BugMap: understanding the expansion of alien species with the support of citizens

Tracking the invasion of alien species requires the rapid gathering of a vast amount of data, goal that can be achieved with the coordinated work of researchers and citizens. In this view, the application of citizen science programs to the monitoring of alien species is becoming particularly popular, although its efficacy should be object of more accurate evaluation through specifically designed experiments. BugMap is a smartphone app specifically designed to track the expansion of Halyomorpha halys, the brown marmorated stink bug (BMSB)) in Trentino (Italy). In the present study, we compare the BMSB distribution provided by data obtained with standard monitoring methods (i.e. attractive traps, visual sampling) and BugMap, in terms of time and spatial coverage. From 2016, BugMap collected more than 3000 records, thanks to the contribution of technicians, farmers and citizens. The photographic validation associated with BugMap showed good accuracy since the vast majority of the records targeted the correct stink bug species. The heat maps generated with these records showed a reliable evolution of the areas with higher concentration of BMSB with time, coherent with the data obtained with the traditional monitoring. Furthermore, BugMap data has proved to be particularly useful to monitor both the BMSB phenology (e.g., first appearance of nymphs and eggs) and presence in different environments (e.g., cultivated areas, woods, parks), throughout the year. Our conclusion is that the real time information provided by BugMap could be employed as an instrument for timely decision-making and to support IPM strategies.