Predicting Resistance: Quantifying the Relationship between Urban Development, Agricultural Pesticide Use, and Pesticide Resistance in a Nontarget Amphipod

Resistance
alleles within the voltage-gated sodium channel (vgsc) have been correlated with pyrethroid resistance in
wild populations of the nontarget amphipod, Hyalella
azteca from California (CA), U.S.A. In the present
study, we expand upon the relationship between land use and the evolution
of pesticide resistance in H. azteca to develop a quantitative methodology to target and screen novel
populations for resistance allele genotypes in a previously uninvestigated
region of the U.S. (New England: NE). By incorporating urban land
development and toxicity-normalized agricultural pesticide use indices
into our site selection, we successfully identified three amino acid
substitutions associated with pyrethroid resistance. One of the resistance
mutations has been described in H. azteca from CA (L925I). We present the remaining two (vgsc I936F and I936V) as novel pyrethroid-resistance alleles in H. azteca based on previous work in insects and elevated
cyfluthrin resistance in one NE population. Our results suggest that
urban pesticide use is a strong driver in the evolution of resistance
alleles in H. azteca. Furthermore,
our method for resistance allele screening provides an applied framework
for detecting ecosystem impairment on a nationwide scale that can
be incorporated into ecological risk assessment decisions.