Orientador: João Vasconcellos Neto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T01:56:00Z (GMT). No. of bitstreams: 1 Maia_DanielledePaula_M.pdf: 1501960 bytes, checksum: 40c726b8f80b787c2869fe8c9fb28f40 (MD5) Previous issue date: 2013 / Resumo: A dinâmica populacional de plantas é fortemente influenciada pela dispersão das sementes. A predação desses propágulos ocasiona significativa redução de sementes viáveis, podendo diminuir a população dessa planta. Besouros da subfamília Bruchinae (Chrysomelidae), antigamente conhecidos como bruquídeos, são um grupo de insetos predadores de sementes que atacam principalmente frutos de palmeiras (Família Arecaceae), podendo por sua vez, suas larvas serem atacadas por vespas parasitoides. Neste trabalho aprofundaram-se os estudos das interações tri-tróficas entre a palmeira Syagrus romanzzofiana, besouros da subfamília Bruchinae (Pachymerinae), como herbívoros predadores de suas sementes, e uma espécie de parasitoide Heterospilus prosopodis (Hymenoptera: Braconidae), como terceiro nível trófico. A área de estudo foi a Universidade Estadual de Campinas, Campinas, São Paulo. Durante vinte e quatro meses foram acompanhadas quarenta palmeiras mensalmente, sendo registradas observações pontuais sobre a fenologia. No mesmo período, frutos maduros recém-caídos do cacho eram coletados para posteriormente serem acondicionados em gaiolas, que eram dispostas ao nível do solo, para mensurar o ataque dos besouros e seus parasitoides. A produção de flores, frutos verdes e frutos maduros ocorreram ao longo de todo o período de estudo. Foram encontradas duas espécies de besouros predando as sementes de S. romanzoffiana: Pachymerus cardo e Pachymerus nucleorum. Esta última ocorreu ao longo de todo o período de estudo, sendo que o pico de predação ocorreu no mês de dezembro. A predação por P.cardo não ocorreu de forma constante durante os anos de estudo. Registrou-se o ataque às larvas de Pachymerus sp. por vespas parasitoides pertencentes à espécie Heterospilus prosopodis. O parasitismo não foi constante durante o tempo do estudo, observando maior emergência de parasitoides nos meses mais quentes e chuvosos. Forças top-down talvez sejam mais importantes na regulação desta interação tritrófica Syagrus romazzofiana, Pachymerus spp. e seu parasitoide onde os efeitos são manifestados principalmente no ciclo seguinte da interação / Abstract: The population dynamics of plants is strongly influenced by seed dispersal. Predation these seedlings causes significant reduction of viable seeds, which can decrease the population of this plant. Subfamily Bruchinae beetles (Chrysomelidae), formerly known as bruchids, are a group of insect seed predators that attacks mainly palm fruits (Family Arecaceae), and can turn their larvae are attacked by parasitoid wasps. In this work deepened studies of tritrophic interactions between the palm S.romanzzofiana, beetles sufamilia Bruchinae (Pachymerinae) as predators of herbivores and their seeds a kind of parasitoid Heterospilus sp. (Hymenoptera: Braconidae) as the third trophic level. The study area was the University of Campinas in Campinas - SP. For twenty-four months were monitored monthly and forty palm off on phenological observations recorded in the same period, newly fallen ripe fruit bunch were collected for later packed into cages that were placed at ground level, to measure the attack of the beetles and their parasitoids. . Production of flowers, green fruits and ripe fruits occur throughout the study period. We found two species of beetles preying on seeds of S. romanzoffiana: Pachymerus cardo and Pachymerus nucleorum, the latter occurred throughout the study period, with peak predation occurred in december and predation by P.cardo not occurred steadily during the years of study. Recorded the attack on larvae Pachymerus sp. by wasp parasitoids of the species Heterospilus prosopodis. Parasitism was not constant during the time of the study, watching largest emergence of parasitoids in the warmer months and rainy / Mestrado / Parasitologia / Mestra em Parasitologia

