Objectives and Research Questions 1. To reconstruct the history of invasion of Lantana in India from where, by who, and when was Lantana species introduced into India?, given its long history in the country, is it still spreading or has it become more or less stable? 2. To study the human adaptation to Lantana invasion: socioeconomic causes and consequences of the use of Lantana as an alternative source of livelihood for forest dependent communities in southern India; how have local communities adapted to the invasion?; what are the key determinants that may have driven communities to use Lantana?; what are the economic consequences of the use of Lantana by local communities? 3. To critically review local practices and forest policy for the management of Lantana in southern India.; how has the use of Lantana by local communities impacted its local regeneration?; does the use of Lantana in local context have implications for its management?; what has been the role of the Forest Department and its policies in managing Lantana?

Euphorbia heterophylla (EPHHL) é uma importante planta daninha na agricultura mundial, e a resistência aos herbicidas dificulta ainda mais o seu controle. Assim, conhecer o nível de resistência, os seus mecanismos e a persistência destas populações resistentes nas lavouras é fundamental para o estabelecimento de estratégias de prevenção e manejo. Foram realizados experimentos, objetivando estudar a resistência de EPHHL aos herbicidas inibidores da ALS e PROTOX nos níveis bioquímico, de planta e populacional. O capítulo I objetivou confirmar a ocorrência de resistência aos inibidores da ALS e determinar se existe resistência cruzada aos herbicidas dos grupos químicos das imidazolinona, sulfoniluréia, pirimidil-benzoato e sulfonanilida em biótipos de EPHHL com resistência múltipla (ALS e PROTOX). O capítulo II objetivou confirmar a existência de novos biótipos de EPHHL com resistência a PROTOX nos estados do Paraná e Rondônia e determinar se existe resistência cruzada aos herbicidas dos grupos químicos difeniléteres, ftalamida, triazolinona, oxadiazol e pirimidinedione. O capítulo III objetivou comparar a atividade da enzima ALS de biótipos com resistência múltipla com biótipo suscetível, na ausência e na presença dos herbicidas inibidores enzimáticos imazapyr, imazethapyr e nicosulfuron. O capítulo IV objetivou caracterizar as atividades das enzimas peroxidase, catalase e superóxido dismutase, em biótipos de EPHHL suscetível e com resistência múltipla, pela aplicação de herbicidas inibidores da PROTOX. E o capítulo V objetivou identificar a persistência de populações resistentes aos inibidores da ALS de EPHHL em lavouras da região Sudoeste e Oeste do Paraná que apresentavam resistência em levantamento prévio e verificar a existência de resistência de EPHHL ao glifosato nestas lavouras. Os resultados destes capítulos confirmaram que os biótipos de EPHHL Bom Sucesso do Sul, Vitorino, Vilhena e Medianeira, com suspeita de resistência múltipla aos inibidores da ALS e PROTOX, apresentam a resistência aos herbicidas inibidores da ALS e da PROTOX e esta sendo cruzada aos 4 grupos químicos dos inibidores da ALS e aos 5 grupos químicos dos inibidores da PROTOX, testados. A resistência dos biótipos de EPHHL aos inibidores da ALS é atribuída à menor sensibilidade da enzima a estes herbicidas. A atividade das enzimas antioxidantes superóxido dismutase, peroxidase e catalase, para os biótipos resistentes e suscetível é dependente do herbicida e da dose utilizada e pode ser um dos mecanismos envolvidos na resistência aos inibidores da PROTOX. Os biótipos de EPHHL resistentes aos herbicidas inibidores da ALS permanecem nas áreas mesmo após longo período de constatação da resistência. Plantas de EPHHL com resistência aos inibidores da PROTOX também permanecem nas áreas, no entanto em menor frequência. / Euphorbia heterophylla (EPHHL) is an important weed species in world agriculture and its control becomes difficult due to herbicide resistance. To develop proper EPHHL management strategies it is important to know the level and the mechanisms of resistance and persistence of resistant populations in the fields. Experiments were carried out to study the resistance of EPHHL to ALS and PROTOX inhibitors at biochemical, plant and population levels. The objectives on chapter I are to confirm the occurrence of resistance to ALS inhibitors and to