Half way DROPSA: Towards an integrated approach to combat exotic pests
It appears that damage caused by spotted winged Drosophila fruit flies in Europe in 2015 wasn’t as bad as in 2014. Nevertheless, the large consortium of 26 Universities, companies and research institutions, joint in the international DROPSA-project, continues the quest for means to fight this invasive and extremely harmful fruit fly, as well as exotic bacterial diseases of fruits. ‘Currently, control options are labour intensive and expensive , but progress has been made into identifying alternatives to combat these problems’, DROPSA-project leader Neil Audsley says.
Within the DROPSA-project, the battle against spotted winged Drosophila (Drosophila suzukii), alongside the fight against exotic bacteria such as Pseudomonas syringae pv actinidiae (Psa), Xanthomonas fragariae (Xf) and X. arboricola pv. pruni (Xap) are the biggest drivers.
Stopping fruit flies using nets
Last year, several cherry farmers in Northern Italy lost 100% of their crops to spotted winged Drosophila. This year, some of these farmers participated in field trials with fruit fly-proof nets around the trees. ‘Of course, this is a very labour intensive and expensive way to fight the fruit fly’, Audsley admits, ‘but it is probably the most effective means to currently protect your crop, and better than losing all your harvest!’
Fighting exotic insects with biological control agents
Originating from Asia, spotted winged Drosophila was first detected in Europe in 2008, where it is extremely harmful to soft fruits such as cherry and strawberries. Natural enemies of the fruit fly have been identified in its region of origin. They could be used to combat the pest in Europe subject to regulatory procedures. Native natural enemies, such as parasitoids and predators that can adapt to the exotic fruit flies, as well as nematodes and entomopathogenic fungi, are also being evaluated. Within the limited time frame of our project, we are more likely to identify “local solutions” than introducing new exotic parasitoids.'
Within DROPSA, field trials to assess bacterial dispersal by wind and rain or irrigation splash are in progress. Diagnostic assays have been developed for Pseudomonas and Xanthomonas. These assays are currently being validated before transfer to stakeholders for on-site pathogen detection.
Some kiwi orchards in Italy are infected with Pseudomonas syringae pv actinidiae. These bacteria may have been introduced to Italy through the import of contaminated pollen that is used to fertilise the fruit. Audsley: ‘Within our project, we are looking for means to keep the orchards clean and free from exotic bacteria’.
Effective control solutions
We are also looking for innovative and effective control solutions, including using novel antimicrobial peptides, biological control agents and enhancing plant defence mechanisms’. "A biodegradable small synthetic antimicrobial peptide has proven to be effective against bacterial pathogens on peach, kiwifruit and strawberry plants, acting in a similar manner to conventional antibiotics. Selected strains of lactic acid bacteria isolated from fruit trees were also effective in preventing bacterial infections on plants. Production will be scaled-up and formulations prepared for testing these products in orchards. “
Before the end of 2017, DROPSA will not deliver one magic bullet that will fight either the SWD, or one of the bacterial pathogens, Audsley warns. ‘The solution will likely lie in an integrated approach that involves a number of management options for both pests and pathogens.’