Les rodenticides anticoagulants (RA) constituent le principal moyen de lutte contre les rongeurs. L’exposition aux RA du renard roux et l’impact des RA sur les populations de ce prédateur sont étudiés. En France, on distingue un contexte « biocide » (BCD) où les RA sont principalement utilisés près des bâtiments et un contexte « phytopharmaceutique » (PP) où la bromadiolone (un RA) est également utilisée en plein champs contre le campagnol terrestre. La contamination des rongeurs aux RA est mesurée : 5 RA sont détectés en contexte BCD alors que la bromadiolone est la molécule majoritaire en contexte PP ; les espèces de rongeurs non ciblées par les RA étant exposées dans les2 contextes. L’exposition est maximale chez les espèces ciblées ou celles au mode de vie similaire.L’exposition du renard est évaluée par la mesure des résidus de RA dans des fèces collectées in situ.La bromadiolone est retrouvée dans 97 % des fèces positives et les RA sont plus retrouvés dans les fèces en cas de traitements PP. En contexte PP, le ratio de fèces positives augmente non linéairement avec la surface traitée dans un rayon d’1 km autour des fèces. L’impact des traitements PP sur les populations de renards est évalué (période 2003-2009, département du Doubs). Les indices d’abondance de renard mesurés sur une commune le printemps d’une année n diminuent avec l’augmentation des quantités d’appâts utilisées les années n-1 et n-2. Pendant la période suivie,la mise en place d’une lutte intégrée contre le campagnol terrestre s’est traduite par une diminution des quantités d’ AR utilisées et donc par une diminution des impacts sur les populations de renards. / Rodents are mainly controlled with anticoagulant rodenticides (AR). AR exposure and impact were studied for red fox populations. In France, we distinguish 2 contexts of AR use: “biocide” (BCD) where AR are used next to buildings and “phytopharmaceutical” (PP) where bromadiolone (an AR) is also applied in the field against the water vole. Rodent contamination to AR was characterized: 5 differentAR were detected in rodents in the BCD context while bromadiolone was predominantly found in thePP context; non target rodents being exposed in both contexts. AR contamination was the highest fortarget species or species with similar lifestyle. Red fox exposure was assessed through themeasurement of AR residues in faeces sampled in the field. ARs were detected more frequently where PP treatments occurred. Every positive faeces contained only bromadiolone except one (BCD context)with chlorophacinone. In PP context, the ratio of positive faeces varied non-linearly with the area of PPtreatments within a 1km-radius around faeces. The impact of bromadiolone PP treatments on red fox populations was assessed (period 2003–2009, Doubs department). Kilometric Abundance Index offoxes measured a year n decreased with higher treatment intensities the years n-1 and n-2. Moreoverwe have shown that a shift to preventive treatments with reduced AR use is less harmful to fox populations.

Lasioderma serricorne (F.) (Fabricius, 1792) (Coleoptera: Anobiidae) is a cosmopolitan plague popularly known as a tobacco beetle that attacks a wide variety of stored agricultural products, like soybeans, escavating galleries in the grains while feeding and consequently generating losses to the producers by the loss of quality and value of the seeds. Due to the risks of intoxication and environment contamination with chemical residues, as well as the emergence of resistant individuals, other approaches to the control of L. serricorne have been sought. The host plant kairomones are molecules with potential for application as food attractants in traps for monitoring and capture insects. On the other hand, the evaluation of essential oils (EO) of native plants cultivated locally, can contribute to the discovery of useful compounds as natural repellents or bio-insecticides, also generating tools useful in integrated pest management (IPM). The objective of this study was to investigate and identify the volatile organic compounds released by stored soybeans from 3 varieties cultivated in Brazil with attractiveness to adults L. serricorne (soybean marketed in large supermarket chains in Maceió-AL and two varieties EMBRAPA BRS284 and BRS360RR) and to test the EO activity of the mature fruits of Schinus terebinthifolius, in order to promote the prospection of natural compounds with potential for application in the integrated management of this pest in storage environments. The attractiveness of grains and extracts prepared by dynamic headspace collection was evaluated in 4-arm olfactometer behavioral bioassays, while the isolation and identification of the bioactive compounds were carried out using gas chromatography coupled to electroanthennography (GC-EAG) and gas chromatography