16 years of practical experience using mating disruption against Eupoecilia ambiguella and Lobesia botrana in vineyards of the Wuerttemberg region (Germany)

Walter K. Kast
Staatliche Lehr- und Versuchsanstalt für Wein– und Obstbau Weinsberg, Postfach 13 09,
D-74185 Weinsberg,
Email: Walter.Kast@lvwo.bwl.de

Abstract
Since 1985 in the region of Wuerttemberg (Germany) mating disruption against Eupoecilia ambiguella is used. Since 1993 it is also used against Lobesia botrana. The use of mating disruption is continuously increasing so that up to now 75 % of the vineyards are treated with pheromones. In the first generation the effect of mating disruption was lower than in the second generation, however sufficient. Sometimes problems occurred at the borderline of the treated area due to an immigration of mature females. Very rarely the disease incidence of the second generation exceeded the damage threshold of 5% attack. The overall rate of successful pheromone treatments was better than in vineyards treated with insecticides. The use of pheromones in viticulture seems to be more a social problem than a technical problem .

Zusammenfassung
Seit 1985 wird die Verwirrmethode gegen den Einbindigen Traubenwickler (Eupoecilia ambiguella) und seit 1993 auch gegen den Bekreuzten Traubenwickler (Lobesia botrana) eingesetzt. Die behandelte Rebfläche ist kontinuierlich angestiegen. Mittlerweile werden über 75 % der Rebfläche behandelt. Probleme bereiten vereinzelte Randflächen, in denen begattete Weibchen zuwandern. In der ersten Generation (Heuwurmgeneration) ist die Wirksamkeit deutlich geringer, aber ausreichend. Insgesamt ist die Erfolgsquote besser als in konventionell mit chemischen Insektiziden behandelten Rebflächen. Wesentliche Veränderungen im Auftreten anderer Schädlinge wurden nicht beobachtet. Lediglich in den ersten beiden Jahren war gelegentlich ein Anstieg der Population der Rebzikade (Empoasca vitis) zu verzeichnen, ohne daß die Schadschwelle überschritten wurde. Die Probleme mit Schadmilben, Roter Spinne (Panonychus ulmi), Gemeiner Spinnmilbe (Tetranychus urticae) und der Kräuselmilbe (Calepitrimerus vitis) verringerten sich wesentlich, vermutlich wegen des Anstiegs der Nützlingspopulationen.

Introduction
Main pests in Southern Germany vineyards are the grape and the vine moth (Eupoecilia ambiguella/Lobesia botrana). While Eupoecilia represents the most common species in the vineyards, Lobesia exists in some sites only. The typical wine-farm is very small (0.8 ha) and most of the vineyards are cultivated as a side-job and grapes are processed in co-operatives. After first successful trials in 1985 the use of mating disruption rapidly increased to now more than 75 % of the total vinegrowing area in the region Wuerttemberg (Figure).

Problems and solutions
One of the biggest problems was the „large area problem„. The larger the covered area is, the better mating disruption is working. In most cases a lot of winegrowers had to work together. Basic structures as co-operatives and reparcelling organizations proved to be very helpful in this case. The dispensers were suspended generally in a joint action, which was processed as a social event.

Furthermore, the public pressure against the use of chemical insecticides and the fact, that most vineyards in the region are located extremely close to residential areas were also very helpful to introduce the use of pheromone treatments. It proved to be important, that in contrast to the use of biological insecticides (Bacillus thuringiensis) everybody could realize the benefit of the new system against pests. Celebrating the suspension as a social event, mating disruption was best reported in the local newspapers and winegrowers had an excellent chance to cultivate a better image.

One of the biggest problems were the higher costs of the new technique. Mating disruption rated on about 120,-- EURO/ha for one species and 170,-- EURO/ha for two species. Additional costs of about 25,-- to 50,-- Euro/ha were needed for the suspension of the dispensers (2 – 3 man-hours/ha) and organization of the project. In contrast, insecticides rated from 15,-- to 90,-- EURO/ha for 1 or 2 sprays. A holistic approach had to calculate additional costs for sprays against mites caused by the reduction of beneficial arthropods especially Thyphlodromus pyri. The reduction of the beneficials by insecticides required at least one additional spray against spider mites. One spray costs 45,-- EURO/ha. The holistic approach concluded, that mating disruption is cost-neutral. The use of mating disruption was supported by the government of Baden-Wuerttemberg starting with 40,-- ´EURO/ha in 1987 up to 100,-- EURO/ha since1998.

Furthermore a control system was established. First control (1 ^st generation) was performed during bloom. In case of finding more than 10 % of larvae attack in some vineyards, the winegrowers were informed that there might be a risk of higher attack in the 2 ^nd generation. In this case the vineyards were controlled very intensively in the second generation especially during the end of the egg position period. A control of the second generation was carried out using data of pheromone traps from outside the treated area. Controls for larvae attack were performed 7 and 14 days after the first peak. If the attack exceeded a threshold of 5 % additional use of insecticides (Parathion) was proposed.

Results
The mating disruption technique proved to be successful. The attack of the first generation is irrelevant with regard of economical losses. But the risk-threshold of 10 % attack in the first generation was exceeded in some cases only, especially in the year 2000. Nevertheless in more than 98 %, the attack of the second generation did not exceed the economical damage threshold of 5 % grape attack. A higher rate of attack was found in some cases along the border line of the treated area and in some hot spots, with an extremely high population density. Soon the winegrowers learned to handle these problems.

The overall rate of successful treatments was better than in vineyards treated traditionally with insecticides. The rate of success increased if the method was used for more than three years. Relevant changes in the abundance of other pests were not observed. In the first and second year in some cases the leaf hopper population (Empoasca vitis) increased but did not exceed the damage threshold. Mite problems decreased very quickly because of the higher number of beneficial arthropods.

Literature

Neumann, U.; Harries, V.; Gasser, A.; Waldner, W.; Kast, W. K. (1992): Recent advances with the mating disruption technique in apples and grapes – factors influencing the success of pheromones. Brighton Crop Protection Conference – Pests and Diseases, 8 C-10, 1045 – 1050.

Kast, W. K.; Munder, H.; Gasser, A. (1991): Erfahrungen mit der Verwirrmethode gegen den Einbindigen Traubenwickler. Der Deutsche Weinbau 10 , 374 – 377.