ORIGINAL ARTICLE Chromosomal analysis and meiosis studies of Oxya chinensis (Orthoptera: Acrididae) from Thailand Sumalee Phimphan 1 • W. Sangpakdee 2 • K. Sangpakdee 3 • A. Tanomtong 1 Received: 29 April 2016 / Accepted: 24 October 2016 Ó Archana Sharma Foundation of Calcutta 2016 Abstract The standard karyotype and meiotic cell divi- sions of Oxya chinensis Thunberg, 1815 (Orthotera: Acri- didae) from Khon Kaen, Thailand were studied by conventional and silver staining techniques. Chromosomal preparations were made from grasshopper testes. The results showed that the male O. chinensis had diploid chromosome number 2n = 23 (XO). Karyotype was pre- sented with eight long (1–4 pairs), eight medium (5–8 pairs) and six short (9–11 pairs) acrocentric chromosomes with minute short arms in all autosomes. The acrocentric X chromosome was approximately same in size as found for medium autosomes. The nucleolar organizer regions (NORs) were found on telomeric regions of all minute short arm acrocentric chromosomes in metaphase, includ- ing X chromosome. In zygotene stage of meiotic cell division, NORs were detected in three regions per cell by silver staining while only one region was found by con- ventional staining. Meiotic cell divisions were also studied to confirm the diploid chromosome number and normal meiotic behaviour. The karyotype formula was found in O. chinensis:2n = 23 (XO); La 4 ? Ma 4 ? Sa 3 ? X- chromosome. Keywords Grasshopper Á Karyotype Á Oxya chinensis Introduction The small Chinese rice grasshopper (Oxya chinensis Thun- berg, 1815) (Fig. 1) is a major insect pest in rice, occurs in all rice—growing areas of Thailand. The male adults are brown, greenish yellow grasshoppers, with about 25–30 mm body length. Females are slightly larger, with a conspicuous broad brown stripe laterally through the eyes and extending pos- teriorly along tegmina. The prominent distal end of hind tibia is dark brown. Males generally have six instars whereas females have 6–7 instars. Eggs are generally laid in a pod just below the soil surface. It was the most common destructive pest in rice of South East Asia in the past, but is presently causing damage to the rice in Thailand [9]. The main prob- lem caused by this rice grasshopper species is on the leaves of young seedlings. This widespread species mainly inhabits rice cultivation in the low–lying grasslands, rice fields, and their surrounding banks. O. chinensis belongs to subfamily Oxyinae, family Acrididae under order Orthoptera. There are 18 species and six subspecies in this genus. Their difference in characters are based on eight morphological characters of the phallic complex according to Hollis’s classification. Some authors reported that taxonomy of Oxya species could be determined using morphological and cytological char- acters [16]. In a previous study, comparisons of karyotypes and chromosome C-banding patterns were investigated in five Oxya species (O. chinensis, O. shanghalensis, O. & A. Tanomtong tanomtong@hotmail.com Sumalee Phimphan joodoof@gmail.com W. Sangpakdee wiwatsang@gmail.com K. Sangpakdee kitti_tui11@hotmail.com 1 Toxic Substances in Livestock and Aquatic Animals Research Group, Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand 2 Biology Program, Faculty of Science, Udon Thani Rajabhat University, Udon Thani 41000, Thailand 3 Faculty of Environmental Culture and Ecotourism, Srinakharinwirot University, Bangkok 10110, Thailand 123 Nucleus DOI 10.1007/s13237-016-0188-x