Environmentally Sustainable Vector Control: Characterization of Cytochrome P450-Monooxygenase Mediated Pyrethroid Resistance in the Southern House Mosquito, Culex pipiens quinquefasciatusEPA Grant Number: F6F21341
Title: Environmentally Sustainable Vector Control: Characterization of Cytochrome P450-Monooxygenase Mediated Pyrethroid Resistance in the Southern House Mosquito, Culex pipiens quinquefasciatus
Investigators: Hardstone, Melissa C.
Institution: Cornell University
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $111,172
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Entomology
Cytochrome P450-monooxygenase mediated resistance (P450) is a vital biochemical enzymatic system that metabolizes xenobiotics and endogenous compounds. Overall, the objective of my project is to characterize this detoxification mechanism in mosquitoes resistant to pyrethroids. The first aim of this study is to identify the overexpressed P450 protein by proteomics. The second aim is to determine the fitness profile and evaluate the population genetics of the mechanism. Understanding this system will aid in vector control management practices to delay the onset of resistance in field populations and decrease the environmental destruction that comes from the overuse of chemicals.
The objectives of this study can be met because we created a resistant laboratory strain of mosquito, differing only at the P450 locus, that is highly related (99.94%) to the susceptible strain. A proteomics approach using mosquito microsomes will be used to identify the P450 gene primarily responsible for pyrethroid resistance. Reproducibly overexpressed proteins of appropriate sizes will be analyzed and full-length cDNAs will be obtained. To determine the fitness profile, three experiments will be conducted: (1) trace resistance allele frequencies through time in neutral and pressured environments, (2) create a life history table, and (3) determine male reproductive fitness. Lastly, to assess population genetics of the P450, we will genotype mosquito samples from many locations where pyrethroids are currently used.
Resistance is a major hurdle in controlling medically important pests and results from this project will provide needed insight to facilitate environmentally responsible vector control. Identification of the P450 responsible for pyrethroid resistance in mosquitoes will allow for the development of a gene specific assay. The fitness profile of the resistance allele is essential when attempting to determine if a fitness cost exists. This biological parameter can be exploited in field populations to potentially decrease resistance without increasing insecticide use. The population genetics results are not only going to allow for the establishment of a biogeographical distribution map, but will also allow us to anticipate areas that may develop P450-mediated resistance.