La Pyrale du Café, Prophantis smaragdina Butler (Lepidoptera: Crambidae: Spilomelinae), est un ravageur des cultures de café présent en Afrique subsaharienne. A La Réunion, P. smaragdina est le principal insecte ravageur de la culture du caféier ‘Bourbon Pointu’, café de haute qualité reconnu à l'échelle internationale. Le plan gouvernemental ECOPHYTO, ajouté aux enjeux environnementaux, contraignent les producteurs de café à réduire l'utilisation de pesticides qui est la seule solution efficace actuelle contre P. smaragdina. Cette thèse a été entreprise afin d'améliorer nos connaissances sur la bio-écologie et l'écologie chimique de P. smaragdina afin de développer une méthode de lutte biologique contre cet insecte. L'étude de la biologie a montré que la population de P. smaragdina était la plus importante au début de la période de fructification c'est-à-dire en janvier. Une corrélation positive entre la température et la densité de population a été montrée. Quatre parasitoïdes de P. smaragdina ont été identifiés à La Réunion. Parmi eux, Pristomerus rivier (Hymenoptera: Ichneumonidae) est révélé comme parasitoïde candidat pour une éventuelle lutte contre P. smaragdina par l'utilisation d’ennemis naturels. Les observations du comportement d’accouplement ont montré que, comme la plupart des lépidoptères hétérocères, la femelle attirait le mâle par l'émission d'une phéromone sexuelle. Quatre molécules suspectés de composer la phéromone femelle ont été identifiées par chromatographie en phase gazeuse couplé à la spectrométrie de masse (GC/MS). Les tests d'électroantennographie (EAG) ont montré que le composé majoritaire identifié induisait une réponse significative des antennes mâles, le faisant candidat pour être le composé majoritaire de la phéromone femelle de P. smaragdina. Les tests de piégeage au champ avec les composés identifiés n'ont, jusque-là, pas entrainé de captures, probablement à cause d’un composé mineur manquant ou d'un mauvais ratio de composés dans les pièges. Il est suggéré que le mâle P. smaragdina émet une phéromone pendant le comportement de cour. L'analyse GC/MS des composés volatiles de pinceaux androconiaux des mâles a mis en évidence cinq composés aromatiques. Les tests EAG des composés identifiés sur les antennes des mâles et des femelles suggèrent que le créosol pourrait jouer un rôle sur les comportements du mâle et de la femelle. / The Coffee berry moth, Prophantis smaragdina (Lepidoptera: Crambidae: Spilomelinae) is an important pest of coffee mainly recorded in sub-Saharan Africa. In Reunion Island, P. smaragdina is the only insect pest of coffee. P. smaragdina larvae, by eating coffee cherry albumen, cause major yield losses in ‘Bourbon Pointu’ (BP) production, which is a high value-added and internationally known coffee. Governmental ECOPHYTO plan, added to environmental concerns, constrain coffee farmers to reduce insecticide spraying which is, until now, the only efficient control method of P. smaragdina. This thesis was undertaken to improve our knowledge of the bio-ecology and chemical ecology of P. smaragdina to develop an efficient and economically sustainable biocontrol method against this insect. Our bio-ecology study showed that P. smaragdina population was the most abundant at the beginning of BP fructification period i.e in January. A positive correlation between temperature and P. smaragdina population density was showed. Four parasitoids of P. smaragdina in Reunion were identified. Among them, Pristomerus rivier (Hymenoptera: Ichneumonidae) is a potential candidate for P. smaragdina biocontrol. Mating behaviour observations showed that, as most of moths, the female emits a sexual pheromone to attract males for mating. Four compounds suspected to compose the female pheromone identified using gas chromatography coupled with mass spectrometry (GC/ MS). Electroantennography (EAG) test on male showed that the major identified compound induced a response of male antennae, it could be the major compound of P. smaragdina female pheromone. Field trapping tests with identified compounds, until now, did not yield any captures, probably because of a lack of minor pheromone components or because of erroneous compounds ratios used in traps. A study of P. smaragdina courtship behaviour suggested that the male of P. smaragdina emits pheromone. Five aromatic compounds were identified in male hair pencil volatiles by GC/MS. EAG tests of those compounds on male and female antennae suggest that creosol could play a role on male and female behaviour.

