RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM MAPPING OF QUANTITATIVE TRAIT LOCI FOR MALARIA PARASITE SUSCEPTIBILITY IN THE MOSQUITO AEDES-AEGYPTI

Susceptibility of the mosquito Aedes aegypti to the malarial parasite Plasmodium gallinaceum was investigated as a quantitative trait using restriction fragment length polymorphisms (RFLP). Two F-2 populations of mosquitoes were independently prepared from pairwise matings betwee n a highly susceptible and a refractory strain of A. aegypti. RFLP wer e tested for association with oocyst development on the mosquito midgu t. Two putative quantitative trait loci (QTL) were identified that sig nificantly affect susceptibility. One QTL, pgs[2,LF98], is located on chromosome 2 and accounted for 65 and 49% of the observed phenotypic v ariance in the two populations, respectively. A second QTL, pgs[3,MalI ], is located on chromosome 3 and accounted for 14 and 10% of the obse rved phenotypic variance in the two populations, respectively. Both QT L exhibit a partial dominance effect on susceptibility, wherein the do minance effect is derived from the refractory parent. No indication of epistasis between these QTL was detected. Evidence suggests that eith er a tightly linked cluster of independent genes or a single locus aff ecting susceptibility to various mosquito-borne parasites and pathogen s has evolved near the LF98 locus; in addition to P. gallinaceum susce ptibility, this general genome region has previously been implicated i n susceptibility to the filarial nematode Brugia malayi and the yellow fever virus.