Bacteria associated with Anopheles arabiensis larvae in Ethiopia show similarities based on breeding site but not developmental stage

Every year, several hundred thousand people die from malaria. Due to resistance development against the current methods of control, insecticides and drugs, other areas also need to be explored. One such area under investigation involves the bacteria associated with the vector mosquitoes and the use of these to prevent transmission of malaria. For the application of bacteria in malaria control, more information about naturally associated bacteria and how they are acquired is needed. The aim of this study was therefore to investigate the bacterial composition of Anopheles larvae and the effect of breeding site and developmental stage. To do this, bacterial composition associated with An. arabiensis larvae from Ethiopia was analyzed using 16S rRNA gene sequencing by MiSeq. We found that mosquito larvae from the same breeding site contained similar bacteria. Of the total variance, 45% could be explained by breeding site. Furthermore, we found that when the breeding sites were classified based on our interpretation of the type of aquatic habitat, the sites of the same type also contained similar bacteria. Of the total variance, 36% could be explained by aquatic-habitat type. However, the bacterial composition was similar for all instars. Additionally, we found that if larvae are pooled and sequenced together, the pool is an adequate representation of all the individual larvae in the pool. Of all the OTUs identified, only one, classified as Thorsellia, was common to all larvae. We conclude that bacteria associated with An. arabiensis larvae can be explained to a large extent by the mosquito-breeding site. Both when classified as individual breeding sites and when grouped according to our interpretation of the type of aquatic habitat.