In the work described in this thesis I studied how increases in nitrogen (N) inputs may affect plant community structure in boreal forest understorey vegetation. These phenomena were investigated in N fertilization experiments and along a national N deposition gradient. After five years of N additions, large changes in understorey vegetation composition were observed in the fertilization study. In plots that received 50 kg N ha'1 year"1 (N2), the abundance of the dominant species, Vaccinium myrtillus, decreased on average by 32 %. No decrease was observed in control plots during the same period. In contrast, the grass Deschampsia flexuosa responded positively to increased N input, being on average more than five times as abundant in the N2 treatments as in controls. Also an increase was seen in the incidence of disease caused by the parasitic fungus Valdensia heterodoxa on leaves of V. myrtillus following N additions. The parasite was on average nearly twice as abundant in N2 plots than in control plots. This could be explained by increased N concentrations in host plant tissue. Disease incidence also increased following experimental additions of glutamine to leaf surfaces of V. myrtillus, suggesting a causal connection between plant N concentration and performance of the fungus. The parasite also played a key role in the observed changes in understorey species composition. D. flexuosa was more abundant in patches in which V. myrtillus was severely affected by V heterodoxa. This suggests that V heterodoxa mediates the increased abundance of D. flexuosa following increased N additions. The fungus mediates changes in the composition of understorey vegetation mainly by increasing light availability via premature leaf loss of V. myrtillus. The incidence of disease due to the parasite was on average higher in large than in smaller N-treated plots, indicating that the response to N fertilization is spatially scale dependent. This shows that using small plot sizes in experiments that simulate changed environmental conditions may be problematic, as important interactions may be underestimated. Comparison of the occurrence of understorey species between regions with different rates of N deposition revealed that the occurrence of the two dwarf shrubs V. myrtillus and V. vitis- idaea was lower in regions with high N deposition compared to regions with low deposition. The opposite pattern was found for V heterodoxa. This is consistent with expectations from N fertilization experiments. For D. flexuosa no differences in occurrence were found between the different regions investigated. The effects on vegetation and mycorrhizal fungi observed following N additions were also found to be long lasting. Nine years after termination of the fertilization, no signs of recovery were detected, and nearly 50 years after termination characteristic signs of N fertilization were found among bryophytes and mycorrhizal fungi. This suggests that the time needed for re-establishment of the original biota following N-induced changes may be substantial. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 2002, härtill 5 uppsatser</p> / digitalisering@umu

Our earth is currently undergoing unprecedented human induced climate change, which is expected to drive widespread changes in species distributions and abundances that will affect natural pest suppression. Recent studies have suggested that climate change may cause changes to predator and herbivore assemblages in ways that alter multi-trophic food webs and affect the stability of ecosystems. Moreover, higher temperatures and increased climatic variability are expected to induce differential responses from predators and their prey that will undoubtedly disrupt species interactions. This thesis aims to test how climate change will impact the ability of natural enemies to continue to control pests in agroecosystems, and how they will continue to survive and function. In a field experiment using 13 farm sites across a natural temperature gradient, I found that temperature had direct positive effects on the abundances of the dominant parasitoid (an aphid specialist) and hyperparasitoid species, highlighting the importance of specific species responses in shaping larger communities. I also found that overall community composition was affected by temperature, with composition in warmer sites changing more throughout the season than cooler sites. In a future of inevitable climatic changes this result tells us we can expect arthropod community structure to change, which will have questionable impacts on overall population dynamics. To build on the field experiments, I used laboratory experiments to test differential responses of species to both drought and temperature and found that natural enemies responded to drought and temperature in a non-additive way, suggesting that the interaction between various climate change drivers is more important than their singular effect. Also, different species of natural enemies responded differently to abiotic factors, highlighting the importance of conserving natural enemies that can maintain important functional attributes in the face of climate change. Although biodiversity can be important for ensuring ecosystem functioning, response diversity, rather than species