Erarbeitung erster Ansätze für die Bekämpfung der Kirschfruchtfliege im ökologischen Landbau unter besonderer Berücksichtigung des Potentials entomopathogener Nematoden

2002 und 2003 wurden erste Versuche zur Bekämpfung der Kirschfruchtfliege Rhagoletis cerasi im Labor, Halbfreiland und Freiland mit verschiedenen Nematodenarten und -stämmen durchgeführt. Im Labor wurde die Wirksamkeit der Nematoden gegen R. cerasi-Larven, -Puppen und -Adulte mit verschiedenen Dosierungen, Temperaturen und Substraten untersucht. Die Versuche fanden in 24er-Kulturplatten, Petrischalen sowie Plastikdosen, d.h. unterschiedlichen Expositionsszenarien, statt. Im Halbfreiland kamen die Nematoden in Plastikobstkisten mit Erde und R. cerasi-Larven zum Einsatz. Die Freilandversuche bestanden aus der Entlassung von R. cerasi-Larven auf mit Nematoden behandelten Flächen auf der Kirschanlage des Instituts. Die Auswertung der Freilandversuche war bzw. ist im Folgejahr durch die Erfassung der schlüpfenden adulten R. cerasi mittels Boden-Fotoeklektoren vorgesehen. Für die Auswertung der Experimente wurden die Befallsraten und Wirkungsgrade (ABBOTT) ermittelt. Steinernema carpocapsae und S. feltiae erwiesen sich über alle Versuche als am wirksamsten. Im Labor wurden bei der Standarddosierung von 50 Nematoden/cm2 in den Kulturplatten Befallsraten bis 91 % und Wirkungsgrade bis 96 %, in den Petrischalen bis 96 % bzw. 98 % sowie Plastikdosen bis 88 % bzw. 89 % erreicht. Sand und der Bodentyp sowie die getesteten Temperaturen hatten im Labor keinen Einfluss auf die Infektionsrate. Eine Dosierung unter 25 Nematoden/cm2 führte nicht zu einer ausreichenden Wirkung. Im Halbfreiland wurde ein Befall von 86 % (Wirkungsgrad 78 %) und im Freiland ein Wirkungsgrad von 88 % erzielt. In beiden Fällen kamen 50 Nematoden/cm2 zum Einsatz. Entomopathogene Nematoden infizierten keine R. cerasi-Puppen, Adulte dagegen im Labor beim Schlupf aus der Puppe im Nematoden-infizierten Sand bis 40 %. Die Ergebnisse zeigen, dass entomopathogene Nematoden, insbesondere S. carpocapsae und S. feltiae, ein beträchtliches Potential zur Bekämpfung von R. cerasi besitzen. Zur endgültigen Klärung sind Versuche unter Praxisbedingungen unumgänglich. Das pflanzliche Insektizid NeemAzal-T/S führte bei einer oralen Aufnahme zu einer deutlichen Reduktion der Fekundität und der Lebensdauer von R. cerasi. Auch hier sind weitere Untersuchungen notwendig

„Bait Sprays“ - eine Alternative zur Bekämpfung der Europäischen Kirschfruchtfliege Rhagoletis cerasi ?

In 2005 initial experiments were carried out to control Rhagoletis cerasi with bait sprays. We used GF-120 fruit fly bait which contains Spinosad and NeemAzal®-T/S mixed in a sugar-yeast hydrolysate solution. 30 ml of bait sprays were applied on single cherry trees in field cages, where we released a defined number of cherry fruit flies. One experiment with GF-120 resulted in a reduction of fruit infestation of 96 % compared with the control. In other trials with GF-120 and Neem bait the effect on the cherry fruit fly population was monitored. After 24 hours GF-120 in a 5 % and 20 % solution led to a high reduction of flies (efficacy 85 %), whereas NeemAzal®-T/S in a 5 %, 10 %, and 20 % solution only resulted in efficacies between 34 % and 42 %. A significant effect of GF-120 was observed already after 3 hours

Bait sprays - an alternative to control the European cherry fruit fly Rhagoletis cerasi ?

In 2005 initial experiments were carried out to control Rhagoletis cerasi with bait sprays. We used GF-120 fruit fly bait which contains Spinosad and NeemAzal®-T/S mixed in a sugar-yeast hydrolysate solution. 30 ml of bait sprays were applied on single cherry trees in field cages, where we released a defined number of cherry fruit flies. One experiment with GF-120 resulted in a reduction of fruit infestation of 96 % compared with the control. In other trials with GF-120 and Neem bait the effect on the cherry fruit fly population was monitored. After 24 hours GF-120 in a 5 % and 20 % solution led to a high reduction of flies (efficacy 85 %), whereas NeemAzal®-T/S in a 5 %, 10 %, and 20 % solution only resulted in efficacies between 34 % and 42 %. A significant effect of GF-120 was observed already after 3 hours

Basic results in biological control of the European Cherry Fruit Fly Rhagoletis cerasi L. (Diptera: Tephritidae) with entomopathogenic nematodes

