Bertha armyworm, Mamestra configurata (Lepidoptera: Noctuidae), is an important pest of cruciferous oilseed crops in western Canada. A nuclear polyhedrosis virus, MacoNPV, isolated from M. configurata, has demonstrated as high as 95% infection in field populations of bertha armyworm. MacoNPV isolates from different geographic areas differ in terms of their virulence to bertha armyworm. Restriction endonuclease (REN) fragment analyses show that all of the geographic isolates are closely related viruses but with some distinct REN pattern differences. Most of these geographic isolates are heterogenous mixtures of genotypes. The thesis describes the cloning and physical mapping of the 156.9 kbp genome of the MacoNPV-90/2 geographic isolate, including 112 restriction sites for six common REN, BamHI, EcoRI, HindIII, PstI, SmaI and XhoI. Twenty plaque purified strains of MacoNPV were isolated in a cultured Mamestra brassicae (Mbr) insect cell line. The EcoRI restriction patterns of these pick plaque (pp) strains fell into 10 different categories. In order to investigate the difference among these pp strains, and between these strains and the parental geographic isolates in terms of REN patterns, virulence to insect hosts, and their growth rates in insect cell lines, some of these isolates were selected for bioassays in bertha armyworm larvae and in the Mbr cell line.

I present a simulation model that should be a useful tool for risk assessment of the impact of insecticide inhibitors of cholinesterase (ChE) applied in irrigated agricultural fields on non-target wildlife. I developed the model as a compartment model based on difference equations (Δt = 1 hour) and programmed with Stella® VII software. Conceptually the model is compartmentalized into six submodels describing the dynamics of (1) insecticide application, (2) insecticide movement into floodable soil, (3) irrigation and rain, (4) insecticide dissolution in water, (5) foraging and insecticide intake from water, and (6) ChE inhibition and recovery. To demonstrate application of the model, I simulate historical, current, and “worst-case” scenarios, that examined the impact of ChE-inhibiting insecticides on white-winged doves (WWDO - Zenaida asiatica) in the Lower Rio Grande Valley of Texas (LRGV), USA. To my knowledge, there are no field data verifying that the cause of ChE deprivation in WWDO is due to the ingestion of ChE-inhibiting insecticide residues dissolved in drinking water. I parameterized the model to represent a system composed of fields of cotton, sorghum, corn, citrus, and brushland that encompasses the activity range of a WWDO in the LRGV. I simulated situations representing the typical scenario of WWDO using irrigated crop fields in the absence and in the presence of rain. I also simulated “worst case” scenarios in which methyl parathion was applied at high rates and high frequency. Based on results of the simulations, I conclude that it is unlikely that WWDO are seriously exposed to ChE-inhibiting insecticides by drinking contaminated water. Only in rare cases, for example, when a rain event occurs just after the application of insecticides, are levels of ChE inhibition likely to approach diagnostic levels (20 %). The present simulation model should be a useful tool to predict the effect of ChE-inhibiting insecticides on the ChE activity of different species that drink contaminated water from irrigated agricultural fields. It should be particularly useful in identifying specific situations in which the juxtaposition of environmental conditions and management schemes could result in a high risk to non-target wildlife.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references. Also available by subscription via World Wide Web.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

Scientific literature indicates potential for using plant extracts to control arthropod pests thereby decreasing the amount of synthetic chemicals introduced into the ecosystem. The research presented below tested several control candidates in a field settig to determine if selected oils can be used to control grasshopper infestations. Two field studies tested the effects of five plant extract oils on grasshopper pests in southern Alberta: Rosmarinus officinalis, Cedrus deodorata, Melaleuca alternifolia, Eucalyptus globulus, and Azadirachta indica. Grasshopper abundance increased in the first study in all plots and decreased in the second study in all plots. A third study was conducted in a greenhouse where grasshoppers were treated with two concentrations of cedarwood and rosemary oil and were monitored for eight days for mortality and behavioural effects. A non-target study was conducted in order to determine if control candidates would negatively affect other beneficial arthropods. Cedarwood, neem oil and carbaryl bait were tested on the mortality of Carabidae and Phalangiidae using pitfall trap sampling. / viii, 98 leaves : ill., maps ; 29 cm.

A systematic survey of the microbial and invertebrate natural enemies of Phyllophaga spp. was conducted from 1979 to 1981 in 45 localities in southern Quebec. Chronic but low (nonepizootic) rates of biotic regulation were found in all host life stages except eggs. The natural enemies included 36 species of predatory and parasitic insects, 15 mite species, six fungal species, five bacterial species, three different nematodes, one virus, one gordian worm, and one sporozoan. Microorganismal pathogenicities to white grubs were demonstrated by infectivity tests and laboratory bioassays using four methods of inoculation. Field-type microplot studies on the fungus Metarhizium anisopliae and the nematode Mikoletzkya aerivora were undertaken in 1982. The fungus and the nematode showed potential as biological suppressants of Phyllophaga grubs by causing 91% and 68% mortality, respectively. Twenty-seven chemicals were tested as attractants against P. anxia adults in 1981 in four localities in southern Quebec. Hexanoic acid was consistently the most attractive chemical to beetles of both sexes.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1991. / Includes bibliographical references (leaves 71-87) / Microfiche. / x, 87 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Adelaide, Dept. of Crop Protection, 1998? / Includes bibliographical references (leaves 120-145).