Karyotypic studies of four species of the blackfly, Simulium (Diptera: Simuliidae)

Abstract

Karyotypic studies were carried out on the mitotic chromosomes from the supraoesophageal ganglia of four species of the blackfly, Simulium. The four species were Simulium alcocki Pomeroy, Simulium damnosum Theobald sensu lacto and two yet unidentified species of Simulium herein referred to as US 1 (unidentified species 1) and US 2 (unidentified species 2). A diploid number (2n) of 6 was obtained for all the species of blackfly studied. A modified method for preparing mitotic chromosomes from the supraoesophageal ganglia was developed. This involved placing the fixed paired supraoesophageal ganglia in 2.5% hydrochloric acid for 1 to 2 s and staining in FLP orcein for 10 to 15 min. Idiograms were constructed for all the four species studied. Standard methods were adopted in the classification and nomenclature used in describing the chromosomes of the four species of blackfly in the investigation. No structural aberrations were observed in any of the species studied.

Key words: Simulium damnosum s. l., Simulium alcocki, sensu lacto, karyotype, mitotic.