Volume: 57 Issue: 2
Year: 2026, Page: 294-297, Doi: https://doi.org/10.51966/jvas.2026.57.2.294-297
Received: Feb. 5, 2026 Accepted: May 4, 2026 Published: June 30, 2026
The brown dog tick, Rhipicephalus sanguineus, is an important ectoparasite of dogs and has considerable veterinary and public health significance. Pyrethroid acaricides, particularly deltamethrin, are widely used for their control; however, the development of resistance has increasingly compromised their effectiveness. Deltamethrin resistance in R. sanguineus isolates has already been reported in Kerala. The present study assessed the role of synergist piperonyl butoxide (PBO), a well-known cytochrome P450 inhibitor, in enhancing deltamethrin toxicity against resistant R. sanguineus populations collected from different regions of Kerala. Ten field isolates were evaluated using a modified larval packet test. All isolates tested with deltamethrin exhibited less than 90 per cent mortality at the discriminating dose of 600 ppm and were considered resistant. Piperonyl butoxide, when tested alone, produced dose-dependent larval mortality, achieving complete mortality at concentrations ≥400 ppm. When deltamethrin was combined with a non lethal dose of PBO (200 ppm), a pronounced reduction in LC50 values was observed across all isolates (p < 0.0001). Synergistic ratios ranged from 93.60 to 5331.08, indicating strong potentiation of deltamethrin toxicity. These findings suggest that cytochrome P450-mediated metabolic detoxification plays a major role in deltamethrin resistance and that PBO can effectively restore susceptibility in resistant R. sanguineus populations.
Keywords: Rhipicephalus sanguineus, acaricide resistance, deltamethrin, piperonyl butoxide, synergist
Amrutha, A., Bindu, L., Kajal, T.A., Siju, J., Aravindakshan, T.V. & Jain, J. (2021). Deltamethrin resistance in Rhipicephalus sanguineus and Rhipicephalus (Boophilus) microplus tick populations in Kerala. Journal of Veterinary and Animal Sciences, 52(1): 19-25. https://doi.org/10.51966/jvas.2021.52.1.19-25
Eiden, A.L., Kaufman, P.E., Oi, F.M., Dark, M.J., Bloomquist, J.R. & Miller, R.J. (2017). Determination of metabolic resistance mechanisms in pyrethroid-resistant and fipronil-tolerant brown dog ticks. Medical and Veterinary Entomology, 31(3):243-251. https://doi.org/10.1111/mve.12240
Food and Agriculture Organization of the United Nations. (2004). Acaricide resistance: Diagnosis, management and prevention. Guidelines: Resistance management and integrated parasite control in ruminants (pp. 25-77). Animal Production and Health Division, Agriculture Department.
Le Gall, V.L., Klafke, G.M. & Torres, T.T. (2018). Detoxification mechanisms involved in ivermectin resistance in the cattle tick, Rhipicephalus (Boophilus) microplus. Scientific reports, 8(1), 12401. https://doi.org/10.1038/s41598-018-30907-7
Lovis, L., Guerrero, F.D., Miller, R.J., Bodine, D.M., Betschart, B. & Sager, H. (2012). Distribution patterns of three sodium channel mutations associated with pyrethroid resistance in Rhipicephalus (Boophilus) microplus populations from North and South America, South Africa, and Australia. International Journal for Parasitology: Drugs and Drug Resistance, 2, 216-224. https://doi.org/10.1016/j.ijpddr.2012.08.001
Sandhu, H.S. (2006). Veterinary Pharmacology and Therapeutics (2nd ed.). New Delhi: Kalyani Publishers. 1283 p.
Shaik, N.R., Lakshmanan, B., Nair, N.S., Anand, A., Radhika, R. & Syamala, K. (2024). Novel polymorphisms in the octopamine receptor gene of amitraz-resistant population of Rhipicephalus sanguineus sensu lato in South India. Experimental Parasitology, 261, 108763. https://doi.org/10.1016/j.exppara.2024.108763
Shakya, M., Nandi, A., Fular, A., Kumar, S., Bisht, N., Sharma, A.K., Singh, K., Kumar, R., Kumar, S., Juliet, S. & Ghosh, S. (2022). Synergistic property of piperonyl butoxide, diethyl maleate, triphenyl phosphate and verapamil hydrochloride with deltamethrin and ivermectin against Rhipicephalus microplus ticks. Ticks and Tick-borne Diseases, 13, 102006. https://doi.org/10.1016/j.ttbdis.2022.102006
Sunkara, P., Chennuru, S., Krovvidi, S. & Chitichoti, J. (2022). Cypermethrin and ivermectin resistance in field populations of Rhipicephalus sanguineus sensu lato (Latrielle, 1806) collected from dogs in south India. Veterinary Research Communications, 46(1), 67-78. https://doi.org/10.1007/s11259-021-09830-2
Vatsya, S. & Yadav, C.L. (2011). Evaluation of acaricide resistance mechanisms in field populations of Rhipicephalus (Boophilus) microplus collected from India. International Journal of Acarology, 37(5), 405–410. https://doi.org/10.1080/01647954.2010.521518
Waldman, J., Klafke, G.M. & da Silva Vaz, I., Jr. (2023). Mechanisms of acaricide resistance in ticks. Acta Scientiae Veterinariae, 51, 1900. https://doi.org/10.22456/1679-9216.128913
© 2026 Anjaly et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Anjaly, S., Radhika, R., Bindu, L., Asha, R., Priya, M.N. Suresh, N.N. & Prathyusha, S. (2026). Evaluation of the role of piperonyl butoxide as synergist in deltamethrin resistant Rhipicephalus sanguineus. Journal of Veterinary and Animal Sciences, 57(2),294-297 https://doi.org/10.51966/jvas.2026.57.2.294-297