Thesis (Ph. D.)--University of Wisconsin, 1980. / Includes bibliographical references (p. 204-217).

Examensarbete.

Helicoverpa zea (Boddie), a pest of cotton that also occurs in field corn, is commonly controlled through the use of foliar-applied insecticides or transgenic crops expressing Bt genes. To prevent the selection of resistant populations, refuge systems have been implemented into the agroecosystem. Historically, structured refuge compliance among growers has been low, leading to the commercialization of seed blended refugia. To test the viability of seed blended refugia in the southern U.S., field studies were conducted in Mississippi and Georgia during the 2016, 2017, and 2018 growing seasons. To quantify adult H. zea emergence from structured and seed blended refuge options, emergence traps were utilized. Kernel damage and moth emergence timings were recorded. Various percentages of stand loss ranging from 0% to 50% were also simulated to determine yield effects in unprotected seed blended refugia. Lastly, H. zea feeding and emergence in a two-gene field corn variety expressing Cry1A.105 and Cry2Ab2 were compared to non-Bt field corn. When compared to a structured refuge, H. zea adult moth emergence from seed blended refugia did not significantly differ. Kernel damage was not different between seed blended treatments and structured refuge treatments. Moth emergence timings were not significantly delayed between the structured refuge and seed blended refuge treatments. Significant yield losses were observed when stand loss was simulated at various levels in field corn, suggesting that there is an opportunity to see yield losses in an unprotected seed blended refuge field corn landscape. Kernel damage did not significantly differ between field corn expressing Cry1A.105 and Cry2Ab2 and non-Bt field corn, possibly due to H. zea resistance to the Cry genes. However, there was a significant difference in emergence from two-gene expressing field corn and non-Bt field corn. This suggests that there may be high pupal mortality in two-gene corn plots. Based on these data, seed blended refuge could be a viable option to replace structured refuge strategies in the southern U.S., however, if left unprotected, yield loss could be observed in a case of high boring insect pressure. The significant loss of refuge plants can also compromise refuge effectiveness.

Efficacy of Baculovirus heliothis against larvae of the tobacco budworm was studied under laboratory, greenhouse, and field conditions. Dosage-mortality studies using a diet surface inoculation technique resulted in LC₅₀ values of less than 2 PIB/mm² for 1- to 5-day-old larvae. Onset of mortality was delayed in older larvae, and a greater quantity of inoculum was needed to produce the same mortality level as larvae matured. Length of the incubation period was shortened by increasing the dose. In laboratory and greenhouse studies, mortality of neonates was enhanced by the addition of commercial feeding stimulants. A cottonseed-base adjuvant was more effective than either virus alone or virus mixed with soybean flour. The value of the bait was particularly apparent when larvae were held for short durations on virus-treated terminals. Water extracts of fresh and dried garbanzo beans were shown to be highly attractive to tobacco budworm larvae, suggesting their potential for use as a feeding stimulant. Both bean treatments performed as well as the commercial cottonseed adjuvant. Virus-water extracts of garbanzo bean leaves and pods were no more effective in producing larval mortality than virus in water alone. Although addition of a feeding stimulant significantly extended activity of virus residues on cotton terminals bioassayed with H. virescens in the laboratory, the combination did not improve efficacy when larvae were allowed to feed on treated plants in the field. It may be that the effect of bait on young larvae was overridden by high temperatures or light intensities in the upper plant canopy. Time of application studies directed at the egg-stage showed that larvae are capable of ingesting lethal quantities of the pathogen while chewing out of treated eggs. Applications should coincide as closely as possible with egg hatch to maximize infection. Following hatching, there was a consistent decline in effectiveness as treatments were delayed. No significant effects on longevity or fecundity resulted from the feeding of virus to adults in a sucrose solution. Transovum transmission of virus to progeny was inefficient, regardless of the dose administered.

No description available.

A laboratory selected strain of Heliothis virescens demonstrating a 400-fold resistance to permethrin exhibited no differences in penetration and only a slight enhancement of metabolism when compared with a susceptible strain. Synergism with piperonyl butoxide and DEF produced similar synergist ratios for the resistant and susceptible strains, but the resistant strain showed a much larger synergist difference. Thin layer chromatography of extracts from larvae dosed with 14C-labelled permethrin demonstrated a small increase in metabolism of the cis-isomer by the resistant strain, but no differences in metabolism of the trans-isomer. The synergism study and the 14C-labelled permethrin experiment both indicate that there is a small increase in metabolism of permethrin in the resistant strain, but not enough to account for the greatly increased LD50 value. Cross-resistance to DDT indicated that target site insensitivity may play a major role in resistance to pyrethroids in this strain.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1928. / Typescript. Vita. Includes reprints of two journal articles by the author from Journal of agricultural research, and Genetics. Includes bibliographical references.

