Date of Award

5-2020

Degree Type

Thesis

Degree Name

Departmental Honors

Department

Biology

First Advisor

Scott Bernhardt

Abstract

Background: Insecticide resistance for sand flies is a concern since sand flies are vectors for Leishmania spp. parasites which cause leishmaniasis affecting millions of people each year. The CDC bottle bioassay is used to assess resistance by comparing known insecticide diagnostic doses and diagnostic times from an insecticide-susceptible population. The objective of this study was to determine diagnostic doses and diagnostic times for α-cypermethrin and the lethal dose for 50% and 90% mortality for α-cypermethrin, permethrin, and DDT for Phlebotomus argentipes.

Methods: The CDC bottle bioassays were performed in 1,000 mL glass bottles with 15-25 sand flies from a laboratory strain of insecticide-susceptible P. argentipes. A range of concentrations of α-cypermethrin, permethrin, and DDT were evaluated. Approximately four replicates at each concentration were completed with a 24-hour recovery period after the exposure tests. 24-hour mortality dose-response survival curves were created. A time-to-knockdown test was conducted withα-cypermethrin to determine the diagnostic doses with diagnostic times.

Results: α-Cypermethrin had the lowest LD50 and LD90 followed by permethrin and then DDT with the highest values. Diagnostic doses with (diagnostic times) for α-cypermethrin were 7.5 μg/mL (30 minutes), 5.0 μg/mL (35 minutes), and 3.0 μg/mL (45 minutes).

Conclusions: The dose-response survival curves, diagnostic doses, and diagnostic times can be utilized by control programs in assessing insecticide resistance in field populations of P. argentipes. The control programs can apply the appropriate insecticide and dose to effectively manage the population. The data presented can also be used a starting point for determining diagnostic doses and diagnostic times for other sand fly species.

Included in

Biology Commons

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