richness, may better promote ecosystem resilience, especially in the face of changing climate. The mechanisms underlying biodiversity effects are often difficult to disentangle, however, by manipulating the diversity of climate responses exhibited by ecosystem service providers, I tested how the rates and stability of prey suppression by predators are affected by climate warming and drought. I found that predator combinations with different individual responses to climate change maintained greater and less variable (i.e. more stable) prey suppression, compared with single predator species or combinations of predators with similar climate responses. This response complementarity became strongest through time and under drought or high temperature treatments. I suggest that response complementarity provides ‘insurance’ effects, which may be more important than previously envisaged for maintaining ecosystem functions such as biological control under global environmental change. Overall, the non-additive effects of different climate drivers, combined with differing responses across trophic levels, suggests that predicting future pest outbreaks will be more challenging than previously imagined.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The fauna of parasitic Hymenoptera is not well known in Brazil, despite its great diversity and biological, ecological and economical importance. In the cultivation of tobacco (Nicotiana tabacum L.) there is the need to inventory the species of natural enemies that occur associated and perform the natural biological control of pests. The objectives of this study were to inventory the biodiversity of parasitic Hymenoptera associated with tobacco under conventional and organic management; to examine the seasonal and spatial distribution; and to check the effect of the presence of adjacent vegetation on populations of parasitoids. The study was conducted in two crops of conventional tobacco and one certified as organic in Santa Cruz do Sul, RS, Brazil. Sampling points were determined and located Outside , at the Border , Inside and in the Middle of the tobacco fields, in which were installed a Malaise trap and four pit-fall traps. Samples were weekly collected from November 2008 to February 2009 and from November 2009 to February 2010. Statistical analysis was performed using the software PAST. Were collected 7.913 hymenopterans parasitoids in conventional tobacco crops during the 2008/2009 and 2009/2010 crop, and 31.574 hymenopterans parasitoids associated with organic tobacco in both seasons of study. The families Ichneumonidae, Braconidae, Scelionidae and Eucoilidae were the most abundant in both types of crop management, as well as Encyrtidae, Eulophidae and Mymaridae. The sampling point "Outside" was the most representative in both crops, reflecting, in general, the need to maintain areas of adjacent vegetation that differ from the main crop in order to contribute to hymenopterans parasitoids associated with tobacco cultivation. However, application of agrochemicals reflected in the decrease of parasitoids sampled, underscoring the need for studies on selectivity of products currently used to control pests in tobacco on beneficial insects. / A fauna de himenópteros parasitoides é pouco conhecida no Brasil, apesar de sua grande diversidade e importância biológica, ecológica e econômica, principalmente no manejo integrado de pragas agrícolas. Com relação ao cultivo do tabaco (Nicotiana tabacum L.), o conhecimento dos inimigos naturais associados nativamente servirá de base a programas de controle biológico na cultura. Assim, os objetivos deste trabalho foram estudar a diversidade, sazonalidade e distribuição espacial de himenópteros parasitoides associados ao tabaco de acordo com o método de cultivo (convencional e orgânico) e verificar o efeito de bordadura sobre populações de parasitoides. O estudo foi realizado em duas lavouras de tabaco convencionais e uma certificada como orgânica, no município de Santa Cruz do Sul, RS. Foram determinados, nas diferentes lavouras, pontos de coleta Fora , Borda , Dentro e Meio nos quais foram instaladas uma armadilha de Malaise e quatro armadilhas tipo pit-fall. As coletas foram realizadas, semanalmente, de novembro de 2008 a fevereiro de 2009 e de novembro de 2009 a fevereiro de 2010. As análises estatísticas foram realizadas utilizando o software PAST. Foram coletados 7.913 himenópteros parasitoides em lavouras convencionais de tabaco nas safras 2008/2009 e 2009/2010; e 31.574 himenópteros parasitoides associados a lavoura orgânica de tabaco em ambas as safras de estudo. As famílias Ichneumonidae, Braconidae, Eucoilidae e Scelionidae foram as mais abundantes em ambos os tipos de manejo da cultura, além de destaque para Encyrtidae, Mymaridae e Eulophidae. O ponto de amostragem Fora foi o mais representativo em ambos os tipos de lavouras, refletindo, de modo geral, a necessidade de manutenção de áreas de vegetação adjacente que difiram da cultura principal para maior aporte de himenópteros parasitoides associados à cultura do tabaco. Também a aplicação de agroquímico refletiu na diminuição de parasitoides amostrados, destacando a necessidade de estudos sobre seletividade dos produtos atualmente utilizados no controle de pragas em tabaco.

