Date of Award

1985

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Extracts of foliage from the insect resistant soybean genotype PI227687 were bioassayed for activity against the soybean looper, Pseudoplusia includens (Walker), in feeding deterrency and growth inhibition tests. Dichloromethane extract had a pronounced deterrent effect on feeding, while petroleum ether and methanol extracts stimulated feeding. The water extract exhibited neutral activity. Flash chromatography of the dichloromethane extract yielded four fractions with moderate deterrent properties, one which was strongly deterrent, and one which was stimulative. Similar fractionation of the methanol extract yielded four fractions; one stimulated feeding, two deterred feeding, and one was neutral. Feeding P. includens larvae on artificial diet supplemented with extract fractions indicated that one dichloromethane fraction and three methanol fractions caused greater mortality than solvent control diets. Chemical analysis of the methanol fractions MEOH 3 and MEOH 4 yielded the closely related flavonoids: coumestrol, phaseol, and afrormosin. The sex pheromone of Chilo plejadellus Zinken was shown to be (Z)-13-octadecenal. This compound was extracted from female abdominal tips and detected by gas chromatography (GC), gas chromatography mass spectroscopy (GCMS) and by comparison with synthetic material. Field tests conducted in Crawley, Lake Providence and Mer Rouge, Louisiana showed that a trap baited with 3.0 mg of (Z)-13-octadecenal was 90% as attractive as traps containing C. plejadellus virgin females. Pheromone traps were more effective in detecting C. plejadellus populations than a fluorescent "black" light trap. Monitoring studies conducted in Texas, Louisiana and Arkansas indicated that rice grown in all three states is being infested by C. plejadellus. Among them, rice grown in Louisiana suffers the highest damage.

Pages

89

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