In broiler operations, various health problems develop during the final two weeks of the growing period, resulting in increased mortality and condemnation losses. At this stage, sickly birds were found to be systemically infected by various bacteria regardless of varied clinical signs. The main objective of the present study was to determine the prevalence and nature of systemic bacterial infections in unthrifty commercial broiler chickens and to establish a reproducible infection model in the laboratory. Thirty-one unthrifty 6-week-old broilers were obtained from three farms, and bacterial isolations were conducted on blood, liver, and hock joint. Bacteria were isolated from 87, 90, and 71% of the blood, liver and hock joint samples, respectively. Mean bacterial counts (log������ CFU/ml or g) of the blood and liver were 2.15 and 2.93, respectively. Among 132 bacterial isolates, major species were; Staphylococcus (60%), Corynebacterium (18%), Escherichia coli (5%), and Stomatococcus (4%). Among 79 Staphylococcus isolates, 77 were coagulase-negative. Major species of staphylococci were; S. lentus (19%), S. simulans (18%), S. cohnii (13%), S. gallinarum (10%) and S. captis (7%). In addition, 6 species of gram-positive and 5 species of gram-negative organisms were isolated. Apparently systemic infections were not caused by predominant pathogenic bacterial species, and adequately described as mixed infections. However, there were some significant relationships between isolated bacterial species and sampling sites, suggesting that certain organisms were abundant in the environment of a particular poultry house. These results indicate that systemic infections in market age broilers are caused by mixed bacterial species and suggest that they are caused by suppressed host antibacterial systems rather than pathogenic factors of microorganisms. Antibiotic susceptibility results showed 100% susceptibility of staphylococcal isolates (n=69) against vancomycin and enrofloxacin. Of these coagulase negative staphylococci showed 19% and 73% resistance against methicillin and penicillin G, respectively. There was also heterogeneity in antibiogram profiles within species of coagulase-negative staphylococci. Pathogenicity of representative field isolates from the above described study was tested in 5-day-old embryonated eggs and in 3- week-old broiler chicks. Consistent lethality was demonstrated with S. aureus in embryos. Staphylococcus intermedius or S. lentus demonstrated some pathogenicity, while S. gallinarum or Corynebacterium were non-pathogenic in embryos. In 3-week-old broilers, however, only S. aureus caused septicemia and death; other bacterial species mentioned above caused neither clinical signs of acute or chronic staphylococcosis nor mortality. / Graduation date: 1998

Graduation date: 1998

The Feldmannia sp. virus is a large icosahedral virus that persistently infects marine brown alga Feldmannia sp.. So far, there is no information available about viral genome replication, gene structure and gene expression in this unique viral-host system. The purpose of this study was to characterize the general features of viral transcripts in the virus producing sporophyte plants. Northern analysis, using four cosmid clones that cover the entire viral genome, showed that there were six major transcripts and at least eighteen minor transcripts in the virus producing sporophyte plants. These transcripts are not evenly distributed in the viral genome. A 5.7 kb BamHI fragment-R was found to encode a 1.5 kb and a 0.9 kb major transcript, and those two major transcripts were chosen for detailed sequence analysis. The 1.5 kb transcript was identified as the putative major capsid protein (MCP) gene. The FsV MCP has significant similarity with the major capsid protein of Chlorella virus-PBCV-1 and with iridoviruses, fish lymphocystis disease virus, frog virus 3, and with African swine fever virus. / Graduation date: 1996

