Population Status of Diptera in the First Post-Fire Year in Central European Russia

In recent years, the frequency of forest fires has increased in many regions worldwide, with many fires developing rapidly and affecting large areas. Such fires lead to profound changes in ecosystem structure and functioning. Diptera play an important role in temperate European forests and, due to their high mobility, are among the first insect groups to colonize burned areas. However, many aspects of post-fire colonization by flying insects remain insufficiently studied. The study was conducted in the Republic of Mordovia (central European Russia) during the first year after the fires of 2021. Insects were collected using beer traps baited with beer and sugar. Sampling was carried out from April to October 2022 at 11 plots. The plots differed in fire intensity, distance from the 2021 fire edge, and the degree of vegetation recovery following the fires of 2010 and 2021. In total, 44 Diptera families were identified, comprising more than 36,000 specimens. Several families were represented by more than 1000 individuals in traps, including Anthomyiidae, Bibionidae, Chloropidae, Drosophilidae, Milichiidae, Muscidae, Polleniidae, Sciaridae, and Tachinidae. The lowest numbers of individuals and families were recorded at plots located farthest from the fire boundary, i.e., at the greatest distance from unburned areas. We found that Diptera abundance in traps correlated significantly with percentage of wood debris on a plot (r = 0.71, p < 0.05), and number of herb species per plot (r = 0.76, p < 0.01). The lowest values of biodiversity indices (Shannon, Simpson, Margalef, Pielou, and Berger–Parker indices) were recorded at a plot located 1 km inside the burned area. The highest values of these indices were observed at plots situated along the fire boundary. At completely burned plots located far from the fire edge, Diptera abundance dynamics were heterogeneous. Seasonal activity of Diptera at other plots was characterized by a slight increase in abundance in May, followed by a decrease by July, and a subsequent gradual increase from August to October.