Salmon farming in Chile faces various challenges, the most significant being the sea louse Caligus rogercresseyi , the causative agent of Caligidosis. This disease leads to substantial economic losses due to reduced fish health, impaired growth performance, and increased treatment costs. It has been traditionally controlled through pharmacological treatments which, when used in large quantities, cause negative environmental impacts. In this context, the microbiota of C. rogercresseyi has garnered interest due to its potential influence on the parasite physiology.
This study aimed to characterize the microbiota of C. rogercresseyi according to sex. Adult individuals were collected from salmon farming centers in southern Chile and separated into males (M) and females (F) for independent extraction of total microbiota. In addition, the intestines of males (MG) and females (FG) were dissected separately to obtain gut microbiota, followed by DNA extraction in both cases. 16S rRNA gene sequencing (Oxford Nanopore) was used to characterize the bacterial profiles of the lice and their guts.
The results indicated significant differences in microbial composition, abundance, and diversity between sexes. Females exhibited greater bacterial richness and diversity in both total and gut microbiota, with a notable presence of the genus Aliivibrio. In contrast, Tenacibaculum was the predominant genus in males , both genera are closely associated with recurrent diseases in salmonids. Additionally, functional analysis revealed that the microbiota influences the parasite’s metabolic pathways in a sex-dependent manner, suggesting a relevant interaction between microbial communities and host physiological traits.
These findings provide key insights into the microbiome of Caligus rogercresseyi and open possibilities for developing more sustainable control strategies, such as targeted microbiome manipulation.
Funding: FONDAP #1523A0007