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Dermacentor marginatus is one of the main tick species in northwestern China, and is a vector of various tick-borne pathogens. Tick control method largely depends on chemical agents, but the disadvantages of using such approach would cause environmental damage and the risk of developing tick resistance to acaricides. Vaccination of tick protective antigen is an eco-friendly approach which is an alternative and promising method to mitigate tick infestation in livestock. In the study, a mu-class glutathione S-transferase (GST) sequence of D. marginatus was cloned and the recombinant protein (rDmGST) was expressed. Transcriptional level of the GST was measured together with native GST activity of the tick. Finally, A vaccine trial on rabbits against D. marginatus was proceeded to evaluate the anti-tick effect of rDmGST. Results reveled that the CDs of the D. margiantus glutathione S-transferase mu 1 gene has 669 base pair nucleotide sequence encoding a 223 amino acid. The deduced GST protein sequence had over 95 % similarity with that of D. variabilis. The rDmGST was efficiently expressed soluble and purified by His trap affinity chromatography. Enzyme activity of native GST and transcriptional profiles of the GST showed up-regulation in different stages and organs of D. marginaus during blood feeding. Polyclonal antibody reacted with rDmGST in Western blotting. Tick challenge on rDmGST inoculated rabbits showed reductions in adult female engorgement rate, total egg mass and egg hatching rate with an overall vaccine efficacy of 43.69 %. The results of the experiment indicated the GST has potential value to be an effective protective antigen of D. marginatus., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

For more than 50 years DEET (N,N-Diethyl-m-toluamide) has been considered the gold standard of repellents. It is applied to the skin or clothing to deter mosquitoes and other blood-sucking invertebrate pests from approaching and/or settling, and ultimately it provides temporary protection from bites. Despite rampant global use, surprisingly little is understood about DEET's mode of action and the molecular targets of the active ingredient. Furthermore, the theories into its mechanism for repellency are largely based off fruit fly and mosquito research. Since ticks possess a unique sensory structure, the Haller's organ, the specific genes and pathways associated with DEET avoidance may differ from insects. In these studies, we collected American dog ticks (Dermacentor variabilis) from four natural populations within Manitoba, Canada. We first carried out behavior assays, which showed DEET effectively repelled the ticks. RNA sequencing revealed that DEET caused a rapid and substantial reduction in the abundance of transcripts encoding cytochrome P450 and acetylcholinesterase genes, which gradually recovered over the 24 h time course. Finally, enzymatic kinetics provided functional support for DEET's role as an effective inhibitor of P450 s. While many facets of its mode of action remain to be worked out, our study provides valuable insights into the molecular underpinnings of DEET's repellence in ticks., (Crown Copyright © 2019. Published by Elsevier GmbH. All rights reserved.)

Background: An imidacloprid/flumethrin collar (Seresto®) was previously shown to prevent infection with Babesia canis, transmitted by Dermacentor reticulatus, in dogs for up to 1 month after application. The present study evaluated the prevention of transmission throughout the claimed efficacy period of 8 months., Methods: Eight animals each were randomly included in groups 1 (negative control) and 2 (Seresto® collar), respectively. Animals in group 2 received the Seresto® collar on Day 0. Tick challenges were performed monthly from the 2nd to the 8th month. Assessment criteria included in situ tick counts 48 hours post-challenge, polymerase chain reaction (PCR) analyses and immunofluorescence assays (IFA). Whenever dogs were diagnosed with babesiosis they were "rescue-treated", excluded and replaced. Consequently, 24 replacement animals were introduced at various time points throughout the study in the control group; thus data for a total of 32 dogs were available in the latter group at study termination., Results: Acaricidal efficacy for in situ counts was 93% on Day 30, and ranged from 97 to 100% thereafter. No B. canis specific DNA or antibodies were detected in any Seresto®-treated dog at any time. Babesia canis-specific DNA and antibodies were detected in 2-6 of 8 control dogs after each challenge, confirming the validity of the challenge model., Conclusions: The Seresto® collar was highly effective against challenges with D. reticulatus ticks for up to 8 months. The high sustained acaricidal efficacy over this period prevented transmission of B. canis, thus fully protecting dogs against infection in this experimental infestation model.

Introduction: Ticks are vectors of human and animal diseases., Materials and Methods: The aim of this study was to investigate the efficacy of four different formulations containing DEET, Icaridin, IR3535 and mix of three compounds: DEET, IR3535 and geraniol, against Dermacentor reticulatus ticks., Results: The repellent effectiveness of these products to adult ticks was different. At 90 minutes after application the repellent A (DEET 30%), repellent D (DEET 30%, IR3535 20%, geraniol 0.1%) and repellent G (IR3535 12%) exhibited a 100% effectiveness in protection against ticks, but the efficacy of repellent C (Icaridin 20%) dropped to 95%., Discussion: DEET is considered by many authors to be the ‘gold’ standard of insect repellents, and we have also confirmed this in our studies with Dermacentor reticulatus. DEET expressed the higher repellency after 7 hours of application (90%) comparing to other formulation - repellent D containing DEET 30%, IR3535 20% and geraniol 0.1%, whose effectiveness dropped to 60%. Repellents C (Icaridin 20%) and G (IR3535 12%) were effective only up to four hours after application (the efficacy was 85% and 40%, respectively)., Conclusions: DEET has proven to be the most effective repellent against Dermacentor reticulatus ticks.

Background: Oral administration of lotilaner flavoured chewable tablets (Credelio™, Elanco) to dogs has been shown to provide a rapid onset of killing activity of infesting ticks, with sustained efficacy for at least 35 days. A study was undertaken in Europe to confirm lotilaner's safety and anti-tick efficacy in client-owned dogs., Methods: In this assessor-blinded study, dogs were enrolled at 19 clinics in Germany, Hungary and Portugal. Qualifying households with no more than three dogs were randomized in an approximate 2:1 ratio to a lotilaner or fipronil/(S)-methoprene (FSM) (Frontline® Combo Spot-on, Merial) treatment group. One household dog with at least three live attached ticks was the primary dog. Treatments were dispensed Days 0, 28 (± 2) and 56 (± 2) for owner administration to all household dogs. Tick counts were performed on primary dogs Days 7 (± 1), and ±2 days on Days 14, 21, 28, 42, 56, 70 and 84; supplementary dogs were assessed for safety ± 2 days on Days 28, 56 and 84. Efficacy was assessed by comparing mean Day 0 live attached tick counts with subsequent counts., Results: The most frequently retrieved ticks were Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus (sensu lato), with Ixodes hexagonus also present. In the lotilaner group (n = 127) geometric mean tick count reductions were at least 98% from the first post-treatment visit (Day 7) through Day 56, when efficacy was 100%. For FSM (n = 68), efficacy remained at least 96% through Day 84, but at no point were all dogs free of live attached ticks. Mean counts in lotilaner-treated dogs were significantly lower than FSM-treated dogs on Days 7, 42, 70 and 84 (P < 0.05). Percent efficacy over all post-enrolment visits was 99.3 and 98.3% for lotilaner and FSM groups, respectively (t (190)  = 2.23, P = 0.0268). Owners successfully administered all treatments, and both products were well-tolerated., Conclusion: Under European field conditions, lotilaner flavoured chewable tablets administered monthly, were > 98% effective in eliminating live ticks from the first post-treatment assessment (Day 7) through Day 56 and maintained 100% of dogs tick-free on Days 70 and 84. Lotilaner was safe, providing superior tick control to FSM administered according to the same schedule.