The purpose of this research is two fold. First to improve pest management of the sciarid fly (Diptera: Sciaridae) by better defining its relation to mushroom production. Secondly, to explore some of the factors and aspects of the biology of the fly which may increase room to room dispersal rates of adults. The effects of different generations of production room Lycoriella mali Fitch infestations and seasons on yield were explored. In models regressing densities of different generations to mushroom yield, significant negative slopes (p=.05) existed in all models. However, flies did not account for as much yield variance as hypothesized (16.43%). Yield is greatest during the winter months when insect pressure is lowest and decreases in summer months when more insects are present. Diflubenzuron (Dimilin 25 WP, Uniroyal Co.) was tested for its effects on fly emergence and oviposition. Diflubenzuron was effective in suppressing fly emergence and remained effective when treated compost was exposed to phase II peak heating. In production room experiments all fly generations had significantly fewer flies in rooms treated with diflubenzuron at fill. L. mali showed a slight preference to oviposition in diflubenzuron treated compost, indicating a possible attractant effect. A criterion table was developed to estimate the age of L. mali. Both younger and larger L. mali carried more ovarioles. The number of ovarioles that L. mali carry dropped significantly after 48 h; this is likely the time the fly becomes parous. The effects of ambient temperature and distance between production rooms on dispersal were explored. The greatest number of dispersing flies were caught during the summer months. As the daily median temperature increased, the number of dispersing flies increased exponentially. Production room blocks on the perimeter of the farm generally had fewer dispersing flies than centrally located production room blocks indicating that it was unlikely that a reservoir population existed outside the farm. Measurements of wing area and age of L. mali captured while dispersing and not dispersing were compared. Dispersing flies had significantly smaller wings than non-dispersers (p=.000). Wing area for dispersing flies decreased along a density gradient, while wing area for non-dispersers did not. The mean age of dispersing flies was not significantly different (p=.082) from non-dispersers, and neither changed along a density gradient. / Graduation date: 1996

Polyclonal antisera were raised against isolates of bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) using conventional serological methods. Infected tissues containing, respectively, 22 recognized BCMV and BCMNV isolates were tested against the two antisera by antigen-coated plate (ACP) ELISA and double antibody sandwich (DAS) ELISA. Results indicated that each immunoglobulin was virus-specific by DAS-ELISA, providing clear distinction between BCMV and BCMNV. A reverse transcription, polymerase chain reaction (RT-PCR)-based assay in combination with restriction endonuclease analyses, was developed for molecular detection of BCMV, BCMNV and their pathogroups. Specific detection of the two viruses was accomplished by constructing two virus-specific primer pairs that amplified a PCR product specific for each virus. Distinction of two BCMNV pathogroups (PG-III and PG-VI) was achieved by restriction enzyme XbaI digestion of BCMNV PCR products. However, none of the tested restriction enzymes clearly differentiated the five recognized BCMV pathogroups. A primer pair Dts/Uny15 specific for BCMV pathogroup V was also developed. By its RT-PCR application, four BCMV-PG-V isolates were differentiated from the other known variants of BCMV pathogroup I, II, IV and VII. Thus, by a combination of RT-PCR and restriction enzyme analyses, it was possible to differentiate both viruses, and two pathogroups of BCMNV, and one pathogroup of BCMV. / Graduation date: 1996

Four sampling techniques were evaluated to estimate clover aphid, Nearctaphis bakeri (Cowen), abundance in red clover fields in the Willamette Valley. The Berlese funnel method detected one to four times more aphids than other sampling techniques. Visual assessment often underestimated the high aphid densities during the flowering and seeding of clover. Sweep net and Schuh shaker techniques had limitations and underrated the numbers of aphids present in the clover fields. Strong correlations (r² = 0. 74 - 0.87) were found between the Berlese funnel technique and visual assessment technique in a 2nd year established field. Numerical differences in the spatial distribution of N. bakeri on clover stems were shown during various stages of plant development over the season. During development of buds and axils, aphid numbers on the lower half of the plant averaged 1.5 times greater than those on the upper half. As the season progressed into the flowering and seeding stage, aphid numbers on the upper stem halves were approximately five times greater than those on the lower half. Winged clover aphids were too few to show definite peaks of flight using water traps, averaging 2.19 aphids per yellow bucket during the June-August period. No significant differences in aphid attractiveness to the different colors were found among water pan traps. Yellow buckets captured approximately five times more alate aphids than did yellow, red, or green pan traps. Traps placed on the south side of the field contained higher numbers of aphids than in other locations in the red clover fields. / Graduation date: 1991

Thesis (M.S.) in Teaching--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 108-117).

Thesis (Ph. D.)--Ohio state University, 1924. / Autobiography. "Reprinted from the Ohio journal of science, vol. XXVIII, no. 1, January, 1928." Bibliography: p. 38.

Thesis (Ph. D.)--Cornell University, 1930. / Cover title. Published also as Bulletin 356 of the Maine Agricultural experiment station. "Literature cited": p. 219-221.

Thesis (Ph. D.)--North Carolina State University, 1999. / Spiral bound. Includes vita. Also available on the Internet. Includes bibliographical references (p. 206-214) and abstract.