Simposio: Invertebrados vectores de enfermedades de importancia veterinaria

SIMPOSIO

Invertebrados vectores de enfermedades de importancia veterinaria

COORDINA: Patrick S. Sebastian

Control de garrapatas duras (Acari: Ixodidae) con importancia veterinaria en Latinoamérica

Las garrapatas duras (Acari: Ixodidae) son ectoparásitos hematófagos obligados que representan un importante problema veterinario y económico a nivel mundial debido a su capacidad para parasitar una amplia variedad de hospedadores, especialmente animales domésticos y de producción. Estas garrapatas actúan como vectores eficientes de múltiples patógenos, incluidos protozoos, bacterias y virus, responsables de enfermedades infecciosas que afectan la salud animal y, en algunos casos, la salud humana. La infestación por garrapatas provoca daños directos, como anemia, lesiones cutáneas y estrés, que impactan negativamente en la producción de carne y leche, así como importantes pérdidas económicas debido a la reducción del rendimiento productivo y la predisposición a infecciones secundarias. Por otro lado, las garrapatas transmiten patógenos por diversas vías, lo que incrementa su potencial vectorial y dificulta su control.
En este contexto, el manejo integrado y el control efectivo de las garrapatas son pilares fundamentales de la medicina veterinaria preventiva para reducir la morbilidad y mortalidad animal, así como para minimizar el impacto económico en los sistemas de producción. El objetivo del simposio es proporcionar un espacio de análisis y discusión sobre los avances científicos y prácticos en el control de garrapatas de relevancia veterinaria, con especial énfasis en Rhipicephalus microplus y garrapatas del género Amblyomma. Se abordarán aspectos epidemiológicos actuales, el desarrollo y la gestión de la resistencia a acaricidas, y la implementación de estrategias integradas que combinen métodos químicos y no químicos en el contexto socioeconómico y ambiental de la región latinoamericana.
Este enfoque busca promover soluciones innovadoras, eficaces y sostenibles que respondan a los desafíos epidemiológicos y productivos que enfrentan los países de la región, en particular Uruguay y Argentina, donde la garrapata común del ganado representa un problema sanitario y económico persistente. El simposio incluirá presentaciones sobre diversas estrategias de control de R. microplus, su impacto en la producción ganadera, evidencia sobre la resistencia de las garrapatas y alternativas no químicas para el manejo de garrapatas duras. Se presentarán resultados recientes de ensayos en Argentina y Uruguay, experiencias sobre el uso de agentes no químicos en Ecuador, y evaluaciones de la eficacia de productos químicos comerciales frente a especies endémicas del género Amblyomma en Argentina.
Esta iniciativa reúne a especialistas en medicina veterinaria, parasitología y entomología, promoviendo un enfoque interdisciplinario para una comprensión integral de la biología, ecología y control de las garrapatas duras, con el objetivo de fortalecer las políticas y prácticas de manejo en América Latina.

Palabras clave: Garrapatas duras, Control de garrapatas, Ganadería, Medicina veterinaria, Resistencia a fármacos, América del Sur.

Biology, Distribution, and economic impact of the Cattle Tick Rhipicephalus (Boophilus) microplus in Argentina

Rossner, María V. ¹

¹ Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Colonia Benítez. Av. Brilini 750 (3505) Colonia Benítez, Chaco, Argentina.
Rossner.mariav@inta.gob.ar

The cattle tick, Rhipicephalus (Boophilus) microplus, is the ectoparasite with major global significance in livestock production. In Argentina, it is found in tropical and subtropical regions of the northeast (NEA) and northwest (NOA), north of the 31ºS parallel. In these areas, tick infestations severely hinder profitable beef and dairy production due to direct losses (weight loss, mortality, hide damage, decreased milk yield) and the high costs of tick control. R. microplus is the sole vector in Argentina for Babesia bovis and Babesia bigemina, which cause bovine babesiosis, and it also transmits Anaplasma marginale (anaplasmosis). Additionally, heavy tick infestations are linked to cutaneous myiasis caused by Cochliomyia hominivorax larvae. The tick’s life cycle is divided into a parasitic phase (on the bovine host) and a non-parasitic phase (in the pasture). The parasitic phase lasts approximately 21–23 days and includes larval, nymphal, and adult stages. Fertilized females (teleogines) feed, engorge, and detach from the host to lay 1,000–3,000 eggs in the soil. The non-parasitic phase includes the pre-oviposition, oviposition, incubation, and larval longevity periods, whose durations depend heavily on environmental conditions. The total duration of the non-parasitic phase varies with the season. It is longest when teleogines drop between mid-summer and autumn (up to six and a half months), and shortest when they fall in spring or early summer (three to four months). While egg-laying occurs year-round, hatching during autumn and winter only happens in the warmest areas of the NEA. In other regions, low temperatures and water deficits prevent egg development during colder months. Egg hatching is dependent on the accumulation of degree-days (DD) above a base temperature of 15.5 ºC. Approximately 270–275 DD are needed within a maximum of 100–110 days in favorable areas or 80–90 days in less favorable areas. If temperatures rise in autumn or winter, eggs may hatch unexpectedly, leading to higher or more prolonged larval pasture infestations. Larval longevity is influenced by temperature and saturation deficit: the higher these values, the shorter larval survival. The seasonal pattern of cattle infestation shows a gradual increase from mid-spring to autumn, peaking during the latter, and then declining into winter and early spring.

