Cytogenetics of two radiation-induced, sex-linked translocations in the yellow-fever mosquito, Aedes aegypti.

CONSIDERABLE work has been done during the last few years on the genetics and cytogenetics of the yellow-fever mosquito, Aedes aegypti. However, the emphasis of this work has been in the areas of genetics of insecticide resistance (BROWN and ABEDI 1962), formal genetics (CRAIG and HICKEY 1967), cytology (AKSTEIN 1962; RAI 1963), and cytogenetics of chemosterilization (RAI 1964a,b; RAI and SHARMA 1970). Relatively less work has been done in cytogenetics of chromosomal rearrangements and in possible manipulation of sterility associated with structural chromosomal heterozygosity for population control. Aedes aegypti is a promising subject for basic cytogenetic studies (RAI 1967a) and their possible application to genetic control (KNIPLING et al. 1968). It is easily maintained and manipulated in the laboratory, has a rich store of genetic variability, and its three linkage groups are well established (CRAIG and HICKEY 1967). Its normal karyotype consists of three pairs of chromosomes which are individually recognizable and these have recently been renumbered I , 2, and 3 ( MCDONALD and RAI 1970b). In brain tissues, they measure approximately 5.4, 7.6, and 6.9 micra, respectively, at metaphase (RAI 1963). Heteromorphic sex chromosomes are absent in this species. Sex is determined by a single gene, M vs. m with the M m genotype determining maleness and mm femaleness (MCCLELLAND 1962). These observations have paved the way for undertaking detailed studies on the genetics of radiation-induced heritable chromosomal rearrangements in A . aegypti and on an evaluation of the sterility associated with these for possible genetic control purposes. The economic importance of this species is well known. It transmits diseases such as yellow fever, dengue, and hemorrhagic fever and is thus one of the most important disease vectors. Furthermore, in view of the environmental contamination that ensues from the use of insecticide chemicals and the fact that most populations of this species develop resistance to the insecticides used, it is imperative that alternative control methods be developed. This paper describes the cytogenetics of two radiation-induced, sex-linked reciprocal translocations in A . aegypti and points out the potential of translocations for possible genetic control purposes. Data on the mating competitiveness,