Background: There is a continuing need for novel approaches to tick control in dogs. One such approach lies in the ability of lotilaner (Credelio™), an isoxazoline with a rapid onset of action, to provide sustained efficacy against ticks. Two studies were undertaken to confirm lotilaner's efficacy, at the minimum dose rate of 20 mg/kg, against the three most common tick species in Europe., Methods: In each of two studies, 16 Beagle dogs, at least 6 months old, were ranked and blocked by tick counts from infestations placed approximately 1 week before treatment. Within blocks, dogs were randomized to receive either lotilaner flavoured chewable tablets at as close as possible to, but not less than the minimum dose rate of 20 mg/kg, or to be sham-treated controls. Study 1 assessed lotilaner efficacy against concurrent infestations with 50 (± 6) Rhipicephalus sanguineus and 70 (± 6) Ixodes ricinus; Study 2 infestations were with 50 (± 2) Dermacentor reticulatus. Infestations were performed on Day -2 with counts on Day 2, 48 (± 2) hours post-treatment. Post-treatment infestations were performed on Days 7, 14, 21, 28 and 35, and ticks were counted 48 (±2) hours post-infestations. Efficacy was determined by the percent reduction in mean live tick counts., Results: Control group infestations for each tick species were adequate for assessing lotilaner efficacy at all assessment times. On Day 2 no live ticks were found on any lotilaner-treated dog. For subsequent counts, in Study 1 lotilaner was 100% effective in eliminating live I. ricinus and R. sanguineus on all but two occasions for each tick; on each of those occasions efficacy was sustained at greater than 98.0%. In Study 2, except for a single unattached live tick found on Day 16, efficacy against D. reticulatus was 100% at every post-treatment assessment., Conclusion: The high and sustained efficacy against the three common species of ticks in Europe, R. sanguineus, I. ricinus and D. reticulatus, demonstrates that lotilaner can be a valuable tool in the treatment of canine tick infestations. Lotilaner flavoured chewable tablets were well tolerated and effectiveness was sustained through at least 35 days.

Background: Dogs worldwide are at risk of Babesia spp. infections. Preventive efficacy of lotilaner tablets (Credelio™, Elanco) against Babesia canis was evaluated in two studies., Methods: Sixteen dogs in Study 1 and 12 dogs in Study 2, all seronegative and polymerase chain reaction (PCR) negative for B. canis, were randomized to a sham-treated control group or a lotilaner (20-43 mg/kg) treatment group, administered on Day 0 (Study 1: n = 8/group; Study 2: n = 6/group). Dogs were each infested with 50 Dermacentor reticulatus, a percentage of which (Study 1: 8.0-30.0%; Study 2: 12.2%) were infected with B. canis, in Study 1 on Days 2, 7, 14, 21 and 28, and in Study 2 on Day 28. Ticks were removed and counted on Day 30 in Study 1, and Day 34 in Study 2. Blood was collected for Babesia detection via smear, PCR and immunofluorescence assay (IFA) in Study 1 on Day 2, then approximately weekly through Day 56, and in Study 2 at weekly intervals between Days 28 to 49, and on Days 63 and 91. Additional samples were collected from dogs with body temperature > 39.4 °C (measured three times weekly, from Days 7 to 56 in Study 1 and from Days 35 to 56 in Study 2) and positive for B. canis on blood smear. Dogs with confirmed infections were rescue-treated, removed from the study and, in Study 1, replaced., Results: Across both studies B. canis infection of ticks ranged between 8.0-30.0%. In Study 1, all control dogs were positive for B. canis on blood smear and PCR on Day 10 and IFA on Day 21; on Day 21 seven of eight replacement control dogs were B. canis-positive; no replacement dogs were B. canis-positive following tick removal on Day 30. In Study 2, all control dogs were B. canis-positive on Day 56. All lotilaner-treated dogs remained B. canis-negative at all assessments in both studies., Conclusion: Lotilaner efficacy was 100% in preventing establishment of B. canis infection, despite post-treatment challenge with infected ticks on Days 2, 7, 14, 21 and 28.

Background: Effective control of tick infestations on dogs is important to reduce the risk of transmission of bacterial, viral, and protozoal pathogens. Laboratory studies were initiated to determine the efficacy of lotilaner against common ticks infesting dogs in the United States., Methods: Eight studies investigated the efficacy of lotilaner against ticks. In two studies dogs were infested with both Dermacentor variabilis and Rhipicephalus sanguineus: one additional study was completed for each of these species. Two studies assessed infestations with Amblyomma americanum and two with Ixodes scapularis. In all studies, dogs were ranked and blocked by counts from pre-treatment infestations and randomly allocated, at least eight per group, to be treated orally with lotilaner (minimum dose rate 20 mg/kg), or to be untreated controls. Treatments were administered on Day 0, within 30 min after dogs were fed. In all studies, infestations were performed with 50 adult ticks on Days -2, 7, 14, 21 and 28, and also on Day 35 for R. sanguineus, D. variabilis and I. scapularis. Tick counts were completed 48 h after treatment or after each subsequent challenge. An adequate infestation was defined as at least 25% of the infestation dose recovered from each of at least six control animals at each evaluation. Efficacy calculations for the primary objective were based on geometric means., Results: In all studies, lotilaner was 100% effective against existing infestations. For post-treatment assessments, on only two occasions did efficacy fall below 99%: in one D. variabilis study efficacy was 98.0% on Day 35 and in one I. scapularis study efficacy on Day 16 was 98.4%. Only mild and transient adverse events were observed, and none were considered to be related to treatment., Conclusion: Lotilaner was completely effective against existing infestations with four common species of ticks, D. variabilis, R. sanguineus, A. americanum and I. scapularis, that affect dogs in North America, with at least 4 weeks efficacy of 98.0% or more against subsequent challenge infestations. These results show that lotilaner is a highly effective isoxazoline that offers sustained efficacy against ticks through and beyond the one-month end-of-dose treatment interval.

Background: Canine babesiosis is a clinically significant emerging vector-borne disease caused among others by the protozoan Babesia canis. The efficacy of sarolaner (Simparica®; Zoetis; at the minimum recommended label dose of 2.0 mg per kg bodyweight) in the prevention of babesiosis was evaluated in twenty-four dogs randomly allocated to either a placebo-treated group or one of two sarolaner-treated groups. At 21 or 28 days after treatment administration, dogs were infested with 50 ± 4 Dermacentor reticulatus ticks of which 25% were confirmed to be infected with Babesia canis. Blood samples were collected from each dog prior to tick infestation and weekly thereafter until 49 days after infestation. The blood was assayed for B. canis antibodies using an indirect immunofluorescence test (IFAT) and for B. canis DNA by PCR assay. A dog was a priori defined as B. canis-positive if it tested positive by both IFAT and PCR at any time during the study., Results: No treatment-related adverse reactions were recorded during the study. All placebo-treated animals displayed clinical signs due to babesiosis and tested positive on both IFAT and PCR. None of the sarolaner-treated animals displayed any clinical symptoms or tested positive on both IFAT and PCR, resulting in a 100% efficacy in the prevention of canine babesiosis (P = 0.0002)., Conclusion: When given 21 or 28 days before tick infestation, a single treatment with sarolaner at the minimum recommended label dose of 2.0 mg per kg body weight prevented the transmission of B. canis by D. reticulatus to dogs.

Dermacentor reticulatus ticks are among the most important arthropod vectors of zoonotic disease agents in Europe. Eleven essential oils, namely basil (Ocimum basilicum), bergamot (Citrus bergamia), clove bud (Syzygium aromaticum), citronella (Cymbopogon winterianus), creeping thyme (Thymus serpyllum), lavender (Lavandula angustifolia), lemon-scented gum (Corymbia citriodora), marjoram (Origanum majorana), peppermint (Mentha piperita), spearmint (M. spicata), and red thyme (Thymus vulgaris) were tested for repellency against adult D. reticulatus ticks at concentrations of 1 and 3%. Clove bud, creeping thyme and red thyme essential oils were the most efficient - repelling 83, 82 and 68% of ticks when diluted to 3%, respectively. The mixture of creeping thyme and citronella containing 1.5% of each showed higher repellency (91%) than individual essential oils at the concentration of 3%., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

