Orientador: Daniel Junior de Andrade / Banca: Odair Aparecido Fernandes / Banca: Marcos Doniseti Michelotto / Resumo: Nas últimas safras, constatou-se aumento significativo na incidência de ácaros-praga nos campos de produção de amendoim. Altas infestações de ácaros comprometem o desenvolvimento e a produtividade da cultura, elevam os custos de produção e ainda podem contribuir para aumento do impacto negativo sobre o meio ambiente. Sabe-se que os principais ácaros-praga que vêm causando prejuízos aos produtores em São Paulo pertencem à família Tetranychidae. Portanto, os objetivos do trabalho foram estudar a distribuição espacial do ácaro Tetranychus ogmophallos Ferreira e Flechtmann (Acari: Tetranychidae) e determinar a depreciação quantitativa e qualitativa causada por esse ácaro à cultura do amendoim. Os experimentos foram realizados a campo e em casa de vegetação. Para realização dos experimentos a campo foram selecionadas duas áreas de amendoim, sendo uma área localizada na Faculdade de Ciências Agrárias e Veterinárias - UNESP/FCAV e outra na zona rural do município de Jaboticabal-SP, Brasil. Nas áreas selecionadas, foram vistoriados materiais vegetais compostos por folhas, folíolos e pecíolos, coletados na parte inferior e superior de plantas distanciadas de 22,5 metros uma das outras. A primeira coleta foi realizada 28 dias após o plantio, e as demais a cada quinze dias. Em contrapartida, foram realizados em casa de vegetação da UNESP/FCAV quatro experimentos para determinar a depreciação quantitativa e qualitativa causada pelo ácaro T. ogmophallos ao amendoinzeiro. Estes experimentos foram instalados em delineamento inteiramente casualizado, compostos por dois tratamentos com vinte repetições cada. Os tratamentos empregados foram plantas infestadas e não infestadas pelo ácaro. Em cada experimento variou-se a época de infestação com o ácaro (15, 30, 60 e 90 dias após a emergência das plântulas). Em cada infestação transferiram-se aproximadamente 3.000 ácaros. Os dados foram submetidos à ... / Abstract: In recent growing seasons, there was a significant increase in the incidence of mite in peanut fields. Large infestations of pest mites affect the development and crop productivity, increases production costs, and contribute to increased environmental contamination due to intensive use of pesticides to control these arthropod. Field Information and observations indicate that the main pest mites that have caused damage to producers in São Paulo belong to Tetranychidae. This work aimed to study the type of spatial distribution of Tetranychus ogmophallos Ferreira e Flechtmann (Acari: Tetranychidae) mite on peanut, which probability distribution model that best represents your behavior in the field, as well as, determine the quantitative and qualitative depreciation caused by the mite to peanut crop. The experiments were carried out in the field and in a greenhouse belonging to the Faculty of Agricultural and Veterinary Sciences - UNESP/FCAV, Jaboticabal - SP. To determine the spatial distribution of the mite on peanut two fields with peanut were selected. In selected fields were examined plant materials consisting of leaves, leaflets and petioles, collected in the lower and top of the plant. The plants were spaced 22.5 m from one another. The first collect of samples of plant material was performed twenties days after planting, and the other every fifteen days. To determine the quantitative and qualitative depreciation experiments were conducted in a greenhouse, arranged in a completely randomized design consisting of two treatments, plants infested and non-infested (control), with 20 repetitions. The age of infestation varied in each experiment based on the number of days (15, 30, 60, and 90) after seedling emergence. Approximately 3,000 mites were transferred for each infestation. Data were submitted to analysis of variance, and means were compared by F test at 5% probability and the aggregation indexes were used to study the ... / Mestre

M.Sc. (Zoology) / This study centres around the findings on mites (Acari: Eriophyidae) (also referred to as "eriophyids") as potential biological control agents of weeds in South Africa. The use of mites in the biological control of weeds is briefly reviewed. Four species of the family Eriophyidae have been used against weeds in other countries. Seventeen eriophyid species, causing symptoms possibly of significance to biological weed control of 12 plant species regarded as weeds in South Africa, are discussed. Methods to rear and study eriophyids in the laboratory have not yet been fully developed and studying these practically invisible arthropods, very closely associated with their host plants, frequently presents difficulties. Reported methods, and those used for the present study, are reviewed and discussed. The eriophyid, Aceria lantanae (Cook), causing flower and leaf galls on Lantana camara L. could not be successfully established in a quarantine laboratory on potted plants propagated from cuttings of L. camara forms from South Africa. The results obtained during this attempt were inconclusive. The failure of establishment on local L. camara forms could be attributed to a variety of factors, of which rearing methods and host incompatibility are the most likely. Convolvulus arvensis is a troublesome agricultural weed and occurs in especially the Orange