LINKAGE OF GOLD, ITS RECESSIVE LETHALITY AND SEX-RELATED VARIATION IN CROSSING-OVER IN CULEX PIPIENS (DIPTERA: CULICIDAE)

Triple backcrosses in all possible phases of 9,791 Culex pipiens L. established the sequence Gold (Gd), yellow-larva (y) and ruby-eye (ru) in linkage group 2. Segregation of none of die factors departed significantly from 1:1. The median recombination values between y and ru are 23.8% in females and 17.2% in males; both agree closely with previously published estimates. The median recombination value between Gd and y is 21.6% and there is no significant difference between that in males and females.Females showed no interference, but that in males was positive and highly significant with an estimated coefficient of coincidence of 0.77 ± 0.06. Recombination was highly variable between families and there was no correlation between the two segments. It is suggested that variability is a function of individual chromosome difference rather than of any factor such as age or temperature. A series of double intercrosses with Gd and y showed that when homozygous, Gd (or a very closely linked gene) was lethal in the early larval stage.The importance of this dominant marker is enhanced by its inferred close proximity to the single dominant gene giving resistance to DDT.