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

Abstract

Domestic dog breeds are hosts for the brown dog 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 volatile tick repellents. We report the use of prototype slow-release formulations of these compounds to reduce the burden of R. sanguineus s. l. on English cocker spaniel dogs. Twelve dogs were randomly assigned to two groups with six dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted twice a day for 45days. The counts on the number of tick stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. The 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 compounds did not interfere with the distribution of the ticks on the body of the dogs, as a similar percentage of ticks was found on the anterior half of the dogs (54.5% for the control group and 56.2% for the treated group). The biological and reproductive parameters of the ticks were not affected by the repellents. 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.

Persistence and efficacy of a new formulation based on dog allomonal repellents against Rhipicephalus sanguineus sensu lato tick

“…The results of this study corroborate results from our earlier work (OLIVEIRA et al, 2017), where it was shown that slow-release formulations of benzaldehyde and 2-hexanone, produced by beagles that are less preferred by brown dog ticks, R. sanguineus s. l., can reduce tick loads on susceptible dogs. However, result differences between this study and the earlier work were observed.…”

“…The difference in persistence between the two studies may be because in the current study, a higher dose and release rate of the repellent compounds was used. However, what cannot be completely ruled out is that the observed greater persistent effect could be due to an increase in the number of ticks released in the experiments and an improvement in the counting of immature tick stages, compared to Oliveira et al (2017). Further work is required to rule out the effect of tick numbers.…”

“…Every week, for 35 days, 4000 larvae, 200 nymphs and 60 adults (30 males and 30 females) were released onto the walls of each stall, totalling six artificial infestations. The number of ticks was stipulated in our previous work, but with an increase in the number of immature stages (OLIVEIRA et al, 2017). Collars containing the sachets with benzaldehyde and 2-hexanone were placed simultaneously with the second infestation and withdrawn after the fifth infestation.…”

“…Previously we showed that by attaching slow-release formulations of 2-benzaldehyde and 2-hexanone to collars, we could reduce the number of ticks on dogs (OLIVEIRA et al, 2017), thus providing the first demonstration of using an allomonal repellent formulation to reduce tick infestation on susceptible dogs. In this new study, we evaluated the persistence and efficacy of a new allomonal formulation that emitted higher release rates of the two compounds, compared to the formulations tested by us previously, for reducing R. sanguineus s. l. loads on English cocker spaniels.…”

Identification of a non-host semiochemical from tick-resistant donkeys (Equus asinus) against Amblyomma sculptum ticks

“…Recently, it was reported for the first time that semiochemicals play an important role in selection of suitable hosts by ticks (Borges et al, 2015), with less-preferred beagle hosts producing volatile cues 2-hexanone and benzaldehyde that act as a repellent allomone against the brown dog tick, Rhipicephalus sanguineus sensu lato. Oliveira Filho et al (2017) demonstrated that a slow release formulation of those compounds decreases R. sanguineus s. l. load on susceptible dogs exposed in an artificially infested environment. For tsetse flies, Glossina morsitans, cattle are the preferred hosts, and repellents produced by non-hosts such as the waterbuck Kobus defassa have been shown to reduce tsetse fly infestations on cattle.…”