Sequence-based identification of Anopheles species in eastern Ethiopia

Area of Science:

• Entomology
• Genetics
• Molecular Biology

Background:

• Accurate identification of malaria vectors is essential for effective surveillance, particularly with the emergence of non-African Anopheles species in Ethiopia.
• Molecular methods enhance the precision and data consistency of vector surveillance.
• Evaluating genetic markers like ITS2 and COI is critical for developing robust Anopheles identification assays.

Purpose of the Study:

• To assess the utility of the internal transcribed spacer 2 (ITS2) and cytochrome oxidase I (COI) genetic loci for identifying Anopheles species in eastern Ethiopia.
• To evaluate the capacity of these genetic markers to differentiate species and reveal population-level variations.

Main Methods:

• Mosquitoes were collected from eastern Ethiopia (Harewe and Meki).
• Polymerase chain reaction (PCR) and Sanger sequencing were used to analyze portions of the ITS2 and COI loci.
• Species identification was performed using NCBI's BLAST and maximum-likelihood phylogenetic analysis.

Main Results:

• Two Anopheles species, Anopheles arabiensis and Anopheles pretoriensis, were identified in the eastern Ethiopian samples.
• The ITS2 locus successfully differentiated both identified Anopheles species.
• The COI locus could not distinguish An. arabiensis from other members of the Anopheles gambiae complex but could differentiate An. pretoriensis from related species.

Conclusions:

• The COI locus presents challenges for species identification within complex groups like the Anopheles gambiae complex.
• The ITS2 marker demonstrates strong potential for delineating Anopheles species in understudied regions.
• These findings support the development of molecular tools for Anopheles vector surveillance in eastern Ethiopia.