No description available.

Genetically modified (GM) maize was developed mainly to control lepidopteran pests such as the maize stem borer (Busseola fusca) (Lepidoptera: Noctuidae). Since the first commercialization of GM crops with insecticidal properties, possible non-target effects such as the effect at the third trophic level on important predators for example lacewing species (Chrysoperla spp.) have been of concern. Contradicting results were reported in previous studies with regard to the effect of Cry 1Ab protein produced by Bt maize on the performance of lacewings. Some studies found that Bt proteins had no effect while others reported that C. carnea performed poorly if they consumed prey that consumed Cry 1Ab protein. In South Africa one of the most common chrysopid species in maize ecosystems is Chrysoperla pudica (Navás) (Neuroptera: Chrysopidae). Evolution of Bt resistant pests, such as B. fusca in South Africa facilitates a new pathway for exposure of predators to healthy prey that consumes Cry 1Ab proteins. The aims of this study was to determine the effect of the Cry 1Ab protein expressed in Bt maize on a non-target organism‟s (C. pudica) biology via indirect exposure, and to determine the concentration of Cry 1Ab protein in the plant, prey and predator. Chrysoperla pudica larvae were indirectly exposed to the Bt-toxin through healthy Bt-maize feeding prey (B. fusca larvae) in two feeding experiments and lacewing survival and life history parameters recorded. Bt had a limited effect on some parameters that were evaluated. The larval and pupal periods of C. pudica larvae that were exposed to the Bt-toxin had a significant difference from that of the control treatment. The Bt-toxin had a significant effect on fecundity, fertility and malformation after emergence of C. pudica adults of which larvae fed only on Bt resistant B. fusca larvae, but not on the mortality rate. Cry 1Ab concentration was the highest in the plant, followed by the prey and lacewing larvae. This study showed that the Cry 1Ab protein had a slight adverse effect only on certain life parameters of C. pudica, and that Cry 1Ab protein was hardly detectable in C. pudica larvae. However, since this study represented a worst-case scenario where diverse prey was not available, insignificant effects is expected under field conditions where prey is diverse. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

L'intérêt des prédateurs généralistes dans la lutte biologique par conservation est peu étudié en verger de pommiers. Cette thèse visait à déterminer le rôle de prédateurs généralistes invertébrés (principalement carabes et araignées) et vertébrés (mésanges et chauves souris) dans le contrôle de trois ravageurs clés du pommier et de définir les éléments paysagers qui leur sont favorables. Pour cela, nous avons effectué des suivis de populations dans des vergers en agriculture biologique et nous les avons associés à des mesures de prédation des ravageurs par analyse moléculaire des contenus stomacaux et faeces des prédateurs à l'aide d'amorces spécifiques développées à cet effet. Nous montrons que les ravageurs sont consommés dès leur apparition dans les vergers, notamment les pucerons par les araignées de la frondaison, ce qui suggère que ces prédateurs ont un potentiel de régulation important. De plus une complémentarité temporelle semble exister entre araignées et carabes dans le contrôle des tordeuses. L'influence des éléments paysagers intra et extra verger diffère selon les taxa de prédateurs considérés. Ce dernier résultat suggère des compromis dans les aménagements à réaliser pour favoriser leur action et la nécessité d'une meilleure compréhension de leur écologie. / Generalist predators have been merely studied in conservation biological control studies in apple orchards. This work aimed to determine the potential of invertebrate (arthropods, mainly carabids and spiders) and vertebrate (great tits and bats) predators at suppressing three key apple pests and then to devise which landscape features are beneficial to them. For this purpose, we monitored pest and predator populations in organic apple orchards of southeastern France and related their abundance and diversity to measures of pest predation using molecular gut content and faeces analysis with specific primers designed for this purpose. We found that pests were consumed as soon as they arrived in the orchard, in particular aphid by canopy spiders, indicating that these predators are likely to be efficient. We also observed some temporal complementarity in predation of tortricids by spiders and carabids. Finally, the influence of landscape features within and surrounding the orchards was different for the different studied taxa suggesting the need for compromises in orchard management for enhancing natural enemy populations and for a better consideration of the ecology of these predators.

