Estudos de genética de populações de pragas agrícolas têm destacado a importância de se conhecer a estruturação genética e os padrões de fluxo gênico entre populações para o refinamento de estratégias de Manejo Integrado de Pragas (MIP). A lagarta-da-maçã do algodoeiro, Heliothis virescens (F.), é um inseto praga amplamente distribuído e importante economicamente por causar danos consideráveis à cultura do algodão no Brasil. O controle dessa praga tem sido feito principalmente pelo uso de inseticidas e de plantas geneticamente modificadas (GM) que expressam proteína(s) de Bacillus thuringiensis Berliner e o potencial de evolução da resistência é alto. O conhecimento de quanto as populações de H. virescens são capazes de trocar informação genética entre si é de fundamental importância para a implantação de estratégias de manejo dessa praga. No entanto, pouco se sabe sobre a estrutura genética e os padrões de fluxo gênico em H. virescens em escalas locais e regionais no Brasil. Assim, o objetivo desse trabalho foi avaliar a variabilidade genética em populações de H. virescens utilizando marcadores microssatélites. Foram amostrados indivíduos de H. virescens oriundos de populações coletadas nas safras de 2007/08, 2008/09 e 2009/10 nas principais regiões produtoras de algodão e soja no Brasil. Foram estudados nove locos polimórficos em 12 populações, em um total de 205 indivíduos. O número médio de alelos por loco foi de 14,11. Os valores de heterozigosidade média esperada (HE) e observada (HO) foram de 0,303 e 0,438, respectivamente. O coeficinete de endocruzamento da espécie f foi de 0,294 (IC 95% de 0,178 a 0,406). As estimativas de estruturação genética foram = 0,132 (IC 95% de 0,072 a 0,218) e RST = 0,252. Esses valores indicam uma estruturação genética moderada entre as populações. Estimativas do número de migrantes indicaram um pequeno fluxo gênico, principalmente no sentido Centro- Oeste Nordeste, embora a maioria dos indivíduos dentro das populações seja residente; adicionalmente, foi verificado que o estabelecimento das populações do algodão ocorre a partir de indivíduos migrantes da soja ou descendentes desses indivíduos. Análises de Componentes Principais e de atribuição usando inferência Bayesiana revelaram a formação de dois grupos, porém não foi possível identificar um padrão de agrupamento (por região, safra ou hospedeiro). Desta forma os resultados do presente trabalho sugerem uma estruturação genética incipiente para as populações de H. virescens no Brasil. Desse modo, é importante levar esses resultados em consideração para que o MIP em geral, e especificamente para que as abordagens para retardar a evolução da resistência sejam implementadas de forma efetiva para o manejo de H. virescens no Brasil. / Agricultural pests population genetics studies have emphasized the importance of genetic structure and patterns of gene flow knowledge for Integrated Pest Management (IPM) strategies. The tobacco budworm, Heliothis virescens (F.), is a widespread and economically important insect pest renowned for causing considerable damage in cotton fields in Brazil. This pest has been controlled by the use of insecticides and genetic modified plants (GM) expressing proteins from Bacillus thuringiensis Berliner, and it has already been shown to present a high potential to develop resistance to these control technologies. To a successful application of these strategies it is needed to know the capacity of the pest populations to exchange genetic information among them. However, for H. virescens a scarce amount of information about genetic structure and patterns of gene flow is available at local and regional scales in Brazil. In this way, the main objective of this study was to evaluate the genetic variability of H. virescens based on microsatellite markers. Specimens were sampled during 2007/08, 2008/09 and 2009/10 from the main cotton and soybean producers regions in Brazil. From this, nine polymorphic loci from 12 populations were studied in 205 specimens. The average number of alleles was 14.11. Expected (HE) and observed (HO) heterozygosity were 0.303 and 0.438, respectively. Inbreeding coefficient f was 0.294 (IC 95% 0.178 - 0.406). Genetic structure indices were: = 0.132 (IC 95% 0.072 0.218) and RST = 0.252. These values point to a moderate genetic structure among H. virescens populations. Migrants estimative indicate a low gene flow, mainly in the Center-Western Northern direction, although most individuals are residents within populations; additionally it was suggested that immigrants to cotton populations come from soybean fields. Genetic relationships inferred by Principal Component Analysis and Bayesian assignment tests identified two groups, although no group pattern was recognized, even by geographic region, year of sampling or host plant. These results suggest an incipient genetic structuring for H. virescens populations within Brazil. Thus, such results should be considered for IPM strategies aiming in an efficient control of H. virescens in Brazil.

