Management der Minderempfindlichkeit von Apfelwicklerstämmen gegenüber dem Apfelwicklergranulovirus

Das Apfelwicklergranulovirus (CpGV) ist effizientes biologisches Bekämpfungsmittel des Apfelwicklers mit großer Bedeutung im ökologischen und integrierten Kernobstbau. 2005 wurde erstmals eine Resistenz gegen CpGV in einzelnen Anlagen beobachtet. Um geeignete Hilfestellungen für den Obstbau zu entwickeln, wurden verschiedene Aspekte der CpGV-Resistenz aufgeklärt: 1. Bisher wurden mehr als 40 Apfelwicklerpopulationen in Europa mit CpGV-Resistenz gefunden. Sie kommen in Deutschland (26), Frankreich (2), Italien (6), Österreich (2), Schweiz (3), Niederlande (3) und Tschechien (1) vor. Vermutlich handelt es sich in allen Fällen um denselben Resistenztyp. 2. Die Resistenz wird durch einen ungewöhnlichen Vererbungsgang (einfaktoriell, Geschlechtschromosomal und mit einer konzentrationsabhängigen Dominanz) sehr effizient selektiert. 3. Der Resistenzmechanismus liegt in einer frühen Blockade der Virusvermehrung. Resistente Tiere zeigten keinen Fitnessnachteil gegenüber nicht resistenten Tieren in Laborexperimenten. 4. Neue CpGV-Isolate können Resistenz brechen. Viele der resistenzbrechenden Isolate wirken in resistenten Apfelwicklerlarven etwas langsamer als in anfälligen Larven. Dadurch ist auch bei Verwendung resistenzbrechender Tiere mit einem etwas erhöhten Schaden zu rechnen, solange bis die Apfelwicklerpopulation wieder auf ein niedriges Niveau reduziert wurde. Aus den Ergebnissen ergeben sich folgende Empfehlungen: 1. Betriebe ohne CpGV-Resistenz - dies ist die ganz überwiegende Zahl - können konventionelle CpGV-Präparate weiter verwenden. Sobald neue CpGV-Isolate zugelassen sind, sollte auch diese eingesetzt werden, um eine Selektion der bekannten Resistenz zu vermeiden. 2. Betriebe mit CpGV-Resistenz oder begründetem Resistenzverdacht sollten sofort neue resistenzbrechende Isolate verwenden. Diese stehen seit 2006 als Versuchspräparate zur Verfügung, ihre Zulassung wird erwartet. 3. Die Apfelwicklerbekämpfung muß auf eine möglichst breite Basis gestellt werden

Foliar application of microdoses of sucrose to reduce codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) damage to apple trees

Abstract BACKGROUND The effects of foliar applications of microdoses of sucrose to reduce the damage by the codling moth have been reported from nine trials carried in France and Algeria from 2009 to 2014. The activity of sucrose alone was assessed by comparison with an untreated control and some treatments with the Cydia pomonella granulovirus or a chemical insecticide. The addition of sucrose to these different treatments was also investigated. RESULTS The application of sucrose at 0.01% reduced the means of infested fruits with a value of Abbott's efficacy of 41.0 ± 10.0%. This involved the induction of resistance by antixenosis to insect egg laying. Indeed, it seems that acceptance of egg laying on leaves treated with sucrose was reduced. The addition of sucrose to thiacloprid improved its efficacy (59.5% ± 12.8) by 18.4%. However, the sucrose had no added value when associated with C. pomonella granulovirus treatments. CONCLUSION Foliar applications of microdoses of sucrose every 20 days in commercial orchards can partially protect against the codling moth. Its addition to thiacloprid increases the efficacy in integrated control strategies, contrary to C. pomonella granulovirus treatments. This work opens a route for the development of new biocontrol strategies