We evaluated the acaricidal activity of Acmella oleracea methanol extract and spilanthol on Rhipicephalus microplus and Dermacentor nitens. The extract was made through maceration with methanol. From this extract, a dichloromethane fraction with 99% spilanthol was obtained and tested on R. microplus larvae and engorged females and D. nitens larvae. For evaluation against larvae, the modified larval packet test was used, and both the methanol extract and dichloromethane fraction were tested at concentrations of 0.2-50mg/mL. The modified larval packet test was also used in the lethal time (LT) test, with the methanol extract at a concentration of 12.5mg/mL and the percentage mortality was assessed after 15, 30, 45, 60, 75, 90, 120min and 24h. The 50% lethal time calculation (LT 50 ) was performed in this test. The engorged female test was performed with R. microplus only, at concentrations of 25-200mg/mL for methanol extract and 2.5-20.0mg/mL for spilanthol. The methanol extract caused 100% mortality of the R. microplus and D. nitens larvae at concentrations of 3.1 and 12.5mg/mL, respectively. Spilanthol resulted in 100% mortality of R. microplus larvae at concentration of 1.6mg/mL and of D. nitens at 12.5mg/mL. In the lethal time assay using the methanol extract, the mortality rate was 100% for R. microplus and D. nitens larvae after 120min and 24h, with LT 50 values of 38 and 57min, respectively. In the test of females, the egg mass weight and the hatching percentage of the groups treated with concentrations equal to or higher than 50.0mg/mL of methanol extract were significantly reduced (p<0.05), while for spilanthol, the reduction of the egg mass weight and hatching percentage occurred from concentrations of 10.0mg/mL and 2.5mg/mL, respectively. Females treated with 200.0mg/mL of extract died before starting oviposition, resulting in 100% effectiveness, while the best efficacy for spilanthol was 92.9% at a concentration of 20.0mg/mL. Thus we conclude that the methanol extract of A. oleracea and spilanthol have acaricidal activity against R. microplus and D. nitens., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Motivated by observations that the canine anti-inflammatory cream DogsBestFriend™ (DBF) appeared to deter flies, mosquitoes, and ticks from treated animals, repellent efficacy bioassays using four species of ticks were conducted with three extracts of Nigella sativa L. (Ranunculaceae), a constituent of DBF. The DBF cream was tested against nymphs of lone star tick, Amblyomma americanum (L.). In vertical filter paper assays, the three extracts applied at 0.413 mg extract/cm(2) filter paper repelled 96.7-100 % of brown dog tick, Rhipicephalus sanguineus (Latreille) nymphs, whereas, at the same rate, only one extract repelled >90 % A. americanum nymphs. Adult (mixed sexes) American dog ticks, Dermacentor variabilis (Say), required a higher concentration to be repelled effectively; two extracts, applied at 0.827 mg extract/cm(2) filter paper, repelled ≥90 % of the D. variabilis. In contrast, all extracts applied at much lower concentration (0.206 mg extract/cm(2) filter paper) repelled 100 % adult blacklegged ticks, Ixodes scapularis Say (only females tested). Of the two more repellent extracts, one lost most of its activity against A. americanum nymphs in <4 h when applied at 0.827 mg extract/cm(2) filter paper, whereas the other repelled 66.7 % of the nymphs at 192 h after application. At 0.206 mg extract/cm(2) filter paper, one extract was as repellent as deet against A. americanum nymphs. In a vertical bioassay in which nylon organdy was substituted for filter paper, DBF, at the rates of 1.67 and 0.835 mg cream/cm(2), repelled 76.7 and 30.0 % A. americanum nymphs, respectively. These findings indicate that when applied appropriately DBF should afford some protection to canines against tick bites.

Novel isoxazoline amide benzoxaboroles were designed and synthesized to optimize the ectoparasiticide activity of this chemistry series against ticks and fleas. The study identified an orally bioavailable molecule, (S)-N-((1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborol-6-yl)methyl)-2-methyl-4-(5-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)benzamide (23), with a favorable pharmacodynamics profile in dogs (Cmax=7.42ng/mL; Tmax=26.0h; terminal half-life t1/2=127h). Compound 23, a development candidate, demonstrated 100% therapeutic effectiveness within 24h of treatment, with residual efficacy of 97% against American dog ticks (Dermacentor variabilis) on day 30 and 98% against cat fleas (Ctenocephalides felis) on day 32 after a single oral dose at 25mg/kg in dogs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: The preventive effect of fluralaner spot-on solution against transmission of Babesia canis by Dermacentor reticulatus ticks was evaluated., Findings: Sixteen dogs, tested negative for B. canis by polymerase chain reaction (PCR) and immunofluorescence assay test (IFAT), were allocated to two study groups. On day 0, dogs in one group (n = 8) were treated once topically with fluralaner spot-on solution (Bravecto™ Spot-on Solution) according to label recommendations and dogs in the control group (n = 8) remained untreated. On days 2, 28, 56, 70 and 84, all dogs were infested with 50 (±4) D. reticulatus ticks harbouring B. canis, with tick in situ thumb counts 48 ± 4 h after each infestation. On day 90, ticks were removed from all dogs and counted. Prior to each infestation, the presence of B. canis in the respective tick batch was confirmed by PCR, and 12-16 % of ticks were found to be infected with B. canis. Efficacy against ticks was 99.5 and 99.3 % on days 4 and 58 after treatment, respectively and 100 % on all other days. Replacement dogs were included for any B. canis infected control dog (in total 19). All control dogs (n = 27) became infected with B. canis, as confirmed by PCR, performed every 7 days, and by IFAT, performed every 14 days after treatment. None of the eight treated dogs became infected with B. canis, as they were tested negative by PCR and IFAT throughout the study until day 112. By comparing infected dogs in the treated group with infected dogs in the untreated control group, a 100 % preventive effect against B. canis transmission was demonstrated., Conclusions: A single topical administration of fluralaner spot-on solution effectively prevented the transmission of B. canis by infected D. reticulatus ticks over a 12-week period.

The efficacy of afoxolaner plus milbemycin oxime (AFX + MO) combination chewables (NexGard Spectra®, Merial) and AFX single-entity chewables (NexGard®, Merial) against induced infestations with Dermacentor reticulatus ticks was evaluated in dogs. Thirty dogs were assigned to blocks of three animals each based on pre-allocation tick counts and were randomly allocated to one of three groups: untreated (control), treated with a combination of AFX + MO chewables to be as close as possible to the minimum effective dose of AFX + MO (2.5 + 0.5 mg per kg body weight), and treated with a combination of NexGard® chewables to be as close as possible to the minimum effective dose of AFX (2.5 mg per kg body weight). Treatments were administered orally once on day 0. Starting 2 days before treatment administration, each dog was infested with approximately 50 ticks weekly for six consecutive weeks. Live ticks were counted at ∼48 h post-treatment (removal count) and at ∼48 h (in situ counts) and ∼72 h (removal counts) following each post-treatment infestation. Treatment with both AFX + MO and NexGard® chewables rapidly eliminated the existing tick infestations (100 % efficacy) within 2 days following treatment administration. Weekly re-infestations were controlled for a minimum of 5 weeks with the efficacy ranging from 92.2 to 99.7 % based on ∼48 h post-treatment in situ counts and between 99.0 and 100 % based on ∼72 h post-treatment removal counts (p < 0.0001 at each occasion). This study demonstrated a high efficacy of both AFX + MO chewable and NexGard® chewable treatments against infestations of dogs with D. reticulatus ticks for at least 5 weeks. In addition, this study indicated no interference between the two compounds with respect to the acaricidal activity provided by AFX.

Background: Ticks are common ectoparasites that infest dogs globally. Acaricides with rapid and sustained speed of kill are critical to control infestations and to reduce the risk of disease transmission. This study evaluated the speed of kill for 5 weeks after a single dose of orally administered Simparica™ (sarolaner) against induced infestations with Dermacentor reticulatus on dogs, compared to Advantix® Spot-on solution for dogs (imidacloprid + permethrin)., Methods: Twenty four dogs were randomly allocated to treatment with either a placebo tablet, a sarolaner tablet (at 2 to 4 mg/kg) or with Advantix® as per label instructions. Dogs were treated on Day 0 and tick counts were performed in situ at 8 and 12 hours and with removal of the ticks at 24 hours after treatment and subsequent re-infestations on Days 7, 14, 21, 28 and 35. Acaricidal efficacy was determined at each time point relative to live tick counts from the placebo-treated dogs., Results: Based on arithmetic (geometric) mean tick counts, the efficacy of sarolaner was ≥75.6 % (89.6 %) within 8 hours of treatment and tick counts were significantly lower than placebo and imidacloprid + permethrin-treated dogs (P < 0.0001), while imidacloprid + permethrin had no significant reduction (P ≥ 0.3990) at 8 or 12 hours after treatment. Sarolaner killed all ticks on the dogs within 24 hours after treatment, while imidacloprid + permethrin efficacy was only 48.1 %. After weekly re-infestations sarolaner significantly reduced the tick counts versus placebo within 8 hours on Days 7, 14 and 35 (P ≤ 0.0239), and at 12 hours and 24 hours (P ≤ 0.0079) until Day 35.Sarolaner efficacy was ≥95.8 % within 24 hours for 35 days. Significantly more live ticks (P ≤ 0.0451) were recovered from imidacloprid + permethrin-treated dogs than from sarolaner-treated dogs at 24 hours after infestation on all days. There were no sarolaner-related adverse reactions during the study., Conclusions: This study demonstrated that Simparica™ had a faster and more consistent speed of kill against D. reticulatus compared to Advantix®. The rapid and consistent efficacy within 24 hours for 5 weeks after a single oral dose of Simparica™ provides effective and reliable control of D. reticulatus and reduces the risk of transmission of tick-borne diseases.