coupled to mass spectrometry (GC-MS). Five EAG-active compounds were identified in the extracts of soybeans: 1-octen- 3-ol, 3-octanol, 1- nonanol, linalool and limonene. The behavioral response of L. serricorne in 4-arm olfactometer bioassays to synthetic compounds was statistically significant for 1- octen-3- ol, 3-octanol, 1-nonanol and linalool, while the attraction for the 4 synthetic blend was comparable to that verified for soybeans. The activity of the EO extracted by steam-drag of the mature fruits of S. terebinthifolius (3 replicates) harvested from matrices located on the A. C. Simões Campus of UFAL, Maceió-AL, on L. serricorne adults was tested in 4-arm olfactometer bioassays , in two concentrations (1 and 10 μL), while the EO composition was analyzed by GC-FID and GC-MS. EO repellency was checked at a dose of 10 μL. A total of 14 compounds were identified in S. terebinthifolius EO, with the main components being β-pinene (49.8%), α-pinene (33.49%), 3-carene (5.85%), germacrene-D (2.08%) and bornylene (1.21%). The attractive compounds identified from the soybean grains act as kayromones for L. serricorne, while the S. terebinthifolius EO has repellent activity against this pest, so the results obtained here can be applied in the development of bioproducts for the integrated management of L. serricorne in and around storage environments, favoring the rational use of insecticides. / Lasioderma serricorne (F.) (Fabricius, 1792) (Coleoptera: Anobiidae) é uma praga cosmopolita conhecida popularmente como besourinho do tabaco que ataca uma grande variedade de produtos agrícolas armazenados, dentre eles a soja, escavando galerias nos grãos enquanto se alimentam e consequentemente gerando prejuízos aos produtores pela perda da qualidade e valor das sementes. Devido aos riscos de intoxicação e de contaminação do meio ambiente com resíduos químicos, assim como o surgimento de indivíduos resistentes, outras abordagens para o controle de L. serricorne tem sido buscadas. Os cairomônios das plantas hospedeiras são moléculas com potencial para aplicação como atraentes alimentares em armadilhas para monitoramento e captura de insetos. Por outro lado, a avaliação de óleos essenciais (OE) de plantas nativas cultivadas localmente, pode contribuir para a descoberta de compostos úteis como repelentes ou bioinseticidas naturais, gerando também ferramentas úteis manejo integrado de pragas (MIP). O objetivo desse estudo foi investigar e identificar os compostos orgânicos voláteis liberados pelos grãos de soja armazenados de três variedades cultivadas no Brasil com atratividade para adultos de L. serricorne (soja comercializada em grandes cadeias de supermercados em Maceió-AL e duas variedades EMBRAPA BRS284 e BRS360RR) e testar a atividade do OE dos frutos maduros de Schinus terebinthifolius, a fim de promover a prospecção de compostos naturais com potencial para aplicação no manejo integrado dessa praga em ambientes de armazenamento. A atratividade dos grãos e de extratos preparados por coleta dinâmica do headspace dos grãos foi avaliada em bioensaios comportamentais em olfatômetro de 4 braços, enquanto o isolamento e identificação dos compostos bioativos foram realizados pelas técnicas de cromatografia gasosa acoplada à eletroantenografia (CG-EAG) e cromatografia gasosa acoplada à espectrometria de massas (CG-EM). Cinco compostos EAG-ativos foram identificados nos extratos dos grãos de soja: 1-octen- 3-ol, 3-octanol, 1-nonanol, linalol e limoneno. A resposta comportamental de L. serricorne em bioensaios em olfatômetro de 4 braços aos compostos sintéticos foi estatisticamente significativa para 1-octen- 3-ol, 3-octanol, 1- nonanol e linalol, enquanto a atração pela mistura dos 4 compostos sintéticos foi comparável à verificada para os grãos de soja. A atividade do OE extraído por arraste a vapor dos frutos maduros de S. terebinthifolius (3 repetições) colhidos de matrizes localizadas no campus A. C. Simões da UFAL, Maceió-AL, sobre adultos de L. serricorne foi testada em bioensaios em olfatômetro de 4 braços, em duas concentrações (1 e 10μL), enquanto a composição do OE foi analisada por CG-FID e CG-EM. Foi verificada repelência do OE na dose de 10 μL. Foram identificados 14 compostos no OE de S. terebinthifolius, sendo os componentes principais: β-pineno (49,8 %), α-pineno (33,49 %), 3-careno (5,85 %), germancreno-D (2,08 %) e bornileno (1,21 %). Os compostos atrativos identificados a partir dos grãos de soja atuam como cairomônios para L. serricorne, enquanto o OE de S. terebinthifolius possui atividade repelente contra essa praga, portanto os resultados aqui obtidos podem ser aplicados no desenvolvimento de bioprodutos para o manejo integrado de L. serricorne dentro e ao redor de ambientes de armazenamento, favorecendo a utilização racional de inseticidas.

