Lambornella clarki (Ciliophora:Tetrahymenidae) resistance in Aedes sierrensis (Diptera:Culicidae):population differentiation in a quantitative trait and allozyme loci.

Heritable variation for resistance to the parasite Lambornella clarki (Corliss & Coats) by its host Aedes sierrensis (Ludlow) and neutral genetic variation among local Oregon mosquito populations were assessed by selection and allozyme frequencies. L. clarki resistance was significantly greater in a population of mosquitoes normally exposed to this parasite than in an unexposed population. Despite this difference between populations, there was no significant increase in heritable resistance to L. clarki within populations of Ae. sierrensis after 1 generation of laboratory selection. Differentiation estimated from allozyme electrophoresis did not coincide with differentiation in L. clarki resistance in Ae. sierrensis populations at the microgeographic scale. Ae. sierrensis has the capacity to respond to foreign clones of the parasite, but electrophoretic surveys may fail to indicate underlying differences in the parasite resistance of mosquito populations.