OPTIMIZATION OF THE IN-VITRO FEEDING OF RHIPICEPHALUS-APPENDICULATUS NYMPHAE FOR THE TRANSMISSION OF THEILERIA-PARVA

An apparatus for artificial feeding of Rhipicephalus appendiculatus ny mphae was modified to improve feeding performance. Heparinized blood w as supplied above a treated artificial membrane while the ticks attach ed below on its undersurface. The feeding apparatus was incubated at 3 7 degrees C in an atmosphere of 3 %, CO2 concentration and a relative humidity of 75-80 %. Under these conditions, 91 % of the engorged nymp hae attained a mean weight of G-ll mg, and an average of 93 % of those nymphae moulted into adults. When this system was used to feed nympha l ticks on blood infected with Theileria parva piroplasms, the mean pr evalence of infection in the resultant female and male ticks was 86 % and 54 %, respectively. The feeding performance and T. parva infection levels were comparable to those of nymphal ticks fed on the blood don or cattle. The apparatus used in this study has potential for modifica tion to suit the artificial feeding needs of other species of ixodid t icks and for use in in investigations to examine other tick/pathogen r elationships.