Orientadores: João Vasconcellos Neto, Miguel Francisco de Souza Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T15:26:25Z (GMT). No. of bitstreams: 1 Freitas_KelsenFerreira_D.pdf: 2228671 bytes, checksum: 0a1e387d8f6a78f2474f17326ed55b42 (MD5) Previous issue date: 2014 / Resumo: As espécies de plantas disponíveis em uma comunidade, sua estrutura e abundância são elementos cruciais que influenciam nas dinâmicas e interações de populações de insetos herbívoros, uma vez que definem a base de recursos e refletem na interação com outras populações de insetos herbívoros, como predadores e parasitoides. Estudos relacionados às moscas-das-frutas concentram-se em levantamentos de espécies, em especial aquelas consideradas pragas, e abordam principalmente os padrões populacionais. A densidade populacional de tefritídeos e lonqueídeos está intimamente ligada à abundância de plantas hospedeiras e de seus inimigos naturais. Os parasitoides das moscas-das-frutas são micro-himenópteros (Hymenoptera) que atacam e se alimentam das larvas dentro dos frutos. O reconhecimento de padrões de interação das moscas-das-frutas com plantas hospedeiras, em especial nas espécies nativas, e as relações com seus inimigos naturais são importantes para a compreensão da utilização dos recursos disponíveis em uma comunidade e pelo reconhecimento de diferenças na dieta entre as espécies ou populações de uma mesma espécie. O objetivo deste trabalho foi estudar a estrutura da comunidade de moscas-das-frutas e seus parasitoides em diferentes espécies de plantas em uma policultura orgânica entre fragmentos de Mata Atlântica localizada no município de Paraibuna. A utilização de plantas hospedeiras difere entre as espécies de moscas-das-frutas. Apesar de a policultura causar alterações da fisionomia vegetal, foi observado que a estrutura da comunidade de moscas-das-frutas possui características encontradas em comunidades de insetos de florestas tropicais, onde espécies de insetos frugívoros são mais especialistas em família de plantas. A utilização de plantas hospedeiras foi distinta entre as espécies de parasitoides. O fruto foi o fator que mais influenciou o parasitismo das larvas de moscas-das-frutas. As espécies da família Myrtaceae são reservatórios para as espécies de parasitoides da família Braconidae. As interações estabelecidas entre as moscas-das-frutas e as espécies de plantas hospedeiras e entre os parasitoides de moscas e as plantas hospedeiras foram marcadas pela heterogeneidade no número de interações, sendo que um pequeno número de espécies de moscas estabeleceu relações com um grande número de espécies vegetais, enquanto que a maioria delas estabeleceu interações com apenas uma espécie vegetal e vice-versa, apresentando as mesmas propriedades de uma rede de interação aninhada. A interação potencial entre moscas-das-frutas e parasitoides também possuem os padrões de aninhamento. A paisagem natural modificada em policultura apresentou semelhanças com outras comunidades de insetos frugívoros de regiões tropicais / Abstract: The plant species found in a community, their structure and abundance are crucial elements that influence the dynamics and interactions of populations of herbivorous insects since they define the resource base and reflect the interaction with other populations of herbivores, predators and parasitoids. The studies related to fruit flies are concentrated on surveys of species, especially those considered pests, and address the population patterns. Many efforts to understand the patterns of communities of endophagous frugivorous insects and the use of host plants. The population density of tephritids and lonchaeids is closely connected to the abundance of host plants and their natural enemies. The parasitoids of fruit flies are hymenopteran parasitoids that attack and feed on the larvae inside the fruit. The acknowledgment of interaction patterns of fruit flies with host plants, especially the native species, and relationships with their natural enemies are important for understanding the use of