Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Knowledge of the diversity and evolutionary histories of insects in South Africa’s fynbos biome lags far behind what is known of the plant groups that make up this global biodiversity hotspot. To address this imbalance, I undertook a molecular phylogenetic study of fynbos-endemic Cephalelini leafhoppers that specialise on restios in the family Restionaceae. My phylogenetic results did not recover the South African Cephalelini as monophyletic, nor did I find monophyly of described species, but several monophyletic clades of species were found within Cephalelini. Furthermore, phylogenetic dating suggested that the divergence between South African and Australian Cephalelini post-dates Gondwanan vicariance, implying intercontinental extreme long distance dispersal of these insects ca. 5-11 MYA. Diversification within the Cephalelini is also much more recent than that of the Restionaceae hosts on which they specialise, negating the possibility of coevolution between plants and insects. Rather, analysis of phylogenetic conservatism of host use reveals that Cephalelini evolution has tracked the evolution of their Restionaceae hosts and that closely related insects feed on the same plant host tribes. A finer scale of tracking of host evolution (such as at the clade or genus level) is expected when taking into account how highly specific I find Cephalelini host use to be, but its absence might be explained by the recent divergence of Cephalelini relative to the age of Restionaceae. Analysis of conservatism of host use was also carried out using a phylogeny of the Restionaceae, and revealed that, overall, Cephalelini host use and avoidance have no phylogenetic bias, indicating many empty potential niches for Cephalelini, or alternately that host use is governed by factors which are phylogenetically unconstrained. Lastly, I also analysed the evolution of specialisation of Cephalelini and find no trend towards increased specialisation within the group, which is contrary to what is expected of the evolution of herbivorous insects. Overall, this study presents the first evidence of intercontinental dispersal of insect fauna between South Africa and Australia and as such highlights an unconsidered factor in the accumulation of faunal diversity in the fynbos biome. I find Cephalelini to be highly specialised in their host preference, but this pattern only becomes apparent at the tribal host level in the evolution of Cephalelini. Although Cephalelini are highly specialised, I find no evidence of evolution towards increasing specialisation within the group. / AFRIKAANSE OPSOMMING: Ons kennis van die evolusie van fynbosinsekte is redelik beperk vergeleke met hoe veel ons weet van die plante wat die merkwaardige diversiteit van die fynbos-bioom uitmaak. In `n poging om hierdie wanbalans reg te stel het ek `n molekulêr-evolusionêre studie onderneem van die fynbos-endemiese blaarspringer-groep Cephalelini, wat op Restionaceae-gasheerplante spesialiseer. Ons het drie geen-areas geamplifiseer vir filogeniekonstruksie en dateringsdoeleindes: insek-kern H3, insek- mitokondriaal COI en insek-simbiont Sulcia 16S. Met behulp van filogenetiese analise is bevind dat die Suid-Afrikaanse Cephalelini nie `n monofiletiese groep is nie en dat beskryfde spesies ook nie monofileties is nie, maar verskeie monofiletiese spesie-groepe is wel gevind. `n Oorkruis-gevalideerde dateringsoefening dui aan dat divergensie tussen Suid-Afrikaanse en Australiaanse Cephalelini meer onlangs as die verbrokkeling van Gondwana plaasgevind het, wat impliseer dat daar uitruiling van insekte tussen die kontinente oor die afgelope 5-11 MJ plaasgevind het. Die diversiteit van Cephalelini het ook veel meer onlangs ontstaan as dié van hulle Restionacaea-gashere wat beteken dat ko-evolusie in die eng sin nie moontlik is nie. ‘n Ontleding van die evolusie van gasheer-keuse deur Cephalelini dui wel aan dat Cephalelini-evolusie die patron van hul Restionaceae-gashere volg en dat naverwante Cephalelini dieselfde stam van Restionaceae as gashere verkies. Die bevinding dat die Cephalelini hoogs gespesialiseerd is in hulle gasheer-keuses lei ‘n mens tot die verwagting dat die evolusie van Cephalelini meer getrou die evolusie van hulle gashere sal volg as wat wel die geval is (dalk op die vlak van groep of genus), maar die relatiewe jeugdigheid van die Cephalelini vergeleke met die ouderdom van die Restionaceae is moontlik die rede hiervoor. Analise van gasheer-keuse is ook uitgevoer op `n filogenie van die Restionaceae wat aantoon dat daar nie ‘n beperking van verwantskappe is tussen gashere wat verkies of verwerp word nie, wat daarop dui dat daar `n menigte nisse is wat oënskynlik onbenut is, of dat Cephalelini gasheer-keuse bepaal word deur `n Restionaceae-eienskappe wat nie filogeneties beperk is nie. Laastens het ek die evolusie van spesialisering deur Cephalelini ontleed, maar geen neiging tot toenemende spesialisering binne die groep gevind nie, wat onverwags is in die lig van vorige studies. As `n geheel bied hierdie studie die eerste bewys van die uitruiling van insek-fauna tussen die Suid-Afrikaanse fynbos-bioom en ander kontinente, wat `n onopgetekende invloed op die diversiteit van diere in die fynbos is. Cephalelini is `n hoogs gespesialiseerde groep insekte, maar uit `n filogenetiese perspektief word dit eers waargeneem op die vlak van gasheerstam. Ten spyte van hulle hoë vlak van spesialisering het ek geen bewys gevind van `n toename daarin binne die evolusie van die groep nie.

