Thesis (Ph. D.)--University of Wisconsin-Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 86-92.

Orientador: Silvia Renata Siciliano Wilcken / Resumo: A banana (Musa spp.) é uma das frutas mais consumidas no mundo, e cultivada na maioria dos países tropicais. No Brasil, a produtividade média é baixa devido a vários fatores, dentre eles a incidência de pragas e doenças. Entre os problemas fitossanitários encontrados na cultura da bananeira os nematóides se destacam, sendo as espécies de maior importância: Radopholus similis, Meloidogyne spp., Helicotylenchus multicinctus, Pratylenchus coffeae e Rotylenchulus reniformis. O presente trabalho estudou a reação de diferentes genótipos de bananeira a Meloidogyne incognita raça 2, M. javanica e Pratylenchus coffeae. Para cada espécie de Meloidogyne foram estudadas dez genótipos de bananeira. No estudo com M. incognita foram estudados os genótipos Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, FHIA 17, Nanicão Magário, SH 3640, Pacovan e Prata Anã. Para M. javanica os genótipos estudados foram Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, Nanicão Magário, SH 3640, Pacovan, Prata Anã e Maçã. No experimento com P. coffeae foi desenvolvido utilizando nove genótipos PV 0344, SH 3640, Maçã, Thap Maeo, Caipira, Grande Naine, FHIA 1, FHIA 18 e Prata Anã. O delineamento em todos os experimentos foi inteiramente casualisado com quatro repetições para P. coffeae e seis repetições nos estudos com M. incognita e M. javanica. Cada parcela foi constituída de uma muda de bananeira proveniente de cultura de tecido. Estas mudas foram plantadas em recipientes plásticos de 2 litros de capacidade, contendo substrato composto de solo, areia e matéria orgânica na proporção 1:1:1, previamente autoclavado. Após uma semana do transplantio efetuou-se a... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: Banana plant (Musa spp.) is one of the more consumed fruit in the world and cultivated in many tropical countries. In Brazil, the productivity is low due to several factors, among them the incidence of pest and diseases. Among the problems found in the culture of the banana, the nematodes are stand out, being the species of larger importance Radopholus similis, Meloidogyne spp., Helicotylenchus multicinctus, Pratylenchus coffeae and Rotylenchulus reniformis. This research studied the reaction of different genotypes of banana to Meloidogyne incognita race 2, M. javanica and Pratylenchus coffeae. Ten banana genotypes were studied in Meloidogyne spp. experiments. The genotypes studied in M. incognita experiment were: Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, FHIA 17, Nanicão Magário, SH 3640, Pacovan and Prata Anã. In M. javanica experiment the genotypes studied were: Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, Nanicão Magário, SH 3640, Pacovan, Prata Anã and Maçã. P. coffeae experiment was developed with nine genotypes, PV 0344, SH 3640, Maçã, Thap Maeo, Caipira, Grande Naine, FHIA 1, FHIA 18 and Prata Anã. Experiments design were completely randomized with four replication for P. coffeae. and six replication in the studies with M. incognita and M. javanica. Each plot was constituted of a plant of banana produced in vitro, planted in pot with 2 liters of capacity, with substratum composed of soil, sand and organic matter in 1:1:1 proportion, previously autoclaved. After a week of the banana plants transplant, the inoculation was made with 5.000 eggs/plant for M. javanica or for M. incognita and 1.000 specimens/plant for P. coffeae. Tomato plants 'Rutgers' were used as control of the viability of the nematodes. The evaluation of the experiments with Meloidogyne was accomplished 120 days after the inoculation. The analyzed parameters were: gall number, of the... (Complete abstract, click electronic address below). / Mestre