Background: The ability of Frontline Tri-Act®/Frontect®, a topical ectoparasiticide containing fipronil and permethrin for dogs, to prevent the transmission of Babesia canis as well as Ehrlichia canis was evaluated by infesting dogs with infected vector ticks., Methods: For the Babesia canis study, 16 dogs were randomly allocated to two groups. Eight dogs were treated on day 0 with a topical spot-on formulation containing 6.76 % w/v fipronil plus 50.48 % w/v permethrin and eight dogs served as the untreated control group. Dermacentor reticulatus ticks, with a B. canis infection rate ranging between 2 and 10 %, were placed onto dogs on days 7, 14, 21 and 28. In situ tick counts were performed on Days 9, 16 and 23. Ticks were counted and removed on Day 30. Infection of the dogs with B. canis was monitored by rectal temperature readings, clinical examinations and blood smears as well as PCR and IFA (indirect fluorescent antibody assay). For the Ehrlichia canis study, another 16 dogs were allocated to two groups. Eight dogs were treated with the fipronil and permethrin combination on days 0 and 28 and eight dogs served as untreated controls. Rhipicephalus sanguineus ticks, carrying an infection rate of 13 % for E. canis, were released in the sleeping kennels of the dogs on days 7, 14, 21, 28, 35, 42, 49 and 56. Ticks were counted in situ on the dogs on a weekly basis. All ticks were removed and counted on the final assessment day 58. Infection of the dogs with E. canis was monitored by rectal temperature, clinical examinations, and testing of blood samples by PCR, IFA and platelet counts., Results: B. canis was transmitted by D. reticulatus ticks to all eight untreated control dogs and to one treated dog, which was confirmed by blood smears, PCR and IFA. E.canis was transmitted by R. sanguineus ticks to all eight untreated control dogs. Two of the dogs in the treated group were found positive based on PCR and/or IFA., Conclusions: Frontline Tri-Act®/Frontect® significantly lowered the risk for dogs to acquire a B. canis infection by 87.5 % over a challenge period of 28 days. The risk for dogs to acquire E. canis was reduced by 75 % over a period of 56 days.

Background: The high competence of D. reticulatus in transmission of tick-borne pathogens prompts investigations of the effect of chemicals used as repellents and acaricides on the behaviour of the tick on the host. Therefore, this paper presents the effect of permethrin and deltamethrin on the attachment and feeding in this tick species., Findings: Attachment to rabbit skin of D. reticulatus females sprayed with pyrethroids and the effect of different doses thereof on feeding were assessed at a temperature of 20 ± 3 °C and 50% humidity. The dynamics of attachment of D. reticulatus females varied in a dose-dependent manner after the application of both pyrethroids. Within the first 0.5 h of the experiments, there was an over six-fold and over twelve-fold increase in the number of females attached to host skin after application of permethrin concentrations of 0.3906-0.7812 μg and 1.5625-3.1250 μg/1 specimen, respectively. In the case of deltamethrin, females treated with the dose of 0.0390 μg of the compound were able to attach to host skin only 4 hours after the infestation. The toxic activity of both pyrethroids increased the duration of the feeding period and decreased the body weight of engorged females and the feeding efficiency index., Conclusions: The accelerated attachment of D. reticulatus females caused by sublethal permethrin doses and delayed or inhibited attachment caused by deltamethrin suggest a necessity of careful selection of the type and dose of pyrethroids to protect hosts from tick attacks.

Background: The preventive effect of fluralaner chewable tablets (Bravecto™) against transmission of Babesia canis by Dermacentor reticulatus ticks was evaluated., Methods: Sixteen dogs, tested negative for B. canis by PCR and IFAT, were allocated to two study groups. On day 0, dogs in one group (n = 8) were treated once orally with a fluralaner chewable tablet according to label recommendations and dogs in the control group (n = 8) remained untreated. On days 2, 28, 56, 70 and 84, dogs were infested with 50 (±4) B. canis infected D. reticulatus ticks with tick in situ thumb counts 48 ± 4 h post-infestation. Prior to each infestation, the D. reticulatus ticks were confirmed to harbour B. canis by PCR analysis. On day 90, ticks were counted and removed from all dogs. Efficacy against ticks was calculated for each assessment time point. After treatment, all dogs were physically examined in conjunction with blood collection for PCR every 7 days, blood samples for IFAT were collected every 14 days and the dog's rectal body temperature was measured thrice weekly. From dogs displaying symptoms of babesiosis or were PCR positive, a blood smear was taken, and, if positive, dogs were rescue treated and replaced with a replacement dog. The preventive effect was evaluated by comparing infected dogs in the treated group with infected dogs in the untreated control group., Results: All control dogs became infected with B. canis, as confirmed by PCR and IFAT. None of the 8 treated dogs became infected with B. canis, as IFAT and PCR were negative throughout the study until day 112. Fluralaner chewable tablet was 100 % effective against ticks on days 4, 30, 58, and 90 and an efficacy of 99.6 % and 99.2 % was achieved on day 72 and day 86 after treatment, respectively. Over the 12-week study duration, a 100 % preventive effect against B. canis transmission was demonstrated., Conclusions: A single oral administration of fluralaner chewable tablets effectively prevented the transmission of B. canis by infected D. reticulatus ticks over a 12-week period.

The present study compares the efficacy of two recent oral ectoparasiticides containing isoxazolines (NexGard(®), containing afoxolaner and administered at a monthly regimen, and Bravecto™ containing fluralaner and administered at a tri-monthly regimen) against Rhipicephalus sanguineus sensu lato and Dermacentor reticulatus ticks on dogs. 24 dogs were randomly allocated to untreated control, NexGard(®) treated, and Bravecto™ treated groups. The treatments were administered on Days 0, 28 and 56 for afoxolaner and on Day 0 for fluralaner. Tick infestations were performed weekly with 50 unfed adult ticks per each species on each dog from Days 30 to 84 (with the exception of R. sanguineus on Day 63). Ticks were counted at 24h post-infestation. The dogs from both treated groups had statistically significantly (p<0.05) less R. sanguineus and D. reticulatus ticks compared to the untreated dogs on all assessment days. Percent efficacy against R. sanguineus ranged from 86.4% to 99.5% at 24h post-infestation for NexGard(®) and from 65.7% to 100% for Bravecto™. Statistically significantly (p<0.05) less R. sanguineus ticks were recorded for NexGard(®) treated dogs compared to Bravecto™ treated dogs on Day 78. Percent efficacy against D. reticulatus ranged from 85.2% to 99.6% at 24h post-infestation for NexGard(®) and from 63.4% to 99.1% for Bravecto™. Statistically significantly (p<0.05) less D. reticulatus ticks were recorded for NexGard(®) treated dogs compared to Bravecto™ treated dogs on Days 71, 78 and 85., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Dermacentor reticulatus is a European hard tick of major veterinary importance because it is the vector of canine babesiosis due to Babesia canis. The efficacy against this particular tick species is therefore a key characteristic for an acaricidal solution for dogs. The repellency, prevention of attachment and acaricidal efficacy of Frontline Tri- Act/Frontect, a new combination of fipronil and permethrin against induced infestations of Dermacentor reticulatus ticks on dogs were evaluated after a single topical administration., Methods: A group of 20 dogs were allocated to two treatment groups. Ten dogs were treated with a topical spot-on formulation containing 6.76% w/v fipronil + 50.48% w/v permethrin once on Day 0 and 10 dogs served as untreated controls. Tick infestations were performed by placing 50 D. reticulatus ticks next to sedated dogs confined to infestation crates on days 1, 7, 14, 21 and 28. Thumb counts on dogs were conducted at 4, 12 and 24 h post-challenge. Tick removal counts were performed 48 h after each infestation. Repellency, prevention of attachment and acaricidal efficacy were calculated., Results: The new combination provided repellency ranging between (56.5-73.5%) at 4 h post-infestation (pi), between (76.3-92.9%) at 12 h pi and between (83.9-96.5%) at 24 h pi, up to 4 weeks post-treatment. Prevention of attachment ranged between (64.1-79.7%) at 4 h pi, between (79.1-94.2%) at 12 h pi and between (84.2-99.6%) at 24 h pi, up to 4 weeks post-treatment. Acaricidal efficacy against D. reticulatus ticks was ≥99.5% for 4 weeks post-treatment., Conclusion: The new combination of fipronil and permethrin demonstrated excellent repellency, prevention of attachment and acaricidal efficacy against D. reticulatus for at least 4 weeks. The results suggest that in endemic areas of canine babesiosis, the application of the new combination can significantly reduce the potential for transmission of B. canis as well as other tick-borne diseases.