determine whether there is cross resistance to other chemical groups, such as imidazolinone, sulfonylurea, pyrimidinyl (thio) benzoates and triazolopyrimidines in biotypes of EPHHL with multiple resistance (ALS and PROTOX). The objectives on chapter II are to confirm the existence of new EPHHL biotypes with resistance PROTOX in the states of Paraná and Rondônia and to determine whether there is cross resistance to other chemical group, such as diphenyl ethers, N-phenyl-phthalimide, triazolinone, oxadiazole and pyrimidinedione. The objectives on chapter III are to evaluate the activity of the ALS enzyme from biotypes with multiple resistance and to compare it to the enzyme activity of susceptible population in the absence and in the presence of the herbicides imazapyr, imazethapyr and nicosulfuron. The objectives on chapter IV is to characterize the activity of several antioxidant enzymes, such as peroxidase, catalase and superoxide dismutase in EPHHL biotypes treated with PROTOXinhibiting herbicides. The objective on chapter V are to identify the persistence of EPHHL populations resistant to ALS inhibitors on fields from Southwest and Western Paraná that were resistant in a previous survey and check for resistance to glyphosate in EPHHL these crops. The results support the hypothesis that EPHHL biotypes from Bom Sucesso do Sul, Vitorino, Vilhena and Medianeira have multiple resistance to ALS and PROTOX inhibitors. Four EPHHL biotypes are cross-resistant to all ALS chemical groups and five populations are cross-resistant to the PROTOX inhibitors tested. The resistance to ALS inhibitors on the EPHHL biotypes evaluated is attributed to the lower sensitivity of the herbicide target enzyme. The activity of all antioxidant enzymes, both on the resistant and susceptible biotypes, is dependent of the herbicide and on the dose used and can be one of the mechanisms of resistance to PROTOX inhibitors. The biotypes of EPHHL resistant to ALS-inhibiting herbicides remain in the area even after long-term observation of resistance. The resistance to PROTOX inhibitors also remains in areas, but less frequently.

CAPES / A forte pressão de seleção exercida pelo uso intensivo do herbicida glyphosate em áreas cultivadas tem selecionado populações de espécies Borreria latifolia (Aubl.) K.Shum. (erva-quente), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) e Richardia brasiliensis Gomes (poaia-branca), pertencentes à família Rubiaceae, com sensibilidade diferencial a este herbicida no Sul do Brasil. A dificuldade de controle com herbicidas sinaliza a necessidade de adoção de práticas de manejo da flora ruderal e de cultivos mais sustentáveis e que resultem em controle mais eficiente das populações a longo prazo. O presente estudo objetivou: (a) selecionar métodos eficazes para a superação de dormência de B. latifolia e G. chodatiana e determinar como os mesmos influenciam na cinética da germinação das sementes dessas espécies; (b) analisar o efeito de temperaturas, da irradiância, do pH, do alumínio e da salinidade no processo germinativo de sementes e no crescimento inicial de plântulas de B. latifolia, G. chodatiana e R. brasiliensis; (c) avaliar os níveis de tolerância ao glyphosate em biótipos de B. latifolia, G. chodatiana e R. brasiliensis por meio de curvas de dose-resposta utilizando dois métodos de avaliação de controle pelo herbicida; (d) e avaliar a eficiência de herbicidas alternativos no controle em pré-emergência, pós-emergência inicial e pós-emergência tardia das três espécies rubiáceas. A associação de KNO3 2%/3h + ácido giberélico 400 ppm resultou na maior porcentagem de germinação de sementes de G. chodatiana. Esse tratamento e também o de calor seco 60°C/30 min+ KNO3 2%/3h foram mais efetivos na superação da dormência de B. latifolia. G. chodatiana e R. brasiliensis toleraram temperaturas mais baixas durante o processo germinativo, enquanto B. latifolia tolerou temperaturas mais elevadas. B. latifolia e R. brasiliensis apresentaram-se fotoblásticas positivas, enquanto G. chodatiana foi indiferente ao fotoperíodo. B. latifolia apresentou germinação e desenvolvimento inicial mais elevado em pH 3, enquanto G. chodatiana e R. brasiliensis demonstraram preferencia por pH entre 5 e 7. B. latifolia e G. chodatiana foram mais tolerantes à presença do alumínio durante o processo germinativo do que R. brasiliensis. Baixos índices salinos foram suficientes