Originally published as Genetics Published Articles Ahead of Print on January 16, 2005.

Genetics, Vol. 169, 1529-1539, March 2005, Copyright © 2005
doi:10.1534/genetics.104.033639

Quantitative Genetics of Vector Competence for La Crosse Virus and Body Size in Ochlerotatus hendersoni and Ochlerotatus triseriatus Interspecific Hybrids

Justin R. Anderson, Jennifer R. Schneider, Paul R. Grimstad and David W. Severson1

Center for Tropical Disease Research and Training, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556

1 Corresponding author: Center for Tropical Disease Research and Training, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556.
E-mail: severson.1{at}nd.edu

La Crosse virus is a leading cause of pediatric encephalitis in the United States. The mosquito Ochlerotatus triseriatus is an efficient vector for La Crosse virus, whereas the closely related O. hendersoni transmits only at very low rates. Quantitative trait loci (QTL) affecting the ability to orally transmit this virus and adult body size were identified in 164 F2 female individuals from interspecific crosses of O. hendersoni females and O. triseriatus males using a combination of composite interval mapping (CIM), interval mapping (IM) for binary traits, and single-marker mapping. For oral transmission (OT), no genome locations exceeded the 95% experimentwise threshold for declaring a QTL using IM, but single-marker analysis identified four independent regions significantly associated with OT that we considered as tentative QTL. With two QTL, an increase in OT was associated with alleles from the refractory vector, O. hendersoni, and likely reflect epistatic interactions between genes that were uncovered by our interspecific crosses. For body size, two QTL were identified using CIM and a third tentative QTL was identified using single-marker analysis. The genome regions associated with body size also contain three QTL controlling OT, suggesting that these regions contain either single genes with pleiotropic effects or multiple linked genes independently determining each trait.