The structures of the new pyrethroids were elucidated utilizing nuclear magnetic spectroscopy and elemental analysis. The biological activity of the pyrethroids has been evaluated for houseflies and yellow fever mosquitoes. A correlation of increase in rapid knockdown and toxicity with decrease in size of halogen has been made. The most effective compound, the difluorovinyl ester, has a toxicity of 123 times greater than pyrethrins. This degree of toxicity has not previously been reported for a 5-benzyl-3-furanmethyl ester. The relative lipophilicities of the dihalovinyl esters, Rm, have been determined by reverse phase partition chromatography. The R values for the dihalo esters correlate with their m effectiveness as rapid knockdown agents. The least lipophilic compound, the difluorovinyl ester, possessed the highest knockdown in this dihalovinyl ester series. The difluorovinyl ester has incorporated a high level of toxicity while maintaining excellent effectiveness as a knockdown agent against houseflies. This combination of high knockdown and high toxicity in a single compound has not been previously reported. Several other pyrethroids were synthesized and evaluated for knockdown and toxicity, in order to make specific comparisons with pyrethroids of known effectiveness. The replacement of the isobutenyl group of the chrysanthemates by the dihalovinyl group has been effective against houseflies and yellow fever mosquitoes in enhancing or maintaining toxicity and knockdown in every pyrethroid series investigated. In the allethronyl series, this dihalovinyl replacement has resulted in a 12-fold increase in rapid knockdown activity against mosquitoes.

Carboxylesterases (CEs) metabolize a wide range of endogenous compounds and xenobiotics containing ester bonds. Crystal structures of mammalian CEs indicate a ?side door? located adjacent to the catalytic gorge that may act as an alternative pore for the trafficking of substrates and products. This study investigated the role of the ?gate? residue of the side door during para-Nitrobenzyl esterase (pnb CE)-catalyzed hydrolysis of esters. Purified recombinant pnb CE proteins were examined for their hydrolytic activity toward several esters. Mutation of the gate residue altered the kinetic parameters of pnb CE toward these substrates, demonstrated by increased Km values and decreased Vmax values. Site-specific mutations of the ?gate? residue also affected the sensitivity of the enzyme toward inhibiting organophosphate compounds. A distinct possibility is that the side door mutants affect substrate hydrolysis by increasing the steric hindrance and/or electrostatic repulsion between the substrate and the active site catalytic residues.

No description available.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.

The chemical fate and biological impacts of cyfluthrin in aquatic ecosystems were investigated using microcosms (1.9 m^3 concrete tanks) during 1989. Results were compared to a concurrent pesticide registration study using mesocosms (634.7 m^3 earthen ponds). Ten spray drift and five soil runoff simulations were conducted. Pesticide loadings were scaled by system volume, with the same experimental design in ponds and microcosms. Aqueous cyfluthrin concentrations and sediment residue values were generally higher in microcosms, while aqueous half-life was shorter in the smaller systems.

Rules which correlate structure and insecticidal activity of pyrethroids have evolved over the last thirty years from the results obtained in the testing of various synthetic pyrethroids. The major portion of these rules have dealt either with the development of new alcohol moieties or variations in the unsaturated side chain of the cyclopropane ring. There has been very little work done concerning modifications of the cyclopropane ring. This study was initiated to discover the affect of substituting an aziridin ring for the cyclopropane ring found in pyrethroids.

A model for the repellent effect of pyrethroid insecticides on insects was developed. Experiments were conducted using a small colony of honey bees in a flight cage. Conditioning to scented feeders allowed the separation of foraging bees from a single colony into treatment and control groups. Permethrin, cypermethrin, fenvalerate and flucythrinate were shown to be contact repellents to honey bees; exposure was primarily to the tarsi and ventral abdomen. The threshold dose of permethrin required to induce repellency was ca. 3.8 ng/bee. Repellency was fully reversible within 24 hours. No permanent effects on either memory or foraging efficiency were observed following acute exposure.

No description available.

No description available.

Larvae of the common green lacewing (GLW), Chrysopa carnea Stephens, have been reported tolerant to synthetic pyrethroid insecticides including permethrin (C/T) (3-phenoxybenzyl-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylate), the trans isomer being more toxic than cis. An investigation was performed to determine the possible role of metabolism in this tolerance. Following topical application, GLW metabolized 80% of cis and 71% of trans within two hrs. About 95% of both cis and trans were metabolized by 50 hrs. Metabolism of C/T in vitro was compared to a susceptible insect, the tobacco budworm (TBW), Heliothis virescens (F.). GLW degraded cis 1.7-fold faster than trans, while TBW metabolized trans at a slightly higher rate than cis. When esterases and oxidases were active together or alone, cis and trans were metabolized faster by GLW than TBW. Metabolism of C/T by GLW was primarily oxidative with hydrolysis as a secondary mechanism. Trans is more toxic to GLW apparently because of this isomer's lower rate of detoxication. Several metabolites of C/T, cis-, and trans-permethrin were identified in studies with GLW in vivo and in vitro. It appeared that cis was metabolized more intensively than trans in vivo. The roles of esterases and oxidases in metabolizing C/T, cis-, and trans-isomers were studied in vitro and the following number of metabolites were identified: with C/T--five with esterases plus oxidases, six with esterases, and seven with oxidases alone. With cis--six metabolites were produced when esterases plus oxidases were active, five with esterases, and four with oxidases alone. With trans--esterases plus oxidases produced four metabolites, three with esterases alone, and seven with the oxidases alone. A few unknowns were exhibited in each case. Hydroxylation at the 2'-position of the phenoxybenzyl group seems to be important for GLW tolerance to C/T. Hydroxylation could be the first step in detoxifying C/T and its isomers. The toxicity of trans to GLW could be explained by the limited routes by which esterases acting alone can degrade this isomer; only three metabolites were produced with esterases while seven were produced with oxidases.