available resources in a community and for recognizing the diet differences between species or populations of the same species. The purpose of this work was to study the structure of the community of fruit flies and their parasitoids in different plant species of an organic polyculture between forest fragments located in Paraibuna ¿ SP. The use of host plants was different among species of fruit flies. Although polyculture causes changes in vegetation type, it was observed that the structure of the fruit flies has features found in insect communities in tropical forests, where most species of frugivorous insects are specialists in plant family community. The use of host plants that sheltered the larvae of fruit flies was different among species of parasitoids. The fruit was the factor that most influenced the parasitism of the larvae of fruit flies. The Myrtaceae species are reservoirs to the parasitoid species of braconids. The interactions established between the fruit flies and species of host plants and between parasitoids and host plants that sheltered larvae of fruit flies were marked by heterogeneity in the number of interactions, where a small number of species of flies established relations with a large number of plant species, while most of these interactions established with only one plant species, and vice versa, with the same properties of a nested interaction network. The potential interaction between fruit flies and parasitoids also have patterns of nesting. The modified natural environment in polyculture showed similarities with other communities of frugivorous insects in tropical regions / Doutorado / Biodiversidade Animal / Doutor em Biologia Animal

Orientador: José Roberto Trigo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T19:23:05Z (GMT). No. of bitstreams: 1 Massuda_KamilaFerreira_D.pdf: 3476211 bytes, checksum: a20550d22526cbcb5a72c290cf3e8ff1 (MD5) Previous issue date: 2015 / Resumo: As interações entre os insetos herbívoros e as plantas foram moldadas ao longo de um extenso processo coevolutivo, que gerou adaptações das plantas para evitarem a herbivoria e contra-adaptações dos herbívoros para superarem as defesas impostas pelas plantas. As folhas de Ipomoea carnea subsp. fistulosa (Convolvulaceae) são atacadas pelos besouros Cassidinae (Chrysomelidae), Chelymorpha reimoseri, Chelymorpha cribraria e Charidotella rubicunda. Esses besouros depositam seus ovos nas folhas e se alimentam das mesmas nos estágios de larva e adulto. Nesse trabalho, demonstramos a eficácia de dois mecanismos de defesa de I. carnea contra a deposição de ovos por C. reimoseri: (1) o descolamento de posturas, devido a formação de neoplasmas abaixo da postura e (2) a atração de parasitoides de ovos, por voláteis liberados de plantas induzidas pela própria postura ou por um indivíduo realmente capaz de ovipor, uma fêmea que copulou. Além disso, demonstramos duas estratégias de defesa para as três espécies cassidíneas supramencionadas contra predadores: (1) a impalatabilidade, devido ao alcaloide swainsonina, sequestrado da planta hospedeira e cuja atividade deterrente foi demonstrada para Gallus gallus e (2) a camuflagem química das larvas de C. reimoseri nas folhas da planta hospedeira, devido à alta similaridade química entre seus compostos cuticulares e os da planta hospedeira larval, que dificulta o reconhecimento por predadores quimicamente orientados / Abstract: The interactions between herbivorous insects and plants have been shaped over a co-evolutionary process that spawned adaptations of plants to avoid herbivory and counter adaptation of herbivores to overcome the defenses imposed by plants. The plant Ipomoea carnea subsp. fistulosa (Convolvulaceae) has as herbivores, beetles of Cassidinae subfamily (Chelymorpha reimoseri, Chelymorpha cribraria, and Charidotella rubicunda), which use the leaves to feed larvae and adults, as well as places for depositing their eggs. This study demonstrated the efficiency of two I. carnea defensive mechanisms against oviposition by C. reimoseri: (1) the