Ecology and larval population dynamics of the primary malaria vector Nyssorhynchus darlingi in a high transmission setting dominated by fish farming in western Amazonian Brazil

Made available in DSpace on 2021-06-25T15:01:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-08 US National Institutes of Health ICEMR Tropical Disease Research-WHO Contract Vale do Rio Jurua in western Acre, Brazil, is a persistent malaria transmission hotspot partly due to fish farming development that was encouraged to improve local standards of living. Fish ponds can be productive breeding sites for Amazonian malaria vector species, including Nyssorhynchus darlingi, which, combined with high human density and mobility, add to the local malaria burden.This study reports entomological profile of immature and adult Ny. darlingi at three sites in Mancio Lima, Acre, during the rainy and dry season (February to September, 2017). From 63 fishponds, 10,859 larvae were collected, including 5,512 first-instar Anophelinae larvae and 4,927 second, third and fourth-instars, of which 8.5% (n = 420) were Ny. darlingi. This species was most abundant in not-abandoned fishponds and in the presence of emerging aquatic vegetation. Seasonal analysis of immatures in urban landscapes found no significant difference in the numbers of Ny. darlingi, corresponding to equivalent population density during the rainy to dry transition period. However, in the rural landscape, significantly higher numbers of Ny. darlingi larvae were collected in August (IRR = 5.80, p = 0.037) and September (IRR = 6.62, p = 0.023) (dry season), compared to February (rainy season), suggesting important role of fishponds for vector population maintenance during the seasonal transition in this landscape type. Adult sampling detected mainly Ny. darlingi (similar to 93%), with similar outdoor feeding behavior, but different abundance according to landscape profile: urban site 1 showed higher peaks of human biting rate in May (46 bites/person/hour), than February (4) and September (15), while rural site 3 shows similar HBR during the same sampling period (22, 24 and 21, respectively). This study contributes to a better understanding of the larvae biology of the main malaria vector in the Vale do Rio Jurua region and, ultimately will support vector control efforts. Univ Estadual Paulista, Inst Biociencias Botucatu, Dept Bioestat Biol Vegetal Parasitol & Zool, Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biotecnol, Botucatu, SP, Brazil London Sch Hyg & Trop Med, Dept Infect Biol, London, England Univ Peruana Cayetano Heredia, Fac Ciencias & Filosofia, Lab ICEMR Amazonia, Labs Invest & Desarrollo, Lima, Peru SUNY Albany, Sch Publ Hlth, Dept Biomed Sci, Albany, NY USA Wadsworth Ctr, New York State Dept Hlth, Albany, NY USA Univ Peruana Cayetano Heredia, Fac Ciencias & Filosofia, Dept Ciencias Celulares & Mol, Lima, Peru Univ Peruana Cayetano Heredia, Inst Med Trop Alexander Humboldt, Lima, Peru Yale Sch Med, Dept Internal Med, Sect Infect Dis, New Haven, CT USA Univ Sao Paulo, Fac Saude Publ, Dept Epidemiol, Sao Paulo, Brazil Univ Brasilia, Nucleo Med Trop, Brasilia, DF, Brazil Univ Estadual Paulista, Inst Biociencias Botucatu, Dept Bioestat Biol Vegetal Parasitol & Zool, Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biotecnol, Botucatu, SP, Brazil US National Institutes of Health ICEMR: U19 AI089681 Tropical Disease Research-WHO Contract: 201460655