Repellency to ticks (Acari: Ixodidae) of extracts of nigella sativa L.(Ranunculaceae) and the anti-inflammatory DogsBestFriend™

Authors: CARROLL, JOHN - Retired ARS Employee; BABISH, JOHN - Brookton Laboratories; PACIORETTY, LINDA - Brookton Laboratories; Kramer, Matthew

Submitted to: Experimental and Applied Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2016
Publication Date: 9/1/2016
Citation: Carroll, J., Babish, J.G., Pacioretty, L.M., Kramer, M.H. 2016. Repellency to ticks (Acari: Ixodidae) of extracts of nigella sativa L.(Ranunculaceae) and the anti-inflammatory DogsBestFriend™. Experimental and Applied Acarology. 70:89-97.

Interpretive Summary: Tick-borne diseases pose a serious threat to humans and domesticated animals throughout much of the habitable world. Repellents provide a critical means of protection against tick bite. Many plants produce chemicals that protect them from herbivorous arthropods; some of these chemicals also repel blood-feeding insects and ticks. In field observations, ticks, mosquitoes and other flies appeared to be repelled from dogs treated with the anti-inflammatory product DogsBestFriend™ (DBF). In laboratory behavioral tests, we evaluated DBF, three extracts of Nigella sativa (the plant from which the DBF formulation is derived), and the widely used repellent deet for their effectiveness in repelling four species of ticks that bite dogs and humans. DBF repelled lone star ticks. Two of the Nigella extracts repelled lone star ticks at concentrations similar to those observed for deet. Blacklegged ticks, brown dog ticks, and American dog ticks were also repelled by the two extracts. One extract repelled 66.7% of lone star tick nymphs eight days after application. These findings are of interest to researchers investigating arthropod repellents and to manufacturers developing repellents.

Technical Abstract: 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 lone star tick, Amblyomma americanum (L.), nymphs. In vertical filter paper bioassays, the three extracts applied at a concentration 0.413 mg extract/cm2 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 American dog ticks (mixed sexes), Dermacentor variabilis (Say), required a higher concentration to be repelled effectively; two extracts, applied at 0.827 mg extract/cm2 filter paper, repelled =90% of the D. variabilis. In contrast, all extracts applied at much lower concentration (0.206 mg extract/cm2 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/cm2 filter paper, whereas the other repelled 66.7% of the nymphs at 192 h after application. At 0.206 mg extract/cm2 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/cm2, 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.