O ataque de insetos herbívoros induz a emissão de voláteis pelas plantas que constituem sinais químicos importantes para os inimigos naturais em busca do hospedeiro/presa. Essas interações tritróficas mediadas pelos voláteis das plantas têm sido bem estudadas em sistemas que envolvem parasitóides larvais. Por outro lado, pouco se sabe a respeito do papel desses odores na localização hospedeira dos parasitóides de ovos. Dessa maneira, o presente estudo teve como objetivos: (i) avaliar o parasitismo, a preferência e o arrestamento de ovos de Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) de diferentes idades para o parasitóide Telenomus remus Nixon (Hymenoptera: Scelionidae); (ii) verificar se ocorre a indução de voláteis induzidos pela oviposição de S. frugiperda na planta de milho atraentes ao parasitóide T. remus; (iii) avaliar o papel dos voláteis induzidos pela herbivoria de S. frugiperda no comportamento do parasitóide especialista T. remus e generalista Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae); e (iv) verificar se a oviposição de S. frugiperda altera as defesas diretas e indiretas induzidas pela herbivoria no milho. Os resultados desse trabalho mostraram que T. remus teve preferência em parasitar ovos de 1 e 2 dias de idade em relação aos 3 dias. Entretanto, a emergência dos parasitóides foi reduzida em ovos de 2 e 3 dias. Todos os extratos hexânicos dos ovos exerceram efeito arrestante sobre T. remus em relação ao solvente, porém o tempo de permanência dos parasitóides foi maior em extratos de ovos de 1 e 2 dias em comparação ao de 3 dias. De acordo com esses resultados, foi avaliado se a planta de milho emite voláteis induzidos pela oviposição de S. frugiperda atraentes ao parasitóide T. remus nos intervalos 1, 2 e 3 dias. Os bioensaios comportamentais e a coleta de voláteis não mostraram que ocorre a indução de voláteis induzidos pela oviposição atraentes ao parasitóide, mas que a oviposição promoveu a supressão da emissão do linalol. Já os voláteis induzidos pela herbivoria do S. frugiperda constituem pistas químicas importantes para os parasitóides de ovos. O parasitóide especialista T. remus não apresentou o comportamento inato de atração pelos voláteis, porém, após a experiência com os mesmos, T. remus passou a ser atraído tanto por misturas compostas majoritariamente por voláteis de folhas verdes (VFVs), que são emitidas logo após o dano; como por misturas mais complexas, compostas por terpenos, emitidas algumas horas após a indução. Já T. pretiosum apresentou um comportamento de atração inato pelos VFVs, embora seja também capaz de aprender misturas compostas por terpenos. A oviposição de S. frugiperda não alterou as defesas diretas do milho, avaliadas pelo peso da lagarta alimentada na planta, porém, provocou a diminuição da liberação de terpenos induzidos pela herbivoria. Os resultados desse trabalho sugerem que a oviposição do herbívoro pode ter implicações relevantes nas interações tritróficas, pois promovem a supressão de voláteis do milho. Além disso, os voláteis induzidos pela herbivoria desempenham um papel importante no comportamento de parasitóides de ovos. / Attack of insect herbivores induces emission of plant volatiles that play an important role as chemical signals to natural enemies in host search. Tritrophic interactions mediated by plant volatiles have been well studied in systems that involve larval parasitoids. By contrast, little is known about the role of these odors in host searching by egg parasitoids. Thus, the current study aimed to: (i) assess parasitism, preference and arrestment of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs with different ages to the parasitoid Telenomus remus Nixon (Hymenoptera: Scelionidae); (ii) verify if S. frugiperda oviposition induces attractive maize volatiles to the parasitoid T. remus; (iii) assess the role of herbivore-induced maize volatiles elicited by S. frugiperda to the specialist parasitoid T. remus and the generalist Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae); and (iv) verify if S. frugiperda oviposition alters direct and indirect herbivore-induced defenses on maize. Results showed that T. remus preferred to parasitize 1- and 2-day-old eggs in relation to 3-day-old. However, parasitoid