Perspectivas atuais e futuras do controle do carrapato Rhipicephalus (Boophilus) microplus e dos agentes por eles transmitidos na bovinocultura

Abstract

Tick Rhipicephalus (Boophilus) microplus infestations in cattle, and tick bonre agents, comprise the complex called tick and tick borne diseases, which represents one of the biggest obstacles to the development of domestic cattle. This paper describes a set of experiments related to the complex control strategies such as chemical control with a prospective study of the distribution of chemical resistance in populations of R.B. microplus in Rio Grande do Sul, chemoprophylactic control with using drugs to control subclinical tick fever in cattle improving the weight gain, the evaluation genetic control of genetic resistance against tick infestation and tick control using entomopathogenic fungi. Samples of ticks from 55 properties of 21 municipalities in Rio Grande do Sul and submitted to the Drummond test were collected to demonstrate the sensitivity of the acaricides drugs; Cattle angus breed weaned were treated with chemoprophylaxis protocols against suclinical TBD based on diaceturate of diminazene, oxytetracycline and dipropionate imidocarb submited to hematological and weight gain analisis. Were genetically selected two batches of heifers resistant and suceptible to tick and infested under field conditions Tick physiological parameters were measured; Samples of native fungi isolates grown, characterized and used to infect tick larvae and entomopathogenic effect were measured. Distribution of more than 70.0% of tick populations with resistance to at least one active ingredient and 41.8% with multiple resistance at high risk of spreading risk among properties was demonstrated; The use of chemoprophylactic protocols promoted an increase in weight gain of 146%. The cattle genetically resistant and susceptible cattle ticks produced estatistic diferences between tick parameters; The fungal isolates produced naturally infected with varied larvae mortality of infected ticks. Conclusions: Drug acaricide resistance presents large and growing distribution in Rio Grande do Sul, with a high degree of risk dispersion between farms; A chemoprophylaxis, can be recommended as an important management tool to accelerate growth and finishing of castings in super early cattle for slaughter; The genetic resistance of cattle is an important factor for reducing infestation by ticks and can be used as a criterion for selection of bulls destined for livestock production in endemic areas of infestation by ticks; Indigenous fungi with entomopathogenic effectss represent important drivers of infestation by ticks and should be better studied to contribute in integrated control strategies. General Conclusions: The integration of biological control strategy using pathogenic microorganisms with the genetic control aimed at adapting the immunological profiles of the players associated with chemical control should be watched and monitored with enhanced strategy.