A new marker, black, a useful recombination suppressor, in(2)2, and a balanced lethal for chromosome 2 of the mosquito Anopheles gambiae

A new marker for the second chromosome of Anopheles gambiae, black, was iso lated from progeny of Co-60-irradiated mosquitoes. The black mutation incre ases melanization of larval setae and portions of the cuticle that are heav ily sclerotized such as the saddle and head capsule. Adults have a sooty co lor that almost completely eliminates white banding on wings, tarsi, and pa lps. Fertility and general vigor of black individuals is reduced relative t o wild-type; however, this does not prevent routine use for genetic crossin g. The black marker was mapped to an interval on chromosome 2 between colla rless and Dieldrin resistance 22 centiMorgans (cM) from collarless and 39 c M from Dieldrin resistance. We also isolated from Co-60-irradiated mosquito es a pericentric inversion, In(2)2, that was marked with dominant alleles o f the independently assorting genes collarless and Dieldrin resistance. Thi s inversion is in coupling with the pericentric inversion 2Rd and covers ap proximately two-thirds of chromosome 2 from divisions 9 to 22. While inbree ding ln(2)2 heterozygotes, we isolated a stock in which the inversion was i n repulsion to a chromosome marked with c b Dl(S) and an unidentified reces sive lethal. This arrangement produced a useful and stable chromosome 2 bal ancer system that has remained intact for 26 generations without selection. These genetic tools will reduce the effort requires to isolate, among othe r things, the genetic factors affecting malaria parasite interactions with the mosquito host.