Free State and the eastern and southern parts of the Cape Province. Biological control may possibly contribute to curbing this weed in South Africa. The eriophyid, Aceria malherbae Nuzzaci, causing deformation and galling on C. arvensis is regarded as one of the most promising candidates for the biological control of this weed. It was imported and successfully established on potted plants in a quarantine laboratory on biotypes of the weed occurring in South Africa. The biology and host specificity of A malherbae are accounted for, by using reported information and data obtained during this study. The biology of A. malherbae broadly conforms to the biology of other eriophyid species. This species has a narrow host range, being restricted to species very closely related to C. arvensis. The symptoms caused by this eriophyid on C. arvensis are described, and seem especially harmful to the reproductive potential of the plant. Two eriophyid species from L. camara from Paraguay, Tegonotus stefneseri and Paraphytoptus magdalenae, are described as new species. An illustrated as well as a dichotomous key to species (Eriophyoidea) described from L. camara, including the two new species, are provided. A key, and a review of known Tegonotus species, incorporated in a compendium based on the original descriptions of 74 species, are included. Shevtchenkella Bagdasarian is considered to be a junior subjective synonym of Tegonotus Nalepa.

Plant-based defence mutualisms involve aspects of plant morphology that influence the performance of plant parasites, their natural enemies and trophic interactions. Leaf domatia, small indentations on the underside of leaves, can be structurally complex, and are often inhabited by potentially beneficial mites and other arthropods. Plant morphological traits such as domatia that enhance mutualistic relationships may result in increased plant growth rates, and reproductive success. New Zealand supports ~60 plant species that have domatia, the most speciose genus being Coprosma. The aim of this thesis was to examine factors that affect the production of leaf domatia and their relationship with foliar mite assemblages. The three main objectives of this thesis are: First, to investigate the production of foliar domatia and their susceptibility to limited resources, particularly to carbon availability. Second, to test if domatia are inducible structures during leaf ontogeny in the presence of foliar mites and/or fungi. Finally, to explore the effect of domatia availability on foliar mite assemblages on leaves with and without resident mites. This thesis tested the stated objectives using C. lucida, C. ciliata, C. foetidissima and C. rotundifolia, with a combination of field investigations and controlled manipulative experiments. The cost of domatia production was investigated using two field surveys and two controlled experiments. Under natural conditions the relationship between leaf morphology and domatia were measured in situ and across an altitudinal gradient. The experimental manipulations used carbon and nutrient stress, induced by temperature, light and fertilizer application. The second objective was experimentally tested under field conditions by manipulating foliar mites and fungal densities on C. rotundifolia. The third objective was investigated by manipulating domatia availability on C. lucida shrubs across three different vegetation types. Under field conditions, the number of domatia per leaf was associated with leaf morphology in C. lucida and C. foetidissima, but not C. rotundifolia. Foliar carbon showed a positive, but weak association with domatia production in C. foetidissima and C. ciliata. Altitudinal induced-carbon stress on domatia production was ambiguous. Domatia production in C. foetidissima was positively associated to altitude in field survey (1), and negatively associated in the second survey, with no correlation found between carbon and altitude. Experimental C. rotundifolia shrubs held under elevated night-time temperatures showed a 2.5 fold increase in respiration, a 34% to 91% decrease in daily carbon gain, and 38% decrease in domatia per leaf mass. Domatia production showed no significant differences under nutrient stress. The results showed little evidence to support a role for induction of domatia. Domatia production in new leaves was similar across all experimental treatments. Diverse vegetation types supported 60% higher mite species. Leaves with domatia supported ~22 to 66% higher mite densities, greater colonisation success and more diverse mite assemblages, than those without domatia. In the pastoral vegetation, the absence of predatory mites on experimental shrubs resulted in no differences in fungivorous mite densities regardless of domatia availability. Plant investment in foliar domatia appears associated with the number of available sites on the leaf under field conditions. The role of carbon availability during leaf ontogeny suggests a complex and highly variable association with domatia production. Domatia are constitutive defence structures that influence mite assemblages, mediating both beneficial and antagonistic relationships. This thesis concludes that domatia are in part, carbon-based non-inducible structures that influence mite assemblages, plant-mite and mite-mite interactions, and increase the probability of successful colonisation.