Insect pathogens as biological control agents: back to the future

The development and use of entomopathogens as classical, conservation and augmentative biological control agents have included a number of successes and some setbacks in the past 15 years. In this forum paper we present current information on development, use and future directions of insect-specific viruses, bacteria, fungi and nematodes as components of integrated pest management strategies for control of arthropod pests of crops, forests, urban habitats, and insects of medical and veterinary importance. Insect pathogenic viruses are a fruitful source of MCAs, particularly for the control of lepidopteran pests. Most research is focused on the baculoviruses, important pathogens of some globally important pests for which control has become difficult due to either pesticide resistance or pressure to reduce pesticide residues. Baculoviruses are accepted as safe, readily mass produced, highly pathogenic and easily formulated and applied control agents. New baculovirus products are appearing in many countries and gaining an increased market share. However, the absence of a practical in vitro mass production system, generally higher production costs, limited post application persistence, slow rate of kill and high host specificity currently contribute to restricted use in pest control. Overcoming these limitations are key research areas for which progress could open up use of insect viruses to much larger markets. A small number of entomopathogenic bacteria have been commercially developed for control of insect pests. These include several Bacillus thuringiensis sub-species, Lysinibacillus (Bacillus) sphaericus, Paenibacillus spp. and Serratia entomophila. B. thuringiensis sub-species kurstaki is the most widely used for control of pest insects of crops and forests, and B. thuringiensis sub-species israelensis and L. sphaericus are the primary pathogens used for medically important pests including dipteran vectors,. These pathogens combine the advantages of chemical pesticides and microbial control agents (MCAs): they are fast acting, easy to produce at a relatively low cost, easy to formulate, have a long shelf life and allow delivery using conventional application equipment and systemics (i.e. in transgenic plants). Unlike broad spectrum chemical pesticides, B. thuringiensis toxins are selective and negative environmental impact is very limited. Of the several commercially produced MCAs, B. thuringiensis (Bt) has more than 50% of market share. Extensive research, particularly on the molecular mode of action of Bt toxins, has been conducted over the past two decades. The Bt genes used in insect-resistant transgenic crops belong to the Cry and vegetative insecticidal protein families of toxins. Bt has been highly efficacious in pest management of corn and cotton, drastically reducing the amount of broad spectrum chemical insecticides used while being safe for consumers and non-target organisms. Despite successes, the adoption of Bt crops has not been without controversy. Although there is a lack of scientific evidence regarding their detrimental effects, this controversy has created the widespread perception in some quarters that Bt crops are dangerous for the environment. In addition to discovery of more efficacious isolates and toxins, an increase in the use of Bt products and transgenes will rely on innovations in formulation, better delivery systems and ultimately, wider public acceptance of transgenic plants expressing insect-specific Bt toxins. Fungi are ubiquitous natural entomopathogens that often cause epizootics in host insects and possess many desirable traits that favor their development as MCAs. Presently, commercialized microbial pesticides based on entomopathogenic fungi largely occupy niche markets. A variety of molecular tools and technologies have recently allowed reclassification of numerous species based on phylogeny, as well as matching anamorphs (asexual forms) and teleomorphs (sexual forms) of several entomopathogenic taxa in the Phylum Ascomycota. Although these fungi have been traditionally regarded exclusively as pathogens of arthropods, recent studies have demonstrated that they occupy a great diversity of ecological niches. Entomopathogenic fungi are now known to be plant endophytes, plant disease antagonists, rhizosphere colonizers, and plant growth promoters. These newly understood attributes provide possibilities to use fungi in multiple roles. In addition to arthropod pest control, some fungal species could simultaneously suppress plant pathogens and plant parasitic nematodes as well as promote plant growth. A greater understanding of fungal ecology is needed to define their roles in nature and evaluate their limitations in biological control. More efficient mass production, formulation and delivery systems must be devised to supply an ever increasing market. More testing under field conditions is required to identify effects of biotic and abiotic factors on efficacy and persistence. Lastly, greater attention must be paid to their use within integrated pest management programs; in particular, strategies that incorporate fungi in combination with arthropod predators and parasitoids need to be defined to ensure compatibility and maximize efficacy. Entomopathogenic nematodes (EPNs) in the genera Steinernema and Heterorhabditis are potent MCAs. Substantial progress in research and application of EPNs has been made in the past decade. The number of target pests shown to be susceptible to EPNs has continued to increase. Advancements in this regard primarily have been made in soil habitats where EPNs are shielded from environmental extremes, but progress has also been made in use of nematodes in above-ground habitats owing to the development of improved protective formulations. Progress has also resulted from advancements in nematode production technology using both in vivo and in vitro systems; novel application methods such as distribution of infected host cadavers; and nematode strain improvement via enhancement and stabilization of beneficial traits. Innovative research has also yielded insights into the fundamentals of EPN biology including major advances in genomics, nematode-bacterial symbiont interactions, ecological relationships, and foraging behavior. Additional research is needed to leverage these basic findings toward direct improvements in microbial control

Impact of Climate Change on Voltinism and Prospective Diapause Induction of a Global Pest Insect – Cydia pomonella (L.)