Thesis (M.Sc. Agriculture (Agronomy) -- University of Limpopo, 2019 / Erratic rainfall and insect infestation are some of the factors that limit cowpea production in Limpopo (Asiwe, 2009). Improved cowpea varieties available for dryland production in Limpopo do not meet the farmer’s needs. Specific trait crosses are needed to be made with adapted varieties for the purpose of developing high yielding, pest tolerant and adapted varieties. Varieties with desired specific traits were planted in isolation plots for outcrossing by insects. F1 lines derived from parental lines that were half sib seeds were harvested and planted as F2, and seeds obtained from F2 generation were used to develop F3 segregating population at University of Limpopo Experiential Farm, Syferkuil, and planted along with parents. This F3 generation forms the current evaluation on which this report is based. Data collected included; aphid severity (measured on a 9-point scale), number of days to 90 % maturity, grain yield, 100 seed weight and number of genotypes selected for advancement. Results showed significant variation among progeny over parents therefore expressing transgressive segregation. Genotypes derived from pedigree TX08-30-5 were five while pedigree IT98K-205-8 and IT97K-499-35 had four genotypes each that expressed early maturity (80-90 days) which are desirable for evading drought. Twenty-three genotypes from pedigree GEC and three from pedigree IT97K-499-35 obtained grain yield (>101 g/plot and >161 g/plot) that was better than their parents. Only one genotype derived from pedigree TX08-30-1 expressed high resistance to aphids better than the parent with a mean aphid score range of 1-2. Four genotypes from pedigree TX08-30-5 obtained bigger 100 seed weight (>18.6 g) compared to parent. These progeny also proved to be high yielders as they expressed heterosis for all yield attributes than their parents. Eighty-two genotypes were selected for advancement. Significant variations were observed among progeny giving opportunity to make selections. In most cases, genotypes outperformed their parents which indicate positive heterosis. The 82 promising genotypes selected will be advanced for further selections from multi location testing for stability and adaptation.

No description available.

Ácaros tetraniquídeos são considerados pragas secundárias em soja, no entanto, nos últimos anos, foram registrados ataques severos e freqüentes destes em diferentes regiões produtoras do Brasil. Experimentos foram realizados em campo e laboratório com o objetivo de estudar os fatores determinantes dos aumentos populacionais de ácaros tetraniquídeos em soja. Para determinar se cultivares transgênicas de soja seriam mais susceptíveis aos ácaros, foi estudado o ciclo biológico e a tabela de vida dos ácaros Mononychellus planki (McGregor) e Tetranychus urticae Koch em três cultivares de soja transgênicas, glifosato-tolerante, e três não-transgênicas com elevada semelhança genética às respectivas cultivares transgênicas. Testes de toxicidade foram realizados em laboratório com agrotóxicos comumente utilizados em soja para determinar os efeitos destes sobre importantes inimigos naturais dos ácaros tetraniquídeos e das lagartas da soja, os fungos Neozygites floridana e Nomuraea rileyi, respectivamente. Em campo, durante duas safras agrícolas (2007/2008 e 2008/2009), foi estudado o efeito de cinco manejos fitossanitários sobre a flutuação populacional de ácaros tetraniquídeos, lagartas, percevejos fitófagos e de alguns de seus inimigos naturais. As cultivares transgênicas não afetaram significativamente o ciclo biológico de M. planki e T. urticae e as pequenas diferenças observadas para alguns parâmetros da tabela de vida destas espécies entre cultivares não estão relacionadas à modificação genética. A avaliação do efeito dos agrotóxicos sobre os patógenos revelou que o fungicida Alto 100 e o herbicida Roundup Ready inibiram o crescimento micelial de N. rileyi. Para N. floridana todos os fungicidas contendo estrubirulinas inibiram completamente a esporulação, enquanto que os produtos do grupo dos triazóis resultaram em taxas intermediárias de esporulação e germinação de conídios. A espécie M. planki foi mais abundante do que T. urticae em campo. O ácaro predador Neoseiulus anonymus e o fungo