Identifying ivermectin titer levels in bovine serum and its affect on tick development in the cattle tick, Rhipicephalus microplus

Rhipicephalus microplus is a tick with major economic importance. It is the primary vector of Cattle Fever. Currently the Cattle Fever Tick Eradication Program monitors any outbreaks in the quarantine zone. This one-host tick is the vector for the protozoans Babesia bigemina and Babesia bovis, which cause Babesiosis. The main focus for controlling this disease is targeting the vector, the tick. Chemical pesticides have been the main source of control, but through their intensive use resistance has increased in certain tick populations. A particular pesticide ivermectin, a macrocyclic lactone, is the last resort against tick outbreaks that exhibit multiple pesticide resistance.  Tick population in the Yucatan have been identified that are resistant to ivermectin. Due to current resistance status, a greater understanding of levels of resistance is needed.  My objectives are to i) determine levels of resistance to ivermectin and ii) identify life history changes that are associated with resistance to ivermectin in the Yucatan strain. We will determine level of resistance is by running bioassays to identify the lethal concentrations_. This will be accomplished by larvae immersed in an array of serial dilutions of ivermectin. Life history characteristics that may be associated with resistance there will be examination at varying insecticide titer levels.  Observations will be documented through an entire lifecycle and see the correlations between life stages and the amount of ivermectin in the cattle.