emergence was reduced in 2- and 3-day-old eggs. All hexanic egg extracts promoted arrestment response for T. remus when compared to the solvent, although residence time was longer in 1- and 2-day old egg extracts in comparison with 3-day old. In view of these results, it was assessed if maize plant emits attractive oviposition-induced volatiles elicited by S. frugiperda to the egg parasitoid T. remus. Behavioral bioassays and volatile collection did not show that maize emits oviposition-induced volatiles elicited by S. frugiperda that are attractive to T. remus. Surprisingly, oviposition suppressed the emission of linalool. Hebivore-induced maize volatiles comprise important chemical cues for egg parasitoids. Specialist parasitoid T. remus was not innately attracted by herbivore-induced volatiles, though experienced wasps responded to blends comprised predominantly by green leaf volatiles (GLVs), which are emitted immediately after damage, or to more complex blends comprised by terpenes, emitted some hours after damage. While T. pretiosum showed an innate behavior towards VFVs, but wasps were also able to learn terpene blend. Oviposition of S. frugiperda did not alter direct defenses on maize, which were assessed by larval weight fed on the plant, however, it decreased emissions of herbivore-induced terpenes. These results suggest that herbivore oviposition can have relevant considerations in tritrophic interactions and herbivore-induced volatiles play an important role in egg parasitoid behavior.

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Para que grandes produtividades sejam obtidas, faz-se necessário o controle de insetos, doenças e plantas daninhas. O controle químico é a principal medida utilizada pelos agricultores para o manejo dessas pragas. No entanto, esses agrotóxicos podem afetar de forma negativa os inimigos naturais presentes nesse cultivo. Chrysoperla externa e Eriopis connexa são dois predadores vorazes encontrados com frequência, predando insetos-praga presentes na cultura do trigo. Para que o controle químico e o controle biológico possam ser associados de forma harmoniosa nas lavouras de trigo é necessário que os produtos químicos utilizados sejam seletivos aos insetos benéficos. Nesse sentido, estudos de seletividade a inimigos naturais podem gerar uma grande quantidade de informações importantes para que a associação desses dois métodos de controle possa ser viabilizada, e com o mínimo impacto ao meio ambiente. Objetivou-se com este trabalho avaliar a seletividade de agrotóxicos utilizados na cultura do trigo aos predadores C. externa e E. connexa, utilizando como base a metodologia da “International Organization for Biological and Integrated Control of Noxious Animals and Plants” (IOBC), através de bioensaios em laboratório sobre larvas, ovos, pupas e adultos, além de testes de pesistência biológica em casa-de-vegetação sobre larvas e adultos. O inseticida diflubenzuron SC foi o único inseticida considerado levemente nocivo as larvas de E. connexa. Os inseticidas inibidores da biossíntese de quitina diflubenzuron SC, diflubenzuron WP, lufenuron e triflumuron apresentaram reduzida mortalidade aos adultos de C. externa e E. connexa. Para os ovos dos predadores, o inseticida etofenproxi foi classificado como levemente nocivo a C. externa, sendo que imidacloprido+beta-ciflutrina, diflubenzuron WP, tiametoxam+lambda-cialotrina A e B, gama-cialotrina e etofenproxi apresentaram a mesma classificação para E. connexa, tendo ainda metomil sendo classificado como moderadamente nocivo aos ovos do predador. Imidacloprido+beta-ciflutrina foi considerado como levemente nocivo as pupas de C. externa enquanto imidacloprido+beta-ciflutrina, tiametoxam+lambda-cialotrina A e B e lufenuron apresentaram efeito total superior a 30% e foram classificados como levemente nocivos as pupas do predador E. connexa. Quanto a persistência, com exceção de tiametoxam+lambda-cialotrina que 7 foi moderadamente persistente, gama-cialotrina, imidacloprido+beta-ciflutrina, metomil e tiametoxam foram persistentes as larvas de C. externa e E. connexa. Gama-cialotrina, imidacloprido+beta-ciflutrina e metomil foram persistentes a C. externa e imidacloprido+beta-ciflutrina e metomil aos adultos de E. connexa. Tiametoxam