Progress in DROPSA
Drosophila suzukii on strawberry
New and emerging pests (Drosophila suzukii), and quarantine bacterial pathogens such as Pseudomonas syringae pv. actinidiae (Psa), Xanthomonas fragariae (Xf) and X. arboricola pv. pruni (Xap) that have been introduced into Europe have been identified as major phytosanitary risks. They pose a major challenge to fruit production and are causing substantial economic losses. DROPSA is addressing the challenges faced by the EU fruit industry by creating new knowledge and understanding of the damage and losses of fruit crops due to D. suzukii, Psa and Xf and Xap. In the first 2 years of the DROPSA project significant progress is made.
Pathway of introduction of fruit pests and pathogens
Alert lists of pests that may be introduced into Europe with fruit trade are being prepared for selected crops. Case studies involving international fruit trade networks and transhipments within the EU as pathways are also being undertaken. The area of origin of populations of D. suzukii and pathogens are being identified from samples collected by all partners using molecular markers. Models are being used to investigate their potential spread and distribution.
Biology of Drosophila suzukii
Various studies (life cycle, host range, population dynamics) are being carried out in China (area of origin) and Europe and North America (area of invasion) to gain a better understanding of the biology and ecology of D. suzukii. In Switzerland, Italy and the Netherlands, over 100 wild and cultivated fruits species have been collected to determine the host range for D. suzukii. The fly emerged from 43 different species and was particularly abundant in fruits of the genera Rubus, Sambucus, Frangula, Cornus and Prunus. The population densities and dispersal of D. suzukii between crops and non-crop habitats have been assessed using traps and by assessing crop damage in cherry and vineyard fields. The natural organisms that kill D.suzukii in their native and invasive regions are being identified for use as biological control agents for this fly.
Control of Drosophila suzukii
Under laboratory conditions, a variety of chemicals provided excellent control of both adult and larval D. suzukii. The most active compounds are currently being tested in the field in Italy. Some strains of entomopathogenic fungi also significantly reduced fly populations in the laboratory and are currently being considered for use in lure and infect strategies. Traps and attractants have been evaluated and standard procedures for monitoring D. suzukii developed. In Italy mass trapping and netting is being evaluated in cherry orchards. Pherobank has also produced an attractant for D. suzukii that is being tested in the Netherlands and Spain.
Biology of bacterial pathogens
Field trials to assess pathogen dispersal by wind and rain/irrigation splash are in progress. Wet strawberry plants infected with Xanthomonas fragariae were mown. Bacteria could be detected up to 100 metres from the source demonstrating mowing wet plants dramatically increases dispersal and intensifies disease severity.
An economic analysis is being undertaken of the prevention and control strategies developed in DROPSA and their implementation in practical solutions and IPM strategies. Ex-ante calculations have been made to provide critical information for use in the development of new strategies. These include sterile insect techniques and netting on cherries and pesticides on strawberries against D.suzukii, and plastic covers against Psa on kiwi fruit.