-170- 



The development of L mexicana in both Lutzomyia species was 

 virtually identical, with most parasites concentrated in the abdominal 

 midgut and cardia and, as the infection progressed, extending forward 

 into the pharynx and mouthparts, and rearward into the hindgut (Fig. 

 4-3). Tables 4-2 and 3 record the locations of flagellates in the 

 alimentary tract of laboratory-reared Lu_. diabol ica and Lv^. shannoni , 

 respectively, upon post mortem dissection, one to 14 days after the 

 infective feed. Table 4-4 describes infections in 1 i ve Lu . diabol ica 

 dissected between 12 hrs and 8 days after the infective feed. 



No parasites were seen in dissections of live flies made less than 

 18 hrs after the infecting blood meal. The first indication of 

 development of ingested amastigotes appeared between 18 and 24 hrs 

 when light to moderate infections of ovoid, slightly motile 

 promastigotes with short flagella were observed in the abdominal 

 midgut, swimming through the blood meal, within the peritrophic sac 

 (Fig. 4-4a). About 50% of these were dividing by binary fission (Fig. 

 4-4b). As they became older they elongated and many formed rosettes 

 consisting of a dozen or more individuals arranged radially about a 

 common point, with their flagella directed toward the center (Fig. 

 4-4c). Without the flagellum they measured about 4 ym long and 

 2-3 ym wide. The flagellum was shorter than the body, measuring about 

 3 ym or 1 ess. 



By day two, the parasite population had increased many-fold, but 

 was still confined primarily to the abdominal midgut with the blood 

 meal. Division continued in about 50% of the ovoid, slightly motile 

 promastigotes. Many, however, had transformed into long-slender, 

 highly motile forms (Fig. 4-4d). In a small percentage of two-day-old 