Background: Two experimental studies using a transmission blocking model with Dermacentor reticulatus ticks infected with Babesia canis were performed to test the ability of Effitix® to prevent the transmission of babesiosis in dogs., Methods: Four groups of seven dogs (experiment 1) and one group of eight dogs (experiment 2) were treated topically with a novel combination of fipronil and permethrin in a spot-on formulation (Effitix®, Virbac) respectively 28, 21, 14 and 7 days (experiment 1) and 2 days (experiment 2) prior to tick infestation. In each study, a control group of seven dogs (experiment 1) and eight dogs (experiment 2) remained untreated. On day 0, all dogs were infested with adult D.reticulatus ticks harboring B. canis. An efficacy failure (successfully infected) was regarded as a dog in the treated groups that was tested serologically positive for B.canis antibodies, using an indirect fluorescent antibody (IFA) assay and tested positive for B.canis by DNA-assay using PCR analysis., Results: B.canis was transmitted by D.reticulatus to all untreated dogs (experiment 1) and six untreated dogs out of eight (experiment 2) as confirmed by IFA and PCR assays. The large majority of treated dogs (92.9% in experiment 1 and 100% in experiment 2) remained sero-negative over the challenge period., Conclusions: The treatment of dogs with Effitix® applied 2 to 28 days prior to infestation with D. reticulatus harboring B.canis, successfully prevented the transmission of canine babesiosis.

The acaricidal efficacy of a novel oral formulation of afoxolaner (NEXGARD(®), Merial) against two European tick species was assessed in dogs experimentally infested with Ixodes ricinus and Dermacentor reticulatus. Three studies, each characterized by a negative controlled randomized block design, were conducted with a total of 52 beagle or mongrel dogs of both sexes. Starting 2 days before treatment, each dog was infested weekly with approximately 50 ticks. The number of live ticks was counted at 48 h post-treatment (Day 2) as well as 48 h following each infestation on Days 9, 16, 23, and 30. Afoxolaner, administered at an average dose of 2.7 mg/kg bodyweight (range 2.5-2.9 mg/kg), rapidly eliminated the pre-existing tick infestations with over 99% acaricidal efficacy and controlled the weekly re-infestations for up to 30 days post treatment with over 96% efficacy on both tick species. Afoxolaner provides excellent acaricidal efficacy against these two major European tick species using the oral route of administration., (Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.)

The repellent activity of eugenol was evaluated on Rhipicephalus microplus and Dermacentor nitens larvae in a bioassay based on the vertical migration of these tick larvae during the host-seek phase. Solutions were used at concentrations of 10, 20, 30, 40, and 50 μl/ml and a control only with the solvent ethanol 50 GL. The larvae's reaction of climbing the rods of filter paper was observed each hour for 12 h and once more at 24 h. The repellence was calculated as a percentage through visual estimation, from the tendency of the larvae to climb the rods when the top part was impregnated with the eugenol solutions. For R. microplus larvae, the four highest concentrations produced repellence levels were greater than 80 % for up to 9 h. The repellence rates after 10 h for the concentration of 10 μl/ml was lower than 2 % (p > 0.05); and after 24 h, the values observed for the concentrations of 40 and 50 μl/ml were 77 and 80 % (p < 0.05). For the D. nitens larvae, the repellence was greater than 80 % for up to 5 h at the concentrations of 40 and 50 μl/ml; and after 9 h, the repellence fell for all treated groups were significantly different than the control were found only at the three highest concentrations. Therefore, eugenol has repellent activity on the larval stage of these two tick species, with the R. microplus larvae being more sensitive.

The acaricidal activity of carvacrol, (E)-cinnamaldehyde, trans-anethole, and linalool was studied on Rhipicephalus microplus and Dermacentor nitens larvae. All the substances were tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 μl/ml, with 10 repetitions per treatment. The modified larval packet technique was employed in the tests and the mortality was evaluated after 24 h. In the groups treated with carvacrol, the lowest concentration (2.5 μl/ml) was sufficient to cause 100% death of the R. microplus and D. nitens larvae. The same concentration of (E)-cinnamaldehyde resulted in death of approximately 99% of the larvae of both tick species and reached 100% at the other concentrations. For trans-anethole, mortality rates above 90% of the R. microplus and D. nitens larvae were only observed starting at the concentration of 15.0 μl/ml and reached 100% at the highest concentration (20.0 μl/ml). Finally, the mortality rates of the groups treated with linalool were low, only reaching 8.4 and 14.5% at the highest concentration (20.0 μl/ml) for larvae of D. nitens and R. microplus, respectively. These results show that carvacrol, (E)-cinnamaldehyde, and trans-anethole have acaricidal activity, particularly carvacrol and (E)-cinnamaldehyde, both of which resulted in high mortality rates for the larvae of these two tick species even at the lowest concentration.

Carbon dioxide (CO(2) ), 1-octen-3-ol, acetone, ammonium hydroxide, L-lactic-acid, dimethyl trisulphide and isobutyric acid were tested as attractants for two tick species, Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae), in dose-response bioassays using Y-tube olfactometers. Only CO(2) , acetone, 1-octen-3-ol and ammonium hydroxide elicited significant preferences from adult A. americanum, and only CO(2) was attractive to adult D. variabilis. Acetone, 1-octen-3-ol and ammonium hydroxide were separately evaluated at three doses against CO(2) (from dry ice) at a field site supporting a natural population of A. americanum nymphs and adults. Carbon dioxide consistently attracted the highest number of host-seeking ticks. However, for the first time, acetone, 1-octen-3-ol and ammonium hydroxide were shown to attract high numbers of A. americanum. Further research is needed to determine the utility of these semiochemicals as attractants in tick surveillance and area-wide management programmes., (© 2012 The Royal Entomological Society.)

Objective: The purpose of this study was to determine Ixodes scapularis and Dermacentor variabilis tick mortality when fed on humans who have consumed 400 μg/kg oral ivermectin., Methods: Six study subjects, 3 in each group, were randomly assigned to receive either 400 μg/kg ivermectin or placebo in a blinded manner. After consuming either ivermectin or placebo, each study subject had 2 colostomy bags attached to his or her abdomen. One of the colostomy bags contained 7 I scapularis nymphs and 7 adults. The other colostomy bag contained 7 D variabilis nymphs and 7 adults. Tick mortality was recorded over the next 24 hours., Results: Fifty-five percent (6 of 11) of the attached I scapularis nymphs exposed to ivermectin had morbidity (3 of 11) or died (3 of 11), compared with 0% morbidity and mortality in the 2 I scapularis nymphs that attached in the placebo group. No I scapularis adults or D variabilis nymphs attached to feed. Among D variabilis adults that attached to feed, there was a 0% mortality rate for both the placebo group (0 of 6) and the ivermectin group (0 of 8)., Conclusions: We demonstrate a novel method to confine ticks to human subjects to study tick-borne diseases. While there was a trend toward I scapularis morbidity and mortality in the ivermectin arm, the low number of ticks that attached in the placebo group limited our analysis. Most ticks began feeding in the last 12 hours of the experiment, significantly limiting their exposure to ivermectin. Ivermectin does not cause early death in D variabilis adults., (Copyright © 2013 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.)

