Brown dog tick, Rhipicephalus sanguineus sensu lato, infestation ofsusceptible dog hosts is reduced by slow release of semiochemicalsfrom a less susceptible host

Authors: FILHO, JAIRES - Federal University Of Goias; FERREIRA, LORENA - Federal University Of Goias; SARRIA, ANDRE - Rothamsted Research; PICKETT, JOHN - Rothamsted Research; BIRKETT, MICHAEL - Rothamsted Research; MASCARIN, GABRIEL - Embrapa; Perez De Leon, Adalberto - Beto; BORGES, LIGIA - Federal University Of Goias

Submitted to: Ticks and Tick Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: The brown dog tick feeds on blood and transmits diseases when it bites dogs, humans, and other animals. Brown dog tick infestation levels in dogs vary according to the dog breed. We showed before that Beagles are less susceptible to brown dog tick infestations than English cocker spaniels due to higher quantities of two substances (2-hexanone and benzaldehyde) in their odor that act as tick repellents. Here, we tested the ability of a slow-release formulation of those compounds to reduce brown doing tick infestation levels in English cocker spaniel dogs. Twelve dogs, kept in kennels, were randomly assigned to two groups (control and treated) with six dogs each. Three dogs of each group were housed per stall, and rotated between the stalls every seven days. Slow-release formulations of the compounds were attached pairwise to collars placed on dogs in the treated group; dogs in the control group were treated the same except that the collars lacked the novel repellents. Five environmental infestations were performed at different intervals with all the parasitic life stages of the brown dog tick: larvae, nymphs, and adult males and females. Collars were replaced by new ones after 15 days, and removed after the last infestation. The dogs were inspected twice a day for 45 days. Engorged ticks were collected to evaluate biological and reproductive parameters by statistical methods. The average tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed during the last count, and for adults, lower average counts were observed consistently. The repellents did not interfere with the biological and reproductive parameters of the brown dog tick. This study proved the concept of using a novel repellent-based formulation to reduce brown dog tick infestations on susceptible dogs.

Technical Abstract: Domestic dog breeds are hosts for the tick Rhipicephalus sanguineus sensu lato, but infestation levels vary among breeds. Beagles are less susceptible to tick infestations than English cocker spaniels due to enhanced production of 2-hexanone and benzaldehyde that act as tick repellents. We report the use of a slow-release formulation of these compounds to reduce the burden of R. sanguineus s. l. on English cocker spaniel dogs. Twelve dogs, kept in kennels, were randomly assigned to two groups (control and treated) with six dogs each. Three dogs of each group were housed per stall, and rotated between the stalls every seven days. Slow-release formulations of the compounds were attached pairwise to collars placed on dogs in the treated group; the control group received clean formulations. Five environmental infestations were performed with 2,000 larvae, 100 nymphs, 30 males and 30 females. The first infestation was made 10 days before the second one, with subsequent infestations being done every seven days. Collars were replaced by new ones after 15 days and removed after the fifth infestation. The dogs were inspected twice a day for 45 days. Engorged ticks were collected to evaluate biological and reproductive parameters. Count data on the number of ticks stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. Mean tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed at the fifth count, and for adults, lower average counts were observed in all counts. The repellents did not interfere with the biological and reproductive parameters of the tick. This study highlights for the first time the potential use of a novel allomone (repellent)-based formulation for reduction of tick infestation on susceptible dogs.