Nucleotide Sequence and Secondary Structure Variations in ITS2-rDNA Region of the Members of Anopheles culicifacies (Diptera: Culicidae) Species Complex

Anopheles culicifacies, major vector of malaria in Sri Lanka is a five member species complex. Differences of the vector competence of siblings, is still poorly delineated. Therefore, the current study was carried out to observe any relationship of the variations in vector competence to ITS2 nucleotide sequences and secondary structure characteristics of the species complex. DNA was extracted from sibling species B and E, the ITS2 region was amplified and sequenced. Sequences for A, C and D siblings were retrieved from NCBI GenBank. The complex divided into two groups, AD and BCE based on primary and secondary structure of the ITS2 sequences. Secondary structures of all species had three helices where pyrimidine-pyrimidine mismatch in Helix II and a UUUGG motif at 5‘ of Helix III were displayed only for B, C and E. Among five types of loops, interior and exterior loops were more conserved than other loop types. Results showed the major vector sibling E and poor or non vector sibling B shares identical nucleotide sequence and secondary structure. Therefore, ITS2 secondary structure is independent of the vector competence of the sibling species.