Molecular cytogenetic studies in the ladybird beetle Henosepilachna argus Geoffroy, 1762 (Coleoptera, Coccinellidae, Epilachninae)

Abstract

The ladybird Henosepilachna argus Geoffroy, 1762 has been cytogenetically studied. In addition we have conducted a review of chromosome numbers and the chromosomal system of sex determination available in the literature in species belonging to the genus Henosepilachna and in its closely related genus Epilachna. Chromosome number of Henosepilachna argus was 2n=18, including the sex chromosome pair, a common diploid chromosome number within the tribe Epilachnini. The study of prophase I meiotic chromosomes showed the typical Xyp “parachute” bivalent as in the majority of species of Coccinellidae. C-banding and fluorescent staining with AT-specific DAPI fluorochrome dye have been carried out for the first time in H. argus. C-banding technique revealed that heterochromatic blocks are pericentromerically located and DAPI staining showed that this heterochromatin is AT rich.Fluorescence in situ hybridizations using rDNA and the telomeric TTAGG sequence as probes have been carried out. FISH using rDNA showed that the nucleolar organizing region is located on the short arm of the X chromosome. FISH with the telomeric sequence revealed that in this species telomeres of chromosomes are composed of the pentanucleotide TTAGG repeats. This is the first study on the telomeric sequences in Coccinellidae.

The presence of the ancestral insect telomeric motif in kissing bugs (Triatominae) rules out the hypothesis of its loss in evolutionarily advanced Heteroptera (Cimicomorpha)

“…Telomeric TTAGG probe generation and FISH assays were carried out following Lorite et al (2002) and Mora et al (2015). Telomeric probes were generated by PCR using the primers (TTAGG) 6 and (TAACC) 6 , following a similar procedure as described by IJdo et al (1991).…”

Isolation of a Pericentromeric Satellite DNA Family in Chnootriba argus (Henosepilachna argus) with an Unusual Short Repeat Unit (TTAAAA) for Beetles

“…A recent revision of the tribe Epilachnini placed the ladybird beetle Henosepilachna argus into the genus Chnootriba [33]. The chromosome number in this species is 2n = 18 with an Xy parachute sex chromosome system [12]. The Y chromosome was minute and for this reason it is often written with a lowercase letter.…”

“…C-banding of C. argus chromosomes showed the presence of large heterochromatic pericentromeric regions on all chromosomes, including the sexual pair. Staining with DAPI showed that the DNA located on these regions was A+T rich [12]. Since satDNA is the main component of the heterochromatin, another or other satDNA families must be present on those pericentromeric regions.…”

“…The ladybird beetle Chnootriba argus is characterized by the presence of large heterochromatic blocks on all chromosomes [12]. Usually, the isolation of the satDNA is carried out by digestion of total genomic DNA using restriction endonucleases.…”

Karyotype stability in the family Issidae (Hemiptera, Auchenorrhyncha) revealed by chromosome techniques and FISH with telomeric (TTAGG)n and 18S rDNA probes

“…In addition, recent publications have shown that the number and chromosomal locations of the major rDNA multigene families are useful for the study of karyotype evolution in other insect groups (e.g. Grzywacz et al 2011: Orthoptera; Gokhman et al 2014: Hymenoptera; Vershinina et al 2015: Lepidoptera; Lachowska-Cierlik et al 2015: Mantophasmatodea; Mora et al 2015: Coleoptera).…”