A group of 8 dogs was treated with an imidacloprid/flumethrin collar (Seresto(®)) 28 days prior to infestation with adult Dermacentor reticulatus ticks, infected with Babesia canis. The ability of the collar to prevent transmission of B. canis in the treated group was compared to an untreated control group. All 8 dogs in the untreated control group became infected with B. canis parasites, which were detected in blood smears as early as day 6 post tick-application. All control dogs developed clinical signs of babesiosis and were rescue-treated with imidocarb dipropionate. These dogs also developed specific B. canis antibodies as identified by serology (IFA test) and were confirmed PCR/RLB positive. None of the 8 dogs treated with the imidacloprid/flumethrin collar became infected with B. canis, which was confirmed by the absence of specific B. canis antibodies and babesial DNA as confirmed by PCR/RLB. The collar caused 96.02% of the ticks to die within 48h post challenge and this increased to 100% within 4 days. Although a high percentage of 44% of the Dermacentor ticks were infected with B. canis, they were unable to transmit the infection to the treated group. Hence, the imidacloprid/flumethrin collar effectively prevented transmission of B. canis 1 month after application onto the dogs., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The Palearctic three-host species Dermacentor reticulatus contributes to the circulation of numerous pathogens in the environment. Reduction of its abundance may therefore decrease the risk of tick-borne diseases in a given area. The aim of the study is to determine the effect of various concentrations of three pyrethroids--(D), cypermethrin (C), and alpha-cypermethrin (AC) on the development of D. reticulatus eggs and larvae. 217 engorged D. reticulatus females were examined in the investigations. After the feeding period, they were sprayed with 0.015625%, 0.03125%, 0.0625%, and 0.125% solutions of D, C, and AC, and kept at a temperature of 25 o C and 90% relative humidity throughout the preoviposition and oviposition periods. Eggs laid by females were kept in the same conditions until larval hatch. Based on the results obtained, parameters of the course of maturation and oviposition, as well as parameters of embryonic development, were determined. The investigations showed that the pyrethroids tested prolonged the egg maturation period, reduced the number and weight of eggs, and caused disturbances in embryogenesis in D. reticulatus. Upon treatment with as little as 0.015625% AC, larvae did not develop and all eggs died 1-2 days after oviposition. C led to a decreased percentage of normal larval hatch--31.96%, 15.51% and 12.5%, respectively, after using three increasing concentrations (control 98.15%), and a high rate of egg and embryo mortality. The least detrimental effect on the D. reticulatus maturation and embryonic periods was exerted by deltamethrin (82.74%, 84.37% and 16.80% of normal larvae in treatment with the three concentrations). Morphological anomalies were observed in larvae during the experimental period. AC appeared to have the most toxic effect during the maturity and egg development periods, while C exhibited lower toxicity. Application of these pyrethroids in engorged D. reticulatus females exerts distant effects that lead to substantial reduction of tick offspring abundance.

The aim of this work was to identify the compounds and to investigate the acaricidal activity of the essential oil from the leaves of Lippia sidoides on Rhipicephalus microplus and Dermacentor nitens. The oil was obtained by hydrodistillation and analyzed by gas chromatography (GC/FID) and gas chromatography/mass spectrometry. In total, 15 compounds comprising 99.97 % of the total peak area were identified. The main constituent of the essential oil was thymol (67.60 %). The acaricidal activity was assessed by the modified larval packet test, with oil concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 μl/ml, and by the female immersion test with concentrations of 10.0, 20.0, 40.0, 60.0, and 80.0 μl/ml. The mortality of the R. microplus and D. nitens larvae was greater than 95 % starting at concentrations of 10.0 and 20.0 μl/ml, respectively. In the test with the engorged females, the L. sidoides essential oil starting at a concentration of 40.0 μl/ml caused a significant reduction (p < 0.05) in the values of the egg mass weight and egg production index. The viability of the eggs was affected in all the treated groups, with significantly lower hatching rates (p < 0.05) in relation to the control group. The control percentages at concentrations of 10.0, 20.0, and 30.0 μl/ml were 54, 57, and 72 %, and reached 100 % at the highest two concentrations (60.0 and 80.0 μl/ml). Therefore, it can be concluded that the essential oil from the leaves of L. sidoides has acaricidal activity on R. microplus and D. nitens.

The aim of this study was to evaluate the acaricidal activity of eugenol, with different solubilizations and concentrations, on Rhipicephalus microplus and Dermacentor nitens larvae and to determine the lethal time. The study consisted of four experiments, and the mortality was assessed using the larval packet test with adaptations. The mortality observed in the first experiment was 100 % for all the groups treated with eugenol solubilized in different solvents. In the second, the hydroethanolic formulation of eugenol was used, and the mortality rates for R. microplus and D. nitens was 100 % starting from the concentration of 5.0 μl/ml. In the third experiment, the mortality was 100 % for larvae of both R. microplus and D. nitens after 1 h of contact. And in the fourth experiment, the mortality was above 90 % and statistically similar (p > 0.05) for the four methods the test evaluated.

Tick infestations in cattle and sheep pose serious health problems when agents of diseases are transmitted. In addition, blood feeding of ticks induces enormous economic losses due to reduced weight gain of infested animals. The present study was designed to investigate the effects of exposure to hairs clipped from cattle and sheep treated with flumethrin (Bayticol®) on European ticks. The dose used was 10 ml/100 kg body weight for both animal species. At intervals of 7 days (days 7, 14, 21, 28 and 35), hairs were cut off from treated and untreated animals along the backline and from the feet just above the claws. These hairs were mingled with stages of the tick species Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus. It was found that in the cases of I. ricinus and D. reticulatus, all specimens died within 5-12 h when coming into contact with cattle hair from the feet or back of animals treated 3 weeks ago and within 6 to 9 h after contact to sheep hair from back or feet. After 4 weeks, the specimens of both tick species that had contact with hair of treated sheep and cattle, independent from the origin backline or feet, were dead after 8 h except for one tick that had contact to hair from feet of cattle. It remained fully motile after a 12-h contact even for the observation time on another 5 days. When having contact to hair of animals treated 5 weeks before, several specimens of Ixodes and Dermacentor survived an exposition of 12 h. There were more survivors in the case of ticks tested on hair of the feet than in the case of contacts with hair of the backline. The exposure of R. sanguineus to hair obtained from animals treated 2 weeks earlier resulted in death in 2-4 h. However, most R. sanguineus ticks when coming in contact with treated hairs (collected from animals treated 3, 4 or 5 weeks earlier) from back or feet survived for atleast 5 days even after exposure for 12 h. These experiments confirmed the positive protection results obtained in former studies with typical cattle ticks in the tropics and/or subtropics. In addition to the killing effects described above, it was noted that flumethrin had a significant repellent effect. If ticks were mingled with treated hair, they tried to flee away and did not seek shelter inside the hair as the controls did in untreated hair.