N. floridana foram os inimigos naturais associados a estes ácaros pragas. Os fungicidas Priori Xtra e Alto 100 reduziram a prevalência de N. floridana, mas não interferiram na dinâmica de N. anonymus. O inseticida piretróide Decis 25 EC reduziu a densidade deste predador, mas não afetou o fungo. No tratamento onde foram aplicados os fungicidas com o inseticida observou-se aumentos populacionais de ácaros fitófagos. A pulverização do herbicida glifosato não afetou N. anonymus e N. floridana, e a presença de plantas daninhas favoreceu o predador. Os picos populacionais mais elevados de Anticarsia gemmatalis foram observados em 2008/09, nas parcelas onde foram empregados fungicidas, e maiores densidades de Pseudoplusia includens foram observadas no tratamento com Decis 25 EC. A aplicação deste inseticida também afetou negativamente a densidade de insetos predadores e resultou em maiores densidades de percevejos fitófagos. O herbicida glifosato não afetou a densidade de pragas e inimigos naturais, no entanto, a presença de plantas daninhas favoreceu os insetos predadores e desfavoreceu os percevejos fitófagos. Em geral, os estudos em campo indicam que o uso de fungicidas e inseticidas são fatores associados aos aumentos populacionais de ácaros em soja. / Spider mites are secondary pests of soybean, however, recently outbreaks has frequently been reported on different producing regions of Brazil. Experiments were carried out in field and laboratory aiming to determine the main factors associates with spider mite outbreaks in soybean. To determine if genetically modified (GM) soybean varieties are more susceptible to spider mites, the life cycle and life table of the mites Mononychellus planki and Tetranychus urticae was studied on three GM soybean cultivars glyphosate-tolerant and three non-transgenic cultivars genetically similar to the transgenic ones. Toxicological tests were carried out in laboratory with pesticides commonly used in soybean to determine the pesticide effect on important natural enemies of spider mites and soybean catterpillars, the fungi Neozygites floridana and Nomuraea rileyi, respectively. In the field during two growing seasons (2007/2008 and 2008/2009), the effects of five plant protection managements were studied on the population dynamics of spider mites, caterpillars, stink bugs and some of their natural enemies. The transgenic cultivars did not significantly affect the life cycle parameters of M. planki e T. urticae and differences observed for some life table parameters between cultivars are not related to the genetic modification. Evaluation of the effect of pesticides on the pathogens showed that the fungicide Alto 100 and the herbicide Roundup Ready inhibited the mycelial growth of N. rileyi. Against N. floridana, all fungicides with strobilurins completely inhibited sporulation, while the triazole products hence showed intermediate rates of sporulation and conidia germination. The spider mite M. planki was more abundant than T. urticae in the field. The predatory mite Neoseiulus anonymus and the fungus N. floridana were the main natural enemies associated to these mite pests. The fungicides Priori Xtra and Alto 100 reduced the prevalence of N. floridana, though this pesticide did not negatively affected N. anonymus. The pyrethroid insecticide Decis 25 EC reduced the density of this predator, but did not affect the fungus. The treatment where fungicides and the insecticide were applied, increases on populations of phytophagous mites were observed. Spraying of the herbicide glyphosate did not affect N. anonymus and N. floridana, and the presence of weeds favored the predator. Higher population peaks of Anticarsia gemmatalis were associated with fungicide applications in 2008/09 and higher densities of Pseudoplusia includens were observed in treatment with Decis 25 EC. This insecticide also negatively affected the density of predatory insects and resulted on higher densities of stink bugs. The herbicide glyphosate did not affect density of pests and natural enemies; however, the presence of weeds favored insect predators, and resulted on lower populations of stink bugs. Overall, the field studies indicate that the use of fungicides and insecticides are important factors associated to spider mite outbreaks in soybean.

