http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/5716 2026-04-13T14:44:58Z 2026-04-13T14:44:58Z Surendran, S.N. Laxshi, K. Jayadas, T.T.P. Kokila, S. Tharsan, A. Nimasha, L. Eswaramohan, T. Raveendran, S. Singh, O.P. Ramasamy, R. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9186 2023-02-20T04:20:12Z 2022-01-01T00:00:00Z

Title: Morphological and odorant-binding protein 1 gene intron 1 sequence variations in Anopheles stephensi from Jaff na city in northern Sri Lanka Authors: Surendran, S.N.; Laxshi, K.; Jayadas, T.T.P.; Kokila, S.; Tharsan, A.; Nimasha, L.; Eswaramohan, T.; Raveendran, S.; Singh, O.P.; Ramasamy, R. Abstract: Three Anopheles stephensi biotypes have historically been differentiated through variations in the mode numbers of egg ridges and adult spiracular indices. Anopheles stephensi odorant-binding protein 1 gene (AsteObp1) sequences in Iran and Afghanistan have been recently interpreted to suggest that the three biotypes are sibling species. AsteObp1 intron 1 sequences, mode numbers of egg ridges and spiracular indices of An. stephensi in Jaffna city in Sri Lanka were therefore investigated in field-collected mosquitoes and short-term laboratory colonies established from them. AsteObp1 intron 1 sequences revealed the region to be polymorphic with four unique sequences, ASJF1-4, present in both short-term laboratory colonies and field-collected An. stephensi. The spiracular index did not relate to the mode number of egg ridges in Jaffna An. stephensi. The results suggested that numbers of egg ridges, spiracular indices and AsteObp1 intron 1 sequences were not useful for differentiating An. stephensi biotypes in Jaffna. It is proposed that the observed differences between An. stephensi mosquitoes in Jaffna now result from normal population variance in the context of rapidly changing bionomics in India and northern Sri Lanka.

2022-01-01T00:00:00Z Surendran, S.N. Jude, P.J. Ramasamy, R. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9126 2023-02-14T09:09:18Z 2011-01-01T00:00:00Z

Title: Variations in salinity tolerance of malaria vectors of the Anopheles subpictus complex in Sri Lanka and the implications for malaria transmission Authors: Surendran, S.N.; Jude, P.J.; Ramasamy, R. Abstract: Background: 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. 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. Results: Specimens 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. Conclusions: The 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.

2011-01-01T00:00:00Z Surendran, S.N. Kajatheepan, A. Jude, P. J. Ramasamy, R. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9125 2023-02-14T09:06:46Z 2008-01-01T00:00:00Z

Title: Use of tilapia, Oreochromis mossambicus, for the control of mosquito breeding in water storage tanks in the Jaffna district of Sri Lanka Authors: Surendran, S.N.; Kajatheepan, A.; Jude, P. J.; Ramasamy, R. Abstract: Mosquito-borne diseases such as dengue, chikungunya and malaria are of public health importance in Jaffna district. The use of larvivorous fish is perceived as an environmentally sound measure to control mosquitoes. A pilot study in the laboratory and field using Oreochromis mossambicus was carried out to evaluate its potentiality to control Aedes and Anopheles larvae. In the laboratory studies, O. mossambicus showed a greater feeding affinity for Aedes than either Anopheles or artificial fish diet, with a predatory index of 239.7 for Aedes, the fish having 2.9 g body weight. In the field trial, the introduction of O. mossambicus into water storage tanks proved to be effective in eliminating Aedes larvae within 3 days.

2008-01-01T00:00:00Z Surendran, S.N. Ramasamy, R. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9124 2023-02-14T09:03:05Z 2010-01-01T00:00:00Z

Title: The Anopheles culicifacies and An subpictus species complexes in Sri Lanka and their implications for malaria control in the country Authors: Surendran, S.N.; Ramasamy, R. Abstract: Anopheles culicifacies, the major vector of malaria in Srilanka, and An.subpictus, a secondary vectory, exist as species complexes in the country. Among the globally reported five sibling species(A-E) of the An.culicifacies complex, only species B and E have been detected in Srilanka. However, all four sibling species (A-D) of the An. subpictus complex present globally are found in Srilanka. This article reviews the data on the characteristics of the sibling species of these two main malaria vedtors in Srilanka and methods for differentiating them, and highlights the importance of understanding the bio-ecological variations among the sibling species in order to develop an effective vector control program in the country. It is proposed that An.culcifacies species E may have evolved from species B in Srilanka and then spread to South India. The development of DNA probes suitable for differentiating the sibling species of An.culicifacies and An.subpictus in field studies is identified as a particular priority for future work.

2010-01-01T00:00:00Z