para inibir boa parte da germinação das sementes das três espécies. Alguns biótipos de B. latifolia e R. brasiliensis apresentaram tolerância média a elevada ao glyphosate, não sendo controlados por doses acima da recomendada. A espécie G. chodatiana não foi controlada com a maior dose utilizada no experimento, sulfentrazone, S-metolachlor e saflufenacil apresentaram boa eficiência no manejo em pré-emergência tanto de B. latifolia quanto de R. brasiliensis, enquanto chlorimuron-ethyl e diclosulan foram eficientes somente sobre R. brasiliensis. Em apresentando elevada tolerância ao herbicida. Os herbicidas pós-emergência inicial os herbicidas fomesafen, lactofem e flumioxazin controlaram as eficientemente apenas B. latifolia. Destaca-se a suscetibilidade da espécie G. chodatiana para aplicações em pós-emergência inicial, pois estádios ontogênicos mais avançados reduzem os níveis de controle da espécie e as alternativas químicas. Diferentes tratamentos, associados ao glyphosate ou em aplicações sequenciais, foram eficazes em controlar as plantas de B. latifolia e R. brasiliensis em estádio de desenvolvimento avançado. / The strong selection pressure exerted by intensive use of glyphosate in cultivated areas has selected populations of the Rubiaceae weed species Borreria latifolia (Aubl.) K.Shum. (broadleaf buttonweed), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) and Richardia brasiliensis Gomes (Brazilian pusley) with differential sensitivity to this herbicide in the South region of Brazil. The control of these weeds with herbicides is troublesome and signals the need to incorporate management practices of ruderal flora and crops, more sustainable and that results in more efficient control for long-term. Therefore, it is very important to expand the information about their biology and management. This study aimed: (a) select efficient methods to overcome dormancy of B. latifolia and G. chodatiana and determine how they influence the kinetics of seeds germination; (b) analyze the effects of temperature, irradiance, pH, aluminum and salinity on seed germination and initial growth of the B. latifolia, G. chodatiana e R. brasiliensis seedlings; (c) evaluate tolerance to glyphosate levels in biotypes of B. latifolia, G. chodatiana e R. brasiliensis through dose-response curves and compare two methods to evaluate herbicidal control; (d) and evaluated the effectiveness of alternative herbicides in pre-emergence and in early and late post-emergence of the three species. The treatment with KNO3 2%/3h + gibberellic acid 400 ppm resulted in higher percentage of G. chodatiana seed germination. This treatment and also the dry heat (60°C/30 min) + KNO3 2%/3h were more effective in overcoming dormancy of B. latifolia. G. chodatiana and R. brasiliensis tolerate lower temperatures during the germination process, while B. latifolia tolerate higher temperatures. B. latifolia and R. brasiliensis are positive photoblastic while G. chodatiana is indifferent to the photoperiod. B. latifolia shows higher germination and early development in pH 3, while G. chodatiana and R. brasiliensis prefer pH range between 5 and 7. B. latifolia and G. chodatiana were more tolerant to the aluminum during the germination process than R. brasiliensis. Low salt levels were sufficient to reduce the seed germination of the three species. Some biotypes of B. latifolia and R. brasiliensis showed medium-high glyphosate tolerance, not being controlled by higher doses than recommended. The G. chodatiana specie was not controlled with the highest dose used, showing a high glyphosate tolerance. The sulfentrazone, s-metolachlor and saflufenacil herbicides sprayed in pre-emergence showed high efficacy both on B. latifolia and R. brasiliensis, while chlorimuron-ethyl and diclosulan were effective only on R. brasiliensis. In early post-emergence the fomesafen, lactofem and flumioxazin herbicides efficiently controlled plants of all species, while bentazon showed high efficacy only on B. latifolia. Noteworthy the susceptibility of the G. chodatiana specie for applications in early post-emergence, because the control effectiveness and the number of effective herbicides are reduced with increasing the plant age. Many treatments with tank mix or sequencial applications with glyphosate, were effective in controlling B. latifolia and R. brasiliensis plants in advanced stage of development.