Ácaros tetraniquídeos são considerados pragas secundárias em soja, no entanto, nos últimos anos, foram registrados ataques severos e freqüentes destes em diferentes regiões produtoras do Brasil. Experimentos foram realizados em campo e laboratório com o objetivo de estudar os fatores determinantes dos aumentos populacionais de ácaros tetraniquídeos em soja. Para determinar se cultivares transgênicas de soja seriam mais susceptíveis aos ácaros, foi estudado o ciclo biológico e a tabela de vida dos ácaros Mononychellus planki (McGregor) e Tetranychus urticae Koch em três cultivares de soja transgênicas, glifosato-tolerante, e três não-transgênicas com elevada semelhança genética às respectivas cultivares transgênicas. Testes de toxicidade foram realizados em laboratório com agrotóxicos comumente utilizados em soja para determinar os efeitos destes sobre importantes inimigos naturais dos ácaros tetraniquídeos e das lagartas da soja, os fungos Neozygites floridana e Nomuraea rileyi, respectivamente. Em campo, durante duas safras agrícolas (2007/2008 e 2008/2009), foi estudado o efeito de cinco manejos fitossanitários sobre a flutuação populacional de ácaros tetraniquídeos, lagartas, percevejos fitófagos e de alguns de seus inimigos naturais. As cultivares transgênicas não afetaram significativamente o ciclo biológico de M. planki e T. urticae e as pequenas diferenças observadas para alguns parâmetros da tabela de vida destas espécies entre cultivares não estão relacionadas à modificação genética. A avaliação do efeito dos agrotóxicos sobre os patógenos revelou que o fungicida Alto 100 e o herbicida Roundup Ready inibiram o crescimento micelial de N. rileyi. Para N. floridana todos os fungicidas contendo estrubirulinas inibiram completamente a esporulação, enquanto que os produtos do grupo dos triazóis resultaram em taxas intermediárias de esporulação e germinação de conídios. A espécie M. planki foi mais abundante do que T. urticae em campo. O ácaro predador Neoseiulus anonymus e o fungo N. floridana foram os inimigos naturais associados a estes ácaros pragas. Os fungicidas Priori Xtra e Alto 100 reduziram a prevalência de N. floridana, mas não interferiram na dinâmica de N. anonymus. O inseticida piretróide Decis 25 EC reduziu a densidade deste predador, mas não afetou o fungo. No tratamento onde foram aplicados os fungicidas com o inseticida observou-se aumentos populacionais de ácaros fitófagos. A pulverização do herbicida glifosato não afetou N. anonymus e N. floridana, e a presença de plantas daninhas favoreceu o predador. Os picos populacionais mais elevados de Anticarsia gemmatalis foram observados em 2008/09, nas parcelas onde foram empregados fungicidas, e maiores densidades de Pseudoplusia includens foram observadas no tratamento com Decis 25 EC. A aplicação deste inseticida também afetou negativamente a densidade de insetos predadores e resultou em maiores densidades de percevejos fitófagos. O herbicida glifosato não afetou a densidade de pragas e inimigos naturais, no entanto, a presença de plantas daninhas favoreceu os insetos predadores e desfavoreceu os percevejos fitófagos. Em geral, os estudos em campo indicam que o uso de fungicidas e inseticidas são fatores associados aos aumentos populacionais de ácaros em soja. / Spider mites are secondary pests of soybean, however, recently outbreaks has frequently been reported on different producing regions of Brazil. Experiments were carried out in field and laboratory aiming to determine the main factors associates with spider mite outbreaks in soybean. To determine if genetically modified (GM) soybean varieties are more susceptible to spider mites, the life cycle and life table of the mites Mononychellus planki and Tetranychus urticae was studied on three GM soybean cultivars glyphosate-tolerant and three non-transgenic cultivars genetically similar to the transgenic ones. Toxicological tests were carried out in laboratory with pesticides commonly used in soybean to determine the pesticide effect on important natural enemies of spider mites and soybean catterpillars, the fungi Neozygites floridana and Nomuraea rileyi, respectively. In the field during two growing seasons (2007/2008 and 2008/2009), the effects of five plant protection managements were studied on the population dynamics of spider mites, caterpillars, stink bugs and some of their natural enemies. The transgenic cultivars did not significantly affect the life cycle parameters of M. planki e T. urticae and differences observed for some life table parameters between cultivars are not related to the genetic modification. Evaluation of the effect of pesticides on the pathogens showed that the fungicide Alto 100 and the herbicide Roundup Ready inhibited the mycelial growth of N. rileyi. Against N. floridana, all fungicides with strobilurins completely inhibited sporulation, while the triazole products hence showed intermediate rates of sporulation and conidia germination. The spider mite M. planki was more abundant than T. urticae in the field. The predatory mite Neoseiulus anonymus and the fungus N. floridana were the main natural enemies associated to these mite pests. The fungicides Priori Xtra and Alto 100 reduced the prevalence of N. floridana, though this pesticide did not negatively affected N. anonymus. The pyrethroid insecticide Decis 25 EC reduced the density of this predator, but did not affect the fungus. The treatment where fungicides and the insecticide were applied, increases on populations of phytophagous mites were observed. Spraying of the herbicide glyphosate did not affect N. anonymus and N. floridana, and the presence of weeds favored the predator. Higher population peaks of Anticarsia gemmatalis were associated with fungicide applications in 2008/09 and higher densities of Pseudoplusia includens were observed in treatment with Decis 25 EC. This insecticide also negatively affected the density of predatory insects and resulted on higher densities of stink bugs. The herbicide glyphosate did not affect density of pests and natural enemies; however, the presence of weeds favored insect predators, and resulted on lower populations of stink bugs. Overall, the field studies indicate that the use of fungicides and insecticides are important factors associated to spider mite outbreaks in soybean.