Orientador: Daniel Junior de Andrade / Banca: Marineide Rosa Vieira / Banca: Renato Beozzo Bassanezi / Resumo: O ácaro Brevipalpus yothersi Baker é vetor da leprose dos citros, principal doença viral da citricultura mundial. Informações sobre a biologia de B. yothersi são essenciais para compreender a dinâmica populacional do ácaro no campo e inferir se mudanças no manejo do pomar em função da região pode alterar a biologia do ácaro. O objetivo do trabalho foi determinar a biologia e elaborar a tabela de vida de fertilidade de B. yothersi coletados em diferentes regiões citrícolas do estado de São Paulo. Os experimentos foram realizados no Laboratório de Acarologia, pertencente à Faculdade de Ciências Agrárias e Veterinárias - FCAV/UNESP, Jaboticabal - SP. Os ácaros foram coletados em pomares cítricos das regiões de Barretos, Jales e Santa Cruz do Rio Pardo, posteriormente, em laboratório, foram multiplicados em frutos de laranja. Os parâmetros biológicos avaliados foram duração das fases de desenvolvimento, oviposição, período de incubação, viabilidade dos ovos, longevidade, taxa líquida de reprodução (Ro), tempo médio de geração (T), taxa intrínseca de crescimento populacional (rm) e taxa finita de crescimento populacional (λ). Estes parâmetros foram avaliados em dois experimentos, o primeiro consistiu na biologia de B. yothersi em frutos isentos de resíduos de produtos fitossanitários à 23±1ºC e o segundo sob frutos com resíduo de espirodiclofeno à 25±1ºC. As observações foram realizadas diariamente, pela manhã e ao fim da tarde. A duração do desenvolvimento, longevidade, período d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The mite Brevipalpus yothersi Baker is the vector of the citrus leprosis, major viral disease of citrus worldwide. Information about B. yothersi's biology are essential to understanding the population dynamics of the mite in the field and infer whether changes in orchard management by region can change the mite biology. The objective was to determine the biology and prepare the fertility life table of B. yothersi collected in different citrus regions of São Paulo state. The experiments were performed in Acarology Laboratory, belonging to the Faculty of Agricultural and Veterinary Sciences - FCAV/UNESP, Jaboticabal - SP. The mites were collected in citrus orchards in the regions of Barretos, Jales and Santa Cruz do Rio Pardo, later in the laboratory were multiplied in orange fruits. The biological parameters assessed were duration of the stages of development, oviposition, incubation period, egg viability, longevity, net reproductive rate (Ro), mean generation time (T), intrinsic rate of increase (rm) and finite rate increase (λ). These parameters were evaluated in two experiments, the first consisted the biology of B. yothersi in fruits free of residues of pesticides at 23 ± 1°C and the second consisting of the biology of B. yothersi under fruit with spirodiclofen residue at 25 ± 1°C . The observations were performed daily, in the morning and in the afternoon. The duration of the development, longevity, pre-oviposition period, oviposition rate and number of B. yothersi eggs s... (Complete abstract click electronic access below) / Mestre

