mitchell, C. Schal, and D. C. Zeldin. 2007. Cockroach allergen reduction by cockroach control alone in low inco me urban homes: a randomized control trial. J. Allergy Clin. Immunol. 120: 849 855. Shahraki, G. H., H. M. Noor, J. Rafinejad, M. K. Shahar, and Y. B. Ibrahim. 2011. Field efficacy of siege gel bait in an IPM program on life stages of German cockroach (Bla taria: Blattellidae) in a residential building. Asian Biomed. 5: 619 624. Sivinski, J. M., and C. Calkins. 1986. Pheromones and parapheromones in the control of tephritids. Fla. Entomol. 69: 157 168. Skotarczak, B. 2003. Canine ehrlichiosis. Ann. Agric. En viron. Med. 10: 137 141. Sonenshine, D. E. 1991. Biology of ticks, vol. 1. Oxford University Press, New York, NY, pp. 51 66, 133 137, 319 321. Sonenshine, D. E. 1993. Biology of ticks, vol. 2. Oxford University Press, New York, NY, pp. 400 401. Sonenshine, D. E. 2004. Pheromones and other semiochemicals of ticks and their use in tick control. Parasitol ogy 129: 405 425. Sonenshine, D. E. 2006. Tick pheromones and their use in tick control. Annu. Rev. Entomol. 51: 557 580. Sonenshine, D. E., G. M. Khalil, P. J. Homsher, and S. N. Mason. 1982. Dermacentor variabilis and Dermacentor andersoni : genital sex pheromones. Exp. Parasitol. 54: 317 330. Srivastava, S. C., and M. G. R. Varma. 1964. The culture of the tick Rhipicephalus sanguineus (Latreille) (Ixodidae) in the laboratory. J. Med. Entomol. 1: 154 157. Stafford III, K. C. 2007. Tick management handbook: a n integrated guide for homeowners, pest control operators, and public health officials for the prevention of tick associated disease. The Connecticut Agric ultural Experiment Station, New Haven, Conn, USA. Steullet, P., and P. M. Guerin. 1992. Perception of breath components by the tropical bont tick, Amblyomma variegatum Fabricius (Ixodidae). J Comp Physiol 170: 665 676. Steullet, P., and P. M. Guerin. 19 94. Identification of vertebrate volatiles stimulating olfactory receptors on tarsus I of the tick Amblyomma variegatum Fabricius (Ixodidae). J. Comp. Phys. 174: 39 47. Syed, Z., and W. S. Leal. 2007. Maxillary palps are broad spectrum odorant detectors i n Culex quinquefasciatus Chem. Senses. 32: 727 738.
129 Takken, W., and D. L. Kline. 1989. Carbon dioxide and 1 octen 3 ol as mosquito attrac tants. J Am Mosq Cont As soc. 5: 311. Takken, W., T. Dekker, and Y. G. Wijnholds. 1997. Odor mediated flight behavi or of Anopheles gambiae Giles sensu stricto and An. stephensi Liston in response to CO 2 acetone, and 1 octen 3 ol (Diptera: Culicidae). J. Insect Behav. 10: 395 407. Vale, G. A., and D. R. Hall. 1985. The role of 1 octen 3 ol, acetone, and carbon dioxide in the attraction of tsetse flies, Glossina spp. (Diptera: Glossinidae). Bull. Entomol. Res. 75: 519 528. Venzal, J. M., A. A. Guglielmone, A. Estrada Pea, P. A. Cabrera, and O. Castro. 2003. Ticks (Ixodida: Ixodidae) parasitising humans in Uruguay. Ann. Trop. Med. Parasitol ogy 97: 769 772. Vickers, R. A., M. J. Furlong, A. White, and J. K. Pell. 2004. Initiation of fungal epizootics in diamondback moth populations within a large field cage: proof of concept for auto dissemination. Entomol. Exp. Appl. 111 : 7 17. Wang, C. L., T. Gibb, and G. W. Bennett. 2009. Interceptors assist in bed bug monitoring. Pest Cont. Tech. 37: 116 118. Wang, C., W. Tsai, R. Cooper, and J. White. 2011. Effectiveness of bed bug monitors for detecting and trapping bed bugs in apart ments. J. Econ. Entomol. 104: 274 278. Weeks, E. N. I., M. A. Birkett, M. M. Cameron, J. A. Pickett, and J. G. Logan. 2011. Semiochemicals of the common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), and their potential for use in monitoring and co ntrol. Pest Manag e Sci. 67: 10 20. Wilson, J. G., D. R. Kinzer, J. R. Sau e r, and J. A. Hair. 1972. Chemo attraction in the lone star tick (Acarina: Ixodidae): I. Response of different developmental stages to carbon dioxide administered via traps. J. Med. Entomol. 9: 245 252. Yoder, J. A. 1995. Allomonal defense secretions of the American dog tick, Dermacentor variabilis (Acari: Ixdodidae) promote clustering. Exp. Acarol. 19: 695 705. Yoder, J. A., J. T. Ark, and D. R. Marous. 2008. Use of squalene and phen olic pheromone derivatives on nonfed stages of the brown dog tick, Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae), with observations for attraction potential. Int. J. Acarol. 34: 191 195. Yoder, J. A., A. J. Jajack, B. Z. Hedges, and J. B. Benoit. 2013. Off host aggregation in the non fed, female brown dog tick, Rhipicephalus sanguineus (Latreille), is induced by tick excreta and enhanced by low relative humidity. Med. Vet. Entomol. 27: 209 215.
130 Yunker, C., T. Peter, R. A. I. Norval, D. E. Sonenshin e, and M. J. Burridge. 1992. Olfactory responses of adult Amblyomma hebraeum and A. variegatum (Acari: Ixodidae) to attractant chemicals in laboratory tests. Exp. Appl. Acarol. 13: 295 301.
131 BIOGRAPHICAL SKETCH Lucas Paul Carnohan was born in Victoria, Tex as, and moved to Idaho when he was six. Lucas graduated from Shoshone high school, and moved to Hickory, North Carolina where he worked toward his undergraduate degree at Lenoir Rhyne University (LRU) Living so far from home was not easy for Lucas, but he was determined to see the world and experience new things, and so he stayed at LRU for the four years of his undergrad uate program He graduated from LRU with a Bachelor of S cience degree with a major in biology and a minor in chemistry. Towards the end of his degree program Lucas began searching for ways to further his education. Lucas had always had a passion for animals, and so he applied and was accepted into the College of Veterinary Medicine at Washington State University. At first he was co nvinced that he would follow through with his plans to become a veterinarian, but then Lucas had a change of heart. He decided to pursue a graduate degree in research, and while searching for programs related to veterinary science, stumbled upon veterinar y entomology. Lucas found an opportunity at the s lab oratory where he could s tudy brown dog ticks. He decided that this was ideally in l of entomology has only grown. He has spent the last two years studying brown dog ticks and comple ting all of the required courses to obtain a Master of Science degree in entomology. Lucas expects to graduate in August of 2013 with his M.S. degree, and th en promptly continue on toward obtaining a Doctor of Philosophy degree in urban entomology. He will be moving to Ft. Lauderdale FL to work in Dr. Nan and is greatly looking forward to it.
132 Eventually, Luc as would like to be closer to his family, who currently reside in Washington. He has not fully decided on a career to pursue after he finishes his Ph D and in fact prefers to leave his options open. Regardless of the route he takes, Lucas intends to ma ke a positive difference in the world, and develop meaningful relationships with interesting people along the way.