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Anopheles culicifacies, major vector o f malaria in Sri Lanka is a five member species complex.
Differences o f the vector competence o f siblings, is still poorly delineated. Therefore, the current
study was carried out to observe any relationship o f the variations in vector competence to ITS2
nucleotide sequences and secondary structure characteristics o f 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 o f all species had three helices where pyrimidine-pyrimidine mismatch in
Helix II and a UUUGG motif at 5’ o f Helix III were displayed only for B, C and E. Among five
types o f 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 o f the
vector competence o f the sibling species.
