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SummaryThe non-banded and C-banded karyotypes of 10 species of South Indian short horned grasshoppers of the family Acrididae with diploid number 23 in males and 24 in females were studied. All the species except Dociostaurus species A. and Leva indica have shown telocentric chromosomes. Interspecific non-banded and banded karyotypic comparison and its evolutionary implications are discussed. Key words Acrididae, Grasshoppers, Chromosomes, Karyotype, C-banding.Karyotype forms the cytological basis of species identity. Acrididae is known for its karyotypic uniformity or conservatism. But the instances of karyotypic variation with respect to number and morphology of chromosomes are observed in natural populations, which will add to the evolutionary pattern of a species.One of the mechanisms of species differentiation is the C-banding of chromosomes. C-banding technique has proven very effective for chromosomal identification and characterization and the pattern of C-banding has been found to be characteristic for a species or at least to a group of species (Kalkman 1984). King and John (1980) have found a remarkable degree of C-band variation between many species of grasshoppers. In addition, Acrididae showed a C-band variation even within the same species (Shaw et al. 1976, John and King 1977.In the present paper the karyotype and the distribution of C-heterochromatin in 10 species of Acrididae are presented and the possible evolutionary significance has been discussed. Materials and methodsThe males and females of 10 species belonging to 3 sub families of Acrididae were collected in and around Mangalore University Campus, South India and chromosome preparations were made using hepatic caecae following the standard Colchicine-hypotonic-cell suspension-flame dry technique. The flame dried slides were treated for C-banding following the method of Sumner (1972) with little modifications. The chromosomes were classified after Levan et al. (1964) and appropriate karyotypes were constructed. Results and discussionThe somatic chromosome preparations of the species of Tryxalinae, Oedipodinae, Catantopinae in the Acrididae under study exhibited XX : XO pattern of sex determining mechanism.

Aneuploidies are the most common chromosomal causes for spontaneous abortions and constitute a major part of genetic disorders among the neonates. Aneuploidy producing agents (aneugens) pose serious genetic hazards to the human population. Therefore, testing for aneuploidy induction should be part of the requirement in drug safety guidelines. The aneugenic potential of pilocarpine nitrate, an alkaloid drug used as an ophthalmic solution was screened by chromosome analysis studies in the bone marrow cells of mice. Using the technique developed by Miller and Adler (1989) we evaluated changes in the mitotic index (MI), induction of chromatid contraction and spreading (C-mitoses) and decrease of anaphase frequencies as indicators of the aneuploidy inducing potency of the drug. Concentrations of pilocarpine nitrate of 4, 8 and 12 mg/kg body weight were administered intraperitoneally to mice. Colchicine-treated and water-treated animals formed the positive and negative controls. The data obtained in the cytogenetic analysis of both dose-response and time-response studies showed a significant induction of C-mitotic effects in the mouse bone marrow. The positive results indicated that the drug is a potential aneugen and should be further evaluated.