Global warming will lead to earlier beginnings and prolongation of growing seasons in temperate regions and will have pronounced effects on phenology and life-history adaptation in many species. These changes were not easy to simulate for actual phenologies because of the rudimentary temporal (season) and spatial (regional) resolution of climate model projections. We investigate the effect of climate change on the regional incidence of a pest insect with nearly worldwide distribution and very high potential for adaptation to season length and temperature – the Codling Moth, Cydia pomonella. Seasonal and regional climate change signals were downscaled to the hourly temporal scale of a pest phenology model and the spatial scale of pest habitats using a stochastic weather generator operating at daily scale in combination with a re-sampling approach for simulation of hourly weather data. Under future conditions of increased temperatures (2045–2074), the present risk of below 20% for a pronounced second generation (peak larval emergence) in Switzerland will increase to 70–100%. The risk of an additional third generation will increase from presently 0–2% to 100%. We identified a significant two-week shift to earlier dates in phenological stages, such as overwintering adult flight. The relative extent (magnitude) of first generation pupae and all later stages will significantly increase. The presence of first generation pupae and later stages will be prolonged. A significant decrease in the length of overlap of first and second generation larval emergence was identified. Such shifts in phenology may induce changes in life-history traits regulating the life cycle. An accordingly life-history adaptation in photoperiodic diapause induction to shorter day-length is expected and would thereby even more increase the risk of an additional generation. With respect to Codling Moth management, the shifts in phenology and voltinism projected here will require adaptations of plant protection strategies to maintain their sustainability

A chromosome-level genome assembly of Cydia pomonella provides insights into chemical ecology and insecticide resistance

The codling moth Cydia pomonella, a major invasive pest of pome fruit, has spread around the globe in the last half century. We generated a chromosome-level scaffold assembly including the Z chromosome and a portion of the W chromosome. This assembly reveals the duplication of an olfactory receptor gene (OR3), which we demonstrate enhances the ability of C. pomonella to exploit kairomones and pheromones in locating both host plants and mates. Genome-wide association studies contrasting insecticide-resistant and susceptible strains identify hundreds of single nucleotide polymorphisms (SNPs) potentially associated with insecticide resistance, including three SNPs found in the promoter of CYP6B2. RNAi knockdown of CYP6B2 increases C. pomonella sensitivity to two insecticides, deltamethrin and azinphos methyl. The high-quality genome assembly of C. pomonella informs the genetic basis of its invasiveness, suggesting the codling moth has distinctive capabilities and adaptive potential that may explain its worldwide expansion

On the inheritance and mechanism of baculovirus resistance of the codling moth, Cydia pomonella (L.)

