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This report regards the research conducted in the synthesis of 2,5-disubstituted-1,3,4-oxadiazoles as potential insecticides which are closely related to the known insecticide DOWCO 416R, 2,5-bis(2,4-dichlorophenyl)-1,3,4-oxadiazole. The following compounds were synthesized: 2-(2,4-dichloro-5-nitrophenyl)-5-(2,4-dichlorophenyl)-1,3,4-oxadiazole, (2-(2,4-dichloro-5-nitrophenyl)-5-phenyl-1,3,4-oxadiazole, 2-(2,4-dichloro-5-aminophenyl)-5-aminophenyl)-5-(2,4-dichlorophenyl)-1,3,4-oxadiazole and 2-(2,4-dichloro-5-aminophenyl)-5-phenyl-1,3,4-oxadiazole. From the commercially available starting material, 2, 4-dichlorobenzoic acid, preparation of the above compounds involved nitration, reduction, esterification, preparation of monoacylhydrazines, preparation of substituted diacylhydrazines and preparation of 2, 5-disubstituted-1, 3, 4-oxadiazoles. All these compounds were characterized via NMR and infrared spectroscopy. In addition, this report includes discussion and recommendations concerning the experimental procedures and conditions for the preparation of these compounds.

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Early interest concerning the control of the green June beetle, Cotinis nitida Linn., also called the fig-eater, was recorded during the middle of the nineteenth century. Since that time farmers in Virginia and other Southeastern States have been trying to find better methods for the control of this insect. The larvae of this beetle, . en present in large numbers, are capable of almost completely destroying certain forage crops such as alfalfa and clover, not by direct feeding, but from the results of their search for food. The adult, although not of prime economic importance in this region, does cause considerable economic losses. It feeds on fruits from a number of different species of plants such as grapes, peaches, raspberries, apples, pears, plums and in particular figs, hence the common name fig-eater. A definite affinity also is shown towards certain grains such as corn and sorghum. / Master of Science

Control strategies for the German cockroach, Blattella germanica (L.), are usually based on the application of liquid insecticides in or near infested harborages. Cockroach mortality occurs when they are exposed to insecticide residue by walking on insecticide-treated surfaces. Cockroach walking depends on the three pairs of legs. Only tarsal pads and arolium on each leg are involved in traveling and picking up insecticide residue. The total contact area at each step was 0.1879 mm² and 0.1771 mm² for laboratory susceptible (VPI) and field-collected (RHA) cockroach strains, respectively. There were no significant differences (P > 0.05) in the walking distance in two steps among three legs, or between the two strains. However, the walking movement rate greatly influences the amount of insecticide accumulated on tarsal pads in a distinct time period. RHA-strain cockroach walked a significantly (P < 0.05) greater distance than VPI-strain on untreated and 10 ug/cm² of cypermethrin treated glass plates. RHA-strain cockroaches picked up significantly (P < 0.05) more cypermethrin than VPI-strain in 5 min, but there was no difference when exposed for 30 movement units. Knockdown time was significantly correlated (P < 0.05) to estimated dose transfer in 0.025 μg/cm² and 0.049 μg/cm² treatments for the VPI-strain, and in 0.245 μg/cm² and 0.392 μg/cm² for the RHA strain. Cockroach knockdown time and mortality were determined by cockroaches walking on different numbers of cypermethrin droplets on treated glass plates. Insecticide dose could be reduced from 10 μg/cm² to 0.025 μg/cm², but resulted in increasing the KT₅₀ from 5.4 min to 15.9 min in VPI-strain cockroaches. To achieve 50% cockroach knockdown, a VPI-strain cockroach must walk on at least 33 droplets (130 μm in diameter) of 0.1% cypermethrin; an RHA-strain cockroach must walk on at least 3174 droplets. High insecticide dosage increased the amount of antennal grooming in VPI-strain cockroaches and stimulated leg grooming in RHA-strain. Walking movement activities decreased in response to increased antennal and leg grooming. / Master of Science

Ph. D.

This study was undertaken for the following reasons: 1. Nicotine and its compounds have long been used as insecticides, and are in great demand at the present. 2. Tobacco, the source of nicotine, is such a valuable commodity that only waste has been used as a source of nicotine for years. 3. <i>N. rustica tabacum</i>, a species of tobacco, has a high nicotine content, and has been grown under climate and environment suitable for other types of tobacco. The purpose of the investigation is as follows: 1. Preparation of a nicotine hydrochloride dust insecticide from the entire tobacco plant. 2. To make a study of the costs of cultivating flue cured tobacco and the costs of cultivating tobacco that could be used for the preparation of the dust. 3. To determine the price at which the tobacco farmer could sell high nicotine content tobacco and still make the profit he realizes from the cultivation of the flue cured tobacco. / Master of Science

