Diversity of midgut bacteria in larvae and females of Aedes aegypti and Aedes albopictus from Gampaha District, Sri Lanka

Abstract

Background: The midgut microbiota of mosquitoes maintain basal immune activity and immune priming. In recent years, scientists have focused on the use of microbial communities for vector control interventions. In the present study, the midgut bacteria of larvae and adults of Aedes aegypti and Ae. albopictus were assessed using both field-collected and laboratory-reared mosquitoes from Sri Lanka.

Methods: Adults and larvae of Ae. aegypti and Ae. albopictus were collected from three selected areas in Gampaha Medical Officer of Health area, Gampaha District, Western Province, Sri Lanka. Bacterial colonies isolated from mosquito midgut dissections were identified by PCR amplification and sequencing of partial 16S rRNA gene fragments.

Results: Adults and larvae of Ae. aegypti and Ae. albopictus harbored 25 bacterial species. Bacillus endophyticus and Pantoea dispersa were found more frequently in field-collected Ae. aegypti and Ae. albopictus adults, respectively. The midgut bacteria of Ae. aegypti and Ae. albopictus adults (X² = 556.167, df = 72, P < 0.001) and larvae (X² = 633.11, df = 66, P < 0.001) were significantly different. There was a significant difference among the bacterial communities between field-collected adults (X² = 48.974, df = 10, P < 0.001) and larvae (X² = 84.981, df = 10, P < 0.001). Lysinibacillus sphaericus was a common species in adults and larvae of laboratory-reared Ae. aegypti. Only P. dispersa occurred in the field-collected adults of Ae. aegypti and Ae. albopictus. Species belonging to genera Terribacillus, Lysinibacillus, Agromyces and Kocuria were recorded from Aedes mosquitoes, in accordance with previously reported results.

Conclusions: This study generated a comprehensive database on the culturable bacterial community found in the midgut of field-collected (Ae. aegypti and Ae. albopictus) and laboratory-reared (Ae. aegypti) mosquito larvae and adults from Sri Lanka. Data confirm that the midgut bacterial diversity in the studied mosquitoes varies according to species, developmental stage and strain (field vs laboratory).

Keywords: 16S rRNA gene; Aedes; Bacteria; Diversity; Midgut; Mosquitoes.

Fig. 1

Relative abundance of bacterial families molecularly identified (16S rRNA gene sequence analysis) in the midgut of Aedes aegypti and Ae. albopictus collected in the field in Gampaha District, Sri Lanka. a Adults, b larvae

Fig. 2

Relative abundance of bacterial families molecularly identified (16S rRNA gene sequence analysis) in the midgut of field-captured mosquitoes and laboratory-reared mosquitoes (Gampaha District, Sri Lanka). a Adults, b larvae

Fig. 3

The distance-based redundancy analysis (dbRDA) plot for distribution of midgut bacteria in field-collected Ae. aegypti and Ae. albopictus adults and in laboratory-reared Ae. aegypti adults. Mt Microbacterium trichothecenolyticum, Kk Kocuria kristinae, Em Elizabethkingia miricola, Be Bacillus endophyticus, Ls Lysinibacillus sphaericus, Sw Staphylococcus warneri, Ss Staphylococcus sciuri, En Enterobacter sp., Pd Pantoea dispersa, Ab Acinetobacter baumannii, An Acinetobacter nosocomialis, Nf Neisseria flavescens, Sl Serratia liquefaciens

Fig. 4

The dbRDA plot for distribution of midgut microbiota in larvae from field-collected Ae. aegypti and Ae. albopictus and laboratory-reared Ae. aegypti larvae

Fig. 5

Phylogenetic tree of 16S rRNA gene sequences from bacterial isolates cultured from the midgut of field-collected Ae. aegypti and Ae. albopictus and laboratory-reared Ae. aegypti. FC-AEA Field-collected Ae. aegypti adults, FC-AEL field-collected Ae. aegypti larvae, FC-AAA field-collected Ae. albopictus adults, FC-AEL field-collected Ae. albopictus larvae, LC-AEA laboratory-reared Ae. aegypti adults, LC-AEL laboratory-reared Ae. aegypti larvae