IOBC wprs Bulletin Vol 22(9), 1999

On the increase of mating disruption in arboriculture and viticulture in Switzerland, 1996-1998

Markus Zuber

Abstract: In the past three years (1996-1998), mating disruption has become a widely used method in orchards (400 ha; 9 % of the total surface in 1998) and vineyards (3600 ha; 25 % of the total surface in 1998) in Switzerland. This is due to economic products, sound technical assistance, good cooperation between government officials and the companies selling the products, and satisfying results. In contrast to the situation in many other European countries, the use of the mating disruption technique in Switzerland was in most cases not dependant on government subsidies. Future use of mating disruption strongly depends on the economic situation in agriculture and therefore also on the price of the technique. Measures like reducing the amount of dispensers per area and reducing or replacing expensive pheromone components are currently being evaluated and discussed.

Key words: Mating disruption, pheromone registration, dispensers

Introduction

In 1986, mating disruption dispensers against the grapeberry moth Eupoecilia ambiguella were registered in Switzerland by BASF. The use of mating disruption against this pest insect became very popular mainly in the German part of Switzerland. Ten years later, in 1996, RAK 2 and RAK 1+2 against Lobesia botrana and against both E. ambiguella and L. botrana, respectively, were registered.

Different types of dispensers were tested over the years against the codling moth, Cydia pomonella, until in 1996, Isomate-C Plus dispensers were registered by Andermatt Biocontrol AG.

In 1997, Isomate-M Plus dispensers were registered against Grapholita funebrana - the only possibility to control this insect in organic farming. The same dispensers are still being tested against Grapholita lobarzewskii - with success.

During the past three years further trials have been carried out to check the possibility of controlling Adoxophyes orana with Isomate-C Special dispensers.

Development

Since registration in 1996 of the Isomate-C Plus dispensers against Cydia pomonella and the RAK 1+2/RAK 2-dispensers, the areas treated with the mating disruption technique have multiplied from one year to the other.

Motivations for using mating disruption are: (1) selling argument (mainly in viticulture); (2) subsidies; (3) easy-to-use technique; (4) reduction in use of insecticides (and acaricides), no residues; (5) low impact on the ecosystem.

Farmers can be motivated by: (1) subsidies, low-cost calculation, direct selling; (2) technical assistance; (3) training, coordination, scientifically approved results; (4) cooperation with government officials; (4) PR-activities (TV, newspapers) to sensitize customers.

Mating disruption in viticulture, however, usually depends on the collaboration of many growers within a single vineyard (sometimes up to 100 growers per 30 ha!). In arboriculture, farmers can decide whether they want to start with mating disruption on their own. Yet, in Switzerland the orchards are not only relatively small, but often high trees stand close by and sometimes a big variety of lepidopteran species are found that cause damage if not controlled by relatively unspecific chemical treatments. These reasons are responsible for the relatively slow increase in the use of mating disruption in Swiss orchards.

Experiences

On the whole, the acceptance of the mating disruption technique among most of the growers as well as among their clients has been very positive. Moreover, farmers have been sensibilized to check the population dynamics of their main pest insects, as well as to observe the biodiversity in their orchards/vineyards more intensively.

The use of the RAK 2, RAK 1+2 and Bocep Viti in Swiss vineyards is mostly a story of success. This enthusiasm leads to the fact that people want to use mating disruption also under conditions which are not really favourable. In 1998, the hot summer led to short and heavy flights of E. ambiguella followed by massive attacks by the first generation. In one major case that started with a high population level, mating disruption was not successful. Yet, surprisingly enough, mating disruption achieved better results in this special case when combined with 0-1 chemical treatment than in a vineyard nearby where only 2-3 chemical treatments were applied.

Mating disruption with Isomate-C Plus dispensers has shown very good results in both organic and IPM production. In cases where mating disruption has continuously been used for more than 2 years the density of dispensers could be reduced to 800 or even 600/ha (instead of the 1000/ha) depending on the size of the orchard. Mating disruption against the leafroller Adoxophyes orana has, however, not been successful. The combined use of mating disruption against C. pomonella and granulosis virus against A. orana (Capex) can be recommended. Even on smaller plots, mating disruption against G. funebrana with Isomate-M Plus/M-Rosso showed satisfying results. The efficacy of the same dispensers, when combined with the C-Plus dispensers gave good results for the control of both C. pomonella and G. lobarzewskii.

Conclusions and future perspectives

Biological restrictions, but mainly economical arguments, still prevent a wider use of mating disruption. Different field studies showed that the density of dispensers can be reduced by at least 40 % after an initial two years with good results. The remaining dispensers must then be concentrated on the borders and, depending on the area, on some transverse lines.

Reduced quantities of pheromone or the use of subsidiary compounds such as citrals can also help to reduce costs to an economically tolerable level.

Acceptance of this technique not only reduces the environmental impact of agriculture, but also helps sensibilize farmers for the need of making controls and paying attention to natural interactions in their cultures. It is important to find economically and ecologically acceptable solutions so that the techniques will continue to be applied even when subsidies dwindle.

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