Diversity and composition analysis of cuticle surface and internal bacterial communities of laboratory-reared field F₁ Culex pipiens pallens

This study investigated the diversity and composition of cuticle surface and internal bacterial communities in larvae of a laboratory strain (SS) versus laboratory-reared F₁ larvae derived from wild Culex pipiens pallens populations.

The findings provided insights into how laboratory colonization influence the bacterial communities of wild mosquitoes. Larvae of Cx. pipiens pallens were collected from Tangkou Town (TK) and Weishan Lake (WSH) in Jining City, Shandong Province, in October 2023, and were subsequently reared in the laboratory to produce the F₁ progeny. 16S rRNA sequencing was used to analyse the diversity and composition of the cuticle surface and internal bacterial communities in laboratory strain and laboratory-reared field F₁ larvae maintained under identical conditions.

The results showed that the dominant bacterial phyla of the larval cuticle surfaces and internal bacterial communities were Proteobacteria, Actinobacteriota and Firmicutes. Alpha diversity analyses indicated no statistically significant differences among the cuticle surface bacterial communities of the SS, TK and WSH groups, whereas the internal bacterial diversity in the TK group was significantly higher than that in the SS group. Beta diversity analysis showed significant differences in the cuticle surface bacterial community composition between the SS and WSH groups (P=0.024), and significant differences were also observed in the internal bacterial communities between the laboratory strain and the field-derived F₁ larvae (TK: P=0.012, WSH: P=0.022). Linear discriminant analysis Effect Size (LEfSe) demonstrated that the significantly different bacterial taxa on the larval cuticle surfaces among the three groups belonged to 1 phylum, 3 classes, 4 orders, 5 families, and 6 genera. In contrast, the significantly different bacterial taxa in the internal bacterial communities of larvae belonged to 1 phylum, 1 class, 4 orders, 5 families, and 7 genera.

In summary, under standard laboratory rearing conditions, the native bacterial communities from field populations of Cx. pipiens pallens were partially transmitted to their laboratory-reared F₁ offspring larvae.