Euphorbia heterophylla (EPHHL) é uma importante planta daninha na agricultura mundial, e a resistência aos herbicidas dificulta ainda mais o seu controle. Assim, conhecer o nível de resistência, os seus mecanismos e a persistência destas populações resistentes nas lavouras é fundamental para o estabelecimento de estratégias de prevenção e manejo. Foram realizados experimentos, objetivando estudar a resistência de EPHHL aos herbicidas inibidores da ALS e PROTOX nos níveis bioquímico, de planta e populacional. O capítulo I objetivou confirmar a ocorrência de resistência aos inibidores da ALS e determinar se existe resistência cruzada aos herbicidas dos grupos químicos das imidazolinona, sulfoniluréia, pirimidil-benzoato e sulfonanilida em biótipos de EPHHL com resistência múltipla (ALS e PROTOX). O capítulo II objetivou confirmar a existência de novos biótipos de EPHHL com resistência a PROTOX nos estados do Paraná e Rondônia e determinar se existe resistência cruzada aos herbicidas dos grupos químicos difeniléteres, ftalamida, triazolinona, oxadiazol e pirimidinedione. O capítulo III objetivou comparar a atividade da enzima ALS de biótipos com resistência múltipla com biótipo suscetível, na ausência e na presença dos herbicidas inibidores enzimáticos imazapyr, imazethapyr e nicosulfuron. O capítulo IV objetivou caracterizar as atividades das enzimas peroxidase, catalase e superóxido dismutase, em biótipos de EPHHL suscetível e com resistência múltipla, pela aplicação de herbicidas inibidores da PROTOX. E o capítulo V objetivou identificar a persistência de populações resistentes aos inibidores da ALS de EPHHL em lavouras da região Sudoeste e Oeste do Paraná que apresentavam resistência em levantamento prévio e verificar a existência de resistência de EPHHL ao glifosato nestas lavouras. Os resultados destes capítulos confirmaram que os biótipos de EPHHL Bom Sucesso do Sul, Vitorino, Vilhena e Medianeira, com suspeita de resistência múltipla aos inibidores da ALS e PROTOX, apresentam a resistência aos herbicidas inibidores da ALS e da PROTOX e esta sendo cruzada aos 4 grupos químicos dos inibidores da ALS e aos 5 grupos químicos dos inibidores da PROTOX, testados. A resistência dos biótipos de EPHHL aos inibidores da ALS é atribuída à menor sensibilidade da enzima a estes herbicidas. A atividade das enzimas antioxidantes superóxido dismutase, peroxidase e catalase, para os biótipos resistentes e suscetível é dependente do herbicida e da dose utilizada e pode ser um dos mecanismos envolvidos na resistência aos inibidores da PROTOX. Os biótipos de EPHHL resistentes aos herbicidas inibidores da ALS permanecem nas áreas mesmo após longo período de constatação da resistência. Plantas de EPHHL com resistência aos inibidores da PROTOX também permanecem nas áreas, no entanto em menor frequência. / Euphorbia heterophylla (EPHHL) is an important weed species in world agriculture and its control becomes difficult due to herbicide resistance. To develop proper EPHHL management strategies it is important to know the level and the mechanisms of resistance and persistence of resistant populations in the fields. Experiments were carried out to study the resistance of EPHHL to ALS and PROTOX inhibitors at biochemical, plant and population levels. The objectives on chapter I are to confirm the occurrence of resistance to ALS inhibitors and to determine whether there is cross resistance to other chemical groups, such as imidazolinone, sulfonylurea, pyrimidinyl (thio) benzoates and triazolopyrimidines in biotypes of EPHHL with multiple resistance (ALS and PROTOX). The objectives on chapter II are to confirm the existence of new EPHHL biotypes with resistance PROTOX in the states of Paraná and Rondônia and to determine whether there is cross resistance to other chemical group, such as diphenyl ethers, N-phenyl-phthalimide, triazolinone, oxadiazole and pyrimidinedione. The objectives on chapter III are to evaluate the activity of the ALS enzyme from biotypes with multiple resistance and to compare it to the enzyme activity of susceptible population in the absence and in the presence of the herbicides imazapyr, imazethapyr and nicosulfuron. The objectives on chapter IV is to characterize the activity of several antioxidant enzymes, such as peroxidase, catalase and superoxide dismutase in EPHHL biotypes treated with PROTOXinhibiting herbicides. The objective on chapter V are to identify the persistence of EPHHL populations resistant to ALS inhibitors on fields from Southwest and Western Paraná that were resistant in a previous survey and check for resistance to glyphosate in EPHHL these crops. The results support the hypothesis that EPHHL biotypes from Bom Sucesso do Sul, Vitorino, Vilhena and Medianeira have multiple resistance to ALS and PROTOX inhibitors. Four EPHHL biotypes are cross-resistant to all ALS chemical groups and five populations are cross-resistant to the PROTOX inhibitors tested. The resistance to ALS inhibitors on the EPHHL biotypes evaluated is attributed to the lower sensitivity of the herbicide target enzyme. The activity of all antioxidant enzymes, both on the resistant and susceptible biotypes, is dependent of the herbicide and on the dose used and can be one of the mechanisms of resistance to PROTOX inhibitors. The biotypes of EPHHL resistant to ALS-inhibiting herbicides remain in the area even after long-term observation of resistance. The resistance to PROTOX inhibitors also remains in areas, but less frequently.

