Bibliography: leaves 165-188. This research examines biological and behavioural interactions among the diamond-back moth, Plutella xylostella L. (Lepidoptera: Plutellidae), Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) and the microbial insecticide, Bacillus thuringiensis Berliner. A deterministic simulation model is developed describing the influence of C. plutellae on the evolution of resistance to Bt in a diamond-back moth poulation.

Genetics, gene flow, and distribution of pesticide resistance traits were examined for organophosphate (OP) resistance in three beneficial phytoseiid mites. Levels and genetics of OP resistance in Amblyseius andersoni were examined first. Laboratory strains from Italy and Oregon, USA, were compared in susceptibility to insecticides used in western Oregon fruit crops. The Italian strain was 80-100 times more resistant to the OPs azinphosmethyl, diazinon, malathion, and phosalone, as well as carbaryl, a carbamate. Significant differences were not found between strains for endosulfan or fenvalerate. Using backcross analysis, response of F1 hybrids to azinphosmethyl indicated OP resistance was semidominant. Through novel statistical analysis, backcross of F1 to parent strains revealed resistance was polygenic, with at least two loci. Reciprocal crosses demonstrated the presence of maternal effects, with increased variation associated with progeny of Oregon females. In the next set of experiments, electrophoresis of allozymes was used to estimate gene flow for Typhlodromus pyri. Ten populations from two apple growing valleys of Oregon were compared. Subpopulations were collected from in and around commercial apple orchards. Four loci unaffected by pesticide use were examined. FST was calculated at 0.115, and Nm as 2.08. No allelic patterns could be discerned for populations among or within valleys; however, more variation was present for mite populations within valleys than between them. Some inbreeding was found within populations. While from dispersal studies one would conclude T. pyri is nondispersive, allozymic analysis indicates there is moderate gene flow. Factors affecting OP resistance distribution in T. pyri and Metaseiulus occidentalis were examined. A diagnostic concentration of azinphosmethyl was used to determine OP resistance frequencies for populations of each species, collected in and near commercial apple orchards in two valleys. OP resistance in T. pyri populations was localized: mites from 10 m or more outside orchards were OP susceptible, while those within orchards were resistant. This indicated limited gene flow. All M. occidentalis populations were resistant, indicating a regional resistance pattern and high gene flow. Factors which were not significant in the distribution of OP resistance were: valley, degree of orchard isolation, host plant, and seasonality. / Graduation date: 1994

With widespread use of pesticides in modern agriculture, the impacts of spray drift have become a topic of considerable interest. The drifting of sprays is a highly complex process influenced by many factors. Advances in aerial application technology and in our ability to measure drift, coupled with the adoption of new technologies for regulating pesticide application have necessitated further research in the pesticide application process. Experiments were conducted to quantify spray drift and describe its movement from aerial applications of pesticide. The effects of spray quality, atomizer type and ground cover were examined. Initial airborne drift amounts were greater than downwind deposits, thus not all of the drifting spray was deposited in the measuring area. Total off-target movement of spray was significantly greater for Fine compared to Coarse sprays. Rotary and hydraulic atomizers, both producing Fine sprays, produced statistically similar off-target movement of sprays. Similarly, no significant statistical differences in spray drift between applications to bare ground and applications to a headed barley crop canopy were not identified. Contrary to expectations, aerial application to bare ground seemed to result in less off-target movement than application to a crop canopy. The vertical spray cloud profiles were similar for all applications with the greatest amount of spray present at the height of release. Spray concentrations diminished from that height upward with diffusion and downward with deposition. The empirical data disagreed with the mechanistic model AgDISP which is currently used in the Canadian regulatory process. The model over-predicted drift deposition by a factor of two to five. Variability in spray deposit values could not be attributed to average differences in meteorological conditions at the time of application. Experiments with appropriate protocols for increased sensitivity may be required to more accurately report subtle differences in drift at distances greater than 200 m from the target area.

This study sought to examine the performance of participants in training courses of the Agricultural and Environmental Services (AES) unit and determine variables affecting participants' scores on the General Standards Examination (GSE). The data sample for the study comprised 150 individuals who completed the 8-hour course between February 2011 and February 2012 and submitted instruments developed for this study (demographic and evaluation survey, pre-test, post-test, and GSE). The demographics of the pest control industry in Texas - or, more specifically, the demographics of those taking a Structural Pesticide Applicator Training (SPAT) course from AES - have not changed much since 1998. The major differences in demographics between the two groups of individuals investigated (commercial and non-commercial applicants) were in age and size of business where employed. Commercial participants tended to be younger than non-commercial participants. Those seeking commercial certification tended to be employed in smaller firms than did those seeking non-commercial certification. This study found moderate, positive correlations between the pre-test, post-test, and GSE. Finally, though the examination scores were correlated, there were statistically significant differences between participants' performances on the pre-test, post-test, and GSE. These differences were quadratic; all three pairs - pre-test and post-test, post-test and GSE, and pre-test and GSE - differed, with pretest scores in the middle, then post-test scores highest, and GSE scores lowest. The researcher recommended that further research be conducted on demographic variables that may affect the outcome of the examinations, and that the rigor and relevance of the pre-test and post-test be increased to predict more accurately the results of the GSE.