To refine our knowledge and to adequately test hypotheses concerning theoretical and applied aspects of invasion biology, successful and unsuccessful invaders should be compared. This study investigated insect establishment patterns by comparing the climatic preferences and biological attributes of two groups of polyphagous insect species that are constantly intercepted at New Zealand's border. One group of species is established in New Zealand (n = 15), the other group comprised species that are not established (n = 21). In the present study the two groups were considered to represent successful and unsuccessful invaders. To provide background for interpretation of results of the comparative analysis, global areas that are climatically analogous to sites in New Zealand were identified by an eco-climatic assessment model, CLIMEX, to determine possible sources of insect pest invasion. It was found that south east Australia is one of the regions that are climatically very similar to New Zealand. Furthermore, New Zealand shares 90% of its insect pest species with that region. South east Australia has close trade and tourism links with New Zealand and because of its proximity a new incursion in that analogous climate should alert biosecurity authorities in New Zealand. Other regions in western Europe and the east coast of the United States are also climatically similar and share a high proportion of pest species with New Zealand. Principal component analysis was used to investigate patterns in insect global distributions of the two groups of species in relation to climate. Climate variables were reduced to temperature and moisture based principal components defining four climate regions, that were identified in the present study as, warm/dry, warm/wet, cool/dry and cool/moist. Most of the insect species established in New Zealand had a wide distribution in all four climate regions defined by the principal components and their global distributions overlapped into the cool/moist, temperate climate where all the New Zealand sites belong. The insect species that have not established in New Zealand had narrow distributions within the warm/wet, tropical climates. Discriminant analysis was then used to identify which climate variables best discriminate between species presence/absence at a site in relation to climate. The discriminant analysis classified the presence and absence of most insect species significantly better than chance. Late spring and early summer temperatures correctly classified a high proportion of sites where many insect species were present. Soil moisture and winter rainfall were less effective discriminating the presence of the insect species studied here. Biological attributes were compared between the two groups of species. It was found that the species established in New Zealand had a significantly wider host plant range than species that have not established. The lower developmental threshold temperature was on average, 4°C lower for established species compared with non-established species. These data suggest that species that establish well in New Zealand have a wide host range and can tolerate lower temperatures compared with those that have not established. No firm conclusions could be drawn about the importance of propagule pressure, body size, fecundity or phylogeny for successful establishment because data availability constrained sample sizes and the data were highly variable. The predictive capacity of a new tool that has potential for eco-climatic assessment, the artificial neural network (ANN), was compared with other well used models. Using climate variables as predictors, artificial neural network predictions were compared with binary logistic regression and CLIMEX. Using bootstrapping, artificial neural networks predicted insect presence and absence significantly better than the binary logistic regression model. When model prediction success was assessed by the kappa statistic there were also significant differences in prediction performance between the two groups of study insects. For established species, the models were able to provide predictions that were in moderate agreement with the observed data. For non-established species, model predictions were on average only slightly better than chance. The predictions of CLIMEX and artificial neural networks when given novel data, were difficult to compare because both models have different theoretical bases and different climate databases. However, it is clear that both models have potential to give insights into invasive species distributions. Finally the results of the studies in this thesis were drawn together to provide a framework for a prototype pest risk assessment decision support system. Future research is needed to refine the analyses and models that are the components of this system.

