ABSTRACT
Chagas disease is one of the most significant vector-borne diseases in Mexico. The presence of "sylvatic" triatomine vectors of Trypanosoma cruzi (Chagas) inside human dwellings necessitates estimating their vectorial capacity. To estimate this capacity in Triatoma protracta nahuatlae (Ryckman), Triatoma sinaloensis (Ryckman), and their laboratory hybrids, 6 biological parameters were examined. Triatoma sinaloensis exhibited the shortest development time (155 days), with a median of 12 blood meals. Mortality rates varied from 35% to 45% in the 3 studied cohorts. All 3 cohorts were aggressive, initiating feeding within 0.5-1 min, and had similar feeding periods ranging from 10 to 18 min. A majority (75.3-97.9%) of the hybrids defecated when feeding, immediately after feeding, or in less than 1 min post-feeding. In contrast, only 7-42% of nymphs of T. sinaloensis defecated during the same period. Our results regarding the 6 parameters studied confirm the potential role of T. p. nahuatlae as an efficient vector of T. cruzi. Triatoma sinaloensis, on the other hand, exhibited limited vectorial capacity primarily due to its poor defecation behavior. Continued surveillance of these "sylvatic" triatomine populations is necessary to prevent an epidemiological problem.
Subject(s)
Chagas Disease , Triatoma , Trypanosoma cruzi , Humans , Animals , Nymph , Laboratories , Feeding BehaviorABSTRACT
Aspects related to hatching, time-lapse between presenting the blood-meal and beginning of feeding, feeding time, postfeed defecation delay, mortality, and fecundity for each stage of Meccus longipennis life-cycle were evaluated. The bugs were maintained in a dark incubator at 27 ± 1ºC and 80 ± 5 percent rh, were fed weekly and checked daily for ecdysis or death. The hatching rate observed for 300 eggs was 76.7 percent and the average time of hatching was 19.8 days. Mean time-lapse between presentation of the blood meal and the beginning of feeding was under 5 min in nymphal stages and postfeed defecation delay was under 10 min in most stages, except in fourth and fifth stages. Mean feeding time was longer than 10 min in most stages, except in fourth stage. One hundred thirty-one nymphs (N) (65.5 percent) completed the cycle and the average time from NI to adult was 192.6 ± 34.8 days. The average span in days for each stage was 18.1 for NI, 21.4 for NII, 29.5 for NIII, 45.5 for NIV and 55.9 for NV. The number of bloodmeals at each nymphal stage varied from 1 to 5. The mortality rate was 3.29 for NI, 6.8 for NII, 2.92 for NIII 3.76 for NIV, and 10.16 for NV nymphs. The average number of eggs laid per female in a 9-month period was 615.6. Based on our results, we conclude that M. longipennis has some biological and behavioral characteristics which influence its capacity of becoming infected and transmitting Trypanosoma cruzi to human populations in those areas of Mexico where it is currently present.
Subject(s)
Animals , Male , Female , Defecation , Feeding Behavior , Life Cycle Stages , Triatominae , Fertility , Laboratories , Life Tables , TriatominaeABSTRACT
Aspects related to hatching, time-lapse between presenting the blood-meal and beginning of feeding, feeding time, postfeed defecation delay, mortality, and fecundity for each stage of Meccus longipennis life-cycle were evaluated. The bugs were maintained in a dark incubator at 27 1 C and 80 5% rh, were fed weekly and checked daily for ecdysis or death. The hatching rate observed for 300 eggs was 76.7% and the average time of hatching was 19.8 days. Mean time-lapse between presentation of the blood meal and the beginning of feeding was under 5 min in nymphal stages and postfeed defecation delay was under 10 min in most stages, except in fourth and fifth stages. Mean feeding time was longer than 10 min in most stages, except in fourth stage. One hundred thirty-one nymphs (N) (65.5%) completed the cycle and the average time from NI to adult was 192.6 34.8 days. The average span in days for each stage was 18.1 for NI, 21.4 for NII, 29.5 for NIII, 45.5 for NIV and 55.9 for NV. The number of bloodmeals at each nymphal stage varied from 1 to 5. The mortality rate was 3.29 for NI, 6.8 for NII, 2.92 for NIII 3.76 for NIV, and 10.16 for NV nymphs. The average number of eggs laid per female in a 9-month period was 615.6. Based on our results, we conclude that M. longipennis has some biological and behavioral characteristics which influence its capacity of becoming infected and transmitting Trypanosoma cruzi to human populations in those areas of Mexico where it is currently present.
