Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 89-98).

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This thesis has two data chapters that consider factors affecting loblolly pine health in localized regions of Mississippi. The first data chapter investigated the abiotic and biotic factors contributing to loblolly pine (Pinus taeda) mortality on private timberland in Mississippi. This assessment considered temperature and precipitation variations, bark beetle populations, foliar and root pathogen tests, and drone survey. The results revealed that the loblolly pine mortality resulted from combination of factors. The second data chapter examined the impact of habitat fragmentation on southern pine beetle (SPB; Dendroctonus frontalis) infestation in Homochitto National Forest (HNF). This was assessed through remote sensing and categorization of SPB spots in HNF over nine years. Results indicated that increased total pine patch area, decreased distance between pine patches, and low patch diversity are important drivers of SPB outbreak in HNF. These results can help improve loblolly pine health and management in the southeastern United States.

Master of Science

The spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) is regarded as a pest of sweetpotatoes in Mississippi; however, its feeding on sweetpotatoes has not previously been documented. They are attracted to cucurbit crops that could be utilized as a trap crop or sentinel plant for management of cucumber beetles in sweetpotatoes. Studies were conducted between 2006 and 2008 to determine if cucurbit plants have the potential to serve as a trap crop or as sentinel plants for the spotted cucumber beetle in sweetpotato fields, and to determine the status of the spotted cucumber beetle as a sweetpotato pest in Mississippi. Cucurbit plants showed some potential to serve as a trap crop or sentinel plant for the spotted cucumber beetle, however, sweetpotato damage assumed to be caused by cucumber beetle larvae did not correlate with the number of adults captured. Spotted cucumber beetle larvae can feed and survive on sweetpotato roots.

Master of Science / Department of Grain Science and Industry / Bhadriraju Subramanyam / Heat treatment of grain-processing facilities involves using elevated temperatures of 50- 60˚C for 24 h or less to manage stored-product insects. Heat is an alternative to a non-ozone depleting fumigant sulfuryl fluoride, which was registered in the United States in 2004 for disinfestation of grain-processing facilities. In this study, life history traits of the warehouse beetle, Trogoderma variabile Ballion, were characterized on ground cat food at 28°C and 65% RH to facilitate harvesting life stages of a specific age for bioassays with heat. Eggs laid by females were observed for daily eclosion. Eggs hatched on days 6 through 10, and the mean proportion for egg hatching was 87%. Larvae hatching from eggs (first instars) were reared on ground cat food and their head capsule widths were measured every 2 d until all larvae became pupae. Head capsule widths indicated six instars and the total larval duration ranged from 28-40 d. Pupae became adults in 3-9 d. Newly eclosed unmated female adults lived 7 d longer than unmated males (16 d), whereas mated males lived 2 d longer than mated females (8 d). Eggs were not observed when food was not provided to male and female pairs. Females started laying eggs 2 d after pairing until the fifth day. The total number of eggs laid by mating pairs in the presence of food ranged from 30 to 135. Exposure of eggs, young larvae, old larvae, pupae, and adults of T. variabile at 46, 50, and 54°C and 15-20% RH for four fixed time periods showed pupae to be generally more heat tolerant than other life stages. At 46, 50, and 54°C, complete mortality of all stages occurred at 1440, 120, and 30 min, respectively. Pupae also were generally more heat tolerant than other life stages during tests in pilot flour and feed mills at Kansas State University and in a commercial grain-processing facility. However, results from pilot and commercial mills were not as conclusive as the results at fixed temperatures in the laboratory.

