through 16 generations. A new larval diet, developed from a modified 

 horn fly [ Haematobia irritans (Linn.)] diet, reduced the average 

 immature development time by 50%, to about 33 days. Quiescence and 

 diapause occurred in both the egg and larval stages, and lasted as 

 long as 270 days in the egg stage of outside-reared sand flies. 



Infection rates of 88% and 95% in Lu. diabol ica and Lu. shannoni , 

 respectively, were obtained by feeding the flies on leishmanial 

 histiocytomas of laboratory- infected hamsters. The development of 

 Leishmania mexicana (strain WR-411) in Lu. diabol ica is described in 

 detail . 



Ultrastructure studies of L mexicana amastigotes and 

 promastigotes revealed that the subpel 1 icular microtubule number 

 varies widely and is not a good criterion for distinguishing the 

 Leishmania species. 



For the first time, transmission experiments demonstrated that Lu . 

 diabol ica and Lu_. shannoni are able to transmit L mexicana to hamsters 

 by individual bites. Transmission occurred after a period of parasite 

 multiplication and development, during which time massive infections 

 were established initially in the midgut, then in the cardia and at 

 the stomodeal valve. These gave rise to short-slender, highly active 

 promasitgotes that spread throughout the alimentary tract and invaded 

 the pharynx and mouthparts. 



Based on the findings of this study, Lutzomyia diabol ica is the 

 suspected vector of human cutaneous leishmaniasis in Texas. 



xv 