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<p>  </p> <p>Environmental conditions, like light quality and herbivory, can induce changes in plant physiology. Light quality can be manipulated using LEDs (light emitting diodes) to improve crop quality and yield in horticultural production. The manipulation of light quality has also been utilized in the management of agricultural insect pests. Previous research has provided evidence that changes in light quality can have effects on the growth and chemistry of cannabis crops (<em>Cannabis spp.</em>). Varieties of cannabis are grown for the production of the valued cannabinoids CBD and THC. Pest of cannabis include herbivorous arthropods that reduce hemp yield and quality. Arthropod herbivory can induce chemical and physical changes in plants. This thesis further investigates the role of light quality on both cannabis biology and the crop-pest interaction between cannabis and the cannabis aphid (<em>Phorodon cannabis</em>). In the experiments described herein, the effects of light quality and <em>P. cannabis </em>herbivory on cannabis were assessed by measuring impact on biomass accumulation, yield, and the production of CBD and THC. The effects of light quality on the life history traits of <em>P. cannabis </em>were also measured. Cannabis grown under red-blue light quality saw a reduction in vegetative growth but no reduction in yield. Light treatments had no measured effect on the concentrations of CBD and THC in the cannabis buds. Aphid herbivory decreased bud yield but increased vegetative growth. Aphid herbivory reduced the concentration of both CBD and THC in cannabis bud tissue. Under blue-rich light quality, <em>P. cannabis </em>experienced higher reproductive rates when compared to red-blue and full-spectrum lighting. </p>

Since many years, the agro-technical programs such as '3 reduction 3 increase', '1 must 5 reduction' and System of Rice Intensification (SRI) have been carried out with definite results. Recently, IPM program (integrated pest management) – a more comprehensive measure (using all possible techniques and methods to keep the pest populations below a level causing economic injury) – has been firstly piloted on a large scale in the Mekong Delta. This paper presents the main results of piloting IPM program in 2,610 hectares during 2014-2017 in Hau Giang province. As results, farmers have better economic benefit in production; the quality of rice has been gradually improved and can overcome the technical barriers of advanced countries in rice trade such as US, EU and Japan. In addition, the environmental and ecological consequences can be avoided due to overuse of fertilizer and pesticide. Field ecosystems will be gradually restored. / Từ nhiều năm nay những chương trình kỹ thuật nông nghiệp như '3 giảm 3 tăng', '1 phải 5 giảm' và hệ thống canh tác lúa cải tiến (SRI) đã được áp dụng và đã có những kết quả nhất định. Còn chương trình quản lý dịch hại tổng hợp IPM - một biện pháp tổng hợp và tích cực hơn (sử dụng tất cả các kỹ thuật và biện pháp thích hợp có thể được, nhằm duy trì mật độ của các loài gây hại dưới mức gây ra những thiệt hại kinh tế) – được thực nghiệm đầu tiên trên diện rộng ở Đồng bằng sông Cửu Long. Bài báo này trình bày những kết quả chính trong thử nghiệm ở 2.610 ha lúa trong thời gian 2014-2017 ở ở tỉnh Hậu giang. Kết quả là quản lý dịch hại ở ngưỡng cho phép, người nông dân có lợi hơn về kinh tế trong sản xuất, chất lượng gạo từng bước được cải thiện và có khả năng vượt qua các hàng rào kỹ thuật trong thương mại lúa gạo của các nước tiên tiến như USA, châu Âu, Nhật Bản. Ngoài ra tránh được hệ quả về môi trường sinh thái do sử dụng quá mức phân bón hóa học và ô nhiễm do thuốc bảo vệ thực vật và hệ sinh thái đồng ruộng dần được phục hồi.