The citrus red mite, Panonychus citri (McGregor), is a relatively new pest to South African citriculture, the first recorded injury to citrus trees was from Rustenberg, Transvaal in 1950 (Smith 1953). In the U.S.A. the biology of this mite has been studied by Quayle (1938), Prendergast (1938), English and Turnipseed (1941), DeBach (1947), DeBach et al. (1950), Ebeling (1959) and Jeppson et al. (1957,1961). However, in South Africa little information is available concerning the ecolopy of the citrus red mite. The majority of the literature pertaining to P. citri in Republic, (Smith (1953), Mentz (1954), Stofberg (1959), Schwartz (1965) and Brodrick (1965) is of a descriptive nature, and mainly concerned with the chemical control of the mite. The only biological investigation on the development of P.citri, and the effect of insecticides and insect predators on its biology, under South African conditions, was made by van Rooyen (1966) at Zebediela, Transvaal. In the control of citrus pests, such as the citrus red mite, that need for a better understanding of their ecology has been well emphasised by DeBach (1951) and Griffiths (1951). DeBach (1951) in particular, stressed the danger of the continued reliance on insecticidal treatment as the only method of nest control, and has pointed out that persistent chemical applications may only serve to intensify the pest problem. He has suggested that a closer study of the environment of the pest species could provide a solution to the problems now encountered as a result of insecticidal control measures. Intro., p. 1-2.

D.Sc. (Botany) / Please refer to full text to view abstract

Made available in DSpace on 2015-03-26T13:30:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1778159 bytes, checksum: 6a20f5725ffe5840db536d099a272853 (MD5) Previous issue date: 2014-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Broad mite, Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae), is distinguished for being a polyphagous pest, cosmopolitan and for have been founded attacking various cultures of global importance including the Capsicum frutescens chili pepper crops. Due to the damage caused farmers incur inappropriate practices in an attempt to control this pest. Thus, there is a necessity to find alternatives to control that pest to have success in the management and reduce the damage. Keeping weeds is a strategy that can increase populations of beneficial arthropods by rendering a most suitable environment for the development of these organisms due to the availabilíty of food resources. However, this can serve as an alternative vegetation shelter to phytophagous by offering food and adequate conditions to remain in the agroecossitema, and generate potential for development of insect pests. Therefore, in this study was aimed to determine the interactions among weeds found in the agroecosystems of chilli pepper and the phytophagous mite P. latus. This study is divided in three parts. In Chapter 1, is described the identification of the main west found in chilli pepper crops associated with P. latus, and the role of those plants on mite infestations in the crop. In chapter 2, was evaluated the potential for host-white mite species by Weeds found in agroecosystems of chili, and was determined the influence of plant breeding mite acceptance of host plants. According to the results obtained in the field, the infestation of P. latus in areas of Chili peppers with presence of weeds was significant compared with areas wíthout weeds. Weeds of Vernonia polysphaera, Ageratum conyzoides, Triumfetta bartramia and C.bonaeriensis.were found with P. latus. There were significant differences in the presence of P. latus in the time assessment. Weeds were significantly affected by the presence of P. latus. Significant difference was observed between the instantaneous population growth rates of P. latus (r¡) between the different plant species evaluated finding plants of C. frutescens, T. bartramia and A. conyzoides with higher population growth at the time assessment. With the study about the potential for host plants of P. latus, showed a significant difference in the amount of dust mites that come off of the whitefly, according to the origin of the creation of dust mites. Mites