CAPES / A forte pressão de seleção exercida pelo uso intensivo do herbicida glyphosate em áreas cultivadas tem selecionado populações de espécies Borreria latifolia (Aubl.) K.Shum. (erva-quente), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) e Richardia brasiliensis Gomes (poaia-branca), pertencentes à família Rubiaceae, com sensibilidade diferencial a este herbicida no Sul do Brasil. A dificuldade de controle com herbicidas sinaliza a necessidade de adoção de práticas de manejo da flora ruderal e de cultivos mais sustentáveis e que resultem em controle mais eficiente das populações a longo prazo. O presente estudo objetivou: (a) selecionar métodos eficazes para a superação de dormência de B. latifolia e G. chodatiana e determinar como os mesmos influenciam na cinética da germinação das sementes dessas espécies; (b) analisar o efeito de temperaturas, da irradiância, do pH, do alumínio e da salinidade no processo germinativo de sementes e no crescimento inicial de plântulas de B. latifolia, G. chodatiana e R. brasiliensis; (c) avaliar os níveis de tolerância ao glyphosate em biótipos de B. latifolia, G. chodatiana e R. brasiliensis por meio de curvas de dose-resposta utilizando dois métodos de avaliação de controle pelo herbicida; (d) e avaliar a eficiência de herbicidas alternativos no controle em pré-emergência, pós-emergência inicial e pós-emergência tardia das três espécies rubiáceas. A associação de KNO3 2%/3h + ácido giberélico 400 ppm resultou na maior porcentagem de germinação de sementes de G. chodatiana. Esse tratamento e também o de calor seco 60°C/30 min+ KNO3 2%/3h foram mais efetivos na superação da dormência de B. latifolia. G. chodatiana e R. brasiliensis toleraram temperaturas mais baixas durante o processo germinativo, enquanto B. latifolia tolerou temperaturas mais elevadas. B. latifolia e R. brasiliensis apresentaram-se fotoblásticas positivas, enquanto G. chodatiana foi indiferente ao fotoperíodo. B. latifolia apresentou germinação e desenvolvimento inicial mais elevado em pH 3, enquanto G. chodatiana e R. brasiliensis demonstraram preferencia por pH entre 5 e 7. B. latifolia e G. chodatiana foram mais tolerantes à presença do alumínio durante o processo germinativo do que R. brasiliensis. Baixos índices salinos foram suficientes para inibir boa parte da germinação das sementes das três espécies. Alguns biótipos de B. latifolia e R. brasiliensis apresentaram tolerância média a elevada ao glyphosate, não sendo controlados por doses acima da recomendada. A espécie G. chodatiana não foi controlada com a maior dose utilizada no experimento, sulfentrazone, S-metolachlor e saflufenacil apresentaram boa eficiência no manejo em pré-emergência tanto de B. latifolia quanto de R. brasiliensis, enquanto chlorimuron-ethyl e diclosulan foram eficientes somente sobre R. brasiliensis. Em apresentando elevada tolerância ao herbicida. Os herbicidas pós-emergência inicial os herbicidas fomesafen, lactofem e flumioxazin controlaram as eficientemente apenas B. latifolia. Destaca-se a suscetibilidade da espécie G. chodatiana para aplicações em pós-emergência inicial, pois estádios ontogênicos mais avançados reduzem os níveis de controle da espécie e as alternativas químicas. Diferentes tratamentos, associados ao glyphosate ou em aplicações sequenciais, foram eficazes em controlar as plantas de B. latifolia e R. brasiliensis em estádio de desenvolvimento avançado. / The strong selection pressure exerted by intensive use of glyphosate in cultivated areas has selected populations of the Rubiaceae weed species Borreria latifolia (Aubl.) K.Shum. (broadleaf buttonweed), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) and Richardia brasiliensis Gomes (Brazilian pusley) with differential sensitivity to this herbicide in the South region of Brazil. The control of these weeds with herbicides is troublesome and signals the need to incorporate management practices of ruderal flora and crops, more sustainable and that results in more efficient control for long-term. Therefore, it is very important to expand the information about their biology and management. This study aimed: (a) select efficient methods to overcome dormancy of B. latifolia and G. chodatiana and determine how they influence the kinetics of seeds germination; (b) analyze the effects of temperature, irradiance, pH, aluminum and salinity on seed germination and initial growth of the B. latifolia, G. chodatiana e R. brasiliensis seedlings; (c) evaluate tolerance to glyphosate levels in biotypes of B. latifolia, G. chodatiana e R. brasiliensis through dose-response curves and compare two methods to evaluate herbicidal control; (d) and evaluated the effectiveness of alternative herbicides in pre-emergence