Call number: LD2668 .T4 1961 W57

Master of Science / Department of Grain Science and Industry / Subramanyam Bhadriraju / Heat treatment of food-processing facilities involves using elevated temperatures (46 to 60°C for 24 h) for management of stored-product insects. Heat treatment is a viable alternative to the fumigant methyl bromide, which is phased out in the United States as of 2005 because of its adverse effects on the stratospheric ozone. However, very little is known about responses of the cigarette beetle, Lasioderma serricorne (F.), a pest associated with food-processing facilities, to elevated temperatures. The main objective of my research was to evaluate stage-specific susceptibility of L. serricorne to elevated temperatures to identify the most heat tolerant stage. In the laboratory, I found L. serricorne was able to develop on ground, pelleted feed at 28°C and 65% RH; however, there is no data on the biology of this species on this diet. Therefore, several life history parameters of L. serricorne were studied on ground, pelleted feed at 28°C and 65% RH, to facilitate harvesting stages of specific ages in large numbers for assays with elevated temperatures. The mean duration for eggs was 8.1 d, and the mean egg survivorship was 92.0%. There were four discrete instars, and the mean durations of first, second, third, and fourth instars were 4.7, 4.5, 4.7, 11.8 d, respectively. The survivorship of first through third instars was about 99%, whereas that of fourth instars was 85%. The mean pupal duration was 4.6 d, and pupal survivorship was 98%. Newly eclosed unmated female adults lived 5 d longer than unmated males (29 d), whereas, mated males lived 6 d longer than mated females (17 d). Mated females started laying eggs on the third day after emergence and continued this activity for an additional six to eight days. Females, on average, laid 105 eggs with a mean daily output of 12 eggs. The data reported here provide new information on the biology of L. serricorne on ground, pelleted feed, which appears to be an optimal diet for mass rearing this species. Exposure of eggs, young larvae (3 to 4- July 2007 did not clearly show which of the life stages was heat- tolerant. However, exposure of all life stages to fixed times at 46, 50 and 54°C and 25% RH in the laboratory indicated eggs to be the most heat-tolerant stage. Time-mortality responses, at each of these three d old), old larvae (20 to 21-d old), and adults during heat treatment of a food-processing facility in 20-22 temperatures, showed that the time for 99% mortality (LT99) based on egg hatchability and egg-to-adult emergence was not significantly different at each temperature. The LT99 based on egg hatchability at 46°C was 605 min and it decreased to 190 min at 50°C and 39 min at 54°C. Therefore, during structural heat treatments eggs should be used in bioassays for gauging heat treatment effectiveness, because treatments aimed at controlling the egg stage should control all other life stages of L. serricorne.

Fossil beetle based palaeoclimatic and palaeoenvironmental reconstructions are presented from the Westport region, West Coast, South Island, New Zealand for the last glacial cycle. They include the longest continuous fossil beetle record from New Zealand, covering 16,000 years over the OIS 3/OIS 2 transition. Early last glacial (OIS 4) and mid- Holocene (OIS 1) reconstructions are also presented. The assumptions underlying fossil beetle research in New Zealand are tested indicating beetles are suitable proxies for reconstructing palaeotemperature and palaeoprecipitation. This thesis provides the first quantitative estimates of temperature and precipitation from the Westport region for the last glacial. Reconstructed temperatures indicate stadial cooling was seasonal. Maximum cooling was ca. 5℃ in winter and ca. 2-3℃ in summer. Winter cooling is consistent with previous quantitative estimates from New Zealand. Mean annual precipitation decreased a maximum 35-40% during stadials. Temperatures and precipitation varied during OIS 3/2 indicating multiple possible drivers for glaciation. A glacial advance ca. 34-28ka BP correlates with ca. 5℃ winter cooling and ca. 40% less precipitation, which supports temperature driven glaciation whereas a glacial advance ca. 24-22ka BP correlates with ca. 3℃ winter cooling and precipitation similar to present, which supports precipitation forced glaciation. Palaeoenvironmental reconstructions of stadial vegetation from the Westport region indicate lowland Nothofagus fusca-type forest during OIS 4 and a forest-grassland mosaic during OIS 3/2. These records contrast with pollen-based reconstructions of a treeless landscape in Westport during stadials but are consistent with quantitative estimates of stadial cooling. A shift of reproductive strategy in arboreal vegetation may explain the lack of tree pollen in stadial pollen records. This is significant for our understanding of glacial palaeoecology and palaeoclimatology as pollen records may not accurately represent stadial vegetation.