detachment of eggs neoplasm formation, below the eggs, and (2) the attraction of eggs parasitoids by volatile released from posture-induced plants and plants induced by an individual capable of laying eggs, a mated female. Furthermore, we demonstrated the effectiveness of two defensive strategies in the three above mentioned cassidine species; (1) the unpalatability, due to swainsonine, an akaloid provided by the host plant, and its deterrent effect against predator, the chicken Gallus gallus; (2) the chemical camouflage of C. reimoseri larvae on its host plant, due to high chemical similarity among their cuticular compounds that turns difficult recognition by a chemical oriented predator / Doutorado / Doutor em Ecologia

Le développement larvaire de Leptopilina boulardi (guêpe endoparasitoïde) a lieu dans la larve de Drosophile hôte, principalement D. melanogaster. La réponse immunitaire de l’hôte est l’encapsulement, formation d’une capsule mélanisée formée de couches d’hémocytes spécialisés, les lamellocytes, autour de l’œuf du parasitoïde. Le succès de L. boulardi repose sur l’injection de venin qui bloque l’action des lamellocytes. Ce venin, contient des composants protéiques et des vésicules originales baptisées vénosomes. J’ai montré que deux facteurs de virulence (VFs), LbGAP et LbGAP2, s’intègrent aux vénosomes lors de leur assemblage qui semble se faire de façon extracellulaire dans le canal reliant la glande à venin au réservoir. La microinjection de vénosomes purifiés comme celle du venin inhibe l’encapsulement. Les vénosomes marqués par fluorescence et les VFs co-immunolocalisent dans les lamellocytes de l’hôte après injection, leur internalisation passe par une endocytose flotilline/raft-domaine dépendante. Le taux d’internalisation diffère fortement entre les espèces hôtes de Drosophile testées (D. melanogaster>D. simulans>D. yakuba>D. suzukii) et il est corrélé au taux de réussite parasitaire, suggérant l’existence d’un récepteur spécifique sur les lamellocytes de D. melanogaster. Grâce à la souche mutante HopTum-l qui produit des lamellocytes constitutivement, j’ai séparé ces cellules et entrepris l’analyse protéomique de leur membrane pour identifier des récepteurs candidats. Mes résultats démontrent que les vénosomes sont des véhicules de transport interespèces impliqués dans la virulence parasitaire et qu’ils représentent un nouveau niveau de spécificité d’hôte. / Endoparasitoid wasps, such as Leptopilina boulardi (Figitidae), develop inside Drosophila host larvae, mainly D. melanogaster. Egg oviposition normally results in a capsule formation by specialized haemocytes, the lamellocytes, associated with a melanization reaction. The parasitic success of L. boulardi relies on injection with the egg of venom that blocks the action of lamellocytes. This venom, synthesized at the level of a specialized gland and stored in a reservoir, contains protein components and original vesicles (venosomes). I have shown that two described virulence factors, LbGAP and LbGAP2 (VFs), are embedded in venosomes during their assembly which seems to occur extracellularly in the duct connecting the venom gland to the reservoir. Microinjection of purified venosomes protects the egg from encapsulation like venom injection. Fluorescently labelled venosomes and VFs co-immunolocalize in lamellocytes after injection and their internalization involves a flotillin/raft-domain-dependent endocytosis. The venosomes internalization rate differs significantly between the Drosophila host species tested (D. melanogaster>D. simulans>D. yakuba>D. suzukii) and is correlated with the parasite success rate, suggesting the existence of specific receptor on lamellocytes of D. melanogaster. Using the HopTum-1 mutant that constitutively produces lamellocytes, I have purified these cells and performed proteomic analysis of their membrane to identify candidate receptors. My results demonstrate that venosomes are interspecies transport vehicles involved in parasite virulence that represent a new level of host specificity.

