{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T15:56:09Z","timestamp":1792511769771,"version":"4.5.0"},"reference-count":16,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2024,11,20]],"date-time":"2024-11-20T00:00:00Z","timestamp":1732060800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2024,11,20]],"date-time":"2024-11-20T00:00:00Z","timestamp":1732060800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Parasites Vectors"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>One bioassay for detecting acaricide resistance in livestock ticks is the adult immersion test (AIT), wherein engorged ticks are briefly immersed into a solution of a particular acaricidal compound and examined for mortality, their egg-laying capacity and offspring hatchability in vitro. Usually, the recommended label dose or an established discriminating dose of an acaricide is used to determine high mortality (\u2265\u200995%) of susceptible tick strains. Such a test intends to detect the presence of resistance in a tick population. However, the adult immersion test does not directly translate the bioassay results to the predicted efficacy in the field. In this paper, we used the AIT as an initial screening bioassay supplemented with the resistance intensity test (RIT), a novel larval-based bioassay, wherein the resistance level can be determined and translated to the expected field efficacy. This was done by adopting World Health Organisation (WHO) guidelines for resistance detection in mosquitoes, which combines a 1\u2009\u00d7\u2009recommended dose with 5\u2009\u00d7\u2009and 10\u2009\u00d7\u2009concentrated doses to reveal low, moderate and high resistance intensity, respectively.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Engorged\n                      <jats:italic>Rhipicephalus microplus<\/jats:italic>\n                      ticks were collected from cattle at six different ranches across Rio Grande do Sul, Brazil, as part of the state\u2019s acaricide resistance surveillance program. Groups of adult ticks from each field collection were subjected to the AIT from each field sample. Additionally, engorged female ticks from each ranch were allowed to lay eggs, and their larval progeny aged 14 to 28\u00a0days were then used in the RIT. Deltamethrin and a combination of cypermethrin, chlorpyrifos and piperonyl butoxide were used in both tests, and the results were statistically analysed.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The in vitro efficacy of deltamethrin against adult ticks in the AIT ranged between 8.74% and 25.38%. The corresponding RIT results on their larval progeny indicated a high resistance level. In the immersion test, the in vitro efficacy of the combination of cypermethrin, chlorpyrifos, and piperonyl butoxide against adult ticks ranged between 49.31% and 100%. The corresponding RIT results on their larval progeny indicated a similar response ranging from fully susceptible to low or moderate resistance. The Pearson correlation coefficient (\n                      <jats:italic>r<\/jats:italic>\n                      \u2009=\u20090.883) showed a high correlation between tick mortality at the 1\u2009\u00d7\u2009recommended concentrations of acaricides in both tests.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The resistance intensity test is a valuable addition to the range of bioassays currently available for detecting acaricide resistance by determining the level of acaricide resistance. This is relevant to whether or not to continue using a particular acaricidal class for controlling cattle ticks.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Graphical Abstract<\/jats:title>\n                  <\/jats:sec>","DOI":"10.1186\/s13071-024-06561-6","type":"journal-article","created":{"date-parts":[[2024,11,20]],"date-time":"2024-11-20T14:49:22Z","timestamp":1732114162000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Resistance intensity test (RIT): a novel bioassay for quantifying the level of acaricide resistance in Rhipicephalus microplus ticks"],"prefix":"10.1186","volume":"17","author":[{"given":"Frans","family":"Jongejan","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura","family":"Berger","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura","family":"Homminga","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Iris","family":"Hulsebos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alita","family":"Petersen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Priscila Teixeira","family":"Ferreira","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jos\u00e9","family":"Reck","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guilherme","family":"Klafke","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2024,11,20]]},"reference":[{"key":"6561_CR1","doi-asserted-by":"publisher","first-page":"S3","DOI":"10.1017\/S0031182004005967","volume":"129","author":"F Jongejan","year":"2004","unstructured":"Jongejan F, Uilenberg G. The global importance of ticks. Parasitology. 