Tesis por compendio / [EN] Aphis spiraecola Patch. (Hemiptera: Aphididae) is a key pest of clementines. Biological control of A. spiraecola is still poorly known and efforts were based on the use and conservation of parasitoids but it did not success. With all this said, the aims of this thesis were: i) to disentangle the reasons behind the low parasitism of A. spiraecola; ii) to determine when and how predators can control A. spiraecola populations; and, finally, iii) to evaluate whether a ground cover of Poaceae plants can enhance the biological control of this aphid in clementines by improving the establishment of its predators. In the first objective we sampled four orchards and determine the parasitoid complex and parasitism (and hyper-) rates weekly. Binodoxys angelicae Haliday (Hymenoptera: Braconidae) was the unique primary parasitoid emerged from mummies of A. spiraecola. At least six hymenopteran hyperparasitoid species were identified attacking this primary parasitoid: Syrphophagus aphidivorus (Mayr) (Encyrtidae), Alloxysta sp. (Forster) (Figitidae), Asaphes sp. (Walker) (Pteromalidae), Pachyneuron aphidis (Bouché) (Pteromalidae), Dendrocerus sp. (Ratzeburg) (Megaspilidae) and Phaenoglyphis villosa (Hartig) (Figitidae). We developed a DNA-based approach to untangle the structure of the aphid-parasitoid food web in citrus. This methodology confirmed that all six species hyperparasitized B. angelicae And they dominated this food web and they were abundant from the beginning of the season. Thus, hyperparasitism probably explains the low impact of B. angelicae on A. spiraecola populations. For the second objective we sampled three clementine orchards to determine the effect of aphid predators on A. spiraecola colonies over a three-year period. Life parameters of A. spiraecola colonies varied among the orchards over the three years. The maximum number of aphids and the longevity of A. spiraecola colonies were negatively correlated with the time of first attack by predators. More importantly, the percentage of shoots occupied by A. spiraecola (damages) remained below or close to the intervention threshold when colonies were attacked prior to ~200 degree days (DD) since the beginning of the aphid colonization. These results suggest that: i) the presence of predators at the beginning of the season should be considered to develop new intervention thresholds and ii) biological control programs should promote the early presence of predators in clementine orchards. To promote the early presence of predators in clementine orchards, in the third objective we evaluated ground cover management. This ground cover management may provide alternative preys to natural enemies. The effect of a sown ground cover (based on Poaceae plants) on the biological control of A. spiraecola was evaluated in four orchards with ground cover management compared with four orchards with bare soil management. This sown Poaceae cover coexists with a complex of wild plants that might also affect biological control of A. spiraecola. Finally, we compared the presence of A. spiraecola and its natural enemies in these orchards. While Poaceae plants represented ~66% of the ground cover, the rest of the cover comprised mainly Malva sp. (13%), Oxalis sp. (5%) and Sonchus sp. (2%). Poaceae plants harbored aphids which appeared sooner in the system than citrus aphids. These aphids serve as alternative prey/hosts for natural enemies. By contrast, Malva sp. and Sonchus sp. harbored aphids with potential to become citrus pest. Although these wild plants may act as reservoirs for A. spiraecola as well as other aphid species that can disrupt the biocontrol services of natural enemies, overall, the sown cover was effective in terms of biological control of A. spiraecola in the citrus canopy. It promoted the early presence of predators in citrus canopies. These attacks resulted in satisfactory aphid control, because citrus orchards with ground cover never exceeded the aphid economic threshold. / [ES] Aphis spiraecola Patch. (Hemiptera: Aphididae) es una de las plagas claves en el cultivo de clementinos. Los esfuerzos realizados hasta la fecha se han centrado en el uso y conservación de parasitoides aunque se desconocen las causas de su baja eficacia. Por todo ello, los objetivos de esta tesis han sido i) desentrañar las razones por las que se dan bajos niveles de parasitismo de A. spiraecola ii) determinar cuándo y cómo los depredadores pueden controlar las poblaciones de A. spiraecola y finalmente iii) determinar si una cubierta de poáceas puede mejorar el control biológico de este pulgón en clementinos mediante la mejora en el establecimiento de sus depredadores. En el primer objetivo se muestrearon semanalmente cuatro parcelas y se identificó el complejo de parasitoides y las tasas de parasitismo (e hiperparasitismo). Los porcentajes de parasitismo fueron bajos (~menos del 5%) y Binodoxys angelicae Haliday (Hymenoptera: Braconidae) fue el único parasitoide primario emergido de las momias de A. spiraecola. Se identificaron al menos seis especies de hiperparasitoides atacando este parasitoide primario: Syrphophagus aphidivorus (Mayr) (Encyrtidae), Alloxysta