A comparative cytogenetic study of Drosophila parasitoids (Hymenoptera, Figitidae) using DNA-binding fluorochromes and FISH with 45S rDNA probe Vladimir E. Gokhman 1 • Nadezhda L. Bolsheva 2 • Shubha Govind 3 • Olga V. Muravenko 2 Received: 18 March 2016 / Accepted: 2 May 2016 Ó Springer International Publishing Switzerland 2016 Abstract Karyotypes of Leptopilina boulardi (Barbotin, Carton et Keiner-Pillault, 1979) (n = 9), L. heterotoma (Thomson, 1862) (n = 10), L. victoriae Nordlander, 1980 (n = 10) and Ganaspis xanthopoda (Ashmead, 1896) (n = 9) (Hymenoptera, Figitidae) were studied using DNA-binding ligands with different base specificity [pro- pidium iodide (PI), chromomycin A 3 (CMA 3 ) and 4 0 ,6- diamidino-2-phenylindole (DAPI)], and fluorescence in situ hybridization (FISH) with a 45S rDNA probe. Fluorochrome staining was similar between the different fluorochromes, except for a single CMA 3 - and PI-positive and DAPI-negative band per haploid karyotype of each species. FISH with 45S rDNA probe detected a single rDNA site in place of the bright CMA 3 -positive band, thus identifying the nucleolus organizing region (NOR). Chro- mosomal locations of NORs were similar for both L. heterotoma and L. victoriae, but strongly differed in L. boulardi as well as in G. xanthopoda. Phylogenetic aspects of NOR localization in all studied species are briefly discussed. Keywords Hymenoptera Á Figitidae Á Karyotypes Á DNA-binding fluorochromes Á FISH Á 45S rDNA Introduction The Hymenoptera are one of the largest, most taxonomi- cally complicated and economically important insect orders, with its world fauna containing more than 150,000 described species (Aguiar et al. 2013). They are also very diverse in terms of bionomics, since members of the main groups of this order can be herbivores, parasitoids, preda- tors as well as pollinators and nectar feeders (Gauld and Bolton 1988). Considerable efforts are currently underway to sequence a number of insect genomes, especially under the i5K initiative (Evans et al. 2013). However, to date, just a few Hymenoptera genomes are fully sequenced. For example, data on full genomes of only twenty members of this order are available at present through the Hymenoptera Genome Database (Elsik et al. 2016). Of these, the genome of the single parasitoid species, Nasonia vitripennis (Walker) (Chalcidoidea, Pteromalidae), has been studied in detail (The Nasonia Genome Working Group 2010). Wasps which belong to the genera Leptopilina Fo ¨rster, 1869 and Ganaspis Fo ¨rster, 1869 (Cynipoidea, Figitidae) are solitary larval/pupal endoparasitoids of various Dro- sophila Fallen, 1823 species (Melk and Govind 1999; Allemand et al. 2002). Since some of these parasitoid/host assemblages represent good models for investigating many general aspects of biology and physiology of insect para- sitism, genomes of these wasp species are under intensive investigation. Transcriptome analyses of these species (Colinet et al. 2013; Goecks et al. 2013; Heavner et al. 2013; Mortimer et al. 2013) are being followed by genome sequencing efforts. In this regard, studying parasitoid karyotypes can provide important information for genome research (Gokhman 2009). Morphometric study of routinely stained chromosomes and genome sizes of three Leptopilina and one Ganaspis & Vladimir E. Gokhman vegokhman@hotmail.com 1 Botanical Garden, Moscow State University, Moscow, Russia 119234 2 Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia 119991 3 Biology Department MR526, The City College of the City University of New York, 138th Street and Convent Avenue, New York, NY 10031, USA 123 Genetica DOI 10.1007/s10709-016-9902-5