Το βακτήριο Wolbachia είναι ένα ενδοκυττάριο και μητρικά κληρονομούμενο συμβιωτικό βακτήριο. Ανήκει στην ομοταξία των Alphaproteobacteria και την τάξη των Rickettsiales. Αποτελεί ίσως τον πιο διαδεδομένο ενδοκυττάριο συμβιωτικό οργανισμό στον πλανήτη, καθώς έχει εντοπιστεί μέχρι στιγμής σε πληθώρα αρθροπόδων και νηματωδών της φιλαρίασης. Πρόσφατες μελέτες εκτιμούν ότι πάνω από το 40% των ειδών αρθροπόδων είναι μολυσμένα με το βακτήριο Wolbachia. Το συμβιωτικό αυτό βακτήριο επηρεάζει τις βιολογικές λειτουργίες και ιδιότητες των ξενιστών του και είναι υπεύθυνο για μια σειρά αναπαραγωγικών ανωμαλιών, όπως η κυτταροπλασματική ασυμβατότητα, η παρθενογένεση, η θανάτωση των αρσενικών εμβρύων και η θηλυκοποίηση. Τα μοναδικά αυτά βιολογικά χαρακτηριστικά του βακτηρίου Wolbachia προσελκύουν όλο και περισσότερο το ενδιαφέρον διαφόρων ερευνητών τόσο για το ρόλο του βακτηρίου σε εξελικτικές διαδικασίες (κυρίως ειδογένεση) όσο και για τη χρησιμοποίησή του σε περιβαλλοντικά φιλικές εφαρμογές καταπολέμησης οργανισμών που είναι επιβλαβείς στους τομείς του γεωργικού και δασικού περιβάλλοντος, και της υγείας. Τα είδη του γένους Glossina (Diptera: Glossinidae), γνωστά και ως μύγες τσε-τσε, αποτελούν ξενιστές του βακτηρίου Wolbachia. Η μύγα τσε-τσε είναι ο σημαντικότερος φορέας των παθογόνων τρυπανοσωμάτων στην τροπική Αφρική, τα οποία προκαλούν την ασθένεια του ύπνου (sleeping sickness) στον άνθρωπο και την αντίστοιχη τρυπανοσωμίαση, γνωστή ως nagana, στα ζώα. Η χρησιμοποίηση του βακτηρίου Wolbachia σε μεθόδους βιολογικής καταπολέμησης της μύγας τσε-τσε προαπαιτεί την πλήρη γνώση της γενετικής του ταυτότητας και των αλληλεπιδράσεων του με το ξενιστή. Προς την κατεύθυνση αυτή, και στα πλαίσια της παρούσας διατριβής, πραγματοποιήθηκε η ανίχνευση του συμβιωτικού βακτηρίου Wolbachia σε περισσότερα από 5300 άτομα από φυσικούς και εργαστηριακούς πληθυσμούς 11 διαφορετικών ειδών μύγας τσε-τσε από 13 Αφρικανικές χώρες. Τα αποτελέσματα έδειξαν τεράστια απόκλιση της παρουσίας του βακτηρίου τόσο μεταξύ ειδών όσο και μεταξύ πληθυσμών του ίδιου είδους. Επίσης, πραγματοποιήθηκε ο γενετικός χαρακτηρισμός των στελεχών Wolbachia από συνολικά 29 αντιπροσωπευτικά δείγματα διαφόρων πληθυσμών και ειδών μύγας τσε-τσε, ενώ σε αρκετά από αυτά παρατηρήθηκαν πολλαπλά στελέχη του βακτηρίου. Διαπιστώθηκε εντυπωσιακή γενετική ποικιλότητα στελεχών Wolbachia που απαντούν στα διάφορα είδη μύγας τσε-τσε καθώς και ασυμφωνία μεταξύ των φυλογενειών των στελεχών Wolbachia και των μυγών τσε-τσε ξενιστών της, γεγονός που σημαίνει οριζόντια μετακίνηση του συμβιωτικού βακτηρίου κατά την εξέλιξη. Επιπρόσθετα, εντοπίστηκαν για πρώτη φορά εκτεταμένα γεγονότα οριζόντιας μεταφοράς βακτηριακών γονιδίων στο γονιδίωμα τριών ειδών μύγας τσε-τσε: στο Glossina morsitans morsitans, Glossina pallidipes και Glossina austeni. Από εξελικτικής σκοπιάς, κρίσιμα ερωτήματα προκύπτουν από τα παραπάνω ευρήματα, και πιο συγκεκριμένα σχετικά με: την προέλευση-μηχανισμό αυτών των γεγονότων οριζόντιας μεταφοράς, τον χρονικό προσδιορισμό τους, τον πιθανό ρόλο τους σε διαδικασίες ειδογένεσης και την επιλεκτική εμφάνισή τους σε ορισμένα μόνο είδη Glossina π.