Comparative insect karyology: Current state and applications

Abstract

The current state of the comparative insect karyology and the main applications of chromosomal analysis of insects are reviewed. The most important characteristics of insect karyotypes in mitosis and meiosis are considered. Karyological studies provide important information on the genetic structure, life cycles and ecological characteristics, evolution, taxonomy, and phylogeny of insects. Insects have two principal mechanisms of sex determination: more common mechanism is based on the presence of sex chromosomes, and another, on haplodiploidy. Karyotypic analysis allows a number of linkage groups as well as the primary sex ratio to be determined. Chromosomal rearrangement can be used for the ecological monitoring of various insect populations and for pest control. Although a full-scale use of karyotypic details for constructing phylogenies of large insect taxa (except for Diptera which have polygene chromosomes) is possible only in combination with other features, chromosomal characters are still very important for phylogenetic purposes because their evolution is more or less independent of the environment. Chromosomal analysis can be used to reveal and identify sibling species, as well as to identify immature phases of insects. Studies of insect chromosomes may reveal cases of hybridization between forms with different karyotypes. At present, squashed and air-dried preparations are used for studying insect chromosomes. Together with morphometric analysis, differential chromosome staining methods, such as C-and AgNOR-banding, fluorochrome staining, in situ hybridization (including chromosome painting), restriction banding, etc. are being used to detect and document karyotypic differences. An outline of trends and prospects of the comparative insect karyology is given.