In 2002 and 2003, within the ‚Bundesprogramm Ökologischer Landbau’, initial experiments to control the European cherry fruit fly Rhagoletis cerasi were carried out under laboratory, semi-field and field conditions with several entomopathogenic nematode species and strains. In the laboratory the efficacy of nematodes against R. cerasi larvae, pupae and adults was examined. To characterize the controlling potential, different nematode dosages, exposure temperatures and substrates were tested in cell wells, petri dishes and plastic boxes. In the semi-field experiments plastic fruit boxes, filled with soil, were used. In the field tests R. cerasi-larvae and nematodes were released in defined areas in a cherry orchard of the institute. For evaluation of the experiments, the infestation rates and efficiencies (ABBOTT) were determined. Steinernema carpocapsae and S. feltiae achieved the highest efficacies. In laboratory, infestation rates in cell wells up to 91 % and efficencies up to 96 %, in petri dishes up to 96 %, respectively 98 %, and in plastic boxes 88 %, respectively 89 %, were attained. The experimental substrates like quartz sand or soil type and the tested temperatures did not result in consistent significant differences in laboratoy tests. A dosage below 25 nematodes per cm2 resulted in insufficient infestation rates. In the semi-field experiments a maximum infestation rate of 86 % (efficiency 78 %) and in a first field test an efficiency of 88 % was obtained. R. cerasipupae were not infested. These results indicate a high controlling potential of entomopathogenic nematodes against R cerasi, especially of the steinernematid species S. carpocapsae and S. feltiae. Further experiments under realistic conditions in the field are forcibly necessary before putting this control method into practice

Kann der Einsatz entomopathogener Nematoden zur nachhaltigen Bekämpfung der Kirschfruchtfliege beitragen?

The cherry fruit fly, Rhagoletis cerasi L., is the major pest of sweet cherries in Europe. Currently, no efficient control method is available and there is the risk of increasing population densities of this pest. Entomopathogenic nematodes caused high mortality of last instar maggots, when entering the soil for pupation, under laboratory and field conditions. First field applications of these biocontrol agents against pupating larvae in 2005 should test their efficacy to reduce pest densities. Accompanying field observa-tions were made to evaluate the degree of natural mortality of the cherry fruit fly during the pupation phase in order to decide if the application of nematodes could substan-tially contribute to control this pest. According to the results in this year, natural mortal-ity factors reduced the cherry fruit fly population from the period between larvae leav-ing the fruit until hatching of adults in the following year by 95%. The emergence rate of adult flies in spring 2006 was low (10 flies/qm) and no significant differences in the densities of emerging flies in untreated and treated areas were detected. Thus, the effect of applying nematodes remained unclear and additional methods are needed to define their impact separately from natural mortality

Biological control of the cherry fruit fly, Rhagoletis cerasi L. (Diptera, Tephriti-dae) by use of entomopathogenic nematodes: first experiences towards practi-cal implementation.

The use of entomopathogenic nematodes (EPN) is a promising approach to control the cherry fruit fly, Rhagoletis cerasi L.. We already demonstrated the high potential of EPN to infect larvae after leaving the cherry for pupation in the soil in laboratory and field experiments. For practice, an appli-cation technique is needed, that is both, grower- and EPN friendly. We tested a tractor mounted spray boom for treatment under the canopy area. The achieved rate of EPN in the soil met the ex-pectations. The activity of EPN in soil samples was high after application, but dropped to 60% of the initial activity within one week. Exact forecasting of larval drop from cherries is another major chal-lenge. To obtain basic data, we recorded the phenology of infestation and larval emergence on trees which were not harvested. Sequential infestation on the same cherry variety was observed and larvae dropped from individual trees for several weeks

Toxicidad de dos aceites esenciales en la Drosophila de alas manchadas

There has been an increase of invasive insect species during the last decade caused by a drastic change in the biotic communities as a result of an enormous increment of the international trade and the intercontinental transportation, as well as the influence by climate change on insect species. Drosophila suzukii Matsumura (Diptera: Drosophilidae) is emerging as a global threat because of its recent range expansion and the economic impact of crop fruit-colonizing populations. The aim of this work was to evaluate the toxicity effect of two essential oils obtained from plants native to Cuba on the invasive spotted wing drosophila. The susceptibility of males and females of D. suzukii to volatile compounds of Thymus vulgaris and Piper auritum at different concentrations was evaluated after 1, 4, and 24 hours of application. Half-maximal effective concentration (EC50) values at 24 h were calculated in each case. Both T. vulgaris (KD107) and P. auritum (KD48) oils made evident their high toxicity to D. suzukii males and females. The essential oil of T. vulgaris (107) at its highest concentration showed the highest percentage of total mortality. T. vulgaris essential oils could be considered as a source of bioactive substances compatible with integrated pest management (IPM) and biological control agents.Durante la última década ha habido un aumento de especies de insectos invasores causado por un cambio drástico en las comunidades bióticas como resultado del incremento del comercio internacional, el transporte intercontinental y la influencia del cambio climático en las especies de insectos. Drosophila suzukii Matsumura (Diptera: Drosophilidae) está emergiendo como una amenaza global, teniendo en cuenta la reciente expansión en su distribución y el impacto económico en la producción de frutas debido a la colonización de sus poblaciones. El objetivo de este trabajo fue evaluar el efecto de toxicidad de dos aceites esenciales obtenidos de plantas nativas de Cuba sobre la Drosophila de alas manchadas. Se evaluó la susceptibilidad de machos y hembras de D. suzukii a compuestos volátiles de Thymus vulgaris y Piper auritum a diferentes concentraciones después de 1, 4 y 24 horas de aplicación. En cada caso, se calcularon los valores de concentración media máxima efectiva (CE50) a las 24 h. Tanto los aceites de T. vulgaris (KD107) como de P. auritum (KD48) hicieron evidente su alta toxicidad para los machos y hembras de D. suzukii. El aceite esencial de T. vulgaris (107) en su concentración más alta provocó el porcentaje más alto de mortalidad total. Los aceites esenciales de T. vulgaris podrían considerarse una fuente de sustancias bioactivas compatibles con el manejo integrado de plagas (MIP) y los agentes de control biológico