sp. (Forster) (Figitidae), Asaphes sp. (Walker) (Pteromalidae), Pachyneuron aphidis (Bouché) (Pteromalidae), Dendrocerus sp. (Ratzeburg) (Megaspilidae) y Phaenoglyphis villosa (Hartig) (Figitidae). Se desarrolló un método basado en la detección de ADN con el cual se confirmó que todas las especies de hiperparasitoides hiperparasitan B. angelicae. Los hiperparasitoides dominaron esta red trófica y fueron abundantes desde el inicio de la estación. De este modo, el hiperparasitismo probablemente explica el bajo impacto que B. angelicae tiene sobre las poblaciones de A. spiraecola. Para el segundo objetivo se muestrearon tres campos de clementinos donde se determinó el efecto de los depredadores en las colonias de A. spiraecola. Los parámetros de vida de las colonias de A. spiraecola variaron entre los diferentes cultivos los tres años. El máximo número de pulgones y la longevidad de las colonias de A. spiraecola se correlacionaron negativamente con el momento del primer ataque del depredador a la colonia. Cabe destacar que el porcentaje de brotes ocupados por A. spiraecola permaneció por debajo o cerca del umbral de tratamiento cuando las colonias fueron atacadas antes de los 200 grados días (GD) desde el inicio de formación de la colonia. Estos resultados sugieren: i) la presencia de depredadores al inicio de la temporada de pulgón debes ser considerado para el desarrollo de nuevos umbrales de tratamiento y ii) los programas de control biológico deben promover el adelanto de la presencia de depredadores en los campos de clementinos. Para promover la presencia anticipada de depredadores en los campos de clementinos, como tercer objetivo se evaluó el manejo de cubiertas vegetales a base de poáceas. Con este manejo se persigue aportar presas alternativas para los enemigos naturales de A. spiraecola. Para ello, se compararon cuatro campos de cítricos con cubierta vegetal frente a cuatro con suelo desnudo. En los campos con cubierta sembrada apareció además de las poáceas sembradas, un complejo de plantas salvajes que podrían afectar también el control biológico de A. spiraecola. Las poáceas representaron un 66% de la cubierta vegetal. Las poáceas y Oxalis sp. albergaron respectivamente pulgones estenófagos de plantas poáceas y Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae). Estas especies de pulgones aparecieron más pronto en el ecosistema que los pulgones de cítricos y sirvieron como presas/hospederos alternativos para los enemigos naturales. Al contrario, Malva sp. y Sonchus sp. albergaron especies de pulgón que podrían ser potenciales plagas de cítricos. El efecto total de la cubierta sembrada resultó positivo para el control de A. spiraecola. Por lo tanto, las parcelas de cítricos con cubierta vegetal tendieron a no / [CA] Aphis spiraecola Patch. (Hemiptera: Aphididae) és una de les plagues clau en el cultiu de clementins. Els esforços realitzats fins ara s'han centrat en el us i conservació de parasitoids encara que es desconeix les causes de la seua baixa eficàcia. Tenint en compte estos antecedents, els objectius d'esta tesis foren: i) desentrampar les raons per les quals els parasitoids no són efectius; ii) determinar quan i com els depredadors poden controlar les poblacions d'A. spiraecola; i finalment iii) determinar si una coberta de poàcies pot millorar el control biològic d'este àfid en clementins mitjançant la millora en el establiment del seus depredadors. En el primer objectiu es van mostrejar setmanalment quatre parcel·les i s'identificà el complex de parasitoids i les taxes de parasitisme (i hiperparasitisme). Binodoxys angelicae Haliday (Hymenoptera: Braconidae) va ser l'únic parasitoid primari emergit de les mòmies d'A. spiraecola. Se van identificar al menys sis especies d' hiperparasitoids atacant este parasitoid primari: Syrphophagus aphidivorus (Mayr) (Encyrtidae), Alloxysta sp. (Forster) (Figitidae), Asaphes sp. (Walker) (Pteromalidae), Pachyneuron aphidis (Bouché) (Pteromalidae), Dendrocerus sp. (Ratzeburg) (Megaspilidae) i Phaenoglyphis villosa (Hartig) (Figitidae). Se desenvolupà un mètode basat en la detecció de DNA amb el que es confirmà que totes les especies d'hiperparasitoids hiperparasiten B. angelicae. Els hiperparasitoids dominaren aquesta xarxa tròfica i foren abundants a l'inici de l'estació. Per tant, l'hiperparasitisme podria explicar el baix impacte que B. angelicae té sobre les poblacions d'A. spiraecola. Per al segon objectiu es mostrejaren tres camps de clementins on es determinà l'efecte dels depredadors en les colònies d'A. spiraecola. Els paràmetres de vida de les colònies d'A. spiraecola variaren entre les tres parcel·les els tres anys. El màxim número d'àfids i la longevitat de les colònies d'A. spiraecola es correlacionaren negativament amb el moment del primer atac del depredador a la colònia. Caldria destacar que el percentatge de brots ocupats per A. spiraecola es mantingué per baix o prop del llindar de tractament quan les colònies foren atacades abans dels ~200 graus dia (GD) des de l'inici de formació de la colònia. Estos resultats sugereixen que: i) la presència de depredadors a l'inici de la estació de l'àfid podria ser considerada per al desenvolupament de nous llindars de tractament