RESUMO
Haematophagous dipterans belonging to 10 genera - Aedes (12), Anopheles (14), Armigeres (01), Culex (09), Toxorhynchites (01), Uranotaenia (01), Sergentomyia (02), Phlebotomus (01), Atylotus (01) and Tabanus (03) were encountered from 12 localities under 6 blocks of Dehradun district (Uttarakhand) during January 2011 to December 2012. The Culicines (50.69%) were more dominant than the Anophelines (38.9%), Toxorhynchites (1.72%), horse flies (6.63%) and sandflies (2.01%). The following species viz., Toxorhynchites splendens and Phlebotomus argentipes have been recorded for the first time while Aedes pseudotaeniatus as reappeared species from the study area. Species diversity is represented through Species richness (S), Shannon index (H) and Shannon Eveness (E) among Aedes, Anopheles, Culex, Sandfly and Horsefly. The species richness (S) and evenness (E) were found as 12, 0.65; 14, 0.84; 09, 0.74; 3, 0.61 and 4, 0.78 respectively by Aedes, Anopheles, Culex, Sandfly and Horsefly. Highest Shannon index was shared by Anopheles (2.214) followed by Culex (1.639), Aedes (1.631), Horsefly (1.085) and Sandfly (0.672) in succeeding order.
RESUMO
BACKGROUND & OBJECTIVE: Though the relationship between mosquito density and transmission of malaria in different regions of the country is known, no studies are available on the relationship between mosquito catches and malaria cases in Kalsi area of Dehradun district in Uttaranchal. Hence, the present study was done to evaluate the role of anopheline mosquitoes catches and prevalence of malaria cases in this area. METHODS: During three consecutive years (2000-2003) mosquitoes were collected from 10 villages in Kalsi area twice a month, during the morning and evening hours. Identification of anopheline mosquitoes was done. Indoor collected female mosquitoes were dissected to see infection. Sporozoites were fixed and stained. Data on temperature and rainfall were also collected. RESULTS: As many as 10 species of anophelines were collected during three consecutive years - January 2000 to December 2002 at Kalsi block in district Dehradun (Uttaranchal). Proportion of the total anopheline species as well as the abundance of Anopheles stephensi was found more in the year 2002 than in 2000 and 2001. Incrimination studies revealed malarial infection (sporozoite positive) in A. fluviatilis and A. stephensi. Of the 5450 blood smears examined, only 50 (0.91%) were found positive for malarial parasite i.e., Plasmodium vivax. There was no case of P. falciparum during the study period. Highest slide positive rate (SPR) of 1.107 per cent was recorded in 2002 while in 2001, highest month-wise malaria positive cases were recorded in the month of August. September shared highest positive cases during 2000 and 2002. While correlating a relationship between mosquito catch especially infected ones and monthly parasite incidence, the density of A. stephensi showed significantly high correlation (r = 0.819; P<0.001). A slight variation in this type of relationship was seen in A. fluviatilis. Both temperature and rainfall were found to be positively correlated with malaria incidence. INTERPRETATION & CONCLUSION: Our findings showed that A. fluviatilis and A. stephensi played a significant role in transmission of malaria in Kalsi area of Dehradun.