Experimental study of smoke pollution from biomass burning impacts on the flight behaviour of Vanessa cardui (painted lady butterfly)

A complex mixture of gases and aerosols emitted from landscape fire, PM_2.5 as the main component can have a significant ecological impact. As an essential part of the ecosystem, insects show sensitivity to smoke pollution. This study investigated the effect of smoke on the flight behaviour of Vanessa cardui (painted lady butterflies). Vanessa cardui was put on a tethered flight mill (TFM) for thirty minutes in three levels of combustion-generated airborne PM_2.5 to quantify the flight performance, including flight distance, average speed, and flight duration, compared with them flying under clean-air conditions. Results indicate that heavy smoke conditions decreased butterfly flight behaviour. For example, when butterflies were exposed to the increasing PM_2.5 concentration with a maximum value at 1500 ug.m^-3 for 20 minutes, the total flight distance decreased by 58%, whilst the average speed declined by 58%, and flight duration reduced by 15%, which compared to clean-air conditions. There is a negative linear correlation between PM_2.5 concentration and flight speed, especially when PM2.5 concentration is over 1000 ug.m^-3.The study has relevance for how air pollution from landscape fires might impact insect flight behaviour and ultimately, the migration and ecosystem services such as pollination they may provide.