Background: The Anopheles gambiae mosquitoes are the most abundant, efficient and widely distributed vectors of the malaria parasite in sub-Saharan Africa. In most African countries, where malaria control programmes are focused on the use of long-lasting insecticide treated bed net, there is need to evaluate the biting behaviour and the identity of such mosquitoes to determine the relevance and appropriateness of the control measure implemented. Method: This study investigated the distribution and molecular characteristics of the Anopheles species in selected forested areas in Cross River State, Nigeria. Mosquitoes were collected using pyrethrum spray catch and Centre for Disease Control light traps modified with yeast and sugar to generate carbon dioxide (CO2). Anopheles gambiae complex was identified using multiplex polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) for molecular forms characterization. Results: One hundred and four Anopheles gambiae s.l. were collected during the study. Multiplex PCR showed 75% of the species complex were A. gambiae s.s. and further characterization using PCR-RFLP showed that 53.8% of the A. gambiae s.l. identified were A. gambiae s.s.while 24.4% were A.coluzzii. The two species of the A. gambiae s.l. were found to be most abundant. The study also reported a 1.3% hybrid form of Anopheles gambiae s.s.and Anopheles coluzzii. Conclusion: The findings suggest the first documented evidence of hybrid forms of A. gambiae s.s./A.coluzzii in South Eastern Nigeria although its epidemiological implication is still not clear.

Distribution of members of the Anopheles gambiae complex in selected forested tourist areas of Cross River State, Nigeria