2004;129:S3-14.","journal-title":"Parasitology"},{"key":"6561_CR2","doi-asserted-by":"publisher","first-page":"1599","DOI":"10.3390\/ani13101599","volume":"13","author":"T Strydom","year":"2023","unstructured":"Strydom T, Lavan RP, Torres S, Heaney K. The economic impact of parasitism from nematodes, trematodes and ticks on beef cattle production. Animals. 2023;13:1599.","journal-title":"Animals"},{"key":"6561_CR3","doi-asserted-by":"publisher","first-page":"150","DOI":"10.1590\/S1984-29612014042","volume":"23","author":"L Grisi","year":"2014","unstructured":"Grisi L, Leite RC, de Martins JRS, de Barros ATM, Andreotti R, Can\u00e7ado PHD, et al. Reassessment of the potential economic impact of cattle parasites in Brazil. Braz J Vet Parasitol. 2014;23:150\u20136.","journal-title":"Braz J Vet Parasitol"},{"key":"6561_CR4","unstructured":"FAO. Expert consultation on the sustainable management of parasites in livestock challenged by the global emergence of resistance: Part 1: Current status and management of acaricide resistance in livestock ticks \u2013 Virtual meeting. Rome, Italy: FAO. 2022."},{"key":"6561_CR5","doi-asserted-by":"publisher","first-page":"6","DOI":"10.1016\/j.vetpar.2014.03.006","volume":"203","author":"RZ Abbas","year":"2014","unstructured":"Abbas RZ, Zaman MA, Colwell DD, Gilleard J, Iqbal Z. Acaricide resistance in cattle ticks and approaches to its management: the state of play. Vet Parasitol. 2014;203:6\u201320.","journal-title":"Vet Parasitol"},{"key":"6561_CR6","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1007\/s00436-017-5677-6","volume":"117","author":"RI Rodriguez-Vivas","year":"2018","unstructured":"Rodriguez-Vivas RI, Jonsson NN, Bhushan C. Strategies for the control of Rhipicephalus microplus ticks in a world of conventional acaricide and macrocyclic lactone resistance. Parasitol Res. 2018;117:3\u201329.","journal-title":"Parasitol Res"},{"key":"6561_CR7","doi-asserted-by":"publisher","first-page":"128","DOI":"10.1016\/j.vetpar.2014.01.012","volume":"201","author":"J Reck","year":"2014","unstructured":"Reck J, Klafke GM, Webster A, Dall\u2019Agnol B, Scheffer R, Souza UA, et al. First report of fluazuron resistance in Rhipicephalus microplus: a field tick population resistant to six classes of acaricides. Vet Parasitol. 2014;201:128\u201336.","journal-title":"Vet Parasitol"},{"key":"6561_CR8","doi-asserted-by":"publisher","first-page":"73","DOI":"10.1016\/j.ttbdis.2016.09.019","volume":"8","author":"G Klafke","year":"2017","unstructured":"Klafke G, Webster A, Dall Agnol B, Pradel E, Silva J, de La Canal LH, et al. Multiple resistance to acaricides in field populations of Rhipicephalus microplus from Rio Grande do Sul state. Southern Brazil Ticks Tick-Borne Dis. 2017;8:73\u201380.","journal-title":"Southern Brazil Ticks Tick-Borne Dis"},{"key":"6561_CR9","doi-asserted-by":"publisher","DOI":"10.1590\/s1984-29612024026","author":"GM Klafke","year":"2024","unstructured":"Klafke GM, Golo PS, Monteiro CMO, Costa-J\u00fanior LM, Reck J. Brazil\u2019s battle against Rhipicephalus (Boophilus) microplus ticks: current strategies and future directions. Rev Braz J Parasitol Vet. 2024;33(2):e001423. https:\/\/doi.org\/10.1590\/s1984-29612024026.","journal-title":"Rev Braz J Parasitol Vet."},{"key":"6561_CR10","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0147138","author":"C McManus","year":"2016","unstructured":"McManus C, Barcellos JOJ, Formenton BK, Hermuche PM, de Carvalho OA, Guimar\u00e3es R, et al. Dynamics of cattle production in Brazil. PLoS ONE. 2016;11(1):e0147138. https:\/\/doi.org\/10.1371\/journal.pone.0147138.","journal-title":"PLoS ONE"},{"key":"6561_CR11","unstructured":"FAO. Guidelines: resistance management and integrated parasite control in ruminants. 2004."},{"key":"6561_CR12","doi-asserted-by":"publisher","first-page":"563","DOI":"10.1017\/S000748530004832X","volume":"53","author":"BF Stone","year":"1962","unstructured":"Stone BF, Haydock KP. A method for measuring the acaricide-susceptibility of the cattle tick Boophilus microplus (Can.). Bull Entomol Res. 1962;53:563\u201378.","journal-title":"Bull Entomol Res"},{"key":"6561_CR13","doi-asserted-by":"publisher","first-page":"212","DOI":"10.1016\/j.vetpar.2011.09.018","volume":"184","author":"GM Klafke","year":"2012","unstructured":"Klafke GM, Castro-Janer E, Mendes MC, Namindome A, Schumaker TTS. Applicability of in vitro bioassays for the diagnosis of ivermectin resistance in Rhipicephalus microplus (Acari: Ixodidae). 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Vet Parasitol. 2022. 302.","DOI":"10.1016\/j.vetpar.2021.109613"},{"key":"6561_CR16","doi-asserted-by":"publisher","first-page":"210","DOI":"10.1186\/s12936-015-0721-4","volume":"14","author":"J Bagi","year":"2015","unstructured":"Bagi J, Grisales N, Corkill R, Morgan JC, Brogdon WG, Ranson H. When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors. 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Ticks were collected according to internationally accepted standards considering animal welfare.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"Not applicable.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"The authors declare no competing interests.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"480"}}