Simulation tools for assessment of tick suppression treatments of Rhipicephalus (Boophilus) microplus on non-lactating dairy cattle in Puerto Rico

Authors: WANG, HSIAO-HSUAN - Texas A&M University; TEEL, PETE - Texas A&M University; GRANT, WILLIAM - Texas A&M University; SOLTERO, FRED - Animal And Plant Health Inspection Service (APHIS); URDAZ, JOSE - Animal And Plant Health Inspection Service (APHIS); PEREZ-RAMIREZ, ALEJANDRO - Puerto Rico Department Of Agriculture; Miller, Robert; Perez De Leon, Adalberto - Beto

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2019
Publication Date: 4/27/2019
Citation: Wang, H., Teel, P.D., Grant, W.E., Soltero, F., Urdaz, J., Perez-Ramirez, A.E., Miller, R., Perez De Leon, A.A. 2019. Simulation tools for assessment of tick suppression treatments of Rhipicephalus (Boophilus) microplus on non-lactating dairy cattle in Puerto Rico. Parasites & Vectors. 12:185. https://doi.org/10.1186/s13071-019-3443-6.
DOI: https://doi.org/10.1186/s13071-019-3443-6

Interpretive Summary: Simulation tools help assess strategies under consideration to manage the health and productivity of livestock herds. Ticks and tick-borne diseases are factors that can impair the health and productivity of dairy cattle herds in tropical and subtropical parts of the world. The southern cattle fever tick (SCFT), Rhipicephalus microplus, transmits the microbes causing bovine babesiosis and anaplasmosis, which are tick-borne diseases that can have lethal effects in infected cattle. Milk production is also diminished in dairy cattle infested with this tick species. The SCFT remains endemic in Puerto Rico where it causes millions of dollars in losses due to mortality and sick cows in dairy herds. Here, we describe a model that simulates climate–livestock–SCFT–landscape interactions. This model was developed as an investigative tool to aid in a research project on integrated management of the SCFT that took place in Puerto Rico between 2014 and 2017. We used the model to assess the efficacy of tick suppression and the probability of tick elimination when applying safer acaricides to different proportions of a herd of non-lactating dairy cattle, which tend to be a source of SCFT infestation for lactating cows in Puerto Rico. Our model showed the dynamics interactions between the parameters evaluated. This information was discussed with the producers participating in the integrated SCFT management research project to document the cost-benefit of the different technologies tested. Our findings documented that explicit simulation of the spatial and temporal dynamics of larvae seeking a host in response to control methods should be part of research involving the evaluation of integrated SCFT management programs. This approach provides the basis to evaluate novel control technologies and to develop protocols for their cost-effective use with other treatment methods.

Technical Abstract: The southern cattle fever tick (SCFT), Rhipicephalus microplus, remains endemic in Puerto Rico. Systematic treatment programmes greatly reduced and even eradicated temporarily this tick from the island. However, a systemic treatment programme that includes integrated management practices for livestock against SCFT remains to be established in the island. We describe a spatially-explicit, individual-based model that simulates climate–livestock–SCFT–landscape interactions. This model was developed as an investigative tool to aid in a research project on integrated management of the SCFT that took place in Puerto Rico between 2014 and 2017. We used the model to assess the efficacy of tick suppression and probability of tick elimination when applying safer acaricides at 3-week intervals to different proportions of a herd of non-lactating dairy cattle. Probabilities of eliminating host-seeking larvae from the simulated system decreased from ~1 to ~0 as the percentage of cattle treated decreased from 65 to 45, with elimination probabilities ~1 at higher treatment percentages and ~0 at lower treatment percentages. For treatment percentages between 65% and 45%, a more rapid decline in elimination probabilities was predicted by the version of the model that produced higher densities of host- seeking larvae. Number of weeks after the first acaricide application to elimination of host-seeking larvae was variable among replicate simulations within treatment percentages, with within-treatment variation increasing markedly at treatment percentages = 65. Number of weeks after first application to elimination generally varied between 30 and 40 weeks for those treatment percentages with elimination probabilities ~1. Explicit simulation of the spatial and temporal dynamics of off-host (host-seeking) larvae in response to control methods should be an essential element of research that involves the evaluation of integrated SCFT management programmes. This approach could provide the basis to evaluate novel control technologies and to develop protocols for their cost-effective use with other treatment methods.