i ii) els programes de control biològic deurien promoure l'avançament de la presència de depredadors en els camps de clementins. Per promoure la l'avançament de la presència de depredadors en els camps de clementins, com tercer objectiu s'avaluà el maneig de cobertes vegetals basades en poàcies. Amb aquest maneig es persegueix aportar preses alternatives per als enemics naturals d'A. spiraecola. Se compararen quatre camps de clementins amb coberta vegetal front a quatre amb sol nu. En els camps amb coberta sembrada creix, junt a les Poáceas sembrades, un conjunt de plantes salvatges que podrien afectar també el control biològic d'A. spiraecola. S'investigà quines especies de plantes componien la coberta vegetal així com les especies d'àfids que les habitaven. Les poàcies representaren un 66% de la coberta vegetal, sent les plantes salvatges més abundants Malva sp. (13%), Oxalis sp. (5%) i Sonchus sp. (2%). Les poàcies hostejaren àfids estenòfags de poàcies. Estes espècies d'àfid aparegueren més prompte en l'ecosistema que aquells àfids associats a cítrics. Al contrari, Malva sp. i Sonchus sp. hostejaren especies d'àfids que podrien ser potencials plagues de cítrics. Este últim grup pot atenuar l'atac dels enemics naturals a les poblacions d'A. spiraecola que habiten les copes. Encara així, l'efecte total de la coberta sembrada a base de poàcies va resultar positiu per al control d'A. spiraecola. En conseqüència les parcel·les de cítrics am / Gómez Marco, F. (2015). Integrated Pest Management of Aphis spiraecola (Hemiptera: Aphididae) in clementines: enhancing its biological control [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53732 / Compendio

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (obscure mealybug), is a common and serious pest of apples and pears in South Africa. Consumer and regulatory pressure to produce commodities under sustainable and ecologically compatible conditions has rendered chemical control options increasingly limited. Information on the seasonal occurrence of pests is but one of the vital components of an effective and sustainable integrated pest management system needed for planning the initiation of monitoring and determining when damage can be expected. It is also important to identify which orchards are at risk of developing mealybug infestations while development of effective and early monitoring tools for mealybug populations will help growers in making decisions with regards to pest management and crop suitability for various markets. It is also essential to determine the presence and efficacy of naturally occurring biological control agents in orchards so as to ascertain the potential of biological control as a viable alternative in orchards. However, under the current integrated pest management protocol, it has been difficult to determine this, due to the sporadic and relatively low incidence of mealybug infestations in some orchards, or by simply relying on naturally occurring field populations of biocontrol agents. Knowledge of the environmental conditions under which P. viburni population levels may become destructive is also essential for timing the release of insectary reared natural enemies as well as understanding the population ecology of this pest and its natural enemies. Information was gathered regarding the seasonal phenology of P. viburni and its natural enemies in pome fruit orchards in the Western Cape Province during the 2007/08 and 2008/09 growing seasons. Seasonal population studies showed that P. viburni has multiple overlapping generations with all life stages present throughout the year. The highest orchard infestations occurred during the summer period until early winter (January to early June). This was followed by a decrease in population from late June to November, before another increase in December. Presence-absence sampling of mealybugs on the host plant revealed that woody parts of the tree, such as the trunk and old stems were the most preferred sites for mealybug habitation, due to the availability of protected refuge sites. Migration of mealybug populations to newer growth and the upper sections of the tree crown, such as the new stems, leaves and eventually the fruit, was observed from December throughout the summer period until the early winter in June. Fruit colonization in both apples and pears commenced in January, when the fruit had developed a size sufficient for P. viburni to penetrate and occupy spaces such as the fruit core, calyx and stem end. There was no evidence of P. viburni occurring beneath the soil surface or on the roots of host trees. Two natural enemies of mealybugs, namely Pseudaphycus maculipennis (Mercet) and Coccidoxenoides perminutus (Girault), were found to be active in apple and pear orchards in the Western Cape. However, the status of C. perminutus as a parasite of P. viburni still needs to be verified despite evidence of emergence from P. viburni mummies, which was not sufficient enough to suggest that it is a useful biological control agent. Seasonal abundance trends of the two natural enemies revealed that their lifecycle is synchronized with that of the host. However, there was no evidence of P. maculipennis