Ph.D. (Nematology) / This thesis consists of three parts: the first and major part dealing with Xiphinema species from southern Africa. the second shorter part with Xiphinema species from the Aldabra Atoll. and the last part with aspects of the ultrastructure of Xiphidorus balcarceanus Chaves & Coornans, 1984 from Argentina. Nine new Xiphinema species are described from southern Africa. The three new species X. erriae, X. ripogranum and X. lacrimaspinae are all related to X. meridianum Heyns. 1971. but can be differentiated by the nature of the uterine spines and inclusions in the pseudo-Z-organ. tail shape. ovejector shape and the presence or absence of males. Two new longtailed species related to X. fJagellicaudatum Luc, 1961. viz. X. judex and X. dracomontanum, can be distinguished by body length. tail length and shape. the nature of the pseudo-Z-organ and presence or absence of males. Three new species with digitate or subdigitate tails are described, viz. X. capriviense from South West Africa-Namibia, which is characterised i.a. by peculiar inclusions in the uterus. X. pongolense from northern Natal which is quite similar to X. umobae Heyns & Spaull, 1979. and X. simplex from the Transkei, in which the uterus is devoid of any inclusions. The last new species to be described is X. ometizulu, which belongs to the X. zulu Heyns, 1965 and X. mampara Heyns, 1979 species complex. The abovementioned species complex was studied in detail, and X. mampara was found to consist of three different forms, one amphimictic, which is herein called X. mampara f. bisexuale. and two parthenogenetic forms. called X. mampara f. major and X. mampara f. minor. Redescriptions based on new populations are given for X. clavatum Heyns, 1965 and X. imitator Heyns, 1965. and additional information is also offered for X. umobae. A dichotomous key is presented for the identification of the 54 species of Xiphinema recorded from southern Africa. and the known distribution of these species is shown in a series of maps. X. brevicolle Lordello & Da Costa. 1961. X. italiae Meyl. 1953 and X. malagasi tuc, 1973 are reported from the Aldabra Atoll. All three species are described and figured, and compared with previous descriptions. The ultrastructure of the cuticle and feeding apparatus of Xiphidorus ba/carceanus was studied and compared with some other Longidoridae species.

D.Phil. (Nematology) / The science of taxonomy or the organisation and labelling of organisms may strike many as dull and stuffy but everyone working in this fascinating field finds that it leads to some of the most searching and interesting questions. Taxonomists are confronted by a well organised world of nature, exactly that what prompted the great taxonomist Linnaeus to develop his clear, hierarchical method of classification. But at the same time they are faced with a bewildering diversity and variation within this organised whole. Seeking to order the stable units in the midst of this diversity is the descriptive task of taxonomy. But many taxonomists go further than that, they seek a theory and ask: what causes life to be ordered? Here they land in the middle of philosophical debate and controversy. The field of taxonomy has, unfortunately, been divided by arguments about what a species is, how to demarcate a species, and even whether they are real or not. Today this "species question" is phrased in broader terms. The real question is not whether species are fixed but whether there is any stable, objective unit in nature. What do the patterns of similarity and difference mean - creation according to a common plan with the potential of variation, or descent from a common ancestor with modifications? Charles Darwin believed that change is unlimited, that species are infinitely variable. He thought that species could vary indefinitely and in any direction. Creationists on the other hand, believe that change is limited by a basic organic "unit", the "created kind" and within the boundary of that fundamental unit, variation can be profuse, but it can never lead to the creation of a new basic type. This is near the essentialism as taught by Aristotle nearly 2000 years ago. Aristotle thought that each species embodies an eternal, unchanging ideal or archetype. The problem with this view is that it assumed a single form or pattern. Most biologists until the time of Darwin held to the typological view, a view considered by many scientists today as very plausible. This theory holds that the organic world is discontinuous, that all major groups of organisms are separate and breed true to type. A species is also defined by a cluster of characteristics - each member of the species may have some but not all of the diagnostic features. Another view is cladism, founded by the entomologist, Willy Hennig. It is concerned with the patterns found in nature and involves the finding of the positive and verifiable characters of the various species and determining how all species fit into the animal kingdom.