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Made available in DSpace on 2014-06-11T19:35:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-25Bitstream added on 2014-06-13T19:06:00Z : No. of bitstreams: 1 gassen_mh_dr_botfca.pdf: 1151986 bytes, checksum: d10ca5877ac7bff31ebce19ef7356faf (MD5) / A cana-de-açúcar colhida sem queima é uma realidade em todo o Estado de São Paulo e os ataques da cigarrinha-da-raiz da cana estão cada vez mais freqüentes e intensos. O controle biológico desta praga com o fungo Metarhizium anisopliae também vem se desenvolvendo e adquirindo relevada importância. Com isso, este trabalho foi conduzido com os seguintes objetivos: avaliar a produção de conídios de diferentes isolados para o controle da cigarrinha-das-raízes, a partir de dois tipos de arroz; avaliar a eficiência dos isolados selecionados como mais produtivos em populações naturais de Mahanarva fimbriolata, na cultura da cana-de-açúcar colhida mecanicamente e; verificar o manejo da população de M. fimbriolata em áreas de cana-de-açúcar colhidas sem queima da palha, observando a influência da umidade sobre sua ocorrência. Foram avaliados 14 isolados, os quais foram produzidos em arroz tipo 1 e arroz parboilizado, em sacos de polipropileno, incubados em sala climatizada para desenvolvimento do fungo. Avaliou-se a concentração e viabilidade de cada isolado para os dois tipos de arroz. Os isolados que apresentaram maior produtividade foram aplicados em campo para avaliar a patogenicidade dos mesmos à cigarrinha-das-raízes, sendo eles: ESALQ 1037, IBCB 425, IBCB 353, IBCB 410, F 99 e IBCB 333. Foram pulverizados 2 kg/ha de arroz+fungo, contendo 1,0 x 1012 conídios/ha, além do tratamento com o inseticida tiametoxam 250 WG e a testemunha, sem aplicação. As avaliações foram realizadas aos 15, 30, 60, 90 e 120 dias após a aplicação (DAA), observando-se o número de ninfas e adultos de M. fimbriolata vivos, mortos, parasitados ou não, em cada parcela. A partir dos resultados, foi possível observar que os isolados IBCB 410 e F 99 causaram, respectivamente, mortalidades de 66,67 e 33,33% para ninfas, aos 15 DAA. Após 30 DAA, os isolados IBCB 425, IBCB 353 e IBCB 333... / The sugar cane is harvested without burning a reality throughout the state of Sao Paulo and the attacks of the leafhopper-root cane are increasingly frequent and intense. Biological control this pest with the Metarhizium anisopliae also has been developing and acquiring increasing importance. Therefore, this work was conducted to evaluate the production of conidial selected for the control of root speatlebug in two types of rice, evaluate the efficiency of the isolates selected as the most productive in natural populations of M. fimbriolata, the culture of cane sugar harvested mechanically, monitor the population of M. fimbriolata in areas of sugarcane harvested without burning the straw, and the influence of temperature and humidity on its occurrence. We evaluated 14 isolates, which were produced in rice type 1 and parboiled rice in polypropylene bags, incubated in a room for fungal growth and were evaluated the concentration and viability of each isolate for both types of rice. The isolates that had higher yields were applied in the field to assess the pathogenicity of the same root speatlebug, namely: ESALQ 1037, IBCB 425, IBCB 353, IBCB 410, F 99 and IBCB 333. Were sprayed 2 kg / ha of rice + fungus, containing 1,0 x 1012 conidia / ha, in addition to treatment with the insecticide tiametoxam 250 WG and the control. Evaluations were performed at 15, 30, 60, 90 and 120 days after the application, noting the number of nymphs and adults of M. fimbriolata alive in each plot, and the number of nymphs and adults dead, infected and non-parasitized. From the results, it was observed that isolates IBCB 410 and F 99 caused mortality to nymphs of 66.67 and 33.33%, respectively, at 15 days after application. After 30 days of spraying, the isolates IBCB 425, IBCB 353 and IBCB 333 had efficiencies... (Complete abstract click electronic access below)

