title: A cline in frequency of autosomal males is not associated with insecticide resistance in house fly (Diptera: Muscidae).
abstract: Geographic variation in the chromosomal location of the male sex determining factor (M) was studied in four house fly, Musca domestica L., populations from the eastern United States. We found a strong clinal trend (29 degrees 41' latitude in Florida to 44 degrees 2' in Maine) in which the percentage of standard XY(M) males increased with increasing latitude. In Florida, 100% of the males possessed the M factor on the third autosome (III(M)). North Carolina had 20% III(M) males and 2.35% with both Y(M) and III(M). Fewer III(M) males were found in New York (4.35%). Populations from Maine contained 100% XY(M) males. In two of three standard laboratory-susceptible strains, all males carried M on an autosome ("autosomal males" or A(M)): CS (III(M)) and SRS (V(M)). Insecticide bioassays of four field-collected strains led us to conclude that resistance is not correlated with sex determination over a broad range of insecticides. For example, high levels of resistance to permethrin (86-99% survival at a diagnostic concentration) were found in all four field-collected strains. The five other insecticides evaluated showed varying levels of resistance among field strains. We conclude that a cline is present in house fly populations from the eastern United States with 100% III(M) males in the south and entirely Y(M) males in the north and that insecticide resistance is not a key factor influencing the evolution or linkage of M.
authors.affiliation: Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Ronda L
authors.initials: RL
authors.lastname: Hamm
authors.forename: Toshio
authors.initials: T
authors.lastname: Shono
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Scott
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002980:Climate; D003434:Crossing Over, Genetic; D005260:Female; D008040:Genetic Linkage; D006793:Houseflies / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D008297:Male; D011156:Population Density; D014481:United States; D014998:Y Chromosome / Q000235:genetics