La contamination des eaux de surface par les polluants agricoles soulève des inquiétudes concernant les effets potentiels sur les organismes aquatiques. L'objectif général de ce projet de maîtrise était d'évaluer le statut physiologique du poisson d'eau douce exposé de façon chronique aux pesticides et autres polluants agricoles. Dans un premier volet, des truites arc-en-ciel (Oncorhynchus mykiss) ont été exposées durant 30 jours à un herbicide communément détecté dans les cours d'eau agricoles, le métolachlore, à des concentrations de 200, 500 et 800 µg/l. Une exposition au métolachlore en microplaque avec des cellules interrénales de truites arc-en-ciel (cellules qui sécrètent le cortisol) a aussi été réalisée. Dans un second volet, des perchaudes ont été capturées à trois reprises entre 2002 et 2003 dans la rivière Yamaska (Québec, Canada), qui est contaminée par les pesticides et autres polluants agricoles. À chacune des campagnes, un site non contaminé (lac Brome) ou très faiblement contaminé par les pesticides (rivière Yamaska Nord) était utilisé comme site de référence. Pour les deux volets, des fonctions biologiques ont été évaluées à l'aide de biomarqueurs: la fonction endocrinienne par le cortisol plasmatique; l'osmorégulation par l'activité de l'enzyme branchiale Na+/K+-ATPase et le métabolisme énergétique par le glucose plasmatique et le glycogène hépatique. L'activité de l'acétylcholinestérase plasmatique a été évaluée comme biomarqueur d'exposition aux inhibiteurs de cholinestérases. Enfin, des indices de condition tels que le facteur de condition, l'indice hépatosomatique et l'hématocrite ont permis de caractériser la condition générale des poissons. Les résultats obtenus pour le volet réalisé en laboratoire révèlent que les truites arc-en-ciel sont peu affectées par une exposition au métolachlore allant jusqu'à 800 µg/l. Une augmentation de l'hématocrite est toutefois notée à l'exposition de 200 µg/l de métolachlore. À 800 µg/l, les truites sont beaucoup plus sensibles au stress de capture. De plus, une perturbation du système d'osmorégulation est révélée par une hausse de l'activité Na+/K+ATPase des branchies, une diminution de l'hématocrite et des réserves énergétiques. L'exposition en microplaque montre que les cellules interrénales sont très résistantes au métolachlore en terme de viabilité cellulaire (concentration létale pour 50% des cellules CL50 = 1092 mg/l). Cependant, la concentration effective qui diminue de 50% la libération de cortisol est beaucoup plus faible (CE50 = 79 mg/l), ce qui suggère un potentiel de perturbateur endocrinien in vitro. Les résultats du volet réalisé en milieu naturel indiquent, pour la seconde campagne d'échantillonnage, que le milieu contaminé par les pesticides et autres polluants agricoles n'affecte pas significativement l'activité des cholinestérases plasmatiques, bien que celle-ci tende à baisser. Ce milieu affecte toutefois négativement la croissance des perchaudes et perturbe la réponse cortisolique. Les perchaudes ont une accumulation de glycogène hépatique et un indice hépatosomatique plus élevé. L'activité des enzymes Na+/K+-ATPase des branchies est plus élevée. Les résultats de ces études ont permis de dresser un portrait des effets des pesticides et autres polluants agricoles sur le statut physiologique du poisson. Ainsi, en approfondissant les différents biomarqueurs affectés, des études ultérieures pourront permettre d'évaluer l'état de santé des poissons. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Perchaude,Truite arc-en-ciel, Métolachlore, Pesticide, Cortisol, Perturbation endocrinienne, Osmorégulation, Hématocrite, Glycogène, Acétylcholinestérase, Rivière Yamaska.