Une régulation biologique plus efficace des ravageurs des grandes cultures par leurs ennemis naturels nécessite une meilleure compréhension de la biologie de ces espèces et de leurs patrons de dispersion dans les paysages agricoles. L’objectif de ce travail est d’améliorer les connaissances sur la dynamique des populations de méligèthes et de leur parasitoïde principal. A l’aide de microsatellites, nous avons montré que la structuration génétique des populations de méligèthes était faible en Europe, celle de T. heterocerus est sensiblement plus forte. Avec des modèles statistiques appliqués aux abondances de méligèthes, nous avons montré qu’ils parcourent en moyenne 1,2 km après l’hivernation. Cette distance moyenne de dispersion est comparable à celle estimée à partir de résultats d’assignation de parentés génétique entre paires d’individus. Avec des relevés de terrain, nous avons quantifié et identifié les déterminants de la présence de méligèthes dans d’autres habitats que le colza. Au printemps, ils peuvent être observés dans des prairies, des friches et des bords de champs, où se trouvent des fleurs jaunes. En été, les méligèthes sont présents dans ces habitats, partout où il y a des fleurs, sans distinction de couleurs, surtout sur les adventices des cultures. Enfin, la présence de parasitoïdes semble plus fortement déterminée par la présence de méligèthes que par des éléments paysagers. Le paysage joue un rôle déterminant sur ce couple d’espèces. De plus, les estimations des paramètres démographiques réalisées pourront aider par la modélisation à dimensionner les actions à mener pour limiter les dégâts causés par les méligèthes. / More effective biological regulation of field crop pests by their natural enemies requires a better understanding of the biology of these species and their patterns of dispersal in agricultural landscapes. The objective of this work is to increase knowledge on the dynamics of pollen beetles populations and their main parasitoid. Using an approach based on the analysis of microsatellites, we have shown that the genetic structuring of pollen beetle populations in Europe is weak. Populations of T. heterocerus are more structured. With statistical models applied to the abundance of pollen beetles, we have shown that they travel an average of 1.2 km, after overwintering. This average distance is comparable to that estimated from results of sibship analysis between pairs of individualsWith fieldwork, we quantified and identified the determinants of pollen beetles presence in habitats other than rapeseed. In spring, pollen beetles can be seen in grasslands, fallows and field edges with yellow flowers. In summer, pollen beetles are present in these habitats, wherever there are flowers, without distinction of colour, especially on the weeds of crops. Finally, the presence of parasitoids seems to be more strongly determined by the presence of pollen beetles than by landscape elements. The landscape plays a decisive role on this pair of species. Moreover, throught modelling, estimates of the demographic parameters carried out would help to shape the actions to be taken to limit the damage caused by pollen beetles.

Agrilus planipennis, the emerald ash borer (EAB), is a destructive invasive forest pest decimating North American ash trees. Population-wide management of EAB focuses on biological control, with the introduction of four parasitic wasps; one egg parasitoid, Oobius agrili and three larval parasitoids- Spathius galinae, Spathius agrili and Tetrastichus planipennisi. This thesis examines some of the factors influencing the establishment of these larval biocontrol agents. Chapter 1 examines the relationship between woodpeckers and the parasitoids S. agrili and T. planipennisi. Both woodpeckers and these parasitoids attack the larval stage of EAB, which means their impacts overlap and potentially interact. To examine this relationship, I established parasitized larvae on ash trees and then used screening to exclude woodpeckers from some sections of the tree. Results show that while there is no evidence of discriminatory feeding for or against parasitized larvae, the presence of parasitized larvae changes woodpecker feeding behavior at a stand-level. I hypothesize that this change is due to these larval parasitoids being a low-food reward and that parasitism contributes to a change and decrease in patch quality, causing woodpeckers to quit foraging sooner than usual. My second chapter focuses on Spathius galinae, which was recently approved for release in the north central and northeastern US in 2015, to provide additional population control. Spathius galinae’s long ovipositor (4-5.3mm) is theoretically expected to help target EAB in ash with larger diameters and bark thicknesses. Using experimentally infested logs of varying thicknesses in the laboratory I tested the limits and preferences for oviposition of S. galinae, to understand its potential impact on EAB. My results demonstrated that although parasitism by S. galinae drops significantly when bark thickness reaches 8 mm, this prevents S. galinae only from reaching EAB larvae in my largest ash trees (S. galinae will play a vital role in providing additional control and in supporting ash regeneration in aftermath areas of EAB invasions.