Selected insecticides were evaluated to determine effects on the potato leafhopper and its predators. Three types of tests were conducted. First, the common predators of the potato leafhopper in alfalfa were examined to determine their response to the stages of the leafhopper. Second, under field conditions, insecticides were tested to detect effects on the populations of the insects. Finally, LC₅₀ toxicities of selected insecticides were investigated under laboratory conditions. In the predation tests, two studies were conducted, namely, predation on egg stage and predation on nymphal and adult stages of the potato leafhopper. An indirect method of determining egg predation was employed because potato leafhopper eggs are not visible, being concealed in the xylem and phloem tissues. Using two sets of treatments (with and without predators), the potato leafhopper females were allowed to oviposit in predation cages and the suspected predators introduced thereafter. Hatching nymphs were counted and used as indications of the number of eggs laid. Nabis americoferus and Orius insidiosis were found to be predaceous on eggs of the potato leafhopper. In the predation tests, using nymphal and adult stages of the potato leafhopper, the following adult and larval stages of insects were confirmed as predators: Hippodamia convergens, Coccinella novemnotata, and Chrysopa carnea. Two field tests, one in summer of 1977 and one in summer of 1978, were conducted to determine the influence of insecticides on populations of potato leafhoppers and its predators in alfalfa. Samples were taken using a 38 cm sweep net employing a 180° motion at 2 days, 1 week, and 2 weeks after treatment. In both tests, significant control was provided by the chemicals against potato leafhoppers 48 hours following application. A gradual population recovery occurred one week and two weeks after treatment. Most of the entomophagous insects sampled were adversely affected by insecticides. No statistical differences in yield and percent dry matter were obtained with various insecticidal treatments. The acute toxicities of selected insecticides on potato leafhopper, tarnished plant bug, and damsel bug were investigated. The bioassay method used was the immersion technique and toxicity was expressed in LC₅₀. The relative toxicities of Nabis americoferus to 50° Empoasca fabae and Lygus lineolaris were obtained by deriving the selectivity ratios. Selectivity ratios are calculated by dividing the LC₅₀ of the non-target organism divided by the LC₅₀ of the pest. The ratios indicated that most of the insecticides tested were highly selective. Among the organophosphates, azinphosmethyl was the most selective, while among the carbamates, carbaryl was the most selective. / Master of Science

Orientador: Antonio Batista Filho / Banca: Carlos Gilberto Raetano / Banca: Edson Luiz Lopes Baldin / Banca: José Eduardo Marcondes de Almeida / Banca: Luis Garrigós Leite / Resumo: A cana-de-açúcar colhida sem queima é uma realidade em todo o Estado de São Paulo e os ataques da cigarrinha-da-raiz da cana estão cada vez mais freqüentes e intensos. O controle biológico desta praga com o fungo Metarhizium anisopliae também vem se desenvolvendo e adquirindo relevada importância. Com isso, este trabalho foi conduzido com os seguintes objetivos: avaliar a produção de conídios de diferentes isolados para o controle da cigarrinha-das-raízes, a partir de dois tipos de arroz; avaliar a eficiência dos isolados selecionados como mais produtivos em populações naturais de Mahanarva fimbriolata, na cultura da cana-de-açúcar colhida mecanicamente e; verificar o manejo da população de M. fimbriolata em áreas de cana-de-açúcar colhidas sem queima da palha, observando a influência da umidade sobre sua ocorrência. Foram avaliados 14 isolados, os quais foram produzidos em arroz tipo 1 e arroz parboilizado, em sacos de polipropileno, incubados em sala climatizada para desenvolvimento do fungo. Avaliou-se a concentração e viabilidade de cada isolado para os dois tipos de arroz. Os isolados que apresentaram maior produtividade foram aplicados em campo para avaliar a patogenicidade dos mesmos à cigarrinha-das-raízes, sendo eles: ESALQ 1037, IBCB 425, IBCB 353, IBCB 410, F 99 e IBCB 333. Foram pulverizados 2 kg/ha de arroz+fungo, contendo 1,0 x 1012 conídios/ha, além do tratamento com o inseticida tiametoxam 250 WG e a testemunha, sem aplicação. As avaliações foram realizadas aos 15, 30, 60, 90 e 120 dias após a aplicação (DAA), observando-se o número de ninfas e adultos de M. fimbriolata vivos, mortos, parasitados ou não, em cada parcela. A partir dos resultados, foi possível observar que os isolados IBCB 410 e F 99 causaram, respectivamente, mortalidades de 66,67 e 33,33% para ninfas, aos 15 DAA. Após 30 DAA, os isolados IBCB 425, IBCB 353 e IBCB 333 ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The sugar cane is harvested without burning a reality throughout the state of Sao Paulo and the attacks of the leafhopper-root cane are increasingly frequent and intense. Biological control this pest with the Metarhizium anisopliae also has been developing and acquiring increasing