Update on the occurrence of Rhagoletis completa and Rhagoletis indifferens in Switzerland
At the second EPPO Workshop on Pest Risk Assessment of non-European fruit flies held in Paris on 1994-03-28/29 further information on the occurrence of Rhagoletis completa and R. indifferens (both EPPO A1 quarantine pests) was given to the participants. According to R. Mani of the Swiss Plant Protection Service, R. completa was found for the first time in 1991 in Ticino. Subsequently the distribution of this pest was monitored by the evaluation of trap catches from 20 localities in the Canton of Ticino and at the international airports of the country. It was found that R. completa is relatively widely distributed in the Canton and that it can be located in the regions of Locarno, ;Lugano and Chiasso in relatively high numbers. In 1991, nearly 2ÿ600 individual walnut husk flies were caught on yellow sticky traps up to 1200 m altitude. Swiss authorities believe that the pest has established in Ticino and that eradication is not feasible.
In contrast, R. indifferens, found also in 1991, has been trapped only in very low numbers mainly around Lugano, but not in Chiasso and Locarno. It is planned to place traps with a higher density in the region in order to detect the extent of the distribution and the density of the populations. The result of these investigations will be the basis of possible decisions by the Swiss authorities to eradicate R. indifferens. Low population densities in the region are partly attributed to the enormous competition of the species with R. cerasi, a fruit fly widely distributed in the region.
Sources
EPPO Secretariat, Paris (1994-03)