and in early and late post-emergence of the three species. The treatment with KNO3 2%/3h + gibberellic acid 400 ppm resulted in higher percentage of G. chodatiana seed germination. This treatment and also the dry heat (60°C/30 min) + KNO3 2%/3h were more effective in overcoming dormancy of B. latifolia. G. chodatiana and R. brasiliensis tolerate lower temperatures during the germination process, while B. latifolia tolerate higher temperatures. B. latifolia and R. brasiliensis are positive photoblastic while G. chodatiana is indifferent to the photoperiod. B. latifolia shows higher germination and early development in pH 3, while G. chodatiana and R. brasiliensis prefer pH range between 5 and 7. B. latifolia and G. chodatiana were more tolerant to the aluminum during the germination process than R. brasiliensis. Low salt levels were sufficient to reduce the seed germination of the three species. Some biotypes of B. latifolia and R. brasiliensis showed medium-high glyphosate tolerance, not being controlled by higher doses than recommended. The G. chodatiana specie was not controlled with the highest dose used, showing a high glyphosate tolerance. The sulfentrazone, s-metolachlor and saflufenacil herbicides sprayed in pre-emergence showed high efficacy both on B. latifolia and R. brasiliensis, while chlorimuron-ethyl and diclosulan were effective only on R. brasiliensis. In early post-emergence the fomesafen, lactofem and flumioxazin herbicides efficiently controlled plants of all species, while bentazon showed high efficacy only on B. latifolia. Noteworthy the susceptibility of the G. chodatiana specie for applications in early post-emergence, because the control effectiveness and the number of effective herbicides are reduced with increasing the plant age. Many treatments with tank mix or sequencial applications with glyphosate, were effective in controlling B. latifolia and R. brasiliensis plants in advanced stage of development.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, March 2017. / Water hyacinth (Eichhornia crassipes) is an example of an alien invasive plant, threatening ecosystems around the world. Taking into consideration all the negative impacts caused by the proliferation of water hyacinth, many control measures have been implemented to manage this weed. These include mechanical control, chemical control and biological control. But in recent years, the focus has shifted towards natural enemies for control (biological control) of water hyacinth because they have many advantages for environmental safety. However, in South Africa, success is limited in most parts of the country. Factors affecting the success of biological control of water hyacinth in South Africa have been attributed in part to weather conditions. Therefore, further studies and other strategies are needed to reinforce the biological control of water hyacinth. This is why this research investigated the influences of temperature on Neochetina eichhorniae larvae feeding and development on water hyacinth, to contribute to the future management of water hyacinth biological control. To measure the effect of temperature on the feeding and development of Neochetina eichhorniae larva, experiments were conducted at four fixed temperatures (15 °C, 20 °C, 25 °C, and 30 °C). Larval feeding is expected to be greater and the development faster at warm temperatures compared with cold temperatures. The results of this study confirmed that, both feeding and larval development increased with an increase in temperature. The highest larval feeding damage was recorded at 30°C and the lowest at 15°C. Similar to the feeding of larvae, warmer temperatures were more favourable to the growth of larvae than cold temperatures; all larvae found at 30°C were in their third instars (with 0.72 mm being the biggest headwidth found) while all larvae at 15°C were in the first instars (with 0.28 mm being the smallest headwidth found). Even if the optimal temperature for larval performance took place at 30 °C (with a high amount of biomass removal), it was at 25 °C that the larvae had a larger effect on the growth of water hyacinth. Larval feeding damage reduced the growth of water hyacinth by 30 % at 25 °C and only affected 24 % of water hyacinth growth at iv 30 °C. Therefore, for the biocontrol of water hyacinth, the ideal temperature to slow the progression of the weed will be recommended at between 25- 30 °C. / LG2017