importance. Therefore, this work was conducted to evaluate the production of conidial selected for the control of root speatlebug in two types of rice, evaluate the efficiency of the isolates selected as the most productive in natural populations of M. fimbriolata, the culture of cane sugar harvested mechanically, monitor the population of M. fimbriolata in areas of sugarcane harvested without burning the straw, and the influence of temperature and humidity on its occurrence. We evaluated 14 isolates, which were produced in rice type 1 and parboiled rice in polypropylene bags, incubated in a room for fungal growth and were evaluated the concentration and viability of each isolate for both types of rice. The isolates that had higher yields were applied in the field to assess the pathogenicity of the same root speatlebug, namely: ESALQ 1037, IBCB 425, IBCB 353, IBCB 410, F 99 and IBCB 333. Were sprayed 2 kg / ha of rice + fungus, containing 1,0 x 1012 conidia / ha, in addition to treatment with the insecticide tiametoxam 250 WG and the control. Evaluations were performed at 15, 30, 60, 90 and 120 days after the application, noting the number of nymphs and adults of M. fimbriolata alive in each plot, and the number of nymphs and adults dead, infected and non-parasitized. From the results, it was observed that isolates IBCB 410 and F 99 caused mortality to nymphs of 66.67 and 33.33%, respectively, at 15 days after application. After 30 days of spraying, the isolates IBCB 425, IBCB 353 and IBCB 333 had efficiencies... (Complete abstract click electronic access below) / Doutor

Bibliography: leaves 62-64 / iii, 64 leaves, [16] plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1985

A couve-flor está entre as folhosas mais produzidas na região do Cinturão Verde de São Paulo. A planta apresenta alto valor nutricional para os consumidores e relevante importância econômica e social para os agricultores. Em campos comerciais, têm sido observadas plantas exibindo sintomas de enfezamento e deformação da inflorescência, além da necrose dos vasos condutores. A doença foi denominada de enfezamento e a sua incidência e severidade têm se tornado mais intensas nos últimos anos, afetando a produção e levando ao abandono do cultivo. O quadro sintomatológico levantou a suspeita de que a doença pudesse estar sendo causada por fitoplasmas. Desta forma, este trabalho teve como objetivos detectar e identificar os fitoplasmas associados às plantas doentes de couve-flor, demonstrar a sua patogenicidade, buscar possíveis insetos vetores do agente patogênico e analisar a distribuição espacial da doença no campo. Amostras de plantas coletadas na região do Cinturão Verde ou enviadas de outras localidades tiveram o DNA total extraído e submetido a reações de PCR. A amplificação de fragmentos genômicos de 1,2 kb evidenciaram a presença de fitoplasmas nos tecidos de 66% das plantas sintomáticas. A detecção de fitoplasmas em plantas assintomáticas revelou a ocorrência de infecção latente e que plantas sem sintomas aparentes podem ser portadoras do patógeno. O emprego de PCR com primers específicos, análises convencionais e virtuais de RFLP e análise filogenética permitiram a identificação de fitoplasmas afiliados aos grupos 16SrIII-J, 16SrXIII e 16SrXV-A, com predominância para a ocorrência do grupo 16SrIII. Secções histológicas feitas à mão da região vascular de plantas de couve-flor doentes observadas em microscópio de luz revelaram que a região do floema apresentava-se escurecido e com início de degeneração celular. Fitoplasmas do grupo 16SrXIII foram encontrados em cigarrinhas da espécie Balclutha hebe coletadas em campo cultivado com couve-flor. Estes insetos foram utilizados em experimentos de transmissão e foram capazes de inocular fitoplasmas em plantas sadias de couve-flor e vinca. A transmissão também ocorreu a partir de plantas doentes de couve-flor para plantas sadias de vinca, através do emprego da planta parasita cuscuta. Análise epidemiológica da doença foi feita em dez campos de cultivo de couve-flor, localizados no município de Sorocaba-SP. Análises do índice de dispersão, lei de Taylor modificada e áreas isopatas evidenciaram que plantas de couveflor com sintomas de enfezamento encontraram-se agregadas no campo, e que os focos da doença tinham início nos bordos da cultura. O presente trabalho demonstrou que o enfezamento da couve-flor está associado aos fitoplasmas, os quais podem estar sendo transmitidos por cigarrinhas, sendo que, em termos epidemiológicos, a doença tem padrão agregado de distribuição no campo. / Cauliflower is among the most produced