Characterization of mechanisms of resistance to common insecticides in noctuid pest species and resistance risk assessment for the new lepidopteran specific compound flubendiamide

Noctuid species, such as the beet armyworm Spodoptera exigua, the cotton bollworm Helicoverpa armigera and the tobacco budworm Heliothis virescens, are well-known pests in many agricultural cropping systems worldwide. The extensive and widespread use of insecticides against these species has led to the development of resistance against almost all commercially used compounds. The focus of this thesis was on the novel lepidopteran specific compound flubendiamde, to get a detailed overview about the efficacy using different kinds of bioassays for a resistance risk assessment. On the other hand, the underlying possible resistance mechanisms of a S. exigua strain from southern Spain was investigated on the toxicological, biochemical, pharmacokinetic and molecular level. The basic of all further experiments was two bioassay techniques, a leaf-disc spray application and an artificial diet bioassay, on 2nd instar larvae. Flubendiamide and 11 competitors with different mode of actions were tested on three susceptible laboratory strains (HELI-AR, HELI-VI, SPOD-EX S) and one field strain from Spain (SPOD-EX E-98). The aim was to get baseline susceptibilities of the three noctuid species and additionally the resistance profile of strain SPOD-EX E-98 against the different insecticides. The results of the two bioassay techniques were comparable with each other, emamectin shown the highest efficacy followed by low EC50-values for flubendiamide, deltamethrin and indoxacarb. The robust artificial diet bioassay was used for a worldwide resistance monitoring for flubendiamide, and resulting in a mean efficacy of 93% in 18 test populations. An interesting cross-resistance pattern against insecticides with different mode of actions demonstrated the S. exigua strain SPOD-EX E-98, and can be called as ?multi-resistant?. High resistance to three classes of insecticides, pyrethroids, benzoylphenyl ureas and carbamates/organophosphates, was detected in this strain, also moderate resistance levels to endosulfan and indoxacarb. The in vivo application study with the synergist PBO (monooxygenase inhibitor) has shown an additionally participation of this enzyme system towards the deltamethrin resistance in this strain. Additionally, PBO and two esterase inhibitors had no effect to the resistance level of triflumuron (benzoylphenyl urea) and so target-site resistance is likely in this case. Using molecular biological methods, a point mutation (kdr) in the voltage-gated sodium channel of the resistant strain SPOD-EX E-98 was detected, this channel is the target of the pyrethroids. This target-site resistance is particularly responsible for the extremely high resistance factor (~900) of the pyrethroid deltamethrin detected in the bioassays. In order to investigate the pharmacokinetic profiles of deltamethrin, triflumuron and flubendiamide in S. exigua larvae radiolabelled compounds were used. No differences in penetration or excretion of the compounds were observed between the two strains. This suggests that physiological changes have not influence as a possible mechanism of deltamethrin and triflumuron resistance. Four biochemical markers, carboxylesterases (CEs), cytochrome P450-dependent monooxygenases (monooxygenases), glutathione S-transferases (GSTs) and acetylcholinesterases (AChEs), were investigated in both S. exigua strains. These enzyme systems are known to be linked with metabolic detoxification/resistance to diverse insecticides. With the exception of GST, in the multi-resistant SPOD-EX E-98 strain was found significantly higher enzyme activities to the other three marker enzymes. The higher CE activity in the multi-resistant strain SPOD-EX E-98 was further investigated, using an nPAGE to obtaining the iso-enzyme banding patterns of both strains. In comparison, the strain SPOD-EX E-98 exhibited an additional thick band and it was not possible to inhibiting this band in vitro through the esterase inhibitor DEF. It is possible that this result is involved in resistance, but only further investigations could be clarify the exact role of the additional band in this resistant strain. The AChE of both S. exigua strains was used for in vitro inhibition studies. The resistant strain SPOD-EX E-98 was insensitive against several organophosphates and carbamates compared with strain SPOD-EX S. Only one exception was detected, the AChE of the resistant strain was more sensible to carbofuran than the enzyme from strain SPOD-EX S. This phenomenon of ?negative cross-insensitivity? is generally correlated with an altered substrate binding site of the AChE. Further investigations of kinetic parameters exhibited a higher turnover of the substrate in strain SPOD-EX E-98. The