had a greater acceptance by plants of T. bartramia, V. polysphaera and C. frutescens. The weeds associated with culture of chili peppers may favor the presence of the mite-white. The maintenance of plants V. polysphaera, A. conyzoides e T. bartramia, C. bonaeriensis growing on the field can increase the potential for development, and alternative hosts as a refuge for the mite-white, by the reproductive success and acceptance of different weeds. / O ácaro-branco, Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae), destaca-se por ser praga polifaga, cosmopolita e ter sido encontrada atacando várias culturas de importância mundial entre elas o cultivo de Capsicum frutescens pimenta- malagueta. Devido aos danos causados os agricultores incorrem em práticas inadequadas na tentativa de controle desta praga. Desta forma, há a necessidade de se encontrar alternativas ao controle da praga para diminuir os danos causados. A manutenção de plantas espontâneas é uma estratégia que permite aumentar populações de artrópodes benéficos ao tornar o ambiente mais adequado para estes, devido à disponibilidade de recursos alimentares. No entanto, essa vegetação pode servir como abrigo alternativo para fitófagos pelo oferecimento de alimento e condições adequadas para permanecer no agroecossitema, e gerar potencial para o desenvolvimento de pragas. Assim, neste trabalho, foi proposto determinar as interações entre plantas espontâneas encontradas dentro do agroecossistema de pimenta-malagueta e o ácaro fitófago P. latus. No Capítulo 1 é descrita a importância da presença de plantas espontâneas na cultura de pimenta-malagueta e avaliação da sua influência sobre as infestações do ácaro-branco dentro da cultura, foram identificadas as principais plantas espontâneas integradas ao plantio de pimenta com presença do ácaro-branco,e avaliado o potencial de crescimentos de P. latus em plantas espontâneas e de pimenta-malagueta a traves da taxa instantânea de crescimento populacional (r¡) sob condições de laboratório. No capitulo 2 foi avaliado o potencial de hospedeiro ao ácaro-branco por espécies de plantas espontâneas encontradas no agroecossistema da pimenta-malagueta, e foi determinada a influência da planta de criação do ácaro na aceitação de plantas hospedeiras. De acordo com os resultados obtidos em campo, a infestação de P. latus em áreas de pimenta-malagueta com presença de plantas espontâneas foi significativa comparada com áreas sem plantas espontâneas. Plantas espontâneas de Vernonia polysphaera, Ageratum Conyzoides, Triumfetta bartramia e Conyza bonaeriensis, foram encontradas Com P. latus. Houve diferença significativa na presença de P. latus no tempo de avaliação. Plantas espontâneas foram afetadas significativamente pela presença de P. latus. Houve diferença significativa entre as taxas instantâneas de crescimento populacional de P. latus(r¡) entre as diferentes espécies de plantas avaliadas encontrando plantas de C. frutescens, T. bartramia e A. conyzoides com maior crescimento populacional no tempo de avaliação. Com o estudo sobre o potencial de plantas hospedeiras de P. latus, mostrou diferença significativa na quantidade de ácaros que se desprendem da mosca-branca, de acordo com a origem de criação dos ácaros. Os ácaros tiveram uma maior aceitação por plantas de T. bartramia, V. Polysphaera e C. frutescens. As plantas espontâneas associadas a cultura da pimenta-malagueta podem favorecer a presença do ácaro-branco. A manutenção de plantas V. polysphaera, A. conyzoides e T. bartramia, C. bonaeriensis, no campo de cultivo pode aumentar o potencial de desenvolvimento, e hospedeiros alternativos como refugio para o ácaro- branco, pelo sucesso reprodutivo e aceitação de diferentes plantas espontâneas.