En programme de lutte intégrée (PLI), les pesticides visant la répression des insectes ravageurs doivent s'agencer avec la lutte biologique qui s'y déroule. La description de l'impact des pesticides utilisés est donc essentielle pour la conservation des agents de lutte biologique en vergers. Dans cette étude, les effets toxicologiques de six nouveaux pesticides à base de spinetoram, novaluron, spirotetramat, chlorantraniliprole, flubendiamide et clothianidin sont décrits, envers les acariens prédateurs Galendromus occidentalis (Nesbitt) et Neoseiulus fallacis (Garman). Réalisés en laboratoire, les épreuves biologiques sont effectués en condition d'exposition extrême, où les toxicités de contact et résiduelle ont été évaluées sur l'éclosion des œufs, le stade larvaire, les femelles adultes et la fécondité. Le spinetoram et le spirotetramat se révèlent toxiques dans la majorité des tests réalisés. La concentration appliquée en verger du spinetoram est 34,33 fois supérieure à la valeur de la CL50 chez G. occidentalis et 14,02 fois supérieure chez N. fallacis. Le novaluron est néfaste aux larves des deux espèces. Le clothianidin démontre une toxicité intermédiaire généralisée, plus prononcée chez N. fallacis. Le flubendiamide et le chlorantraniliprole ne sont pas toxiques, à l'exception de ce dernier sur des larves de G. occidentalis. Le spinetoram et le spirotetramat devraient être évités en PLI en présence de ces acariens prédateurs. À ceux-ci s'ajoute le clothianidin en présence de N. fallacis. La tolérance de ces deux Phytoseiidae devra être vérifiée sur le terrain concernant le novaluron, en plus du chlorantraniliprole et le clothianidin spécifiquement pour G. occidentalis. L'étude démontre la compatibilité du flubendiamide avec les deux espèces et du chlorantraniliprole avec N. fallacis. Ces connaissances essentielles permettront de mieux gérer l'utilisation de ces produits en PLI et ainsi conserver ces agents efficaces de lutte biologique dans nos vergers. ______________________________________________________________________________

With widespread use of pesticides in modern agriculture, the impacts of spray drift have become a topic of considerable interest. The drifting of sprays is a highly complex process influenced by many factors. Advances in aerial application technology and in our ability to measure drift, coupled with the adoption of new technologies for regulating pesticide application have necessitated further research in the pesticide application process. Experiments were conducted to quantify spray drift and describe its movement from aerial applications of pesticide. The effects of spray quality, atomizer type and ground cover were examined. Initial airborne drift amounts were greater than downwind deposits, thus not all of the drifting spray was deposited in the measuring area. Total off-target movement of spray was significantly greater for Fine compared to Coarse sprays. Rotary and hydraulic atomizers, both producing Fine sprays, produced statistically similar off-target movement of sprays. Similarly, no significant statistical differences in spray drift between applications to bare ground and applications to a headed barley crop canopy were not identified. Contrary to expectations, aerial application to bare ground seemed to result in less off-target movement than application to a crop canopy. The vertical spray cloud profiles were similar for all applications with the greatest amount of spray present at the height of release. Spray concentrations diminished from that height upward with diffusion and downward with deposition. The empirical data disagreed with the mechanistic model AgDISP which is currently used in the Canadian regulatory process. The model over-predicted drift deposition by a factor of two to five. Variability in spray deposit values could not be attributed to average differences in meteorological conditions at the time of application. Experiments with appropriate protocols for increased sensitivity may be required to more accurately report subtle differences in drift at distances greater than 200 m from the target area.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 65 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 54-57).

No description available.

The chemical fate of organophosphorus pesticides is influenced by several factors, one being the chemistry of their aquatic environment. Dissolved metal ions have been shown in several instances to promote the hydrolysis of organophosphorus pesticides, with various reasons forwarded as to the intimate mechanism of metal ion promoted hydrolysis. Several postulates have suggested metal ion co-ordination of Lewis sites to be an important factor in promoting the reaction. In view of this, the study herein reports on the promoted hydrolysis of diazinon at various pH’s in the presence of several metal ions including Hg2+, Cu2+, Cd2+ and Ag+. The observed 1H and 31P NMR data indicated complexation of Cu2+ and Ag+ with diazinon through the formation of a six-membered ring (chelate), via co-ordination at both nitrogen and sulfur Lewis base sites. In contrast, NMR results with Hg2+ indicated Hg2+ ion promoted hydrolysis of diazinon through co-ordination at sulfur alone, possibly through stronger binding to the altered transition state than the reactant state. Another possibility would entail lowering of the pKa of H2O on metal complexation, thus facilitating nucleophilic attack. Electrospray ionization mass spectrometry (ESI-MS) substantiated the proposed metal ion complexation. In the case of Cu2+ and Ag+, complexation between diazinon and metal ions was observed at given m/z ratios, while subsequent MS/MS analysis of the complexed ions revealed co-ordination at both S and N sites by Cu2+ and Ag+. No complexation between diazinon and Hg2+ was observed in ESI-MS; however Hg2+ was shown to complex the hydrolytic product O,O diethyl phosphorothioic acid, presumably through sulfur. Hydrolysis of diazinon was studied at several pH’s at 22oC in the presence of Hg2+, Cu2+, Cd2+ and Ag+, by following spectrophotometrically the appearance of 2-isopropyl-6-methylpyrimidin-4-ol. Kinetic data showed Hg2+, Cu2+ and Ag+ to be extremely effective in neutral-to-mildly acidic conditions, with a reduced effect in the presence of Cd2+. Smaller rate enhancements were also observed at slightly lower pH of 4.0. Possible factors include; 1) Competing acid hydrolysis involving protonation at one heterocyclic N of diazinon (N-3). 2) The dominant nature of the HgCl2 species at pH 4.0. 3) Metal speciation. / Thesis (Master, Chemistry) -- Queen's University, 2008-01-31 13:47:24.044