Predicted and actual distribution of the invasive species Drosophila Suzuki (Diptera: Drosophilidae) in Bulgaria
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Author: Olia Karadjova, Zhenya Ilieva, Elena Petrova, Mariana Laginova
In 2008, the spotted wing drosophila, Drosophila suzukii 1931 (Diptera: Drosophilidae) was detected for the first time in Europe (Spain). Currently the species is distributed in most Balkan countries and in 2014 it was also found in Bulgaria. The host plants of D. suzukii include cherry, strawberry, raspberry, blackberry, blueberry, peach, grape, plum, apricot and many others. In 2011 a climatic model was developed to determine the potential for permanent establishment and spread of the invasive species in Bulgaria. Specialized software (CLIMEX v. 3) was used to create maps of the ecoclimatic indices (EI). The model predicts that under the current climatic conditions D. suzukii can be established on the whole territory of the country and develop 3–7 generations per year. In 2014 and 2015 a total of 670 adult individuals were trapped. The sex ratio was 3.5 males to 1 female. The greatest numbers of D. suzukii adults were captured using Tephri-traps, followed by specialized Riga cup traps. The high male to female ratio and the low number of flies trapped in spring were likely due to the development of transient populations of the species or insufficient effectiveness of the traps. No damages by D. suzukii were observed on fruit crops. In the region of Plovdiv the number of trapped flies was significantly higher in comparison with Blagoevgrad and Kjustendil. The developed predictive model indicates up to 7 generations per yearfor the regionof Plovdiv. This prognosis was confirmed by the monitoring data: D. suzukii was established at the highest number of sites and with greatest abundance in the area.

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