Made available in DSpace on 2015-03-26T12:36:04Z (GMT). No. of bitstreams: 1 texto completo.pdf: 676402 bytes, checksum: a5b1799aa7d49fbc648126a5b6da326b (MD5) Previous issue date: 2014-02-28 / O ácaro-branco Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae) é uma praga chave de distribuição mundial que ataca várias espécies de plantas de alto valor econômico. No Brasil, este ácaro é considerado praga chave da cultura de pimenta malagueta e do pinhão manso, devido a sua frequente ocorrência em areas produtoras e aos danos causados. Na maioria das vezes seu controle é baseado na aplicação de produtos químicos, com todos os problemas derivados de seu uso abusivo. Uma alternativa ao controle químico é o uso do controle biológico. Os principais inimigos naturais dos ácaros fitófagos são ácaros da família Phytoseiidae. Vários inimigos naturais hão sido registrados em associação com o ácaro-branco no Brasil, os fitoseídeos (Amblyseius herbicolus, Neoseiulus barkeri, Euseius concordis, Iphiseiodes zuluagai and Typhlodromus transvaalensis) e uma espécie da família Blattisociidae (Lasioseius floridensis). Como um primeiro passo para a seleção de agentes de controle biológico para o ácaro-branco, foram avaliadas as taxas de predação e oviposição das espécies A. herbicolus, N. barkeri e L. floridensis em duas situações: uma mistura dos estádios do ácaro-branco e em todos os diferentes estádios da praga. Num segundo passo, foi avaliado em condições de casa de vegetação, a eficiência dos fitoseídeos, A. herbicolus e N. barkeri, no controle do ácaro branco em pimenta malagueta em diferentes relações predador: presa. Num segundo experimento, foi avaliado o controle em plantas de pimenta malagueta infestadas com o ácaro-branco, com e sem liberação de predadores e seu impacto na produção de frutos. Um terceiro passo, foi avaliado o controle do ácaro- branco em plantas de pinhão manso e pimenta malagueta infestadas artificialmente com a praga em condições de campo, com e sem liberação dos fitoseídeos e seu efeito na produção da pimenta malagueta. Nos experimentos de laboratório, os fitoseídeos predaram e ovipositaram quando se usou a mistura dos estádios do ácaro-branco e em cada um dos estádios. Amblyseius herbicolus apresentou uma maior taxa de predação e oviposição, nas duas situações avaliadas em comparação a N. barkeri. Entretanto, L. floridensis apresentou taxas de predação e oviposição baixas ou nulas nas duas situações avaliadas. Em casa de vegetação, A. herbicolus e N. barkeri controlaram as populações do ácaro-branco nas diferentes relações predador:presa; as plantas controle mostraram sintomas de um ataque severo sete dias após a infestação, incluindo a queda de folhas. No segundo experimento, os fitoseídeos mantiveram baixas as populações de ácaro-branco através do tempo. Assim mesmo, as plantas de pimenta malagueta com presença dos predadores apresentaram um maior número de frutos com maior peso do que as plantas controle. As plantas controle exibiram danos severos, incluindo queda de folhas. Em condições de campo, plantas de pinhão manso sem predadores exibiram altíssimas populações do ácaro-branco, sintomas severos, queda de folhas e altos valores na escala de notas de dano. Entretanto, plantas com predadores mostraram baixas populações da praga ao longo do tempo e não manifestaram sintomas severos. Em pimenta malagueta, as plantas sem predadores apresentaram maior número de ácaros-branco, curvamento e bronzeamento das folhas, porém a queda de folhas foi muito menor que registrada no experimento de casa de vegetação. Plantas de pimenta malagueta com presença de predadores exibiram baixo número de ácaros-branco e não apresentaram bronzeamento nem queda de folhas. Não houve diferença estatística no número e peso de frutos entre plantas de pimenta malagueta com e sem predadores, mas as plantas controle apresentaram frutos mais pequenos. Os predadores A. herbicolus e N. barkeri, foram efetivos no controle de populações do ácaro-branco nos diferentes passos avaliados neste estudo. As duas espécies predaram e ovipositaram ao se alimentar da praga. Em condições de casa de vegetação as plantas de pimenta malagueta foram beneficiadas pela presença dos predadores apresentando baixas populações da praga através do tempo, resultando na produção de frutos maiores e mais pesados. Em campo, os dois fitoseídeos tiveram a capacidade de manter em baixas densidades as populações do ácaro- branco no tempo, tanto em pinhão manso quanto em pimenta malagueta evitando o aparecimento de sintomas severos como os registrados nas plantas controle. Amblyseius herbicolus e N. barkeri podem ser considerados bons agentes de controle biológico do ácaro-branco. As duas espécies controlaram populações da praga em diferentes relações predador:presa, em condições de cultivo protegido e no campo. Os predadores conseguiram-se manter e aumentar em número no tempo, tanto em casa de vegetação quanto no campo, confirmando os resultados de laboratório. Adicionalmente, os predadores conseguiram