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a serious pest of crucifer vegetables (Brassica sp.) worldwide because of a lack of effective natural enemies in certain regions and because of insecticide resistance. In 2003, laboratory and field studies were initiated in Virginia to better understand P. xylostella, its primary natural enemies, and their susceptibilities to insecticides in order to develop an economically and environmentally sound integrated pest management program for collards in the state. Ecological life table studies of P. xylostella immature stages on collards located on the Eastern Shore and on Kentland Farm, near Blacksburg at the New River Valley, VA revealed that most (98 to 99%) of P. xylostella died from natural causes. Mortality factors varied between the two regions. Neonates, small larvae, and large larvae disappearing were major mortality factors. Rainfall, predation, and dispersal probably contributed the most to this mortality. Egg mortality played a bigger role at the New River Valley compared with the Eastern Shore. Three parasitoid species were found that contributed to the mortality of P. xylostella: Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae); Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae); and Microplitis plutellae (Muesebeck) (Hymenoptera: Braconidae). Additional studies conducted in the laboratory using leaf-dip bioassays revealed that P. xylostella collected from the Eastern Shore of Virginia, showed significant tolerance levels to esfenvalerate, acetamiprid, methomyl, methoxyfenozide, indoxacarb, and acephate compared with a susceptible strain of P. xylostella. The highest tolerance ratio (1,876 fold) was to esfenvalerate, a commonly-used pyrethroid. All of the insecticides tested in this study were quite toxic to the adult stage of the parasitoids, D. insulare and O. sokolowskii. The insect growth regulator, methoxyfenozide was considerably less toxic than other insecticides such as esfenvalerate, methomyl, acephate, spinosad, indoxacarb, and emamectin benzoate at field-rate and 1% of field-rate concentrations. The aforementioned insecticides as well as some other insecticides were evaluated several times in the field for efficacy against P. xylostella as well as other pests of collards. The most efficacious insecticides over five field experiments included acephate, emamectin benzoate, esfenvalerate, methomyl, methoxyfenozide, novaluron, indoxacarb, and spinosad. These insecticides were followed in relative efficacy by Bt kurstaki, acetamiprid, and azadirachtin, which provided relatively inconsistent control of lepidopteran larvae over the experiments. Effective insecticide options in collards that are less toxic to natural enemies and that can fit well into integrated pest management programs include indoxacarb, spinosad, novaluron, emamectin benzoate, methoxyfenozide, and Bacillus thuringiensis subsp. kurstaki. / Ph. D.