FEIJÃO, A. R. Crescimento, trocas gasosas, partição de íons e metabolismo do nitrogênio em plantas de milho submetidas à salinidade e diferentes fontes de N. 2009. 111 f. Dissertação (Mestrado em Bioquímica) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2009. / Submitted by Francisco Lacerda (lacerda@ufc.br) on 2014-10-03T19:20:26Z No. of bitstreams: 1 2009_dis_arfeijão.pdf: 674672 bytes, checksum: 5d66d02c1147abcb46edeb17e2f22ddb (MD5) / Approved for entry into archive by José Jairo Viana de Sousa(jairo@ufc.br) on 2014-11-11T23:34:23Z (GMT) No. of bitstreams: 1 2009_dis_arfeijão.pdf: 674672 bytes, checksum: 5d66d02c1147abcb46edeb17e2f22ddb (MD5) / Made available in DSpace on 2014-11-11T23:34:24Z (GMT). No. of bitstreams: 1 2009_dis_arfeijão.pdf: 674672 bytes, checksum: 5d66d02c1147abcb46edeb17e2f22ddb (MD5) Previous issue date: 2009 / This work aimed to study the effect of N source in the growing, gas exchanges, ion partitions and N metabolism in maize plants (Zea mays L.) submitted to salinity. For this, maize seeds were sown in plastic cups with vermiculite and maintained in greenhouse. After that, the seedlings were transferred to a hydroponics culture with N concentration of 6 mM, in the forms of NO3-, NO3-/NH4+ or NH4+. After five days in these conditions, we started the addition of NaCl, which was gradually increased each day by 25 mM until it reaches a final concentration of 100 mM. The harvests were carried out 4, 11 and 18 days after the beginning of the salt treatment. In control conditions, the plants fed with the mixed NO3-/NH4+ were the ones which presented the greatest shoot growth, compared to other N treatments. There was a great growth reduction when the plants were submitted to salinity, but this effect was not influenced by the N source used. Generally, the salinity reduced the stomatal conductance (gs), transpiration (E), photosynthesis (A) and the relation between the intercellular and outercellular CO2 concentration (Ci/Co ) in plants of all N treatments and in different times of harvest. However, in plants fed with NH4+ and after 18 day of salt treatment a great reduction in the gs, A and E and an increase in the Ci/Co ratio were observed. The Na+ contents increased with salinity, despite that, in plants fed with NH4+, these contents were lower than in the other N treatments in salinity conditions. The K+ contents, on the other hand, were reduced by salinity, and the plants fed with the mixed NO3-/ NH4+ and only NH4+ absorbed less K+ than the ones fed only with NO3-, mainly in the leaves and stems of plants after 11 days and in leaves and roots of plants after 18 days of salt stress. This way, there was influence of N source in the Na+/K+ ratio, particularly in roots of plants after 18 days of exposure to salt stress, whose lower increases in this parameter were observed in the plants treated only with NO3-. The greatest increments in the Cl- contents caused by salinity were observed in plants fed with NO3- and with the mixed NO3-/ NH4+. However, in control conditions, these contents were increased in leaves and stems of plants fed only with NH4+. The NO3- contents were higher in plants fed with NO3- and NO3-/NH4+, when compared to the ones fed only with NH4+, both in control and salinity conditions. The greatest and lowest Cl-/NO3- ratio were found, respectively, in plants treated with NO3- and with NH4+. The shoot NH4+ contents were little influenced by salinity or by N source, however, in roots of plants fed with NH4+ and under salinity, there was a great accumulation of these ions after 18 days of stress. The soluble carbohydrates contents, in general, increased by salinity, except in the leaves and stems (after 18 days of salt stress) and in the roots (during all the experimental period) of the plants treated with NH4+. Generally, the soluble proteins and soluble amino acids contents were increased by salinity, and the biggest quantities of these solutes were observed in the roots of plants fed with NH4+ and after 18 days of salt stress. The total N contents were reduced by salinity and it was observed especially in plants fed only with NO3-. In the leaves, the activities of nitrate reductase (NR) and nitrite reductase (NiR) were greater in plants fed with NO3- and with the mixed NO3-/ NH4+. Little influence of salinity in NiR activity was observed in maize leaves. In the leaves, the salinity influenced differently the activity of glutamine synthetase (GS) between the different sources of N and time of salt exposure. However, in the roots, in general, the GS activity increased withy salinity, except for the plants fed with NH4+, which were not influenced by this stress. After 18 days of salt exposure, the GS activity was greater in the plants fed with NH4+, compared to the other N treatments. The activity of glutamate synthase (GOGAT), in the leaves, in generral, increased with salinity, despite that, this activity was reduced in the roots mainly in the plants fed with NO3-, after 4 days, and with NH4+, after 11 and 18 days. These results suggest that the several N sources did not influence the tolerance of maize plants to salinity. However, the