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The problems posed by alien invasive plants to our environment and the need for clearing and control has been highlighted by the Working for Water (WFW) programme. Alien plant control requires careful planning, including budgeting. To date, costing and budgeting in alien plant control has largely been a combination of experience on the part of weed 'experts', coupled with much guess work. Weed controllers have through experience calculated the amount of time (or the work rate), recorded as labour days, required for different control actions of different weed habits. These work rates are for weed clearance under ideal conditions and do not take into account the effect of factors such as gradient, access and distance to the weed infestation. Factors affecting the work rate has been researched and modelled by researchers in both alien plant control and the timber industry. While the existing work rate model is useful in its present theoretical state, the model may be improved upon to make it more practical and applicable to the varying conditions of different areas. This research built on existing theoretical research on alien control work rates, and concentrated on two main areas: the adaption and incorporation of the existing research on work rates into a Geographical Information System (GIS), and the creation and demonstration of a Spatial Decision Support System (SDSS) for the management of alien plant control. The eMpofana river in the KwaZulu-Natal midlands was selected as the study area, as there was an existing alien plant control programme. Initially all factors, such as slope, access to weed infestations, terrain and penetrability of infestations, affecting the work rate in the research area were identified. An existing work rate model was then modified to account for the conditions of the research area. Regression analysis was used to derive the relationship between the various factors affecting work rate, creating a work rate model applicable to the study area. Using the results of the regression analysis together with work rate figures adapted from an existing alien plant control programme, a SDSS for alien plant control along the eMpofana River was created. The use of the work rate model and the SDSS in the development of weed control programmes was demonstrated by examining four different management approaches, each having a different management objective . The SDSS provides a spatial component to weed control planning and costing that has thus far not existed. What this research has achieved is the advancement of an alien control work rate model from a theoretical to a more realistic costing process. While some factors affecting work rate may not have been accounted for, the model does address the present inaccuracies in labour costing, and ultimately alien plant control costing. The research has highlighted the disadvantages of GIS in terms of affordability and expertise. The model has wider uses than the eMpofana River, and is the ground work for the further development of a user friendly model applicable throughout South Africa. More effective project budgeting will decrease the likelihood of project failure and this will directly benefit long-term weed control efforts. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

Weed control is a major cost for growers in the sugarcane industry, especially for monocotyledonous species such as Cynodon and Rottboellia spp. The introduction of imazapyr-tolerant sugarcane would be advantageous as this herbicide has shown to be effective against the above-mentioned weeds but it also kills sugarcane. In a previous study in our laboratory, several sugarcane putative-mutant lines of variety N12 were generated by in vitro exposure of embryogenic callus to 16 mM ethyl methanesulfonate (EMS), followed by selection on imazapyr-containing medium. Tolerance to a low dose of imazapyr was confirmed in seven of those lines when the herbicide was applied (182 g a.i. ha-1) to 3 month-old plants in pots. The aim of the present study was to identify which of the seven herbicide mutant lines had agronomic characteristics at least equivalent to un-mutated N12. The objectives were to: 1) confirm tolerance to increased rate (312 and 625 g a.i. ha-1) of imazapyr in field plants; 2) measure the agronomic characteristics of these lines; 3) determine the effect of residual soil herbicide activity on germination of sugarcane setts. The seven mutant lines (Mut1-Mut7) and un-mutated N12 were clonally propagated in vitro by shoot multiplication followed by rooting and planted in three plots (untreated, sprayed with 312 or 625 g a.i. ha-1 imazapyr), in the field, in a randomized complete block design. In the untreated control plot there were no significant differences between the control and the mutant plants for agronomic traits (tiller number/plot, stalk height and stalk diameter) or estimated yield (kg/plot) after 10 months, indicating that the mutation process had no effect on general plant phenotype. In the sprayed (312 and 625 g a.i. ha-1) plots, Mut1, Mut4, Mut5, Mut6 and Mut7 plants showed tolerance to imazapyr as the leaves remained green compared with Mut2, Mut3 and N12 control plants, which displayed chlorotic leaves and eventually died in the plot sprayed with 625 g a.i. ha-1. Post-herbicide application, the yields of Mut5, Mut6 and Mut7 (52.33, 43.43 and 41.43 kg/plot, respectively) from the 312 g a.i. ha-1 plot were not significantly different from that of N12 control (53. 