vegetable in the region of the Green Belt of Sao Paulo State. It has high nutritional value and relevant social and economic importance for farmers. In commercial fields, it has been observed plants exhibiting symptoms of stunting, deformation of the inflorescence and conductive vessel necrosis. The disease was named cauliflower stunt and its incidence and severity have become more intense in the past years, the production is being affected and the field is abandoned by the growers. The symptomatology raised the suspect that the disease could be caused by phytoplasmas. Thus, this study aimed to detect and identify phytoplasmas associated to diseased cauliflowers, demonstrate its pathogenicity, look for possible insect vectors of the pathogen and analyse the spatial distributions of disease in the field. Plant samples collected in the region of the green belt or sent from other locations had the total DNA extracted and subjected to PCR reactions. Amplification of genomic fragments of 1.2 kb revealed the presence of phytoplasmas in 66% of the symptomatic plants. The detection of phytoplasmas in asymptomatic plants revealed the occurrence of latent infection and that plants without visible symptoms may be infected. The use of specific primers, conventional and virtual RFLP analysis and phylogenetic analysis allowed the identification of phytoplasmas affiliated to 16SrIII-J, 16SrXIII and 16SrXV-A groups, and predominantly the occurrence of 16SrIII group. Histological sections made by hand of the vascular region of symptomatic cauliflower were observed under light microscope and revealed that the phloem was darkened and with beginning of cellular degeneration. The 16SrXIII phytoplasma was found in Balclutha hebe from cauliflower field. These insects were used in experiments and were able to transmit phytoplasmas to healthy cauliflower and periwinkle. The transmission also occurred from diseased cauliflower to healthy periwinkle through the parasitic plant dodder. Epidemiological analysis of the disease was made in ten plots of cauliflower, located in Sorocaba, SP. Dispersion index, modified Taylors law and isopath areas analysis showed that cauliflower plants with symptoms of stunting were aggregated in field and initial foci were at the edge of the plot. This study demonstrated that cauliflower stunt is associated with phytoplasmas, that may be being transmitted by insects (Homoptera) and, in epidemiological terms, the diseased plants show aggregated pattern of distribution in the field.

O Huanglongbing (HLB) é uma das mais temidas doenças da citricultura mundial, associada a bactérias do gênero Candidatus Liberibacter, que foram detectadas no Brasil em 2004. Em 2008, detectou-se outra bactéria associada a sintomas de HLB no Estado de São Paulo, que foi caracterizada como sendo um fitoplasma do grupo 16 SrIX. Fitoplasmas são molicutes fitopatógenos restritos ao floema de plantas, disseminados por insetos vetores. O presente trabalho buscou identificar cigarrinhas potencialmente vetoras do fitoplasma associado ao HLB e plantas hospedeiras desses insetos, bem como desenvolver uma técnica de quantificação de DNA desse patógeno em insetos e plantas. Amostragens de cigarrinhas foram realizadas quinzenalmente por 12 meses em dois pomares de laranja com histórico de ocorrência do fitoplasma 16SrIX na região norte do Estado de São Paulo, usando-se armadilhas adesivas amarelas em duas alturas (0,3 e 1,5 m) da copa de árvores cítricas, e rede de varredura na vegetação espontânea. Dados faunísticos identificaram uma espécie de Agalliinae (Agallia albidula Uhler) e três de Deltocephalinae, [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)], como os cicadelídeos (Hemiptera: Cicadellidae) mais abundantes e frequentes nas áreas estudadas. Essas espécies predominaram na amostragem com rede de varredura e na menor altura de coleta com armadilhas adesivas, indicando comportamento de alimentação em vegetação rasteira. Com observações visuais, verificou-se associação das espécies com certas plantas invasoras, e influência da composição florística da vegetação rasteira sobre a abundância das cigarrinhas. S. marginelineatus e P. flavicosta ocorreram com maior frequência em Sida rhombifolia L. e Althernantera tenella Colla, respectivamente, enquanto que A. albidula foi predominante em Conyza bonariensis (L.) Cronq., e B. hebe ocorreu exclusivamente em gramíneas, principalmente Panicum maximum Jacq.. Plantas invasoras amostradas nas áreas foram testadas para a presença do fitoplasma 16SrIX, porém sem resultados positivos. No entanto, amostras de campo da cigarrinha