Ph.D. (Zoology) / Please refer to full text to view abstract

Entomopathogenic Steinernema nematodes (Nematoda: Steinernematidae) have a mutualistic relationship with Xenorhabdus bacteria (Gamma-Proteobacteria Enterobacteriaceae). The two partners form an insecticidal alliance that is successful in killing a wide range of insects. A few studies have shown that Steinernema IJs have an enhanced virulence and reproductive fitness when they associate with their cognate symbionts. However, there are unanswered questions regarding the physiological interactions that govern and perpetuate the interactions between different nematode developmental stages and their bacterial partners. In this study, we evaluated gonad development and maturation time of first-generation adults of S. carpocapsae and S. feltiae adults when reared under four bacterial scenarios: a) cognate symbiotic, b) non-cognate symbiotic bacterial strain, c) non-cognate symbiotic bacterial species and d) non-symbiotic bacteria (Serratia proteamaculans). For comparative purposes, we also considered adult nematodes reared in vivo in Galleria mellonella larvae to assess nematode development under natural conditions. Furthermore, in this study we also measured production of nematode pheromones (ascarosides), which play a key role in mating and reproduction. For this purpose, we considered in vitro rearing methods (with cognate and non-cognate Xenorhabdus symbionts) to qualitatively and quantitatively characterize ascarosides produced by first-generation adults. Our data showed that for both Steinernema spp. tested, time to adult maturation and gonad development was tightly dependent on the bacterial conditions under which juveniles were reared. However, contrasting results were observed when assessing total body length and gonad size. S. feltiae males and females size (body length and width) and respective gonad length were smaller when reared with a non-cognate symbiotic species. Additionally, non-symbiotic bacteria did not sustain S. feltiae maturation to adult stages. Contrarily, S. carpocapsae juveniles developed to adults when reared with any of the bacterial conditions tested, including with non-symbiotic Serratia proteamaculans. Additionally, S. carpocapsae adults, unlike S. feltiae, did not exhibit enhanced body and gonad size when reared with their cognate symbiont. In fact, S. carpocapsae males and females had larger gonad lengths when reared with a non-cognate symbiotic strain, XnAna (X. nematophila associated with S. anatoliense). S. carpocapsae males and females had significantly underdeveloped gonads when reared with non-symbiotic bacteria. In both Steinernema spp., sex ratio was not impacted by the bacterial condition. However, sex ratio (female:male) S. carpocapsae, decreased from 2:1 to 1:1 when reared with non-symbiotic bacteria. The body and gonad sizes of Steinernema spp. reared in vitro with their cognate symbiont were significantly smaller than those grown in vivo. Ascaroside production in either Steinernema spp. was not significantly impacted by the rearing conditions. In S. carpocapsae, a significant increase in glucoside-1 was observed when the nematodes were reared with cognate or non-cognate bacteria. No detectable quantities of asc-C11 were produced by S. feltiae nematodes when reared with a non-cognate symbiotic bacterial species. We conclude that bacterial symbionts influenced maturation and development of first-generation adults’ in both Steinernema spp. tested in this study. However, response to the bacterial symbionts was species specific. Additionally, this study showed that Xenorhabdus as a food source plays an important role in the type and amount of ascarosides produced by Steinernema spp.

Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / Available potato (Solanum tuberosum L.) cultivars do not have any genotype that is resistant to the root-knot (Meloidogyne species) nematodes. Due to the susceptibility of potato cultivars to Meloidogyne species, alternative management strategies had to be researched and developed after the withdrawal of methyl bromide from the agro-chemical markets, amongst which were the cucurbitacin-containing phytonematicides. However, of the available application methods of phytonematicides, the ground leaching technology (GLT) and botinemagation technology were not suitable for use in most high-rainfall potato-producing regions, where production is under rain-fed conditions. The objective of the study, therefore, was to determine whether pre- and post-emergent application of Nemafric-BG phytonematicide would have effects on growth of potato and suppression of M. javanica population densities. Parallel pot trials of pre- and post-emergent application of Nemafric-BL phytonematicide were conducted under greenhouse conditions in autumn (February-April: Experiment 1) 2017 and validated (Experiment 2) in 2018. Each plant was inoculated with 3000 M. javanica eggs and second-stage juveniles (J2). Five treatments, namely, 0, 2, 4, 8 and 16 g concentration of Nemafric-BG phytonematicide, arranged in randomised complete block design, were either applied mixed with seed tubers for pre-emergent or spread on the soil surface after emergence for post-emergent trials. In all cases, plant growth variables were assessed using the Curve-fitting Allelochemical Response Data (CARD) model, whereas nutrient elements (Fe, K, Na and Zn) and nematode variables were assessed using analysis of variance, with data subjected to lines of the best fit. In pre-emergent application trial, plant height (R2 = 0.98) and fresh root mass (R2 = 0.99) exhibited quadratic relations, characterised by density dependent growth patterns with increasing concentrations of Nemafric-BG xv phytonematicide in Experiment 1, similar trends were also observed on plant height (R2 = 0.99) and root mass (R2 = 0.99) in Experiment 2. In contrast, in post-emergent application trial, plant height (R2 = 0.97), fresh root mass (R2 = 0.99) and dry shoot (R2 = 0.98) exhibited quadratic relations in Experiment 1, which ascribed to DDG patterns, similar trends were also observed in Experiment 2 on plant height (R2 = 0.99), fresh root mass (R2 = 0.96) and dry shoot (R2 = 0.99) of potato cv. ꞌMondial G3ꞌ. In pre-emergent application trials, Mean Concentration Stimulation Point (MCSP) = 24.18 and 7.82 g, respectively, in Experiment 1 and Experiment 2, with ∑k being equivalent to 20 and 6 units for potato to the product, respectively, in Experiment 1 and Experiment 2. In contrast, post-emergent application trials, MCSP = 9.87 and 12.10 g, respectively, in Experiment 1 and Experiment 2, whereas the ∑k value for potato to the product was 11 and 6 units, respectively in Experiment 1 and Experiment 2. Increasing concentrations of the phytonematicide significantly (P ≤ 0.05) affected the selected nutrient elements. In pre emergent application trials, K (R2  =  0.96) Na (R2  =  0.90) and Zn (R2  =  0.83) each with increasing Nemafric-BG phytonematicide concentrations exhibited positive quadratic fashion, while Fe (R2  =  0.87) exhibited negative quadratic relations in Experiment 1. In Experiment 2, K (R2  = 0.99), Na (R2  = 0.90) and Zn (R2 =  0.97) contents each in leaf tissues against the increasing concentrations of the phytonematicide exhibited negative quadratic relations, while Fe (R2  = 0.88) exhibited positive quadratic relations. In post emergent trials, Fe (R2 = 0.91, Na (R2 = 0.90) and Zn (R2 = 0.99) contents in leaf tissues against increasing Nemafric-BG phytonematicide concentration exhibited negative quadratic relations, whereas K (R2 = 0.86) exhibited positive quadratic relation in Experiment 1. In Experiment 2, Fe (R2 = 0.93), K (R2 = 0.92), Na ( R2  = 0.79) and Zn (R2 xvi = 0.89) contents in leaf tissues of potato exhibited positive quadratic, respectively. In pre emergent trial for Experiment 1, eggs in roots (R2 = 0.78), J2 in roots (R2 = 0.85), J2 in soil (R2 = 0.97) and Pf (R2 = 0.78) of M. javanica against increasing pre-emergent application concentrations of Nemafric-BG phytonematicide exhibited negative quadratic relations, characterised by DDG patterns. Similar trends were observed on eggs in roots (R2 = 0.82), J2 in roots (R2 = 0.99), J2 in soil (R2 = 0.84) and Pf (R2 = 0.85) in Experiment 2. In contrast, in post-emergent application trial, eggs in roots (R2 = 0.87), J2 in roots (R2 = 0.99), J2 in soil (R2 = 0.91) and Pf (R2 = 0.99) of M. javanica against increasing post emergent application concentrations of Nemafric-BG phytonematicide also exhibited negative quadratic relations in Experiment 1, which ascribed to DDG patterns. Similar trends were also observed on eggs in roots (R2 = 0.72), J2 in roots (R2 = 0.68), J2 in soil (R2 = 0.85) and Pf (R2 = 0.83) in Experiment 2. Results from the study demonstrated that Nemafric-BG phytonematicide stimulated plant growth at lower concentration and the product does not have any detrimental effects in accumulation of nutrient elements in leaf tissues. Therefore, it is concluded, that the product could be applied at the recommended rates of 7.82 and 9.87 g/plant in pre and post-emergent application, respectively, for the management of root-knot nematodes, provided the active ingredient does not accumulate in potato tubers or have any detrimental effects in accumulation of nutrient elements in tubers and temper with nutritional value of potatoes.

The objectives of this research were to evaluate management options for tobacco thrips, Frankliniella fusca (Hinds), and reniform nematode, Rotylenchulus reniformis (Linford & Oliverira), in cotton productions systems. When evaluating tillage practices for pest control, conservational tillage reduced thrips densities and damage, while the impact on nematode densities is less understood and in this study had no impact. Insecticide seed treatments remain a vital resource for controlling thrips in Mid-South cotton production systems. When incorporating an early season herbicide application for weed control, systems with an insecticide seed treatment generally tolerated herbicide injury better than those with early season stress from thrips and nematodes. When using foliar applications as an alternative option for thrips management, early season automatic applications at the cotyledon stage followed by one or two sequential applications provided similar efficacy to the insecticide seed treatment. For reniform nematode management, 1, 3-dichloropropene reduced densities lower than that of the untreated control or aldicarb; however, depending on environmental conditions this practice may not result in yield increases great enough to warrant the cost of application. These data highlight the importance of effective control of thrips whether it be via at-planting or foliar applications. 1, 3-dichloropropene reduced nematode densities and is an effective option in nematode management; however, nematodes are a stress pathogen and the ability to minimize other seasonal stresses ,such as water stress, will determine if a nematicide application may be needed. While environmental conditions may be optimal to allow for plant recoverability, effective early season pest management decreases the potential for delayed crop maturity which could lead to increased input cost or reduced yield later in the season.

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