Blaich, R.

Forneck, Astrid

Merkt, N.

English

JKI Open Journal Systems (Julius Kühn-Institut)

Vitis 37 (2), 95-96 (1998) Research Note A tripartite aseptic culture system for grape (Vitis spp.), phylloxera (Daktulosphaera vitifoliae) and mites (Tarsanemus sp.) AsTRJD FoRNECK, N. MERKT and R. BLAICH Introduction: Grape phylloxera (Homoptera: Phylloxeri-deae) is one of the most important insect pests of grapes. The monophagaus dwarf aphid parasitizes leaves and roots of susceptible hosts damaging the vines and eventually destroying them. The use of resistant rootstocks for phylloxera control was the first example of successful pest control by biological means in grape, but there is evidence that this resistance is being overcome by new strains oftbis pest. The evolution of new strains necessitates both the development of new rootstocks and research on integrated control methods including the search for parasites, para-sitoids or other insect pathogens. This paper presents a method for maintaining phylloxera and an insect antagonist under aseptic conditions and shows that under certain conditions Tarsanemus can eliminate phylloxera populations. Material and methods: Vitis labrusca (from the collec-tion ofthe Universität Hohenheim) was micropropagated in a dual culture system as described by FüRNECKet al. ( 1996) in growth chambers at 25 °C, with 30-40 )lmol·m-2·s·1 ( 16 h) light. V. labrusca was used as phylloxera host because the leaf galls ofthis species are partially open allowing observa-tions within the galls without disrupting the system. Phylloxera eggs were gathered from a greenhouse-based colony originating from Bingen (Germany), the Tarsanemus sp. mite eggs from plants in our greenhouse. Both kinds of eggs were surface-steri1ised according to GRZEGORCZYK and WALKER ( 1997) either separate1y or together; they were in-oculated simultaneously using a sterile brush. Results and Discussion: The pyhlloxera population estab1ished readily on roots and leaves of V. labrusca form-ing leaf galls and nodosities, respectively. This was not ham-pered by the mite populations which, due to the smaller inoculum, built up more slowly. After a lag period, mites were observed associated both, with dead and live phylloxera of all stages including eggs. lt was clear, that the mites caused the phylloxera's death because continuous obser-vation showed that none ofthe aphids survived the interac-tion. Within 2 d they died and started to decay. Under nor-mal conditions phylloxera stages, even without nutrient sup-ply, survive at least for 5 d under septic conditions. Mites were first observed in leaf galls and on the plant's apex to-Corresponcence to: Prof. Dr. R. BLAICH, Universität Hohenheim, Institut für Obst-, Gemüse- und Weinbau, D-70599 Stuttgart, Deutschland. Fax: +49-711-4593946. E-mail: rblaich@uni-hohenheim.de gether with phylloxera larvae. Their nurober increased rap-idly and they migrated over the entire plant, their contact with phylloxera morphs being accidental rather than due to a purposeful search. Some mites were also found to feed on the plant leaves and roots laying eggs close to the root hairs. Dead morphs of phylloxera infested with mites de-cayed considerably faster than usual and mites could be observed laying up to 10 eggs near or on a single phylloxera body. The eggs hatched after 5-7 d and the larvae migrated away from the empty carcass. Both male and female mites could be observed (Figure), the latter laying 2-3 eggs over a 5-7 d period. All tripartite cultures were discontinued after approximately 80 d because the phylloxera populations had been eliminated. Although no microbes could be detected at that time, the mite's feces covering the nutrient agar might be a problern for Ionger experiments. Figure: Male (above) and female Tarsanemus sp. Tarsanemus may never be a suitable organism for phylloxera control in the field because at this time we know little about the mite's ecological habitat, feeding preferences and host specificity. Nevertheless, this method maintaining grape, phylloxera and the prospective antagonists under aseptic conditions provides the opportunity to study popu-lation dynamics, feeding behavior and other aspects ofpara-sites, parasitoids or insect pathogens of phylloxera which could increase the ability to biologically control phylloxera. Financial support from the Deutsche Forschungsgemeinschaft and the Bundesland Baden-Württemberg is gratefully acknowl-96 AsTRIO FoRNECK, N. MERKT and R. BLAICH edged. The authors would like to thank Dr. J. ScHLIESSKE, Universität ofHamburg, for his generous help in identifying the mites, R. WIND, Institut fiir Rebenzüchtung Geilweilerhof, Siebeldingen for his sup-port in SEM technique. FoRNECK, A.; WALKER, M. A.; MERKT, N.; 1996: Aseptic dual culture of grape (Vitis spp.) and grape phylloxera (Daktulosphaira vitifoliae Fitch). Vitis 35, 95-97. ÜRZEGORCZYK, W.; WALKER, M. A.; 1997: Surface sterilization of grape phylloxera eggs in preparation for in vitro culture with Vitis species. Amer. J. Enol. Viticult. 48, 157-159. 

A tripartite aseptic culture system for grape (Vitis spp), phylloxera (Daktulosphaera vitifoliae) and mites (Tarsanemus sp.)

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A tripartite aseptic culture system for grape (Vitis spp), phylloxera (Daktulosphaera vitifoliae) and mites (Tarsanemus sp.)

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