Four studies were conducted to show the effectiveness of a novel combination of fipronil, amitraz and (S)-methoprene in a spot-on formulation (CERTIFECT™, Merial Limited, GA, USA) for the therapeutic and preventive control of Ixodid tick species affecting dogs in Europe: Ixodes ricinus, Dermacentor reticulatus and Rhipicephalus sanguineus. In each, untreated control dogs were compared to others treated with the novel combination. All dogs were infested with 50 adult, unfed ticks prior to treatment and at 7-day intervals after treatment. Ticks on all dogs were counted at 18, 24 and 48 h after treatment (therapeutic efficacy) or infestation (preventive efficacy). Therapeutic efficacy of fipronil, amitraz and (S)-methoprene was excellent as shown by significant (p<0.05) and greater than 97% and up to 100% reductions in the 48 h tick counts and significant (p<0.05) detachment/death of ticks evident at 18-24h after treatment for all three tick species. Preventive efficacy was demonstrated by significant (p<0.05) and greater than 93% and up to 100% reductions in tick counts at 48 h after repeat infestations out to 35 days after treatment for I. ricinus and out to 42 days after treatment for D. reticulatus and R. sanguineus. The time to substantial disruption of establishment of new tick infestations after treatment was less than 18-24h and was maintained for up to 28 days after treatment of I. ricinus and D. reticulatus infestations, and 4h to at most 18 h and maintained up to 35 days after treatment of R. sanguineus. Similar preventive efficacy profiles for each of the Ixodid species tested suggest that CERTIFECT kills all Ixodid species starting 4h after contact as demonstrated for R. sanguineus., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Four groups of seven dogs were treated topically with a novel combination of fipronil, amitraz and (S)-methoprene in a spot-on formulation (CERTIFECT™, Merial Limited, GA, USA) on 28, 21, 14 and 7 days prior to tick infestation, respectively and acaricidal efficacy and transmission blocking compared with an untreated control group (seven dogs). All dogs were infested with adult Dermacentor reticulatus ticks harbouring Babesia canis canis. Babesia canis canis was transmitted by D. reticulatus to all seven untreated control dogs, confirmed following demonstration of clinical signs, by the detection of B. canis parasites in thin blood smears and B. canis canis PCR-RLB DNA assay on blood and the development of B. canis canis antibody titres by 14-21 days after tick infestation. The majority of treated dogs remained sero-negative for 42 days after infestation. Therefore, the treatment of dogs with CERTIFECT applied up to 28 days prior to infestation with D. reticulatus harbouring B. canis canis, successfully prevented the development of clinical signs of canine babesiosis., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A novel combination of fipronil, amitraz and (S)-methoprene (CERTIFECT™, Merial Limited, GA, USA) was evaluated for the prevention of attachment of ticks and its ability to cause detachment of ticks. For the two prevention of attachment studies, 20 purpose-bred beagles were allocated each to two equal groups based on pretreatment tick counts (treated and untreated). Each dog was exposed to 50 adult Rhipicephalus sanguineus and Dermacentor variabilis weekly starting 24h after treatment. In study 1 infestations with R. sanguineus were discontinued after Day 7 but continued to Day 28 for D. variabilis in both studies. Counts of ticks by species were made 2, 4 and 24h after exposure to ticks. Ticks not attaching to dogs were evaluated for viability. For the evaluation of detachment study, 16 purpose-bred beagles were allocated each to two equal groups based on pretreatment tick counts (treated and untreated). Each dog was infested with 50 unfed R. sanguineus and D. variabilis adults on Day -2. Ticks were thumb counted without removal on all dogs on Day -1, and at 4, 12, and 24h after treatment. Ticks were counted and removed at 48 h after treatment. Dogs treated with the novel combination had significantly (p<0.05) lower total numbers of attached R. sanguineus and D. variabilis than untreated controls at 4h through Day 7. For R. sanguineus, percent reduction of attachment at 24h after infestation through Day 29 ranged from 94.5% to 100%. For D. variabilis, the percent reduction of attachment at 24h through Day 22 was above 98.0%. These studies demonstrate that novel combination can disrupt attachment of R. sanguineus and D. variabilis for up to 28 days following treatment. Of those ticks that are exposed to the treatment, even if they do not attach to the dog and remain in the environment, greater than 90% (p<0.05) die within 24h for 2-3 weeks following treatment. Also, for those dogs infested with ticks at the time of treatment, the novel combination causes significant detachment (p<.05) starting at 12h and reaching 98.9% by 48 h after treatment. This product provides an effective means for controlling ticks infesting dogs and limiting the spread of tick transmitted diseases. Additionally, the mortality of ticks exposed to CERTIFECT will reduce infestation of the dog's environment., (Copyright © 2011 Elsevier B.V. All rights reserved.)

2-Tridecanone and 2-undecanone are both found naturally in the trichomes of wild tomato plants and are important in plant resistance to herbivory. 2-Undecanone is the U.S. Environmental Protection Agency (EPA)-registered active ingredient in the commercially available arthropod repellent, BioUD(®) . The goal of this study was to examine the tick repellency of 2-tridecanone. Two-choice bioassays were conducted using 8% 2-tridecanone vs. the repellent carrier (absolute ethanol) and compared with two-choice studies using 8% 2-undecanone vs. absolute ethanol. Unfed, host-seeking adult (mixed sex) Amblyomma americanum (L.) (Acari: Ixodidae) and Dermacentor variabilis Say (Acari: Ixodidae) were used to evaluate repellency and time to repellent failure at room temperature. The present study shows in filter paper assays (0.63 mg test compound/cm(2) ) that 2-tridecanone was 87% repellent to A. americanum at 12 h after application, but had no statistically significant repellency at 15 h and 24 h, and was 72% repellent to D. variabilis at 15 h, but had no statistically significant repellency at 24 h. By contrast, 2-undecanone was 74% and 75% repellent to A. americanum and D. variabilis, respectively, at 2 h after application, but no statistically significant repellency was noted at 2.5 h and 3 h. In two-choice assays on cheesecloth, 2-tridecanone at 0.25 mg/cm(2) was 85% repellent to A. americanum 6 h after application, demonstrating its potential use as an arthropod repellent that can be used on clothing without the need for formulation. No statistically significant repellency was found at 9 h or 12 h. The potential use of 2-tridecanone as a tick repellent is discussed.

The present paper investigates the efficacy of common anti-tick repellents in Europe and in the USA. There were tested Ixodes ricinus, Dermacentor reticulatus, and Rhipcephalus sanguineus when they are placed onto hands and clothes of male and female humans being treated with common tick repellents. It was seen that DEET needed high concentrations to repel ticks, while essential oils are mostly inefficient. On the other hand saltidin=icaridin, p-menthan-diol and IR 3535 showed long-lasting effects, which in the case of combinations of saltidin and Vitex extracts were even increased.

Background: Varying reports concerning the duration and reliability of different permethrin preparations' efficacy can be found in the literature. The aim of this study was to investigate the dynamics of the distribution and efficacy of four different spot-on formulations with permethrin as the active ingredient formulated with different solvents. To examine the influence of these solvents on the speed of distribution and the acaricidal activity of permethrin in the coat, an in vivo study under laboratory conditions was performed. Six dogs per test period were treated with the recommended dose and 1, 14 and 28 days after treatment dogs were infested with Dermacentor reticulatus ticks: a) on the back, near the application site, and b) on the hind leg, the greatest possible distance from the application site. Efficacies were determined 6 hours after tick infestation to examine the repellent effect and the speed of kill of the products which plays an important role in the context of tick transmitted diseases., Results: After six hours of exposure, a significant acaricidal efficacy (p < 0.001) could be observed in all treated groups over the whole duration of the study, regardless of which product was used. While the arithmetic mean of attached ticks was < 3 on Day 1, numbers increased over the course of the study to a mean of > 9 on Day 28. However, most of these ticks were dead even 28 days after treatment, as the mean of live attached ticks was still < 2. Significant differences could neither be found between the different permethrin spot-on formulations, nor between the two parts of the body (p > 0.05)., Conclusions: All products were able to kill ticks within six hours following infestation from Day 1 to Day 28 after treatment. Additionally, no significant difference between the tick numbers on the back and the hind leg could be found at any time, which implies a homogenous distribution of permethrin over the body. The efficacy of all four products was comparable during the whole study period, showing that the different solvents do not significantly affect the dynamics of distribution.