aumentar seu número em baixas densidades de ácaro-branco, indicando que eles podem fazer uso de recursos alternativos como o pólen ou néctar das flores de pimenta malagueta. O potencial de controle destes fitoseídeos pode ser aproveitado em outras culturas susceptíveis ao ataque do ácaro-branco, como papaia, feijão, batata ou gérbera, tanto em casa de vegetação quanto em campo aberto. / The broad mite Polyphagotarsonemus latus (Banks 1904) is an important worldwide pest, with economic impact of several crops. In Brazil, this mite is considered a key pest of chili pepper and physic nut, due to their frequent occurrence in planting areas and damage caused to plant hosts. Its control is based on application of agrotoxics with several problems derived from misuse. An alternative to chemical control is biological control. The main natural enemies of phytophagous mites are predatory mites from the phytoseiidae family. Several natural enemies have been recorded in association with broad mites in Brazil, including the phytoseiids (Amblyseius herbicolus, Neoseiulus barkeri, Euseius concordis, Iphiseiodes zuluagai and Typhlodromus transvaalensis) and one blattisociid mite species (Lasioseius floridensis). As a first step to select biological control agents for broad mites, we evaluated the predation and oviposition rates of predatory mite of species A. herbicolus, N. barkeri and L. floridensis on a mixture of broad mite stages and on all different stages of the pest. As a second step, we evaluated under greenhouse conditions the phytoseiids A. herbicolus and N. barkeri on chili pepper with different predator:prey ratios. In a second experiment, we evaluated the control on chili pepper plants infested with broad mites, with and without predators and their impact on fruit production. In a third step, we assessed the control of broad mites on physic nut and chili pepper plants, artificially infested with the pest, under field conditions with and without phytoseiids and their effect on the chili pepper production. In laboratory experiments, the phytoseiids preyed and oviposited when offered a mix of broad mite stages or on each stage separately. Amblyseius herbicolus showed higher predation and oviposition rates on the mix of broad mite stages and on each stage separately compared with N. barkeri rates. Meanwhile, L. floridensis showed oviposition and predation rates low or zero on the mix of broad mite stages and on each stage separately. In the greenhouse, A. herbicolus and N. barkeri controlled broad mite population in the different predator:prey ratios; control plants showed symptoms of a severe attack seven days after infestation, including foliar abscission. In a second experiment, the phytoseiids maintained the broad mite populations at low density over time. Chili pepper plants with predators had a higher number of fruits with greater weight that control plants. Control plants showed higher values on scale notes of injury with severe damage, including foliar abscission. Under field conditions, physic nuts and chili peppers without predators showed a very high population of broad mites with higher values on scale notes of injury. These plants showed severe symptoms and foliar abscission. However, plants with predators showed a low population of pest through time with low values on scale notes of injury without presence of severe symptoms. In chili pepper, plants without predators had higher number of broad mite, curling and bronzing of leaves, but leaf fall was much lower than recorded in the greenhouse experiments. Chili pepper plants with predators showed low number of broad mites and showed no symptoms. There was no statistical difference in the number and weight of fruits from chili pepper plants with and without predators, but control plants had smaller fruits. The predators A. herbicolus and the Brazilian strain of N. barkeri showed effectivess in controlling broad mite populations on the different steps evaluated in this study. Both predators preyed and oviposited when feeding on the pest. Under greenhouse conditions, chili pepper plants were benefited by presence of predators, showing low populations of broad mites through time, resulting in the production of larger fruits with higher weight. In field, both phytoseiids had the ability to maintain broad mite populations on low density through time on physic nut and chili pepper plants, preventing the development of severe symptoms in the plants. Amblyseius herbicolus and N. barkeri can be considered good biological control agents of the broad mite. Both species controled pest populations with different predator:prey ratios in protected cultivation and in the field. Predators were able to maintained and increased on number through time when fed on broad mite, confirming the laboratory results. The potential of control of A. herbicolus and N. barkeri can be exploited in other crops susceptible to broad mite attack as bean, papaya, potato or gerbera, both on the greenhouse and open field conditions.