foi considerado moderadamente persistente a C. externa e gamacialotrina, tiametoxam e tiametoxam+lambda-cialotrina a E. connexa. O inseticida tiametoxam+lambda-cialotrina foi levemente persistente aos adultos de C. externa. O herbicida glufosinato de amônio foi classificado como moderadamente nocivo a fase larval de ambos os predadores. Quase todos os herbicidas foram classificados como inócuos aos ovos dos dois predadores, com exceção de metsulfuron-metil que foi classificado como levemente nocivo aos ovos de E. connexa. O herbicida 2,4-D amina foi classificado como levemente nocivo a pupas de C. externa e pirimidinadiona apresentou a mesma classificação a pupas de E. connexa. Os fungicidas piraclostrobina+epoxiconazole B e picoxistrobina+ciproconazole são nocivos as larvas de C. externa. Piraclostrobina+epoxiconazole A foi levemente nocivo a fase de ovo, e propiconazol foi levemente nocivo a fase de pupa de C. externa. O fungicida piraclostrobina+epoxiconazole A foi considerado nocivo as larvas de E. connexa. Piraclostrobina+epoxiconazole A e tebuconazole A foram levemente nocivos a fase de ovo, e piraclostrobina+epoxiconazole A e propiconazol foram levemente nocivos a fase de pupa do coccinelídeo. / The wheat crop hasp great importance in the human and animal nutrition. In order to obtain large yields, it is necessary the control of insects, diseases and weeds. The chemical control through the use of pesticides is the main measure used by farmers to manage these pests. However, these pesticides can negatively affect the natural enemies present in this crop. Chrysoperla externa and Eriopis connexa are two very voracious predators and are found often preying on aphids present in wheat crop. In order for chemical control and biological control to be harmoniously associated in the wheat crop, it is necessary that the chemicals used must be selective for beneficial insects. So, studies of selectivity to natural enemies can generate a large amount of important data for the association of these two control methods can be made feasible, with minimal impact to the environment. The objective of this work was to evaluate the selectivity of agrochemicals used in the wheat crop to the predators C. externa and E. connexa, based on the methodology of the International Organization for Biological and Integrated Control of Noxious Animals and Plants (IOBC) Through laboratory bioassays on larvae, eggs, pupae and adults, in addition to tests of biological persistence in greenhouse conditions on larvae and adults. The insecticide diflubenzuron SC was the only insecticide considered to be slightly harmful to E. connexa larvae. The chitin biosynthesis inhibitors diflubenzuron SC, diflubenzuron WP, lufenuron and triflumuron showed reduced mortality on adults of C. externa and E. connexa. For the eggs of the predators, the insecticide etofenproxi was classified as slightly harmful to C. externa, and imidacloprid+beta-cyfluthrin, diflubenzuron WP, thiamethoxam+lambda-cyhalothrin A and B, gamma-cyhalothrin and etofenproxi showed the same classification for E. connexa, being methomyl classified as moderately harmful to the predator eggs. Imidacloprid+beta-cyfluthrin was considered as slightly harmful the pupae of C. externa while imidacloprid+betacyfluthrin, thiamethoxam+lambda-cyhalothrin A and B and lufenuron had a total effect superior to 30% and were classified as slightly harmful to the pupae of the predator E. connexa. Regarding the insecticide persistence, with the exception of thiamethoxam+lambda-cyhalothrin that was moderately persistent, gammacyhalothrin, imidacloprid+beta-cyfluthrin, methomyl and thiamethoxam were persistent to C. externa and E. connexa larvae. Gamma-cyhalothrin, 9 imidacloprid+beta-cyfluthrin and methomyl were persistent to C. externa and imidacloprid+beta-cyfluthrin and methomyl to adults of E. connexa. Thiamethoxam was considered moderately persistent to C. externa and gamma-cyhalothrin, thiamethoxam and thiamethoxam+lambda-cyhalothrin to E. connexa. The insecticide thiamethoxam+lambda-cyhalothrin was slightly persistent to C. externa adults. The herbicide ammonium glufosinate was classified as moderately harmful to the larval phase of both predators. Almost all herbicides were classified as innocuous