Waltonella flexicauda: Development controlled by a genetic factor in Aedes aegypti

Strains of Aedes aegypti, one selected for susceptibility and the other for refractoriness to the frog filariid, Waltonella flexicauda, were crossed. The progeny of these crosses indicated that refractoriness was dominant. An allelism test was constructed between the susceptible strain and the REFM strain, homozygous for red-eye and filarial susceptibility, Brugia malayi ( Macdonald and Sheppard, 1965, Annals of Tropical Medicine and Parasitology 59, 74–87). The F 1 progenies and both parental-types were susceptible to W. flexicauda infection, thus suggesting allelism. Through further selection, susceptibility in the refractory strain was reduced to nearly 0%. The F 1 progeny of reciprocal crosses between the new refractory strain and a selected white-eye ( w), susceptible strain were 14 and 18% susceptible, suggesting incomplete dominance. The linkage data from the backcross progenies indicated that susceptibility to W. flexicauda was located on linkage group I, 5 units from the sex locus and 10 units from the w locus. This factor for susceptibility did not control development of Brugia pahangi or Dirofilaria immitis. The new filarial susceptibility factor was designated f m2 .