Das Cydia pomonella Granulovirus (CpGV, Baculoviridae) wird seit Ende der 1980er Jahre als hoch-selektives und effizientes biologisches Bekämpfungsmittel zur Kontrolle des Apfelwicklers im Obstanbau eingesetzt. Seit 2004 wurden in Europa verschiedene Apfelwicklerpopulationen beobachtet die resistent gegenüber dem hauptsächlich angewendeten Isolat CpGV-M aufweisen. Die vorliegende Arbeit befasst sich mit der Untersuchung der Vererbung und des Mechanismus der CpGV Resistenz. Einzelpaarkreuzungen zwischen einem empfindlichen Laborstamm (CpS) und einem homogen resistenten Stamm (CpRR1) zeigten, dass die Resistenz durch ein einziges dominantes Gen, das auf dem Z-Chromosom lokalisiert ist, vererbt wird. Massernkreuzungen zwischen CpS und einer heterogen resistenten Feldpopulation (CpR) deuteten zunächst auf einen unvollständig dominanten autosomalen Erbgang hin. Einzelpaarkreuzungen zwischen CpS und CpR bewiesen jedoch, dass die Resistenz in CpR ebenfalls monogen dominant und geschlechtsgebunden auf dem Z-Chromosom vererbt wird. Diese Arbeit diskutiert zudem die Vor- und Nachteile von Einzelpaarkreuzungen gegenüber Massernkreuzungen bei der Untersuchung von Vererbungsmechanismen. Die Wirksamkeit eines neuen CpGV Isolates aus dem Iran (CpGV-I12) gegenüber CpRR1 Larven, wurde in Bioassays getestet. Die Ergebnisse zeigen, dass CpGV-I12 die Resistenz in allen Larvenstadien von CpRR1 brechen kann und fast so gut wirkt wie CpGV-M gegenüber CpS Larven. Daher ist CpGV-I12 für die Kontrolle des Apfelwicklers in Anlagen wo die Resistenz aufgetreten ist geeignet. Um den der CpGV Resistenz zugrunde liegenden Mechanismus zu untersuchen, wurden vier verschiedene Experimente durchgeführt: 1) die peritrophische Membran degradiert indem ein optischer Aufheller dem virus-enthaltenden Futtermedium beigefügt wurde. Das Entfernen dieser mechanischen Schutzbarriere, die den Mitteldarm auskleidet, führte allerdings nicht zu einer Reduzierung der Resistenz in CpR Larven. Demnach ist die peritrophische Membran nicht am Resistenzmechanismus beteiligt. 2) Die Injektion von Budded Virus in das Hämocoel führte nicht zur Brechung der Resistenz. Folglich die die Resistenz nicht auf den Mitteldarm beschränkt, sondern auch in der Sekundärinfektion wirksam. 3) Die Replikation von CpGV in verschiedenen Geweben (Mitteldarm, Hämolymphe und Fettkörper) von CpS und CpRR1 wurde mittels quantitativer PCR verfolgt. In CpS Larven konnte in allen drei Gewebetypen sowohl nach oraler als auch nach intra-hämocoelarer Infektion eine Zunahme der CpGV Genome in Abhängigkeit der Zeit festgestellt werden. Dagegen konnte in den Geweben aus CpRR1 nach oraler sowie intra-hämocoelarer Infektion keine Virusreplikation detektiert werden. Dies deutet darauf hin, dass die CpGV Resistenz in allen Zelltypen präsent ist. 4) Um zu untersuchen ob ein humoraler Faktor in der Hämolymphe ursächlich an der Resistenz beteiligt ist, wurde Hämolymphe aus CpRR1 Larven in CpS Larven injiziert und diese anschließend oral mit CpGV infiziert. Es konnte jedoch keine Immunreaktion beobachtet und kein Faktor in der Hämolymphe identifiziert werden, der Resistenz induzieren könnte. Auf Grundlage dieser Ergebnisse kann festgestellt werden, dass in resistenten Apfelwicklerlarven die virale Replikation in allen Zelltypen verhindert wird, was auf eine Virus-Zell Inkompatibilität hinweist. Da in CpRR1 keine DNA Replikation beobachtet wurde, wird die CpGV Resistenz wahrscheinlich durch eine frühe Unterbindung der Virusreplikation verursacht.Das früh exprimierte Gen pe38 codiert für ein Protein, das wahrscheinlich für die Resistenzbrechung durch CpGV-I12 verantwortlich ist. Interaktionen zwischen dem Protein PE38 und Proteinen in CpRR1 wurden mit Hilfe des Yeast Two-Hybrid (Y2H) Systems untersucht. Die detektierten Interaktionen sind noch nicht durch andere Methoden bestätigt, jedoch wurden zwei mögliche Gene auf dem Z-Chromosom und eines auf Chromosom 15 gefunden, wie möglicherweise an der CpGV Resistenz beteiligt sind.The Cydia pomonella granulovirus (CpGV, Baculoviridae) is the most important biocontrol agent of the codling moth in apple production. It is successfully used since the late 1980s, particularly in organinc apple production. Since 2004, several codling moth populations which are resistant to the commonly used isolate CpGV-M have been observed in Europe. This thesis is focused on the analysis of the inheritance and the mechanism of CpGV resistance. Single pair crosses between a susceptible laboratory strain (CpS) and a homogeneous CpGV resistant strain (CpRR1) revealed that CpGV resistance is inherited by a single dominant gene, which is located on the Z-chromosome. Mass crossing experiments between CpS and a heterogeneous resistant, field collected strain (CpR) initially suggested an autosomal incomplete dominant mode of inheritance. However, single pair crosses between CpS and CpR disclosed that CpR and CpRR1 share the same mode of inheritance of CpGV resistance. This thesis also discusses the advantages of single pair crossings compared to mass crossings in terms of elucidating the mode of resistance inheritance. The efficacy of a new CpGV isolate (CpGV-I12) originating from Iran was tested against CpRR1 larvae in bioassays. CpGV-I12 is able to overcome resistance in all larval stages of CpRR1 and works almost as well as CpGV-M against CpS larvae. CpGV-I12 is suitable for codling moth control in orchards where resistance against CpGV-M has occurred. In order to investigate the mechanism underlying CpGV resistance, four different experimental approaches were followed: First, the peritrophic membrane was degraded by adding an optical brightener to the diet containing virus. However, the removal of this mechanical barrier in the midgut did not lead to enhanced CpGV infection in resistant larvae suggesting that the PM is not involved in resistance. Second, injection of CpGV budded virus directly into the insect’s haemocoel did not overcome resistance. Accordingly, CpGV resistance is not restricted to the midgut but also present in secondary infection. Third, CpGV replication was traced by quantitative PCR in three different tissues of susceptible (CpS) and resistant (CpRR1) insects. After both oral and intrahaemocoelar infection, the amount of CpGV copies detected in all three tissue types of CpS increased with time elapsed. Virus replication could not be detected in any of the isolated tissue types of CpRR1. This indicates that CpGV resistance is present in each of the cell types. Fourth, CpGV caused mortality was analysed after transfusion of haemolymph between resistant (CpRR1) and susceptible (CpS) codling moth larvae to determine the possible action of a humoral factor involved in CpGV resistance. Thus, no immune response was observed and no factor in the haemolymph wich induces resistance could be identified. Based on these results it is proposed that virus replication is affected in all cell types, suggesting a virus-cell incompatibility in resistant codling moths. Because no DNA replication could be observed it is proposed that CpGV resistance is caused by an early block of virus replication. The early transcribed gene pe38 encodes for a protein which is putatively responsible for the resistance overcoming capacity of CpGV-I12. Interactions between the protein PE38 and proteins of CpRR1 were investigated using the yeast two-hybrid (Y2H) system. The interactions found are not confirmed by other methods yet. Nevertheless, the Y2H screening revealed two putative genes located on the Z-chromosome and one located on chromosome number 15, which may be involved in resistance to CpGV