A report that the ethylene oxide fumigation of animal diets reduced their nutritive value has prompted a more detailed study of the reactions of this commercially-used fumigant. It has been demonstrated that the 24-hour fumigation of commercial casein, egg albumin and lactalbumin with ethylene oxide greatly reduced the ability of these proteins to support the growth of weanling rats when the proteins were fed as 9% of a purified diet as the sole source of amino acid nitrogen. Thorough drying of the proteins reduced the extent of subsequent fumigation damage. The nutritional quality of the three proteins was completely restored by the supplementary feeding of L-histidine-HCl, DL-methionine, and L-lysine-HCl, or, in some cases, only one or two of these amino acids. Microbiological assay confirmed a reduction in the biological availability of 11% to 83% of the histidine, 6% to 55% of the methionine and 51 to 92% of the lysine, depending on the protein and the amount of moisture present during fumigation. Histidine was generally the most labile amino acid and lysine the least labile. Additional amino acids appeared to be affected when an hydrolysate of casein was fumigated. The ethylene oxide fumigation of soybean alpha protein improves its growth-promoting quality for the rat. Evidence is presented that fumigation inactivates the heat-labile proteinaceous growth inhibitor, long recognized as a component of soybean protein. Chemical justification for the destructive action of ethylene oxide on the biological value of histidine, methionine, and certain B-vitamins was sought by reacting model compounds in aqueous solution with the fumigant and identifying the products. At 25°C. and atmospheric pressure ethylene oxide readily hydroxyethylates tertiary as well as primary and secondary amine nitrogen and also the sulfur of thioethers. Imidazole and histidine yield the 1,3-bis-(2-hydroxyethyl)imidazolium derivatives; nicotinamide, nicotinic acid, and pyridine yield the corresponding N-(2-hydroxyethyl)pyridinium compounds; and N-acetylmethionine is converted to s-(2-hydroxyethyl)-N-acetylmethionine, thetin. The reaction of ethylene oxide with amino acids results in hydroxyethylation of the primary amino groups but no esterification of carboxyl groups was observed. The extent of ethylene oxide-imidazole reaction in fumigated proteins could be determined colorimetrically. In the presence of ethylene oxide the mercapto group of cysteine appears to become doubly alkylated to produce a sulfonium compound which causes a flaccid paralysis, respiratory failure and death when injected subcutaneously into weanling rats. The structure of the compound bears certain similarities to other synthetic spasmolytics. Evidence is presented that the reaction of ethylene oxide with pyridoxine, riboflavin and folic acid involves the hydroxyethylation of tertiary heterocyclic nitrogens. A striking resemblance was observed between the alkylating capacity of ethylene oxide and the sulfur and nitrogen mustards. New compounds described are 1,3-bis-(2-hydroxyethyl)imidazolium chloride; N¹-(2-hydroxyethyl)nicotinic acid, betaine; and N-(2-hydroxyethyl) nicotinic acid chloride. N-(2-hydroxyethyl)nicotinamide chloride was also crystallized and its melting point found to be 14 degrees centigrade higher than previously reported in the literature. Other reaction products were studied in solution or as solid adducts of reinecke's salt or phosphotungstic acid. The proteolytic activity of chymotrypsin was progressively reduced by exposure of the cystalline enzyme to ethylene oxide vapor or by treatment of the enzyme in aqueous solution with the fumigant. However, treatment of chymotrypsin in aqueous solution with ethylene oxide did not impair its ability to hydrolyze p-nitrophenyl acetate. Likewise, the imidazole groups of native chymotrypsin appear to be protected from the hydroxyethylating action of ethylene oxide. Denaturing the protein in 8 M urea uncovered the imidazole groups and permitted reaction with the fumigant. On the basis of these studies it is felt that the effect of existing commercial ethylene oxide fumigating processes on the nutritive value of foods and feedstuffs bears closer investigation. / Ph. D.

Inhibited immune responses have been observed following occupational, inadvertent, or therapeutic exposure to chemically diverse xenobiotics. In the present studies, preliminary data were generated showing limited but significant systemic immunotoxicity following low-level topical exposure to the pyrethroid insecticide, permethrin (formerly not considered an immunotoxicant). Permethrin was applied to the shaved dorsal interscapular region of C57Bl/6N mice at doses of 0.5, 1.5, or 5.0 μl/day. The highest of these doses was approximately equal to 215 μg/kg/day, which is about seven times the estimated daily human exposure in individuals wearing permethrin treated clothing for insect protection. Mice were thus exposed to permethrin daily for 10 or 30 consecutive days, or every other day for 7 or 14 exposures. Body weight was not affected by the treatment. However thymic weight was decreased and splenic weight increased 2 days after termination of the topical exposure. Histopathology of immune organs showed no significant changes. Splenic macrophages showed significantly depressed chemiluminescent responses up to 10 days following termination of exposure, but macrophage phagocytic activity was not affected. Cell surface markers of thymocytes, splenocytes and bone marrow cells were not affected. Antibody production as shown by plaque forming cell (PFC) assay decreased significantly at 10 days after dosing termination. Taken together, these data indicate that low-level topical permethrin exposure may produce systemic immunotoxicity. / Master of Science