activity in Ceres. No predators were found during the course of this study. The rate of P. viburni parasitism at harvest was 46.52%, with P. maculipennis and C. perminutus constituting 98.966% and 1.034% of the parasitoids recovered from mealybug mummies, respectively. Studies on the use of pheromone traps as early monitoring tools for P. viburni showed that there was a positive and significant relationship between the fruit infestation and number of P. viburni adult males caught in pheromone-baited traps (r2 = 0.454). The action threshold level was estimated to be 2.5 male P. viburni caught per trap per fortnight at an economic threshold of 2% fruit infestation. / AFRIKAANSE OPSOMMING: Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) (ligrooswitluis), is ‘n algemene en ernstige plaag van appels en pere in Suid-Afrika. Druk deur verbruikers en regulasies om kommoditeite onder volhoubare en ekologies verenigbare toestande te produseer het chemiese beheeropsies toenemend beperk. Inligting oor die seisoenale voorkoms van plae is een van die essensiële komponente van ‘n effektiewe en volhoubare geïntegreerde plaagbestuurprogram. Dit is in die aanvanklike beplanning van monitering en om te bepaal wanneer skade verwag kan word. Dit is ook belangrik om boorde vroegtydig te identifiseer wat die risiko het om witluisbesmettings te ontwikkel. Die ontwikkeling van effektiewe en vroeë moniteringstegnieke vir witluisbevolkings sal produsente help met besluitneming rakende plaagbestuur en die geskiktheid van gewasse vir verskeie markte. Dit is ook noodsaaklik om die teenwoordigheid en effektiwiteit van biologiese beheer agente wat natuurlik in boorde voorkom te bepaal ten einde die potensiaal van biologiese beheer as ‘n lewensvatbare alternatief vas te stel. Onder die huidige geïntegreerde plaagbestuurprotokol was dit egter moeilik om laasgenoemde te bepaal weens die sporadiese en relatiewe lae voorkoms van witluisbesmettings in sommige boorde of deur bloot staat te maak op die veldpopulasies van biologiese beheer agente wat natuurlik voorkom. Kennis van die omgewingstoestande waaronder P. viburni bevolkingsvlakke skadelik raak is ook noodsaaklik vir die beplanning van vrylating van biologiese beheer agente, asook om die bevolkingsekologie van hierdie plaag en sy natuurlike vyande te verstaan. Inligting oor die seisoenale fenologie van P. viburni en sy natuurlike vyande in sagtevrugte boorde in die Westelike Kaapprovinsie is gedurende die 2007/08 en 2008/09 groeiseisoene versamel. Seisoenale bevolkingstudies het getoon dat P. viburni verskeie oorvleuelende generasies het met alle stadia teenwoordig regdeur die jaar.

The Eurasian spruce bark beetle Dendroctonus micans is a major pest of spruce which is expanding its range in France, Turkey, England and Wales. Its monospecific predator Rhizophagus grandis has followed naturally the bark beetle into most areas and, since the 1960s, has also been mass-produced and successfully released within newly infested locations. In this scope, the development of an effective trapping method would be very useful to assess the bark-beetle presence at previously uninfested sites, or predator establishment after release or natural spread. We demonstrated the efficiency of oxygenated monoterpenes-baited kairomone traps to monitor R. grandis in various epidemiological conditions, including areas localized behind or at the limit of the pest’s distribution, or in areas where artificial releases were performed. Because the predator is strictly species-specific, another exciting possibility offered by the kairomone trapping is the indirect monitoring of the pest itself in areas of unknown status (e.g. areas under colonization, or considered as at risk at medium- term). R. grandis is also considered as one of the most valuable natural enemies to strike aggressive North-American Dendroctonus species. In this respect, R. grandis has been recently applied in a neo-classical biological program against the red turpentine beetle D. valens, which invaded China from North America in the late 1990’s. In laboratory tests conducted on pine logs in the laboratory, or on living pine trees in the field, we demonstrated that R. grandis adults can successfully enter and reproduce into D. valens galleries. In Europe, R. grandis is the only species regularly found in the brood systems of D. micans, where adults and larvae attack the gregarious larvae of their prey. In such enclosed systems, R. grandis’ functional response is therefore influenced by various interrelated components, such as the prey density, the predator density, or the prey distribution. Measuring the predator’s success in terms of larval survival and growth rates, we demonstrated the time spent by R. grandis larvae to wound and kill their prey to be the main factor limiting their development. This factor may be considerably influenced by the proportions of diseased, wounded or molting prey rise in the brood system, for instance as a result of an increase in prey density, or due to the presence of conspecific adults (which wound their prey but do not consume them entirely). Furthermore, our tests suggest that no cannibalism or noticeable intraspecific competition