S. marginelineatus foram positivas por PCR e sequenciamento para o referido fitoplasma. Indivíduos de S. marginelineatus criados em laboratório e mantidos por um período de acesso à aquisição de 72 h em citros infectado com o fitoplasma 16SrIX, foram capazes de transmití-lo para citros, após 21 dias de latência, porém com baixa eficiência (0,5%). Por meio de PCR quantitativo desenvolvido para esse fitoplasma, verificou-se baixo título do patógeno tanto em S. marginelineatus, quanto em plantas cítricas infectadas, o que pode explicar, pelo menos em parte, a baixa eficiência de transmissão pelo inseto tendo citros como fonte. Isto sugere a existência de outros hospedeiros mais adequados como fontes de inóculo para aquisição do fitoplasma por S. marginelineatus ou outro vetor ainda desconhecido. / Huanglongbing (HLB) is a severe citrus disease associated to phloemlimited bacteria in the genus Candidatus Liberibacter, which were detected in Brazil in 2004. In 2008, another bacterium was found in association with HLB symptom in the São Paulo State, and characterized as a phytoplasma belonging to 16SrIX group. Phytoplasmas are vector-borne phytopathogenic mollicutes that inhabit plant sieve elements. The goals of this study were to identify potential leafhopper vectors of the HLB-associated phytoplasma and their host plants, as well as to establish a real-time PCR procedure for pathogen quantification in vectors and plants. Leafhoppers were sampled fortnightly for 12 months by yellow sticky cards placed at two heights (0.3 and 1.5 m) on the citrus tree canopy and by sweep net in the ground vegetation of two sweet orange groves with history of infection by the 16SrIX phytoplasma, in the northern region of São Paulo State. Faunistic analyses indicated 1 Agalliinae (Agallia albidula Uhler) and 3 Deltocephalinae [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)] species that were the most abundant and frequent leafhoppers (Hemiptera: Cicadellidae) in the experimental areas. These species predominated in sweep net and in sticky traps catches at 0.3 m above soil, showing that they inhabit the ground vegetation. Visual observations indicated a strong association of leafhopper species with some weeds and the influence of weed species composition on leafhopper abundance in the ground vegetation. S. marginelineatus and P. flavicosta were more frequent on Sida rhombifolia L. and Althernantera tenella Colla, respectively, while A. albidula was observed more often on Conyza bonariensis (L.) Cronq., and B. hebe occurred solely on grasses, more abundantly on Panicum maximum Jacq. Fourteen weed species sampled in the area were PCR tested for infection by the 16SrIX phytoplasma, but none was found infected. Nevertheless, 3 out of 30 field-collected samples (10 adults per sample) of S. marginelineatus tested positive for this phytoplasma by PCR and sequencing. Healthy lab-reared adults of S. marginelineatus were able to transmit inefficiently (0,5%) the 16SrIX phytoplasma to healthy citrus after a 72-h acquisition access period on infected citrus plants followed by a 21-day latent period on S. rhombifolia plants. By using the qPCR method developed for this phytoplasma, a very low pathogen titer was found both in S. marginelineatus and in infected citrus plants, which may explain, at least partially, the low transmission efficiency by this vector using citrus as a source plant. It also suggests that existence of alternative hosts that might be more adequate as inoculum sources for phytoplasma acquisition and spread by S. marginelineatus or another vector yet to be discovered.

Landnutzungsänderungen, Habitatverlust und Fragmentierung gehören zu den Hauptursachen des weltweiten Biodiversitätsrückgangs. In Mitteleuropa zählen Kalkmagerrasen zu den artenreichsten Lebensräumen. Sie weisen eine hohe Vielfalt an xero- und thermophilen Pflanzen- und Invertebratenarten auf, sind jedoch zunehmend durch landwirtschaftliche Intensivierung und Nutzungsaufgabe gefährdet. Sie sind auf Beweidung und Mahd angewiesen, was jedoch für die Landwirte heutzutage unwirtschaftlich geworden ist. Daher finden sich zunehmend kleine Fragmente innerhalb einer für die meisten der spezialisierten Magerrasenarten ungeeigneten, von intensiver Landwirtschaft geprägten Umgebung. Der erste Teil dieser Arbeit untersucht den Einfluss der Fragmentgröße, der Habitatkonnektivität, der Zusammensetzung der umgebenden Landschaft und der Pflanzenartenzahl auf die Zusammensetzung der Zikadengemeinschaft. Zikaden sind eine überaus artenreiche Gruppe phytophager Insekten mit enger Bindung an die Vegetationsstruktur