Abstract
BackgroundAnopheles subpictus sensu lato, a widespread vector of malaria in Asia, is reportedly composed of four sibling species A-D based on distinct cytogenetic and morphological characteristics. However An. subpictus species B specimens in Sri Lanka are termed An. subpictus B/ An. sundaicus because of recent genetic data. Differences in salinity tolerance and coastal/inland prevalence of An. subpictus sibling species that were not previously established in Sri Lanka are presented here.ResultsSpecimens with morphological characteristics of all four Indian An. subpictus sibling species were found in Sri Lanka. Sibling species A, C and D tended to be predominant in inland, and An. subpictus species B/An. sundaicus, in coastal localities. Sibling species C was predominant in both adult and larval inland collections. Larvae of An. subpictus B/An. sundaicus were found in inland and coastal sites, including a lagoon, with salinity varying from 0 to 30 ppt. An. subpictus sibling species A, C and D larvae were present in water of salinity between 0 to 4 ppt. An. subpictus C, D and An. subpictus B/An. sundaicus larvae showed compatible differential salinity tolerance in laboratory tests. The first instar larvae of An. subpictus B/An. sundaicus showed 100% survival up to 15 ppt in comparison to species C and D where the corresponding values were 3 ppt and 6 ppt respectively. However all third instar larvae of An. subpictus B/An. sundaicus survived up to 30 ppt salinity whereas An. subpictus C and D tolerated up to 4 ppt and 8 ppt salinity respectively.ConclusionsThe results suggest that An. subpictus species B/An. sundaicus breed in fresh, brackish and nearly saline water while An. subpictus species C and D do so in fresh and less brackish waters in Sri Lanka, as in India. Because of the established role of An. sundaicus s.l. and An. subpictus s.l. as malaria vectors, the findings indicate a need for greater monitoring of brackish water breeding habitats in Asia. Tolerance to 15 ppt salinity may also constitute a simple method for differentiating An. subpictus B/An. sundaicus larvae from those of An. subpictus species C and D in field studies.
Highlights
IntroductionA widespread vector of malaria in Asia, is reportedly composed of four sibling species A-D based on distinct cytogenetic and morphological characteristics
Anopheles subpictus sensu lato, a widespread vector of malaria in Asia, is reportedly composed of four sibling species A-D based on distinct cytogenetic and morphological characteristics
While sibling species A, C and D tended to Laboratory investigations on salinity tolerance of larvae Larvae from mosquitoes with characteristics of An. subpictus B/An. sundaicus, and An. subpictus C and D differed in their ability to tolerate salinity
Summary
A widespread vector of malaria in Asia, is reportedly composed of four sibling species A-D based on distinct cytogenetic and morphological characteristics. Differences in salinity tolerance and coastal/inland prevalence of An. subpictus sibling species that were not previously established in Sri Lanka are presented here. The limited data on bio-ecological differences between members of the An. subpictus complex in Sri Lanka and elsewhere in Asia and their geographical distribution have been recently reviewed [1,6,13].
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