bioassays confirmed these results and so the resistance mechanism of the two chemical classes is an altered AChE in the resistant strain.Die phytophagen Larven der Familie der Noctuidae, wie z.B. Spodoptera exigua, Helicoverpa armigera und Heliothis virescens sind weltweit als wirtschaftlich bedeutende Schadinsekten bekannt und befinden sich in einer Resistenzproblematik gegenüber fast allen kommerziell erhältlichen Insektiziden. Der Fokus dieser Arbeit lag auf einem neuen insektiziden Wirkstoff, Flubendiamide, und die Einschätzung über das Risiko einer möglichen Resistenzentwicklung. Verschiedene Arten von toxikologischen Untersuchungen wurden eingesetzt um einen Überblick zu bekommen. Des Weiteren lag das Interesse auf einem S. exigua Stamm aus Südspanien, dessen mögliche Resistenzmechanismen auf biochemischer, pharmakokinetischer und molekularer Ebene untersucht wurden. Die Grundlage für alle Versuche bildeten zwei Biotestsysteme, eine Sprühapplikation auf Blattmaterial und ein Kunstfutter-Biotest. Flubendiamide und 11 Konkurrenzinsektizide mit unterschiedlichen Wirkmechanismen wurden an drei sensiblen Laborstämmen (HELI-AR, HELI-VI, SPOD-EX S) und einem Freilandstamm aus Spanien (SPOD-EX E-98) getestet. Ziel war es Basisdaten und ein mögliches Resistenzprofil für den Stamm SPOD-EX E-98 herauszuarbeiten, wobei beide Testsysteme vergleichbare Ergebnisse erzielten. Emamectin zeigte die beste Wirkung dicht gefolgt von niedrigen EC50-Werten für Flubendiamide, Deltamethrin und Indoxacarb für die drei Laborstämme. Der robuste Kunstfutter-Biotest kam zusätzlich in einem weltweiten Resistenz-Monitoring mit Flubendiamide zum Einsatz, wobei ein durchschnittlicher Wirkungsgrad von 93% bei 18 Testpopulationen erreicht wurde. Der S. exigua Stamm SPOD-EX E-98 zeigte sich interessanterweise kreuzresistent gegenüber verschiedenen Insektiziden mit unterschiedlichen Wirkmechanismen und kann somit als "multiresistent" bezeichnet werden. Eine starke Resistenz gegenüber den drei Insektizidklassen, Pyrethroide, Benzoylharnstoffe und Carbamate/Organophosphate wurde für diesen Stamm festgestellt, zusätzlich moderate Resistenzfaktoren für die Wirkstoffe Endosulfan und Indoxacarb. Die in vivo Versuche mit dem Synergisten PBO (Monooxygenase-Inhibitor) zeigten eine zusätzliche Beteiligung dieses Enzymsystems an der vorhandenen Deltamethrin-Resistenz dieses Stammes. Zusätzlich konnte kein Effekt, sowohl mit PBO als auch mit Esterase-Inhibitoren, auf den Resistenzlevel von Triflumuron (Benzoylharnstoff)erzielt werden. Daher muss in diesem Fall eine Target-Site-Resistenz angenommen werden. Mit molekularbiologischen Methoden konnte eine Punktmutation (kdr) im spannungsabhängigen Natriumkanal, dem Wirkort der Pyrethroide, des Stammes SPOD-EX E-98 ermittelt werden. Diese Target-Site-Resistenz ist teilweise fürden extrem hohen Resistenzfaktor(~900)des Pyrethroids Deltamethrin verantwortlich. In weiteren Experimenten wurde das pharmakokinetische Profil von radioaktiv markierten Wirkstoffen (Deltamethrin, Triflumuron, Flubendiamide) in S. exigua Larven nachvollzogen. Zwischen den beiden S. exigua Stämmen ergab sich keine veränderte Aufnahme oder Exkretion der Wirkstoffe, sodass gegenüber Deltamethrin und Triflumuron eine Veränderung auf physiologischer Ebene als Resistenzmechanismus auszuschließen ist. In den zwei S.exigua Stämmen wurden vier biochemische Marker, Carboxylesterasen (CEs), Monooxygenasen, Glutathion S-Transferasen (GSTs) und Acetylcholinesterasen (AChEs), untersucht, von denen bekannt ist, dass sie als Resistenzfaktoren in Frage kommen. Das Ergebnis zeigte, außer bei GSTs, in allen anderen drei Enzymsystemen signifikant erhöhte Aktivitäten des multi-resistenten Stammes SPOD-EX E-98. Zusätzlich zu der erhöhten CE-Aktivität des Stammes SPOD-EX E-98 konnten mittels nPAGE die Isoenzym-Bandenmuster für beide S. exigua Stämme bestimmt werden. Im Vergleich fiel eine zusätzliche starke Bande im Stamm SPOD-EX E-98 auf, die auch nicht durch den Esterase-Inhibitor DEF inhibiert werden konnte. Diese zusätzliche Bande kann möglicherweise als Resistenzfaktor in dem resistenten Stamm eine Rolle spielen, hierzu sind aber noch weitere Untersuchungen nötig. In vitro Inhibierungsstudien von AChE aus beiden S. exigua Stämmen zeigten das der Stamm SPOD-EX E-98 unempfindlicher gegenüber Organophosphaten und Carbamaten ist, nur in Bezug auf Carbofuran zeigte sich die AChE aus dem Stamm SPOD-EX E-98 sensibler als das Enzym aus dem Stamm SPOD-EX S. Dieses Phänomen der "negativen Kreuzinsensitivität" wird generell mit einer veränderten Substratbindestelle der AChE in Verbindung gebracht, dieses konnte bei der Untersuchung der kinetischen Parameter bestätigt werden, in Form einer erhöhten Substratumsetzung in dem Stamm SPOD-EX E-98. Dieses Ergebnis spiegelt sich auf Biotestebene wieder und kann für beide Wirkstoffgruppen als Resistenzmechanismus angesehen werden