und -zusammensetzung. In der Umgebung von Göttingen wählten wir 14 große (>1 ha) und 14 kleine (<1 ha) Kalkmagerrasenflächen entlang von Gradienten zunehmender Konnektivität mit anderen Magerrasenflächen, zunehmender Pflanzenartenzahl und zunehmender Landschaftskomplexität, d.h. dem Prozentsatz Ackerfläche innerhalb eines 500 m-Radius, aus. Zunehmende Isolation verringerte die Zikadenartenzahl in einfachen (von Feldern geprägten), jedoch nicht in komplexen Landschaften. Dieser Effekt wurde von den Generalisten getrieben. Die Artenzahl der Generalisten nahm auf kleinen Fragmenten mit zunehmender Konnektivität zu, wogegen sie auf großen Flächen unverändert blieb. Weiterhin nahm die Artenzahl der Generalisten mit steigender Pflanzenartenzahl auf vernetzten Magerrasen stärker zu als auf unvernetzten. Unsere Ergebnisse zeigen, dass die Insektenartenvielfalt auf Kalkmagerrasenfragmenten nicht nur durch Konnektivität allein geprägt wird, sondern vielmehr von einem Zusammenspiel aus Konnektivität, Landschaftszusammensetzung und Pflanzenartenzahl bestimmt wird. Im zweiten Teil dieser Arbeit verfolgen wir das Ziel, zur Lösung der sogenannten SLOSS-Debatte (“Single Large Or Several Small”) beizutragen, in der diskutiert wird, ob es besser ist, wenige große oder mehrere kleine Fragmente eines Habitattyps zu erhalten. Man nimmt an, dass kleine Fragmente aufgrund der größeren abgedeckten geographischen Distanzen eine größere Heterogenität und dadurch eine höhere Gesamtartenzahl aufweisen. Dagegen weisen große Fragmente stabilere Lebensraumbedingungen und größere Populationen auf. Neben Zikaden und Pflanzen wurden auch Daten zu Wanzen und 114 Schnecken aufgenommen. Sowohl die Gesamtartenzahl aller vier Taxa als auch die Zahl der Spezialisten war auf mehreren kleinen Fragmenten wesentlich höher als auf einem oder zwei großen Fragmenten gleicher Gesamtgröße. Jedoch war die Artenzusammensetzung auf großen und kleinen Fragmenten unterschiedlich und einige der seltensten Spezialisten waren an große Flächen gebunden. Hingegen spielte die Zusammensetzung der umgebenden Landschaft keine wichtige Rolle für Artenzahl und -zusammensetzung. Diese Ergebnisse stellen den Fokus auf entweder große oder kleine Habitatfragmente infrage. Für einen erfolgreichen Biodiversitätserhalt ist daher der Schutz sowohl großer als auch kleiner Habitatfragmente zwingend notwendig. Im dritten Teil dieser Arbeit untersuchen wir den Einfluss der Bewirtschaftungsart (Beweidung, Mahd, Nutzungsaufgabe), der Landschaftszusammensetzung und Konnektivität auf die Artenzahl, Artenzusammensetzung und merkmalsbasierte Reaktionen (Körpergröße und Rote Liste-Status) von neun Taxa: Pflanzen, Schmetterlinge, Bienen, Heuschrecken, Schwebfliegen, Spinnen, Wanzen, Kurzflügler und Zikaden. Wir wählten 30 kleine Kalkmagerrasenfragmente (<1 ha) entlang von unabhängigen Konnektivitäts- und Landschaftskomplexitätsgradienten aus. Ein zunehmender Prozentsatz an Ackerfläche in der Umgebung der Fragmente führte zu einem Verlust von 29 % der Gesamtartenzahl. Wir nehmen an, dass Landschaften, die von Ackerfläche dominiert werden, weniger Alternativhabitat und Nahrungsressourcen bieten, was zu einer verringerten Artenzahl führt. Habitatkonnektivität erhöhte im Allgemeinen die Artenzahl. Dieser Effekt war bei den großen, vermutlich ausbreitungsfähigeren Arten eines Taxons stärker ausgeprägt als bei den kleinen Arten. Beweidung hatte einen deutlich negativeren Einfluss auf die Artenzahl als Mahd (einmal jährlich) oder kurzzeitige Nutzungsaufgabe (5-15 Jahre). Der Grund dafür könnte der durch Beweidung verursachte größere Schaden und die Entnahme der Nahrungsressourcen phytophager Insekten sein. Zudem führte jeder der drei Bewirtschaftungsweisen zu einer unterschiedlichen Artenzusammensetzung aller Taxa. Daher sollte die bevorzugte Bewirtschaftungsoption kleiner Kalkmagerrasenfragmente ein Wechsel zwischen Mahd und kurzzeitiger Nutzungsaufgabe in Kombination mit einer Diversifizierung der umgebenden Landschaft sein. Zusammenfassend lässt sich sagen, dass die allgemein verbreitete Konzentration auf große Habitatfragmente überdacht werden sollte, da der Schutz sowohl kleiner als auch großer Fragmente unerlässlich ist. Bei der Planung von Schutzmaßnahmen für fragmentierte Offenlandlebensräume sind lokale Einflüsse wie Fragmentgröße und Bewirtschaftung zwar wichtig, aber nicht ausreichend: Landschaftsfaktoren wie Habitatkonnektivität und Landschaftszusammensetzung müssen ebenfalls in die Schutzbemühungen mit einbezogen werden um das langfristige Überleben von spezialisierten Pflanzen- und Invertebratenarten zu sichern.