χ. στo υποείδos Glossina morsitans centralis που είναι πολύ συγγενικό του Glossina morsitans morsitans δεν παρατηρήθηκε το φαινόμενο. Εξίσου σημαντική και επιβεβλημένη κρίνεται η διεξοδική διερεύνηση του ενδεχομένου τα βακτηριακά γονίδια που ενσωματώθηκαν στο ευκαρυωτικό γονιδίωμα της μύγας τσε-τσε να ευθύνονται για την έκφραση νέων λειτουργιών-ιδιοτήτων (ή να μεταβάλλουν τις ήδη υπάρχουσες), ιδίως μάλιστα εάν αυτές συνδέονται με την αποδοτικότητα μετάδοσης της νόσου της τρυπανοσωμίασης μέσω του φορέα της, δηλαδή της μύγας τσε-τσε. Τέλος, διαπιστώθηκε πιθανή αρνητική συσχέτιση της παρουσίας του βακτηρίου Wolbachia με τον παθογόνο ιό Salivary Gland hypertrophy Virus (SGHV), γεγονός που συζητείται στα πλαίσια βιολογικών εφαρμογών καταπολέμησης του εντόμου-φορέα και της τρυπανοσωμίασης. Παράλληλα, μεγάλο ενδιαφέρον παρουσιάζει η προοπτική χρησιμοποίησης του βακτηρίου Wolbachia για τη βιολογική καταπολέμηση εντόμων αγροτικής ή /και περιβαλλοντικής σημασίας, όπως είναι οι αφίδες και η καρπόκαψα καστανιάς. Το γεγονός αυτό προϋποθέτει την ανίχνευση και τη γενετική ταυτοποίηση του βακτηρίου σε φυσικούς πληθυσμούς εντόμων. Στα πλαίσια της παρούσας διατριβής πραγματοποιήθηκε ανίχνευση και χαρακτηρισμός του βακτηρίου Wolbachia σε 78 συνολικά άτομα από 22 είδη αφίδων, από 26 φυσικούς πληθυσμούς από την Ελλάδα. Από αυτούς τους 26 πληθυσμούς, μόλις οι 4 βρέθηκαν να είναι μολυσμένοι με το βακτήριο Wolbachia και συγκεκριμένα πληθυσμοί των ειδών: Aphis fabae, Aphis hederae, Metopolophium dirhodum και Baizongia pistaciae. Τα αποτελέσματα αυτά δείχνουν για πρώτη φορά ότι η παρουσία του βακτηρίου Wolbachia στις αφίδες είναι πιθανά πιο διαδεδομένη από ότι προέκυπτε από προηγούμενες μελέτες. Επίσης, μελετήθηκε η ανίχνευση και ο χαρακτηρισμός του βακτηρίου Wolbachia στα είδη Cydia splendana, Cydia fagiglandana και Pammene fasciana. Το βακτήριο Wolbachia ανιχνεύθηκε για πρώτη φορά στα συγκεκριμένα είδη και μάλιστα διαπιστώθηκε ότι η συχνότητα εμφάνισής του ποικίλει τόσο μεταξύ των δύο ειδών Cydia όσο και μεταξύ των πληθυσμών του κάθε είδους. Στο είδος Pammene fasciana, το βακτήριο ανιχνεύθηκε σε όλα τα άτομα που μελετήθηκαν. Τα αποτελέσματα της παρούσας διατριβής συζητούνται από τη σκοπιά τόσο της οικολογικής και εξελικτικής σημασίας τους όσο και της προοπτικής χρησιμοποίησης του συμβιωτικού βακτηρίου Wolbachia για τον πληθυσμιακό έλεγχο επιβλαβών εντόμων όπως οι μύγες τσε-τσε, οι αφίδες και η καρπόκαψα καστανιάς. / Wolbachia is an intracellular and maternally inherited symbiotic bacterium that belongs to the class of Alphaproteobacteria and the order of Rickettsiales. It is the most ubiquitous intracellular symbiotic organism of the planet, since it has been estimated that over 40% of insect species, in addition to filarial nematodes, crustaceans, and arachnids are infected with Wolbachia. In arthropods Wolbachia affects the biological functions and properties of its hosts and it is responsible for a number of reproductive abnormalities, such as cytoplasmic incompatibility (CI), thelytokous parthenogenesis, feminization of genetic males and male killing. These unique biological characteristics of Wolbachia are attracting the interest of various researchers for: (a) decyphering the role of Wolbachia in evolutionary processes (mainly speciation), and (b) for its use in environmentally friendly applications for the control of agricultural pests and disease vectors. The species of genus Glossina (Diptera: