The development of the feeding lesions of the ixodid tick Boophilus microplus was followed throughout the parasitic life-cycle on cattle of both Zebu and European breeds, using histological techniques.The feeding lesion of this tick must be the result of an interaction between the tick and its host as it is neither the result of simple mechanical trauma, nor of lysis of the host tissues by salivary secretions of the tick alone, nor is it solely a result of an inflammatory response.The histological evidence suggests that the diet of the tick in each instar changes as the lesion develops; first, tissue fluids are available, then tissue fluids along with leucocytes which have infiltrated the lesion, and finally these two components along with whole blood.An early intense infiltration of eosinophils into the area of the mouthparts, typical of an immediate hypersensitive or anaphylactic response, was noted with European cattle on secondary and subsequent exposures to larvae. Hypersensitivity to tick infestation, which has been equated with resistance to infestation, was seen as an extreme of a normal spectrum of sensitization which results in an abnormal susceptibility.The definitive lesion was similar with all hosts studied. It consisted of a cavity containing leucocytes, predominantly neutrophils, some lymphocytes and erythrocytes in an area of heavily infiltrated collagen.It is concluded that this host-parasite relationship illustrates the concept of adaptation tolerance as proposed by Sprent (1962).It is with much pleasure that we acknowledge the continued generous financial support by the Australian Meat Research Committee (formerly the Australian Cattle and Beef Research Committee), which has made possible this project.
Determination of Moisture Content of Expressed Plant Tissue Fluids