Acaricides can be conveyed to ticks via the blood of their hosts. As fruit and kernel extracts from the Meliaceae family, and, in particular the tetranortriterpenoid azadirachtin (AZA) inhibits tick egg production and embryogenesis in the Ixodidae ticks, we investigated the effects of Neem Azal, an extract containing 43% AZA, given as a feed additive to lambs artificially infested with engorging adult Dermacentor vairiabilis ticks. After tick attachment, the lambs were allotted to three dietary treatments: AZA0 (control, n=10), AZA0.3 (n=5), and AZA0.6 (n=5), with feed containing 0%, 0.3%, and 0.6% AZA on DM basis, respectively. In half of the AZA0 lambs, ticks were sprayed on day 4 after attachment with an ethanol:water:soap emulsion containing 0.6% AZA (AZA0S). In spite of its very pungent odor, the neem extract was well accepted by all but one lamb. No differences were found between treatment groups in liver enzymes in blood, and there was no indication of toxicity. The plasma AZA concentrations after 7 and 14 days of feeding AZA were (4.81 and 4.35 microg/mL) for the AZA0.6 and (3.32 and 1.88 microg/mL) for the AZA0.3 treatments, respectively (P<0.0001). Treatments were not lethal to ticks, but tick weights at detachment were 0.64, 0.56, 0.48, and 0.37 g for ticks from the AZA0, AZA0.3, AZA0S, and AZA0.6 treatments (P<0.04), respectively, suggesting that blood AZA impaired blood-feeding. The highest mortality rate after detachment was for AZA0.6 (P<0.09). As AZA affects embryo development and ticks at the molting stages, we expect that following treatments of hosts for longer periods, one-host ticks will be more affected than the three-host tick D. variabilis.

Rocky Mountain spotted fever is caused by the tick-borne bacterium Rickettsia rickettsii. Symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. The disease is prevalent in most of the USA, especially during warmer months. The trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. Other signature symptoms include headache and abdominal pain. The antibiotic therapy of choice for R. rickettsii infection is doxycycline. Preventive measures for Rocky Mountain spotted fever and other tick-borne diseases include: wearing long-sleeved, light colored clothing; checking for tick attachment and removing attached ticks promptly; applying topical insect repellent; and treating clothing with permethrin.

This study evaluated overall efficacy, percentage of dogs free of live ticks, retention of ticks, and efficacy against retained ticks of fipronil (9.8% w/w) + (S)-methoprene (8.8% w/w) and imidacloprid (8.8% w/w) + permethrin (44% w/w) spot-on topical solutions against Dermacentor variabilis-infested dogs. Tick control was significantly greater (P < .05) on dogs treated with fipronil + (S)-methoprene than on control dogs for the entire 30-day study period. Conversely, the combination product of imidacloprid + permethrin demonstrated activity significantly (P < .05) different from that seen on control dogs only up to day 23. Significantly (P < .05) more dogs treated with fipronil + (S)-methoprene were free of live ticks compared with controls on days 3, 9, and 16. There was never a significant difference (P > .05) between control and imidacloprid + permethrin-treated dogs in numbers of dogs free of live ticks. After the initial 10-minute tick exposure, lower numbers of ticks were retained on the imidacloprid + permethrin-treated dogs than on the fipronil + (S)-methoprene-treated dogs. However, when evaluating the effectiveness of the acaricides on "retained ticks," it appears that while some of the ticks were rapidly knocked down on the imidacloprid + permethrin-treated dogs, efficacy against ticks still retained at 10 minutes was never greater than 50%.

The functional role of an endosymbiotic conidial fungus (Scopulariopsis brevicaulis) prevalent within the integumental glands and hemocoel of the American dog tick (Dermacentor variabilis) was investigated to explore the nature of this tick/fungus association. D. variabilis is normally highly resistant to Metarhizium anisopliae, a widely-distributed entomopathogenic fungus, but when mature female ticks harboring S. brevicaulis were fed a solution containing a mycotoxin (Amphotericin B) to purge this mycobiont internally, the ticks inoculated with M. anisopliae displayed classic signs of pathogenicity, as evidenced by recovery of M. anisopliae from ticks by internal fungus culture, greatly accelerated net transpiration water loss rates (nearly 3x faster than ticks containing S. brevicaulis naturally) and elevation of critical equilibrium humidity (CEH) closer to saturation, implying a reduced capacity to absorb water vapor and disruption of water balance (water gain not equal water loss) that resulted in tick death. The presence of S. brevicaulis within the tick was previously puzzling: the fungus is transmitted maternally and there is no apparent harm inflicted to either generation. This study suggests that S. brevicaulis provides protection to D. variabilis ticks against M. anisopliae. Thus, the S. brevicaulis/tick association appears to be mutualistic symbiosis. Given that both organisms are of medical-veterinary importance, disruption of this symbiosis has potential for generating novel tools for disease control.

This study evaluated the effectiveness of two topical spot-on formulations, imidacloprid (8.8% w/w)--permethrin (44.0% w/w) and fipronil (9.8% w/w)--(S)-methoprene (8.8% w/w), to repel, prevent the attachment of, and kill adult Rhipicephalus sanguineus and Dermacentor variabilis on dogs. Twelve purpose-bred beagles were distributed into three groups of four dogs each; one group served as untreated controls and each of the other two groups received one of the test products. Dogs were exposed to 25 adult ticks of each species for 10 minutes on posttreatment days 3, 7, 14, 21, and 28. Nonattached or repelled ticks were collected and evaluated for viability, and on-dog tick counts were conducted at 3, 24, and 48 hours after tick exposure. The imidacloprid-permethrin formulation provided significant repellency of R. sanguineus and D. variabilis for up to 3 and 4 weeks after treatment, respectively; and provided good overall control for R. sanguineus and D. variabilis during the study period. The fipronil--(S)-methoprene formulation provided good overall tick control during the study period.

Ticks impact human and animal health worldwide and new control methods are needed to circumvent drawbacks of tick control by acaricide application including selection of drug resistant ticks and environmental pollution. Using RNA interference we silenced the expression of a single gene, subolesin, and produced ticks with diminished reproductive performance and prevented successful mating and production of viable offspring. We propose a sterile acarine technique (SAT) for reduction of tick populations by release of subolesin-silenced ticks. Conservation of subolesin among tick species suggests that SAT may be useful for control of many medically and economically important tick species.

We colocalized nitric oxide synthase (NOS) activity in epithelial cells that surround the salivary gland duct in female Dermacentor variabilis with NADPH diaphorase histochemistry and immunohistochemistry using a polyclonal anti-endothelial NOS. Using size-exclusion chromatography, a fraction with a molecular mass of about 185 kDa that had diaphorase activity was eluted from tick salivary gland homogenate. This fraction converted arginine to citrulline with the production of nitric oxide (NO), which was detected by using electron spin resonance spectroscopy. The complete activity of the diaphorase fraction was dependent on NADPH, FAD, tetrahydrobiopterin, calmodulin, (CaM), and Ca(2+), but was not dependent on dithiothreitol. The arginine analog N(G)-monomethyl-L-arginine inhibited the activity of this fraction. NO and arginine activated soluble guanylate cyclase to produce cGMP in dopamine-stimulated isolated salivary glands. Dopamine-stimulated isolated salivary glands treated with tick saline containing either EDTA, the NOS inhibitor N(G)-nitro-L-arginine methyl ester, or the calcium/CaM binding inhibitor W-7 showed no increase in cGMP. The NO donor sodium nitroprusside significantly increased cGMP levels in unstimulated isolated salivary glands. A possible function for NO in salivation by this ixodid tick is discussed., (Copyright 2000 Academic Press.)

The effects of metepa on the cytology and fertility of male Dermacentor variabilis treated as unfed adults are determined. Evidence of cellular damage is found in testicular areas where actively dividing cells and some enlarging spermatocytes are found. The amount of cellular damage correlates positively to the concentration of the chemosterilant and results in decreases numbers of spermatids. In crosses of treated males to untreated females, resulting egg masses hatch normally; however, the percentage of females producing egg masses that hatch is reduced.

Fumigation of eggs with the antiallatotropin precocene 2(P2) disrupted development late in embryogenesis in the American dog tick Dermacentor variabilis. An age (time) gradient of responses in embryos was noted. Subsequent developmental effects included partial failure of stadia to attach, feed, ecdyse and partial-to-complete sterility in adult females. No precocious metamorphosis or adultiformes were observed, but a change in sex ratio of surviving adults was noted. A subsequent application of juvenile hormone 3 (JH 3) to P2-sterilized females enabled them to feed and successfully complete the gonadotrophic cycle. Restoration of gonadotrophic function by exogenous JH 3 suggested the possibility of a naturally occurring JH in D. variabilis.