Triatoma infestans is the most important Chagas disease vector in South America. Two main evolutionary lineages, named Andean and non-Andean, have been recognized by geographical distribution, phenetic and genetic characteristics. One of the main differences is the genomic size, varying over 30% in their haploid DNA content. Here we realize a genome wide analysis to compare the repetitive genome fraction (repeatome) between both lineages in order to identify the main repetitive DNA changes occurred during T. infestans differentiation process. RepeatExplorer analysis using Illumina reads showed that both lineages exhibit the same amount of non-repeat sequences, and that satellite DNA is by far the major component of repetitive DNA and the main responsible for the genome size differentiation between both lineages. We characterize 42 satellite DNA families, which are virtually all present in both lineages but with different amount in each lineage. Furthermore, chromosomal location of satellite DNA by fluorescence in situ hybridization showed that genomic variations in T. infestans are mainly due to satellite DNA families located on the heterochromatic regions. The results also show that many satDNA families are located on the euchromatic regions of the chromosomes.

Hippodamia variegata is one of the most commercialized ladybirds used for the biological control of aphid pest species in many economically important crops. This species is the first Coccinellidae whose satellitome has been studied by applying new sequencing technologies and bioinformatics tools. We found that 47% of the H. variegata genome is composed of repeated sequences. We identified 30 satellite DNA (satDNA) families with a median intragenomic divergence of 5.75% and A+T content between 45.6% and 74.7%. This species shows satDNA families with highly variable sizes although the most common size is 100–200 bp. However, we highlight the existence of a satDNA family with a repeat unit of 2 kb, the largest repeat unit described in Coleoptera. PCR amplifications for fluorescence in situ hybridization (FISH) probe generation were performed for the four most abundant satDNA families. FISH with the most abundant satDNA family as a probe shows its pericentromeric location on all chromosomes. This location is coincident with the heterochromatin revealed by C-banding and DAPI staining, also analyzed in this work. Hybridization signals for other satDNA families were located only on certain bivalents and the X chromosome. These satDNAs could be very useful as chromosomal markers due to their reduced location.

Next-generation sequencing data analysis on Triatoma infestans Klug, 1834 (Heteroptera, Cimicomorpha, Reduviidae) revealed the presence of the ancestral insect (TTAGG)n telomeric motif in its genome. Fluorescence in situ hybridization confirms that chromosomes bear this telomeric sequence in their chromosomal ends. Furthermore, motif amount estimation was about 0.03% of the total genome, so that the average telomere length in each chromosomal end is almost 18 kb long. We also detected the presence of (TTAGG)n telomeric repeat in mitotic and meiotic chromosomes in other three species of Triatominae: Triatoma dimidiata Latreille, 1811, Dipetalogaster maxima Uhler, 1894, and Rhodnius prolixus Ståhl, 1859. This is the first report of the (TTAGG)n telomeric repeat in the infraorder Cimicomorpha, contradicting the currently accepted hypothesis that evolutionarily recent heteropterans lack this ancestral insect telomeric sequence. Next-generation sequencing data analysis on Triatoma infestans Klug, 1834 (Heteroptera, Cimicomorpha, Reduviidae) revealed the presence of the ancestral insect (TTAGG)n telomeric motif in its genome. Fluorescence in situ hybridization confirms that chromosomes bear this telomeric sequence in their chromosomal ends. Furthermore, motif amount estimation was about 0.03% of the total genome, so that the average telomere length in each chromosomal end is almost 18 kb long. We also detected the presence of (TTAGG)n telomeric repeat in mitotic and meiotic chromosomes in other three species of Triatominae: Triatoma dimidiata Latreille, 1811, Dipetalogaster maxima Uhler, 1894, and Rhodnius prolixus Ståhl, 1859. This is the first report of the (TTAGG)n telomeric repeat in the infraorder Cimicomorpha, contradicting the currently accepted hypothesis that evolutionarily recent heteropterans lack this ancestral insect telomeric sequence.

Chagas disease or American trypanosomiasis affects six to seven million people worldwide, mostly in Latin America. This disease is transmitted by hematophagous insects known as “kissing bugs” (Hemiptera, Triatominae), with Triatoma infestans and Rhodnius prolixus being the two most important vector species. Despite the fact that both species present the same diploid chromosome number (2n = 22), they have remarkable differences in their total DNA content, chromosome structure and genome organization. Variations in the DNA genome size are expected to be due to differences in the amount of repetitive DNA sequences. The T. infestans genome-wide analysis revealed the existence of 42 satellite DNA families. BLAST searches of these sequences against the R. prolixus genome assembly revealed that only four of these satellite DNA families are shared between both species, suggesting a great differentiation between the Triatoma and Rhodnius genomes. Fluorescence in situ hybridization (FISH) location of these repetitive DNAs in both species showed that they are dispersed on the euchromatic regions of all autosomes and the X chromosome. Regarding the Y chromosome, these common satellite DNAs are absent in T. infestans but they are present in the R. prolixus Y chromosome. These results support a different origin and/or evolution in the Y chromosome of both species.