Title

Characterizing Organophosphate Resistance in the Mosquito Culex tarsalis

Lead Author Major

Biological Sciences

Format

Oral Presentation

Faculty Mentor Name

Tara Thiemann

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Culex tarsalis, a mosquito species prevalent on the western coast of the United States, is a primary vector for West Nile virus in California, which makes this species a major target for vector control. Cx. tarsalis is found primarily in rural areas where agricultural pesticides are used, resulting in potential resistance to these pesticides. Organophosphates, one class of pesticides, act as an inhibitor of acetylcholinesterase (AChE) preventing the degradation of acetylcholine from the synaptic cleft and resulting in overstimulation of the nervous system and death of the insect. The purpose of this project was to determine if a mutation in the AChE gene (ace-1) is responsible for organophosphate resistance in Cx. tarsalis. Adult female Cx. tarsalis were collected using CO2-baited traps from two locations, Sutter and Yuba Counties. A bottle bioassay was conducted using Naled, an organophosphate pesticide, in order to determine which individual mosquitoes were susceptible or resistant. DNA was extracted from these mosquitoes, and polymerase chain reaction (PCR) and DNA sequencing methods were used to amplify and sequence a portion of the ace-1 gene. Additionally, a microplate enzyme assay was conducted to determine if higher concentrations of detoxifying enzymes are responsible for resistance to organophosphates. While results are preliminary, there is no current evidence of a DNA mutation linked to organophosphate resistance in these field populations of Cx. tarsalis. Resistance demonstrated in the bottle bioassays may be due to an upregulation of detoxifying enzymes like alpha-esterase and acetylcholinesterase.

Location

DeRosa University Center, Room 211

Start Date

30-4-2016 3:00 PM

End Date

30-4-2016 5:00 PM

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Apr 30th, 3:00 PM Apr 30th, 5:00 PM

Characterizing Organophosphate Resistance in the Mosquito Culex tarsalis

DeRosa University Center, Room 211

Culex tarsalis, a mosquito species prevalent on the western coast of the United States, is a primary vector for West Nile virus in California, which makes this species a major target for vector control. Cx. tarsalis is found primarily in rural areas where agricultural pesticides are used, resulting in potential resistance to these pesticides. Organophosphates, one class of pesticides, act as an inhibitor of acetylcholinesterase (AChE) preventing the degradation of acetylcholine from the synaptic cleft and resulting in overstimulation of the nervous system and death of the insect. The purpose of this project was to determine if a mutation in the AChE gene (ace-1) is responsible for organophosphate resistance in Cx. tarsalis. Adult female Cx. tarsalis were collected using CO2-baited traps from two locations, Sutter and Yuba Counties. A bottle bioassay was conducted using Naled, an organophosphate pesticide, in order to determine which individual mosquitoes were susceptible or resistant. DNA was extracted from these mosquitoes, and polymerase chain reaction (PCR) and DNA sequencing methods were used to amplify and sequence a portion of the ace-1 gene. Additionally, a microplate enzyme assay was conducted to determine if higher concentrations of detoxifying enzymes are responsible for resistance to organophosphates. While results are preliminary, there is no current evidence of a DNA mutation linked to organophosphate resistance in these field populations of Cx. tarsalis. Resistance demonstrated in the bottle bioassays may be due to an upregulation of detoxifying enzymes like alpha-esterase and acetylcholinesterase.