Pyrethroid resistance and its inheritance in a field population of Hippodamia convergens (Guérin-Méneville) (Coleoptera: Coccinellidae)

Citation: Rodrigues, A. R. S., Ruberson, J. R., Torres, J. B., Siqueira, H. A. A., & Scott, J. G. (2013). Pyrethroid resistance and its inheritance in a field population of Hippodamia convergens (Guérin-Méneville) (Coleoptera: Coccinellidae). Retrieved from http://krex.ksu.eduThe convergent lady beetle (CLB), Hippodamia convergens (Guérin-Méneville), a species widely distributed and used in biological control, has exhibited high survival under field and laboratory conditions when treated with field rates of the pyrethroid λ-cyhalothrin, a highly unusual phenomenon for a natural enemy. This work investigated and characterized the phenomenon of pyrethroid resistance in a population of this species collected in Georgia, USA. The mechanism and level of resistance were evaluated by treating parental populations with λ-cyhalothrin ± piperonyl butoxide (PBO). The inheritance bioassay utilized parental crosses and backcrosses between parental populations to obtain testable progenies. Adult beetles from populations and progenies were topically treated with different doses of λ-cyhalothrin (technical grade) to calculate knockdown (KD) and lethal (LD) doses, and to investigate the dominance based on a single dose and whether resistance is autosomal and monogenic (null hypothesis). Genetic variation in the parental populations was examined by applying a discriminating dose for resistant individuals (0.5 g/L). The data indicate that resistance is due to at least two factors: knockdown resistance and enzymatic detoxification of the insecticide. The knockdown effect is recessive and linked to the X-chromosome. Variability in proportions of individuals within families dying following knockdown indicated genetic variation in the resistant population. Further studies should be done to investigate the role of sex linked inheritance of resistance in the species and interactions of the various mechanisms involved in resistance

The occurrence and distribution of resistance of codling moth to Cydia pomonella

International audienceThirty-five codling moth (CM, Cydia pomonella L., Lepidoptera, Tortricidae) populations collected in different commercial orchards in six European countries were tested for their susceptibility to Cydia pomonella granulovirus (CpGV-M). Including previously published data on CpGV-M resistance, a total of 38 CM colonies showed considerably elevated LC50 values, independent of the country origin. When only few test individuals are available, determination of mortality of neonate larvae at a discriminating concentration range of 10(4) to 10(6)OB/ml (>log4) as a direct measure of percentage susceptible individuals in a CM population is more advisable than calculation of LC50 values. The >log4 mortality alone or in combination with the LC50 value can be used for identification of resistance in a population. Results indicated a locally separated but widely spread occurrence of CM populations with low susceptibility to CpGV-M. The most plausible hypothesis for the emergence of CpGV-M resistance is its selection by repeated use of CpGV products