plants fed with NO3- had better results in ion relations. And greatest GS activities observed in roots of the plants fed with NH4+, after 18 days of stress, helped in the osmotic adjustment, as a consequence of the accumulation of soluble proteins and soluble amino acids. / O objetivo deste trabalho foi estudar o efeito da fonte de N no crescimento, nas trocas gasosas, na partição de íons e no metabolismo do N em plantas de milho (Zea mays L.) submetidas à salinidade. Para isto, sementes de milho foram semeadas em copos plásticos contendo vermiculita, sendo mantidas em casa de vegetação. Em seguida, as plântulas foram transferidas para um meio hidropônico com concentração de N igual a 6 mM, nas formas de NO3-, NO3-/NH4+ ou NH4+. Após cinco dias nestas condições, iniciou-se a adição de NaCl, que foi feita em parcelas de 25 mM por dia, até atingir a concentração final de 100 mM. As coletas foram realizadas aos 4, 11 e 18 dias após o início do tratamento salino. Em condições controle, as plantas nutridas com a mistura NO3-/NH4+ foram as que apresentaram o maior crescimento da parte aérea, em comparação aos demais tratamentos de N. Houve uma forte redução do crescimento quando as plantas foram submetidas à salinidade, mas este efeito foi independente da fonte de N empregada. De maneira geral, a salinidade reduziu a condutância estomática (gs), a transpiração (E), a fotossíntese (A) e a relação entre a concentração interna e externa de CO2 (Ci/Co) das plantas de todos os tratamentos de N e nos diferentes tempos de coleta. Entretanto, nas plantas cultivadas com NH4+ e aos 18 dias do tratamento salino, foram observados uma redução acentuada na gs, A e E e um aumento na relação Ci/Co. Os teores de Na+ aumentaram com a salinidade, contudo, nas plantas nutridas com NH4+, esses teores foram menores do que os dos demais tratamentos de N em condições de salinidade. Os teores de K+, por sua vez, foram reduzidos pela salinidade, sendo que as plantas nutridas com a mistura NO3-/ NH4+ e apenas NH4+ absorveram menos K+ do que as cultivadas apenas com NO3-, principalmente nas folhas e colmos das plantas aos 11 dias e nas folhas e raízes das plantas aos 18 dias de estresse salino. Dessa forma, houve influência da fonte de N na relação Na+/K+, particularmente nas raízes das plantas aos 18 dias de exposição ao estresse salino, cujos menores aumentos nesse parâmetro foram observados nas plantas tratadas apenas com NO3-. Os maiores incrementos nos teores de Cl- causados pela salinidade foram observados nas plantas cultivadas com NO3- e com a mistura NO3-/ NH4+. Porém, em condições controle, esses teores foram aumentados nas folhas e colmos das plantas cultivadas apenas com NH4+. Os teores de NO3- foram maiores nas plantas nutridas com NO3- e NO3-/NH4+, quando comparadas às nutridas somente com NH4+, tanto em condições controle quanto de salinidade. A maior e a menor relação Cl-/NO3- foram encontradas, respectivamente, nas plantas tratadas com NO3- e com NH4+. Os teores de NH4+ da parte aérea foram pouco influenciados pela salinidade ou pela fonte de N, porém, nas raízes das plantas nutridas com NH4+ e sob salinidade, houve um grande acúmulo desses íons aos 18 dias de estresse. Os teores de carboidratos solúveis foram, em geral, aumentados pela salinidade, com exceção nas folhas e colmos (aos 18 dias de estresse salino) e nas raízes (durante todo o período experimental) das plantas tratadas com NH4+. De maneira geral, os teores de proteínas solúveis e de N-aminossolúveis foram aumentados pela salinidade, sendo que as maiores quantidades destes solutos foram observadas nas raízes das plantas tratadas com NH4+ e aos 18 dias de estresse salino. Os teores de N-total foram reduzidos pela salinidade, sendo isto observado especialmente nas plantas nutridas apenas com NO3-. Nas folhas, as atividades da redutase do nitrato (NR) e da redutase do nitrito (NiR) foram maiores nas plantas tratadas com NO3- e com a mistura NO3-/ NH4+. Foi observada pouca influência da salinidade na atividade da NiR das folhas de milho. Nas folhas, a salinidade influenciou diferentemente a atividade da sintetase da glutamina (GS) entre as diferentes fontes de N e tempos de exposição à salinidade. Porém, nas raízes, de maneira geral, a atividade da GS aumentou com a salinidade, com exceção das plantas tratadas com NH4+, que não foram influenciadas por este estresse. Aos 18 dias de exposição à salinidade, a atividade da GS foi maior nas plantas tratadas com NH4+, em comparação com os demais tratamentos de N. A atividade da sintase do glutamato (GOGAT), nas folhas, em geral, aumentou com a salinidade, contudo, nas raízes essa atividade foi reduzida principalmente nas plantas cultivadas com NO3-, aos 4 dias, e com NH4+, aos 11 e 18 dias. Esses resultados sugerem que as diversas fontes de N não influenciaram na tolerância das plantas de milho à salinidade, entretanto as plantas nutridas com NO3- foram melhores nas relações iônicas e as maiores atividades da GS observadas nas raízes das plantas cultivadas com NH4+, aos 18 dias de estresse, ajudaram no ajustamento osmótico, como conseqüência do acúmulo de proteínas solúveis e N-aminossolúveis.