Glossinidae) known as tsetse flies, have been found to be infected with Wolbachia. Tsetse flies are the sole vectors of pathogenic trypanosomes in tropical Africa, causing the “sleeping sickness” in humans and the “nagana” in animals. The potential use of Wolbachia for the control of tsetse flies, prerequisite a thorough knowledge of its genetic identity and the interactions with the host. To further characterize the prevalence of Wolbachia in tsetse flies an extensive screen of more than 5300 specimens from natural and laboratory populations of 11 different Glossina species originating from 13 African countries was carried out. Our results indicated a huge divergence in the prevalence of Wolbachia, both among the species and among populations of the same species. Further characterization by MLST and wsp genotyping was carried out for the Wolbachia strains of 29 representative populations and species of tsetse flies. An impressive genetic diversity of Wolbachia strains in tsetse flies was revealed. Interestingly, disconcordance between the phylogeny of Wolbachia and that of the tsetse flies was observed, suggesting horizontal transmission of Wolbachia during the evolution. Moreover, extended horizontal gene transfer events were detected for first time in Glossina morsitans morsitans, Glossina pallidipes και Glossina austeni. These results raise critical questions concerning: (a) the origin/mechanism of these horizontal gene transfer events, (b) their temporal determination, (c) their potential role as agents of speciation and (d) their selective appearance in only some Glossina species e.g in the subspecies Glossina morsitans centralis which is closely related with Glossina morsitans morsitans the phenomenon was not observed. Equally important will be to examine if genes from the chromosomal insertions were potentially expressed and examine if these genes are associated with the vectorial capacity of tsetse flies for the trypanosoma transmission. Finally, a negative correlation between the presence of Wolbachia with the Salivary Gland Hypertrophy Virus (SGHV) was identified. This is further discussed in the context of biological applications for control of tsetse fly-vector and trypanosomiasis. Finally in this thesis, the detection and characterization of Wolbachia in 78 specimens of 22 aphids species, from 26 natural populations, from Greece was examined. Only 4 out of 26 populations were found to be infected with Wolbachia, and specifically the species: Aphis fabae, Aphis hederae, Metopolophium dirhodum και Baizongia pistaciae. These results indicated that the presence of Wolbachia in aphids is probably more prevalent than it was derived from previous studies. Also, detection and characterization of Wolbachia in the Cydia splendana, Cydia fagiglandana and Pammene fasciana was carried out. Wolbachia was detected for first time in these species, and it was found that the prevalence of Wolbachia varies between the two species of Cydia and among populations of each species, with the infection in Pammene fasciana being fixed. At the end the ecological and evolutionary importance of Wolbachia, together with the use of the bacterium for the population control of harmful insects like tsetse flies, aphids and moths is further discussed.