Abstract
Hard ticks affect cattle in tropical and subtropical areas across the world. In Ecuador, the main species affecting cattle are Rhipicephalus microplus and the complex Amblyomma cajennense sensu lato. Both cause economic losses to cattle farmers by decreasing milk and meat production, and transmitting pathogens. They can indirectly affect human and environmental health, due to the toxicity of acaricides used to control ticks and acaricide residues. In Ecuador as in other countries, acaricide resistance in cattle ticks has become an acute problem in cattle management. Although several studies have modelled the distribution of R. microplus and A. cajennense s.l. worldwide and in South America, suitable models for Ecuador are still lacking. Ecuador’s contrasted environment, spanning across the Andes, requires calibrating a specific model. The aim of this study was to model the distribution of R. microplus and A. cajennense s.l. in continental Ecuador using Random Forest with 19 bioclimatic variables and vapour pressure deficit (CHELSA database). In total, 2895 farms were surveyed and georeferenced between 2012 and 2015. R. microplus was present in 38.51% and A. cajennense s.l. in 16% of farms. Cross-validation values for the Random Forest models were, for R. microplus and A. cajenense s.l. respectively: accuracy = 0.97, 0.98, Sensibility = 0.97, 0.99, and Specificity = 0.96, 0.93. The final models included ten bioclimatic variables i.e. Bio 1, Bio14, Bio4, Bio12, Bio 13, Bio3, vapour pressure deficit max and min, Bio 2, and Bio 18. The predicted models showed the potential risk of the presence of R. microplus and A. cajennense s.l. distribution in continental Ecuador. We discuss the interest of these models for managing this issue at the national level, including through a better understanding of areas at risk, and better use of chemicals acaricide. This may be particularly important if cattle farming further develops in the Amazon region. We also discuss the challenge of focusing on the climatic envelope, while tick presence is also affected by management practices.