to the eggs of both predators, with the exception of metsulfuron-methyl which was classified as slightly deleterious to E. connexa eggs. The herbicide 2,4-D amine was classified as slightly harmful to pupae of C. externa and pyrimidinedione presented the same classification to E. connexa pupae. The fungicides pyraclostrobin +epoxiconazole B and picoxystrobin+ciproconazole are harmful to C. externa larvae. Piraclostrobin+epoxiconazole A was slightly harmful to the egg phase, and propiconazole was slightly harmful to the pupa phase of C. externa. The fungicide pyraclostrobin+epoxiconazole A was considered to be harmful to E. connexa larvae. Piraclostrobin+epoxiconazole A and tebuconazole A were slightly harmful to the egg phase, and pyraclostrobin+epoxiconazole A and propiconazole were slightly harmful to the pupal phase of the coccinellidae.

To date, few studies have focused on the effects of genetically modified trees (GM trees) on the environment. One concern with GM trees is that they may have unanticipated effects on non-target organisms, i.e. effects on organisms that are not direct targets of the genetically modified trait. The main objective of this thesis was to study potential non-target effects from the interaction between GM trees and natural enemies, including phytopathogens and herbivorous insects. To study this I used a system consisting of GM trees featuring changes in growth-related characteristics, and naturally occurring enemies. The GM trees used were the aspen hybrids Populus tremula x tremuloides: one unmodified wild type clone T89 (control) and transgenic lines with altered expression of gibberellin (GA 20-oxidase), sucrose (SPS) or pectin (PME); and Populus tremula x alba: one unmodified wild type clone INRA 717-1-B4 (control) and lines modified to suppress the activity of the enzymes in the lignin biosynthetic pathway, i.e. CAD, COMT, CCR or CCoAOMT. The natural enemies used were the parasitic phytopathogens Melampsora pinitorqua, M. populnea and Venturia tremulae, and the herbivorous leaf-beetle Phratora vitellinae. To address this question inoculation experiments, feeding preference experiments, analyses of secondary chemistry and field inventories were performed. The results of the studies showed that the GM trees significantly affected the interaction with the natural enemies, both in the laboratory as well as in the field. For instance, both M. pinitorqua and V. tremulae showed an altered disease incidence on the GM trees of P. tremula x tremuloides compared to the unmodified wild type T89, where all tested transgenic lines exhibited altered susceptibility to the pathogens. However, there were also differences in aggressiveness to the aspens depending on pathogen population. The results from the field inventory showed that lines within all tested transgenic construct, COMT, CAD, CCoAOMT and CCR of P. tremula x alba differed significantly from the wild type INRA 717-1-B4 in susceptibility to M. populnea. In addition, the susceptibility to the rust also differed significantly between lines carrying the same transgenic constructs. Furthermore, we found that overexpression of SPS in P. tremula x tremuloides, unintentionally induced changes in plant secondary chemistry, where the GM-line SPS33A exhibited the largest deviation from the wild type T89 in contents of plant phenolics and nitrogen, and that these changes coincide with a concurrent decrease in herbivory by P. vitellinae on this line. I argue that the altered interactions are the result of physiological changes in the trees. They can originate from direct effects i.e. altered expression of the modified trait, indirect effects of the genetic modification process e.g. pleiotropy, or effects from the transformation process e.g. position effects, to which the tested natural enemies respond. The result stresses the importance of further research on the causes and mechanisms responsible for the altered interaction between GM trees and non-target organisms, as well as evaluating the potential environmental effects of cultivation of GM trees in the field. Such research will require collaboration between researchers from different disciplines, such as plant ecology and physiology, functional genomics, proteomics and metabolomics.