Keywords: Cattle tick, Ecology, Ectoparasite.

Epidemiology and control of the cattle tick Rhipicephalus microplus

SARLI, Macarena¹ & TORRENTS, Jorgelina¹

¹ Instituto de Investigación de la Cadena Láctea (IdICaL) (INTA-CONICET), Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela (INTA EEA. Rafaela), Ruta 34 Km 227, CP 2300, Rafaela, Santa Fe, Argentina
E-mail address: sarli.macarena@inta.gob.ar

The tick Rhipicephalus microplus is a major pest of cattle in tropical and sub-tropical areas of the world that causes a relevant clinical and economic impact on livestock production. Riphicephalus microplus generates depression of milk production and weight gain, mortality, hide damage and morbidity. In addition, the costs of its control and the effects related to tick-transmitted hemoparasites (Babesia bigemina, Babesia bovis and Anaplasma marginale) must be added. The problem of infestation with R. microplus affects a population of approximately 16 million cattle in sub-tropical areas of the northeast and northwest of Argentina, in the provinces of Salta, Tucumán, Jujuy, Santiago del Estero, Santa Fe, Córdoba, Catamarca, Formosa, Misiones, Entre Ríos, Corrientes and Chaco. The economic losses caused by R. microplus in Argentina have been estimated at about 200 million dollars per year. The most widely used control method, and almost exclusive in most livestock farms, is the application of synthetic chemical acaricides. Despite the availability of commercial acaricides formulated with different chemical groups (pyrethroids, organophosphates, formamidines, benzoylureas, phenylpyrazoles, avermectins) or combinations of two or more drugs, the emergence of populations of ticks resistant to one or more groups of drugs constitutes a limitation for the application and effectiveness of these tools. Another relevant problem associated with the use of chemical acaricides are the restrictions for the consumption of meat or milk imposed by the long residual periods of certain drugs. Furthermore, many of them are not indicated for use in dairy cows. In this sense, the integrated control scheme for R. microplus is a tool that involves the simultaneous combination of two or more techniques, one of which should not be chemical, to reduce the tick populations and minimize resistance to acaricides. The three main techniques that can be used in the integrated control scheme for R. microplus are: I) the application of synthetic chemical acaricides, II) pasture rotation and resting, and III) the use of bovine biotypes with natural resistance to tick infestation. These techniques should also be complemented by prevention schemes against bovine babesiosis and anaplasmosis and periodic monitoring of the resistance status of ticks to acaricide drugs.

Keywords: Rhipicephalus microplus, Control, Resistance

Control of Rhipicephalus microplus in a challenging epidemiological context in Uruguay

PARODI, Pablo¹

¹Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), Tacuarembó-Uruguay
E-mail address: pparodi@inia.org.uy

The cattle tick, Rhipicephalus microplus, is one of the main sanitary challenges for Uruguay’s livestock sector. This ectoparasite significantly affects animal health, productivity, and the overall competitiveness of the beef industry. Economic losses associated with tick infestations and the diseases it transmits are estimated to exceed 45 million USD annually, due to weight loss, treatment costs, animal mortality, and trade restrictions. Most of the Uruguay’s territory offers favorable ecological conditions for the tick’s life cycle. Temperate climates, high humidity, and abundant vegetation provide an ideal environment for its reproduction and survival. This situation is exacerbated by the spread of tick populations with multi-resistance to various acaricide classes, which greatly complicates traditional control approaches. The current challenges in managing R. microplus revolve around four key issues: (1) deterioration of the animals’ general health and productivity, (2) food safety concerns due to chemical residues, (3) deaths caused by tick-borne diseases such as babesiosis and anaplasmosis, and (4) marketing restrictions due to the presence of ticks on cattle, which directly impact farmers’ income. Given this scenario, control strategies must be comprehensive, sustainable, and tailored to each farm. Annual planning with veterinary advisors is essential, starting with an on-farm diagnostic assessment and acaricide resistance profiling. The rational use of chemical control should take into account the selection pressure exerted by systematic treatments, promoting the rotation of molecules with different modes of action and avoiding underdosing. Additionally, pasture rotation and post-treatment field monitoring are crucial to evaluate the effectiveness of interventions. One promising tool is the implementation of the hemovaccine, which, when integrated into health management programs, helps reduce the incidence of tick-borne diseases and decreases reliance on chemical treatments. In such a complex epidemiological context as Uruguay’s, eradicating the cattle tick is extremely difficult using currently available tools. Therefore, it is imperative to develop and incorporate new biotechnological solutions, such as more effective vaccines, gene-editing strategies, and the genetic selection of tick-resistant animals. These innovations should be integrated into a broader Integrated Pest Control (IPC) framework, combining chemical, biological, immunological, and management-based control methods to achieve greater sustainability and resilience in livestock production systems in the face of R. microplus.

Keywords: livestock, food safety, sustainability.

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