Responses of the pest Drosophila suzukii population to environmental variables in southern Spain (Granada, Andalusia) – results of a pilot study

In this study conducted in Granada province in southern Spain, we analysed the flying activity and sex-ratio variability of the invasive pest Drosophila suzukii (the spotted wing drosophila) in the context of environmental factors and compared it with co-occurring Drosophilidae in a village garden. The studied D. suzukii population showed overwintering capabilities and successful maintenance in village garden with non-crop plants. Its flight period showed two peaks: female-biased, in November, and male-biased, in May. The sex ratio varied throughout the year and was mostly female-biased. We observed the effect of temperature on Drosophilidae and rainfall and temperature on the D. suzukii. Catches of the studied species were minimal at the minimal temperatures below 0 °C, and absent or near absent when the maximal temperature exceeded 30 °C. Moreover, we did not observe D. suzukii in samples when the minimum temperature below 0 °C was combined with heavy rainfall. The spotted wing drosophila seems to be more sensitive to precipitation than native Drosophilidae, as its proportion in the samples decreased with increasing rainfall. This pest also shows more pronounced short peaks in which it makes an important proportion of the biocoenosis of in comparison with other Drosophilidae.