O Huanglongbing (HLB) é uma das mais temidas doenças da citricultura mundial, associada a bactérias do gênero Candidatus Liberibacter, que foram detectadas no Brasil em 2004. Em 2008, detectou-se outra bactéria associada a sintomas de HLB no Estado de São Paulo, que foi caracterizada como sendo um fitoplasma do grupo 16 SrIX. Fitoplasmas são molicutes fitopatógenos restritos ao floema de plantas, disseminados por insetos vetores. O presente trabalho buscou identificar cigarrinhas potencialmente vetoras do fitoplasma associado ao HLB e plantas hospedeiras desses insetos, bem como desenvolver uma técnica de quantificação de DNA desse patógeno em insetos e plantas. Amostragens de cigarrinhas foram realizadas quinzenalmente por 12 meses em dois pomares de laranja com histórico de ocorrência do fitoplasma 16SrIX na região norte do Estado de São Paulo, usando-se armadilhas adesivas amarelas em duas alturas (0,3 e 1,5 m) da copa de árvores cítricas, e rede de varredura na vegetação espontânea. Dados faunísticos identificaram uma espécie de Agalliinae (Agallia albidula Uhler) e três de Deltocephalinae, [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)], como os cicadelídeos (Hemiptera: Cicadellidae) mais abundantes e frequentes nas áreas estudadas. Essas espécies predominaram na amostragem com rede de varredura e na menor altura de coleta com armadilhas adesivas, indicando comportamento de alimentação em vegetação rasteira. Com observações visuais, verificou-se associação das espécies com certas plantas invasoras, e influência da composição florística da vegetação rasteira sobre a abundância das cigarrinhas. S. marginelineatus e P. flavicosta ocorreram com maior frequência em Sida rhombifolia L. e Althernantera tenella Colla, respectivamente, enquanto que A. albidula foi predominante em Conyza bonariensis (L.) Cronq., e B. hebe ocorreu exclusivamente em gramíneas, principalmente Panicum maximum Jacq.. Plantas invasoras amostradas nas áreas foram testadas para a presença do fitoplasma 16SrIX, porém sem resultados positivos. No entanto, amostras de campo da cigarrinha S. marginelineatus foram positivas por PCR e sequenciamento para o referido fitoplasma. Indivíduos de S. marginelineatus criados em laboratório e mantidos por um período de acesso à aquisição de 72 h em citros infectado com o fitoplasma 16SrIX, foram capazes de transmití-lo para citros, após 21 dias de latência, porém com baixa eficiência (0,5%). Por meio de PCR quantitativo desenvolvido para esse fitoplasma, verificou-se baixo título do patógeno tanto em S. marginelineatus, quanto em plantas cítricas infectadas, o que pode explicar, pelo menos em parte, a baixa eficiência de transmissão pelo inseto tendo citros como fonte. Isto sugere a existência de outros hospedeiros mais adequados como fontes de inóculo para aquisição do fitoplasma por S. marginelineatus ou outro vetor ainda desconhecido. / Huanglongbing (HLB) is a severe citrus disease associated to phloemlimited bacteria in the genus Candidatus Liberibacter, which were detected in Brazil in 2004. In 2008, another bacterium was found in association with HLB symptom in the São Paulo State, and characterized as a phytoplasma belonging to 16SrIX group. Phytoplasmas are vector-borne phytopathogenic mollicutes that inhabit plant sieve elements. The goals of this study were to identify potential leafhopper vectors of the HLB-associated phytoplasma and their host plants, as well as to establish a real-time PCR procedure for pathogen quantification in vectors and plants. Leafhoppers were sampled fortnightly for 12 months by yellow sticky cards placed at two heights (0.3 and 1.5 m) on the citrus tree canopy and by sweep net in the ground vegetation of two sweet orange groves with history of infection by the 16SrIX phytoplasma, in the northern region of São Paulo State. Faunistic analyses indicated 1 Agalliinae (Agallia albidula Uhler) and 3 Deltocephalinae [Balclutha hebe (Kirkaldy), Planicephalus flavicosta (Stål) e Scaphytopius (Convelinus) marginelineatus (Stål)] species that were the most abundant and frequent leafhoppers (Hemiptera: Cicadellidae) in the experimental areas. These species predominated in sweep net and in sticky traps catches at 0.3 m above soil, showing that they inhabit the ground vegetation. Visual observations indicated a strong association of leafhopper species with some weeds and the influence of weed species composition on leafhopper abundance in the ground vegetation. S. marginelineatus and P. flavicosta were more frequent on Sida rhombifolia L. and Althernantera tenella Colla, respectively, while A. albidula was observed more often on Conyza bonariensis (L.) Cronq., and B. hebe occurred solely on grasses, more abundantly on Panicum maximum Jacq. Fourteen weed species sampled in the area were PCR tested for infection by the 16SrIX phytoplasma, but none was found infected. Nevertheless, 3 out of 30 field-collected samples (10 adults per sample) of S. marginelineatus tested positive for this phytoplasma by PCR and sequencing. Healthy lab-reared adults of S. marginelineatus were able to transmit inefficiently (0,5%) the 16SrIX phytoplasma to healthy citrus after a 72-h acquisition access period on infected citrus plants followed by a 21-day latent period on S. rhombifolia plants. By using the qPCR method developed for this phytoplasma, a very low pathogen titer was found both in S. marginelineatus and in infected citrus plants, which may explain, at least partially, the low transmission efficiency by this vector using citrus as a source plant. It also suggests that existence of alternative hosts that might be more adequate as inoculum sources for phytoplasma acquisition and spread by S. marginelineatus or another vector yet to be discovered.