Understanding direct and indirect defense mechanisms that enhance host plant resistance (HPR) and biological control is critical for successful development of an integrated pest management (IPM) approach. Cassava green mite (CGM) (Mononychellus tanajoa Bondar (Acari: Tetranychidae)) is a major arthropod pest of cassava (Manihot esculenta Crantz) in Africa. Strategies to control CGM include HPR and biological control by use of exotic natural enemies particularly the predatory mite Typhlodromalus aripo DeLeon (Acari: Phytoseiidae). The success of the latter depends on continuous survival of the natural enemy which requires suitable host plants and weather conditions. Various plant morphological traits have been recognized as indirect defense mechanisms that enhance HPR to CGM, and/or attract T. aripo in cassava. It was envisaged that integration of HPR and classical biological control approaches through manipulation of such indirect defense traits would lead to a more sustainable management of CGM in view of anticipated climate change. Lack of information on farmers’ perception of CGM and preferred varietal attributes, and gene action controlling the inheritance of CGM resistance also limits success of resistance breeding and adoption of varieties. This research was undertaken to gather information on farmers’ perceptions of cassava varietal attributes and cultural practices in relation to CGM resistance, identify suitable sources of resistance and environments for future breeding; and to determine the nature of gene action controlling CGM resistance and the inheritance of plant morphological traits that enhance the ability of cassava to host and support continuous survival of natural enemies. High fresh storage root yield (FSRY), high storage root dry mass percentage (SRDM%), earliness combined with extended underground storability, and resistance to foliar pests and diseases are the major factors that influence adoption and retention of genotypes by farmers. Moles, termites and CGM are the most widespread and most damaging pests. However, due to the non-conspicuous nature of CGM, its effects are under-estimated and are given limited attention by farmers. The majority of the farmers are familiar with CGM leaf damage symptoms but they cannot associate them with the actual pest. Participation of farmers in field training and field research activities helps them to know CGM. Crop rotation, intercropping, removal of shoot tips, selective pruning of infested shoots, and burning of cassava fields are some of the ways used by farmers to manage CGM. Farmers associate hairy broad-leaved, tall cassava genotypes and pink leaf pigmentation (anthocyanin) with low CGM damage. There is substantial genetic variability in the Zambian cassava germplasm for CGM resistance and associated plant morphological traits such as leaf pubescence (Pbs), leaf retention (LR), stay green (SG), tip size (TS), tip compactness, and plant height (PH), stem diameter (StD), SRDM% and FSRY. Genotypes with wide or specific adaptability for these traits have been identified, and should be recommended for general or localized production and for use as sources of desired genes in crop improvement. Genotypes L9.304/147, 92/000, TME2, 4(2)1425, I60/42 and L9.304/175 combine wide adaptability with high levels of resistance to CGM. Genotypes Kapeza, L9.304/147 and 4(2)1425 are able to produce 13-15 t ha ¯¹ at 9 months after planting suggesting their potential for early bulking. This study has shown that both additive and non-additive gene effects play a role in the expression of CGM resistance and associated plant morphological traits. The best combinations of parents for resistance against CGM were 4(2)1425 x L9.304/147 and Mweru x L9.304/147, while L9.304/147 x I92/000 displayed combined resistance to CGM and cassava mosaic disease (CMD). The resistance of cassava to CGM is positively correlated with Pbs, LR, and TS, SG, PH, StD. Overall, the study has shown that there is wide diversity in the expression of valuable indirect defense traits among genotypes, indicating that there is scope for integration of biological control and host plant resistance for CGM in Zambia. The release of genotypes that exhibit high level of intra-season and inter-season stability for enhanced expression of LR, SG, and Pbs will minimize the impact of CGM on FSRY and SRDM% that results from seasonal effects. Such genotypes should also provide habitat for and thus help to ensure the survival of T. aripo in cassava fields. The study has contributed to the promotion of food security through identification of early-bulking genotypes which also have good potential for extended underground storability of roots. Early-bulking, high FSRY and SRDM% and SRR resistance are farmer-preferred traits. Therefore, enhancement of such traits through plant breeding is likely to increase the adoption of new genotypes by farmers. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.