Degree Type

Dissertation

Date of Award

1988

Degree Name

Doctor of Philosophy

Department

Entomology

First Advisor

W. B. Showers

Abstract

A relative sampling technique was used daily to sample for adult European corn borer (ECB), Ostrinia nubilalis (Hubner), in aggregation sites within the grass. The flush bar, a meter-long aluminum bar, was swept through the grass canopy in ten meter-long sweeps and numbers of ECB moths were counted as they flushed from the 10 m[superscript]2 area. European corn borer egg masses were scouted within hybrid seed corn fields adjacent to flush bar sampling sites on a three to five day schedule;Daily numbers of flushed moths were averaged within samples and accumulated between scouting dates. Egg mass numbers were accumulated in a running sum over scouting dates. The running sum of egg masses was regressed on the running sum of mean adult numbers. The regression analysis confirmed a dependent relationship between egg mass numbers in the field on adult numbers in the grass around the field. A predictive equation was established to estimate egg mass levels within the field by adult numbers flushed in the grass;An oviposition preference by ECB females was documented for scouted egg mass numbers within hybrid seed fields. ECB females deposited greater numbers of egg masses on the tassled male inbred than on the detassled female inbred. Differences also existed between locations of egg masses on the plant. The majority of egg masses were located on the ear leaf and three leaves below. There was a trend for the male inbred to have a greater proportion of egg masses above the ear than the female inbred. Although the male inbred received larger numbers of egg masses, the ratio of larvae and tunnels/egg was not greater than that of the female inbred;A partial plant scouting technique for European corn borer egg masses was compared with the standard whole plant examination technique. The level of accuracy obtained by partial plant examination was found to be lower than that suggested for hybrid plants. There was a trend for a greater recovery rate of egg masses on the male inbred than on the female inbred;The efficacy of an adult directed control strategy applied to the grass was compared with a standard larval field treatment. Methomyl applied in the grass for adult control in combination with fenvalerate applied to the field for larval control significantly reduced larval numbers and tunnel damage. There were insignificant differences between the grass treatment, the field treatment and the untreated check.

DOI

https://doi.org/10.31274/rtd-180813-11175

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Mary Ellison Derrick

Language

en

Proquest ID

AAI8825911

File Format

application/pdf

File Size

142 pages

Included in

Entomology Commons

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