The ecology and evolution of a species is often considered only within the context of pairwise interactions even though a species' distribution and abundance may be determined by interactions with many species within and between trophic levels. Multiple herbivores often share the same host and may interact indirectly by altering the relationships between herbivores, their host plants and their parasitoids. However, the relationships between parasitoids and herbivore hosts have typically been studied in isolation of other herbivore species. I examined how the outcomes of species interactions change when multiple relationships are considered. Chapter 1 examined the potentially conflicting selection pressures Manduca sexta exerts on Nicotiana tabacum (tobacco), since M. sexta has pollinating adults but herbivorous larvae. I demonstrated that high nectar amino acids do not affect floral visitation, but increased oviposition of herbivores on leaves. Thus, the relative costs and benefits of nectar rewards may depend on the community of pollinators and their life histories. In the remaining chapters I examined how feeding on tobacco by the aphid Myzus persicae altered the interactions between a parasitoid (Cotesia congregata) and its hornworm host (M. sexta). Chapter 2 demonstrated that aphids reduced hornworm abundance and parasitism. Changes in hornworm abundance were not due to density-dependent changes in moth oviposition, but the proportion of caterpillars attacked by parasitoids was inversely density dependent with hornworm density. Chapter 3 examined whether changes in hornworm abundance and parasitism reflected aphid-induced changes in host plant quality or volatile emissions. Aphids increased hornworm mortality, did not affect parasitoid performance, and increased parasitoid search time. In combination with Chapter 2, results suggest that aphids can mediate parasitoid-caterpillar interactions through changes in host plants that reduce hornworm survival and alter parasitoid behavior. Chapter 4 addressed how the outcome of interactions that are altered by aphids changed with spatial scale, and found no effect spatial scale on hornworm abundance and parasitism. In this system, aphids alter parasitoid-caterpillar interactions through changes in plant quality that reduce hornworm performance and abundance, and in turn, influence parasitoid attack. This work demonstrates that the outcome of multispecies interactions may not be predictable from pairwise interactions. / Ph. D.

Horticulture is a major foreign exchange earner in Kenya and provides employment to approximately 75% of the population. However, the growth of the horticultural industry is constrained by pests such as the leafminer flies, Liriomyza sativae, L. trifolii and L. huidobrensis (Diptera: Agromyzidae). These pests do not only cause damage to crops, but are also tagged as quarantine pests, resulting in export rejections, loss of export markets and consequently loss of revenue to smallholders. The management of leafminers worldwide has commonly relied on the use of chemical insecticides, but due to associated negative effects thereof, biological control using parasitoids and entomopathogenic fungi has been proposed as major components of integrated pest management (IPM) strategies. The indigenous ectoparasitoid Diglyphus isaea and exotic endoparasitoid Phaedrotoma scabriventris are the two key natural enemies being considered. A number of endophytic fungal isolates have been identified with potential for use as biological control agents of pests. Although there have been previous reports on toxicity of fungal endophytes to leafminers, no attempts have been made to exploit them for control of Liriomyza leafminers. The objectives of this study were to investigate the mechanisms by which fungal endophytes control Liriomyza spp., as well as the interactions between these endophytic fungi and the L. huidobrensis, endoparasitoid Phaedrotoma scabriventris and ectoparasitoid Diglyphus isaea. This study showed that under laboratory conditions, while used separately, parasitism rates of L. huidobrensis by D. isaea and P. scabriventris were 63.6 ± 7.7% and 30.4 ± 10.9% respectively and increased to 77.0 ± 5.3% when used simultaneously. In addition, both parasitoids induced leafminer mortality through larval-feeding and stinging. In order to identify and characterize endophytic fungi that could possibly be used for control of these pests, fungi were isolated from the aboveground parts of maize, sorghum, Napier grass, Coleopteran larvae and Busseola fusca pupae. Identified fungi were evaluated endophytically in two host plants species (Phaseolus vulgaris and Vicia faba) through seed inoculation. The fungal isolates that succeeded in colonizing the host plants were all pathogenic to L. huidobrensis, causing 100% mortality within 13.2 ± 0.7-15.0 ± 0.6 days. They were also able to reduce the longevity of the progeny, the number of pupae and adult emergence and survival. In addition, results also showed that endophytically-inoculated and L. huidobrensis-infested V. faba plants had no adverse effects on parasitism rates and life history parameters of P. scabriventris and D. isaea. Bio-prospecting for fungal endophytes in P. vulgaris and V. faba seeds, followed by morphological and molecular identification revealed the presence of various species of fungal entomopathogens, including Beauveria bassiana, Epacris microphylla, Phanerochaete chrysosporium and Metarhizium anisopliae. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2013