Preventing tick attachment to dogs using essential oils

Abstract

Preventing tick bites using repellents could make a valuable contribution to an integrated tick management programme for dogs. Here, the ability of a range of essential oils or active ingredients of commercially available repellents, to abolish the orientation and taxis of the tick Ixodes ricinus towards sebum extracted from dog hair was examined in laboratory bioassays. Substantial differences between oils were observed, but turmeric oil was both able to prevent a climbing response by ticks and had a longer residual activity than other oils. A blanket-drag field assay was then used to compare the attachment of ticks to blankets impregnated with one of: turmeric oil, DEET (positive control), orange-oil or excipient only (negative controls). In total, 899 ticks were counted, with an average of 23.3 (SD ± 21.3) ticks per blanket drag for excipient-only (n = 16), 26.9 (SD ± 28.6) for orange oil (n = 16), 2.6 (SD ± 2.0) for turmeric oil (n = 16) and 3.4 (SD ± 3.7) for DEET (n = 16). Finally, in a participatory in vivo trial, tick acquisition by 15 untreated control dogs was compared with 24 dogs sprayed with turmeric-oil and 16 dogs sprayed with orange oil (both 2.5% v/v diluted in water with a 1% coco glucoside excipient) before each walk in known tick infested areas. The percentage of dogs with ticks attached to the legs or belly of dogs sprayed with turmeric oil suspension (15% ± 19.4%) was significantly lower than that of ticks attached to the same areas of dogs sprayed with orange oil suspension (85% ± 19.4%) and unsprayed dogs (73% ± 26.2%) (P < 0.05). The data indicate that turmeric-oil may form a valuable component of a tick management programme for domestic dogs.

Essential oils as tick repellents on clothing

“…Across both experiments, attachment to excipient-only blankets averaged 25.2 (SD ± 26.2) ticks per 10 m walk, which is comparable to the results reported for previous sampling efforts in similar habitat at this site (Goode et al 2018). The tick counts on trousers give a better indication of the risk to humans of walking in these habitats than analyses based on blanket-dragging alone, and for trousers attachment averaged 6.2 (SD ± 10.2) ticks per 10 m walk.…”

“…Here, no significant decline in residual repellency of 5% spearmint and oregano oil was detected for blankets and trousers over a 24 h period following oil application, showing that 5% spearmint and oregano oils impart protection against I. ricinus for an extended period post-application. Previous work has shown thyme oil to maintain 100% repellency against I. ricinus after 1 h of drying (Goode et al 2018).…”

“…Numerous laboratory studies have highlighted the tick-repellent efficacy of different essential oils (e.g., Pålsson et al 2008;El-Seedi et al 2012;Štefanidesová et al 2017) suggesting that they hold considerable potential for development as practical tick repellents. However, field investigations of repellency are currently very limited (Ellse and Wall 2013;Goode et al 2018).…”

“…The repellency of various essential oils to ticks has been demonstrated previously. In a laboratory bioassay, 5% (v/v) spearmint oil was shown to inhibit the natural climbing behaviour of 100% of I. ricinus on which it was tested (Goode et al 2018). Separately, El-Seedi et al (2012) applied spearmint oil at 15 μg/cm 2 to cloths fixed over vials; 89.5% of ticks within vials were repelled after 5 min.…”

“…During subsequent blanket-drag trials, spearmint oil demonstrated 59.4% repellency in comparison to an excipient-only solution. In laboratory bioassays, thyme oil has demonstrated 68.2% repellency at 3% (v/v) and 100% repellency at 5% (v/v) against Dermacentor reticulatus and I. ricinus, respectively (Štefanidesová et al 2017;Goode et al 2018). However, field trails are relatively rare; turmeric oil was shown to be both able to prevent the attachment of ticks to impregnated blankets and to significantly reduce the rate of tick acquisition by dogs sprayed before each walk, in known tick-infested areas (Goode et al 2018).…”