occurred between R. grandis larvae, whereas some lighter mode of competition probably took place. R. grandis also exhibits a reproductive numerical response to prey density, which mainly relies on the perception of chemical stimuli and inhibitors released in the bark beetle brood system. In the current study, we developed a non-destructive approach to follow the dynamics of volatile compound production, using sequential sample collection on SPME fibers. Our tests demonstrated that the larval activity of D. micans or D. valens strongly influences the release of some oxygenated monoterpenes. However, our attempts to correlate the relative quantities of some identified chemicals to offspring production were less successful as it concerns the identification of potential oviposition stimuli and inhibitors. The problematic rose by the progression of D. micans, as well as detailed results of each of the described above studies are discussed in the two published papers and the three manuscripts forming this thesis. Bringing all these studies together, several perspectives are also presented in the general discussion. / Ravageur des épicéas, Dendroctonus micans est toujours en voie d’extension en France, en Turquie, en Angleterre et au Pays de Galles. Dans la plupart de ces zones, le dendroctone est accompagné de manière naturelle par son prédateur monospécifique, Rhizophagus grandis. Depuis les années 1960, le prédateur a également fait l’objet d’une production de masse et de programmes de lâchers dans les zones d’arrivée récente du scolyte. Dans le cadre de la lutte biologique contre D. micans, les gestionnaires forestiers doivent donc estimer au plus tôt la présence du ravageur dans des zones jusque là indemnes, mais également vérifier l’établissement du prédateur par progression naturelle ou résultant d’introductions délibérées. Dans la présente étude, nous avons démontré l’efficacité de pièges d’interception appatés à l’aide de monoterpènes oxygénés pour la capture de R. grandis. Celle-ci s’est faite dans différentes conditions épidémiologiques, incluant notamment des zones situées en arrière du front de progression du scolyte et des zones où des lâchers artificiels ont été réalisés. Comme R. grandis est strictement inféodé au dendroctone, un autre avantage de la technique est la possibilité de réaliser un dépistage indirect du ravageur dans les zones où son statut est incertain (zones en cours de colonisation, ou considérées comme à risque à moyen terme). Par ailleurs, R. grandis est également considéré comme un des meilleurs ennemis naturels potentiels pour lutter contre d’autres espèces de Dendroctonus aggressifs. Dans cette optique, R. grandis a été récemment utilisé dans un programme de lute biologique contre D. valens, ravageur invasif arrivé en Chine dans la fin des années 1990 en provenance d’Amérique du Nord. Nous avons démontré la capacité de R. grandis à s’introduire et à se reproduire dans les galeries de D. valens lors de tests de laboratoire, mais aussi sur des arbres vivants en pinèdes. En Europe, R. grandis est strictement inféodé aux galeries de D. micans, où larves et adultes du prédateur s’attaquent aux larves grégaires du scolyte. Dans ce système clos, la réponse fonctionelle de R. grandis est influencée par plusieurs facteurs étroitement corrélés, la densité de proies, la densité de prédateurs, et la distribution des proies. En mesurant l’efficacité de prédation de R. grandis en termes de survie des larves et de taux de croissance, nous avons démontré l’influence sur leur développement du temps passé par les larves à blesser et à tuer leurs proies. Ce facteur est par ailleurs fortement dépendant de la proportion de larves malades, blessées ou en cours de mue au sein du système ; une proportion qui peut augmenter en réponse à une augmentation de la densité de proies, ou lorsque des adultes sont présents (ceux-ci blessent les proies mais ne les consomment pas entièrement). Enfin, nos tests suggèrent qu’il n’existe que peu de cannibalisme ou de compétition intraspécifique entre larves de R. grandis, tandis que des modes de compétition moins importants prennent vraisemblablement place. R. grandis présente également une réponse numérique reproductive à la densité de proies disponibles, principalement basée sur la perception de stimuli et d’inhibiteurs présents dans les galeries du scolyte. Par la collecte de composés volatils présents dans ces systèmes à l’aide de fibres SPME, nous avons développé une méthode non-destructive pour suivre la dynamique de production des médiateurs chimiques. Nos tests ont démontré que l’activité des larves de D. micans ou D. valens influence fortement la dynamique de production de certains monoterpènes oxygénés. En revanche, il n’a pas été été possible de corréler les différents composés identifiés au nombre de larves de R. grandis présentes dans le système. La problématique soulevée par la progression de D. micans, de même que les résultats détaillés de chacune des études décrites ci-dessus sont discutés dans les deux papiers publiés et les trois manuscrits formant cette thèse. Les différentes perspectives apportées par ce travail sont également présentées dans la discussion générale.