Phytozid - Application of tansy extract and its ingredients as insecticides against the codling moth
In Austrian conventional fruit production permitted insecticides and repellents against the codling moth are in most cases of synthetic and biotechnological origin. In contrast for organic fruit farming only few possibilities for pest control such as pheromones and granulosevirus are available. In this respect, the sustainable usage of repellents or insecticides gained from plants or plant extracts against the codling moth is of increasing interest for both cultivation methods.
Main goals of this project were the large scale recovery of repellent compounds from the native plant tansy (Tanacetum vulgare L.) against the economically important pest codling moth (Cydia pomonella). Tansy raw extracts were used for field trials and lab testing to establish strategies for pest control based on natural substances.
The raw extract was tested in one apple plantation in field trials as well as in diagnostic lab scale tests. Cultivation of tansy was carried out in two habitats over a period of two years (2009 and 2010), the determination of the extract yield, depending on the developmental state of the plant, only for the vegetation period of 2009 since data from self-financed preparatory work of the contractor1 (Thesis Anne Hambammer) from 2008 were incorporated.
To investigate the development of the extract yield in 2008 at 6 dates (n = 20) and 2009 at 4 dates (n = 10) samples were taken, extracted by the lab extraction system (ASE = Accelerated Solvent Extraction) and the extract yields were determined. At sampling dates the development stages of plants adapted on the extended BBCH method2 (Entwicklungsstadien mono- und dikotyler Pflanzen – BBCH Monografie) were described.
In addition to the evaluation of the optimal harvest time regarding extract yield and quality also an optimization of important parameters in solvent extraction (different temperatures and solvents – e.g. CO2 extraction) was performed to enhance the amount of repellent active compounds in the raw extract.
From these investigations n - hexane could be identified as appropriate solvent for the extraction of active repellents from tansy. A part of the herbal material harvested in the first year was used for extraction and further processing in pilot plant scale to provide larger quantities of the raw extract. Parts of the dried raw extract were used for fractionation, semi preparative isolation and structure elucidation of major active substances in laboratory scale (milligram range). With another part of the raw extract fractionation in gram range was performed.
The rest of the raw extract was used for repellent formulation, field trials in one apple plantation and the diagnostic bore tests in lab scale and greenhouse trials. The repellent formulation was abutted on conventional pesticides and was conducted by using emulsifiers that may be suitable for organic farming. All investigations were accompanied by HPLC/UV-DAD or GC/MS analysis respectively.
From 1 kg (dry matter = DM) of plant material 10.8 g raw extract were obtained (about 1% extract yield). The raw extract was applied in different concentrations respectively (0.4, 0.1 and 0.04%) in the field and laboratory diagnostic trials. In the field trials an effect against the codling moth could be shown, whereas the higher dose (0.4%) led to better results than the lower one (0.1%). When evaluating the level of infestation of the apples in the first codling moths generation 2010 results in the range of conventional pesticides were reached.
The overall impact decreased by the end of the season in the way, that infestation of codling moth was too high and effect of the applied dosages too low. Reasons for that effect have to be investigated, maybe shorter application intervals or higher concentrations should be applied. In the diagnostic tests, the extract with the highest concentration (0.4%) showed a significantly higher deterrent effect compared to the lower concentrations.
As active substances monomethylolivetol and its derivative 3-methoxy-5-undecylphenol from the natural product group of resorcinols were identified.
To confirm and ensure the results further experiments with higher concentrations of the extract have to be performed possibly in conjunction with other active compounds from plants.
Mag. Susanne Wagner
JOANNEUM RESEARCH Forschungsgesellschaft mbH - Institut für Nachhaltige Techniken und Systeme
Project or cooperation partner
- ao. Univ.-Prof. Dr. Franz Hadacek
Universität Wien, Fakultät für Lebenswissenschaften
Department für ökologische Chemie und Ökosystemforschung
Althanstraße 14, 1090 Wien