61 kg/plot) in the untreated plot. However, in the 312 g a.i. ha-1 plot, the yield and agronomic trait measurements of the untreated N12 control were significantly higher than those of the herbicide-susceptible plants Mut2 and Mut3. Similarly, in the 625 g a.i. ha-1 plot, the recorded yields for Mut4, Mut6 and Mut7 were 41.60, 43.44 and 36.30 kg/plot, respectively, indicating that their imazapyr tolerance and yield characteristics were comparable to the untreated N12 control. Imazapyr is conventionally applied to a fallow field 3-4 months prior to planting sugarcane as there is residual herbicide activity in the soil that suppresses sugarcane germination and growth. Therefore, in order to establish if the herbicide-tolerant mutants could germinate in iii an imazapyr-treated field, 3-budded setts of the mutant lines (Mut1-Mut7) and N12 control were planted in two plots, one unsprayed and one sprayed with 1254 g a.i. ha-1 imazapyr, 2 weeks previously. Germination was calculated after 3 weeks as the number of germinated setts in each plot/no. germinated setts in unsprayed plot x100. In the sprayed plot, the setts from Mut1, Mut4 and Mut6 displayed the highest germination percentages (60, 71 and 74%, respectively) compared with Mut2 (24%), Mut3 (46%), Mut5 (34%), Mut7 (40%) and the N12 control (12%). The in vitro acetolactate synthase (ALS) enzyme activity of 10 month-old plants from the untreated plot was assessed in the presence of 0-30 μM imazapyr to determine the herbicide concentration that inhibited ALS activity by 50% (IC50). The IC50 values for the mutated lines were between 3 and 30 μM, i.e. 1.5-8.8 times more tolerant to imazapyr than the N12 control plants, with Mut6 displaying the highest IC50 value (30 μM). On the basis of the results, it was concluded that Mut1, Mut6 and Mut7 lines were more tolerant to imazapyr than N12 and the other tested lines. Future work includes phenotypically assessing these lines for traits including sucrose content, fibre content, actual yield (tons cane ha-1) and altered pest and disease resistance. Once isolated and sequenced, the ALS gene conferring imazapyr tolerance can be used in genetic bombardment in the genetic modification approach as the gene of interest or as a selectable marker. In addition, the imazapyr-tolerant line can be used for commercial purposes in the field and as the parent plant in the breeding programme. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Durban, 2013.

[Truncated abstract] In the crop growing areas of Western Australia, two economically important weed species, Lolium rigidum Gaud. (annual ryegrass) and Raphanus raphanistrum L. (wild radish), have evolved widespread herbicide resistance to multiple chemistry groups. Consequently, grain growers in the region have adopted an integrated approach to weed management that includes many non herbicide tools, however many more are needed as these weed species become increasingly more difficult to control. This thesis examines, in a series of field trials carried out in the Western Australian crop growing area, the potential for weed seed predation of annual ryegrass and wild radish by naturally occurring granivores as a new weed management tool for grain growers . . . The study discusses the implications of these results with the view to manipulating predation of weed seed through agricultural management practices. Ants were shown to be the dominant seed predator in this environment, especially in the centre of fields. The study has identified that the ant species Melophorus turneri (Forel), Monomorium rothsteini (Forel), Pheidole hartmeyeri (Forel) and Rhytidoponera metallica (Smith) are potential biological control agents for annual ryegrass seeds while P. hartmeyeri was identified as the only species suitable for biological control of wild radish seed pods. Ants were found to be sensitive to disturbance and some to crop residue type and these effects are discussed in relation to seed removal. This study of weed seed predation in agricultural fields is the most complete in this environment and can be used to inform further work in this area. It has identified that naturally occurring granivores can be used as a weed management tool.