Jahresbericht : für das Schuljahr ... / Die Agrarverhältnisse in Bosnien und der Herzegowina

von Karl KonanzIn FrakturErschienen: 1 -

Immunmodulation durch Delta-9-Tetrahydrocannabinol in der perioperativen Schmerztherapie

Delta-9-Tetrahydrocannabinol (D-9-THC) alter the innate immunity expected to induce immediate early events in surface marker profiles of circulating leukocytes. Methods: Blood samples of 100 patients were taken before, 1 day after and 2 days after prostectomy and subjected to flow cytometric analysis. The patients were separated into two groups - 50 patients got 8 times D-9-THC, the other 50 patients got a placebo product. D-9-THC-related changes in surface antigen expression were compared to the findings of the placebo group. Results: Medians of the most NK-cell surface antigens like CD161 and Va24 and the most T-lymphocytes surface antigens like CD4, CD8, CD3 were not found to be different in both groups, 48 h after surgery. Also the monocytic CD14 were similarly expressed in both groups before and after trauma. The pathogen receptors TLR2 and TLR4 were more upregulated by D-9-THC treatment. The death receptor CD95 and those two epitopes - DX-2 and APO-1 - were more upregulated on all cells and subpopulations by D-9-THC-patients than placebo. The B7 moleclues CD80, CD86 and the dendritic cell activation antigen CD83 decreased after surgery by D-9-THC-treatment. Conclusions: The death receptor epitope CD95FITC = APO-1 = Fas is increased in patients with systemic inflammatory response syndrome (SIRS) and our findings show an increase of APO-1. The conclusion is that the D-9-THC treated patients sicken more often than untreated patients. Also the decrease of the costimulation factors of B7-complex CD80 and CD86 or the dendritic cell activation antigen implicate a suppression of the immune system and therefore a higher risk to sicken more often

Lobbying in British Columbia's designated resort municipalities : the case of short term rentals

This thesis focuses on the subject of short-term rentals and their host companies, such as Airbnb, to study the influence of business interests at the local level of government in British Columbia. Worldwide, these companies and their listings have grown exponentially in the last five years, but not without controversy, as they have met up against tenant rights groups, municipalities, and hotel associations who are upset about its effects on housing, neighborhoods and the traditional accommodation sector. Government regulations and municipal policy making are examined to understand the power of lobbying in this context. The lobbying efforts of both Airbnb and the hotel/motel associations are investigated and analyzed, from data collected from both interviews and a survey of local officials in British Columbia’s fourteen designated resort municipalities. The findings confirm that lobbying in municipalities is very active, but the practices are distinct from other levels of government. Recommendations include a lobbyist registrar at the local level to foster transparency and accountability, and a new way of looking at how all levels of government ought to approach regulating the new normal of online platform industries.Arts and Sciences, Irving K. Barber School of (Okanagan)Graduat

Advanced Multi-color Fluorescence Imaging System for Detection of Biotic and Abiotic Stresses in Leaves

The autofluorescence of a sample is a highly sensitive and selective optical property and gives the possibility to establish non-destructive techniques of the investigation of plants, like detecting the chlorophyll fluorescence related to stress phenomena. In this study, an advanced multi-color fluorescence imaging system and data analysis were presented. The advantage of an imaging system is the additional receiving of spatial information over a sample area, this is a strong improvement compared to spot measurements commonly used. The purpose was to demonstrate the possibility of the detection and characterization of stress symptoms using this system. Specific fluorescence ratios were identified to characterize the stress status over the whole leaf, here shown on barley grown under different nitrogen supply (abiotic stress). Due to the changes, it is possible to make conclusions about leaf pigments (chlorophylls and phenolics) related to stress response. The second aim was to use the shape of local symptoms (biotic stress) as a criterion. For this purpose, three structural different kinds of fungal symptoms were analyzed using shape descriptors. It shows that an additional image shape analysis can be very useful for extracting further information, in this case the successful discrimination of fungal infections

Advanced Multi-Color Fluorescence Imaging System for Detection of Biotic and Abiotic Stresses in Leaves

The autofluorescence of a sample is a highly sensitive and selective optical property and gives the possibility to establish non-destructive techniques of the investigation of plants, like detecting the chlorophyll fluorescence related to stress phenomena. In this study, an advanced multi-color fluorescence imaging system and data analysis were presented. The advantage of an imaging system is the additional receiving of spatial information over a sample area, this is a strong improvement compared to spot measurements commonly used. The purpose was to demonstrate the possibility of the detection and characterization of stress symptoms using this system. Specific fluorescence ratios were identified to characterize the stress status over the whole leaf, here shown on barley grown under different nitrogen supply (abiotic stress). Due to the changes, it is possible to make conclusions about leaf pigments (chlorophylls and phenolics) related to stress response. The second aim was to use the shape of local symptoms (biotic stress) as a criterion. For this purpose, three structural different kinds of fungal symptoms were analyzed using shape descriptors. It shows that an additional image shape analysis can be very useful for extracting further information, in this case the successful discrimination of fungal infections