Transposable elements in the transcriptome of Aedes (Stegomyia) aegypti (Linnaeus, 1762)

The Aedes (Stegomyia) aegypti mosquito is the main vector of arboviruses such as dengue, urban yellow fever, chikungunya and Zika. The extensive use of insecticides to control this vector has led to the selection of resistant populations, compromising the effectiveness of control programmes. Insecticide resistance is often related to the integration of transposable elements (TEs) in specific genes. TEs can also contribute to the regulation of gene expression in response to insecticides. In this paper, we performed transcriptome analysis of the mosquito Ae. aegypti using bioinformatics tools to identify and characterize TEs. We also evaluated the relative expression of these mobile elements in susceptible strains and resistant strains exposed to the organophosphate insecticide malathion. In total, 6915 transcripts showed significant similarity with TEs and/or characteristic domains. Retrotransposons (Class I) accounted for 67% (4604 sequences) of the elements identified, while DNA transposons (Class II) were less abundant, with 2311 annotations (33%). TEs were classified into 39 superfamilies, with Gypsy and MITEs being the most abundant. Expression data of mobile elements showed both up- and downregulated elements in resistant strains challenged with the organophosphate insecticide malathion compared to susceptible strains. Mobile element expression data showed both upregulated and downregulated elements in resistant strains challenged with the insecticide compared with susceptible strains. These data contribute significantly to knowledge about the expression of some groups of mobile elements present in the genome of this species. Therefore, TE insertions may have a potential role in the resistance observed in this species, and suggest the role of stress on their expression. Such results provide insights into understanding molecular and cellular mechanisms that can be used in strategies to control mosquitoes.