Date of Award:

5-1-1987

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Biology (Entomology)

Committee Chair(s)

William A. Brindley

Committee

William A. Brindley

Committee

D. Davis

Committee

G. Beckstrand

Committee

W. Farnsworth

Abstract

Monitoring and early detection is critical to resistance management. Diagnostic tests such as colorimetric spot tests and electrophoresis are very efficient techniques in accurately distinguishing between resistant and susceptible individuals. All biological assays were conducted by simple contact exposure in vials containing different concentrations of trichlorfon and/or permethrin (0.01 to 30ug/vial). Vials used for control in bioassays were treated with acetone only. Synergist ratio (SR), percent synergism (%S) and log percent synergism (L%S) were calculated to determine synergism effects by four synergists: S, S, S-tributyl phosphorotrithioate (DEF), diethyl maleate (DEM), piperonyl butoxide (PB) and triphenyl phosphate (TP). DEF proved to provide the most synergistic effect and DEM the least. Colorimetric spot tests were conducted using both filter paper and tile test methods. One method consisted of pretreating filter paper (Whatman No. 1) with substrate (1-naphthylproprionate) before use. Fast Red TR or Fast blue B salts were used for staining. The tile test consisted of homogenizing individual insects in wells containing four drops of substrate (freshly prepared) using a glass rod. Electrophoresis was conducted using gradient plate gels. The data collected from colorimetry, contact bioassay and electrophoresis were analyzed or plotted using SPSSx, MINITAB, SAS and TELLAGRAF. Using colorimetric test data it was established that lygus bugs in northern Utah are strongly susceptible while those from central-west Idaho and central-east Oregon are strongly resistant to trichlorfon. Although sex of the insects showed some significance, color of the insect did not show any significance in terms of non-specific esterases activity. The data generated from bioassay experiments had lower LC50 values for lygus bug populations in northern Utah than in Idaho Oregon regions. With the use of synergists with permethrin and/or trichlorfon lower LC50 values could, generally speaking, be obtained. This however, indicated a dependence on the type of chemical and location. Although percent samples with electrophoresis plate zone I staining are higher than percent samples with zone staining for both populations, the absolute values of percent zone I staining are higher for Idaho-Oregon populations than those from northern Utah. Generally speaking, this study showed a good correlation between bioassay, spot tests, and electrophoresis in assessing insecticide tolerance and esterase activity. The LC50, for trichlorfon, in northern Utah lygus bug populations is about 3 ug/vial while in Idaho-Oregon regions that value is about 45 ug/vial. Also in Utah, percent samples with zone I staining ranges from 50 to 100 and zone IV staining ranges from Oto 40, while in Idaho-Oregon regions these values are respectively 65 to 100 for zone I and Oto 60 for zone IV. Further studies, however, would be needed to fully characterize the specific potentials of each technique.

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .