Environmental factors influencing flight activity of forensically important female blow flies in Central Europe.

Abstract

In forensic entomology, evaluation of a possible delay between a person's death and insect colonization is crucial. We monitored the seasonal flight activities of the most abundant blow flies in an urban habitat in Frankfurt/Germany based on 152 sampling days between April and October 2017. Thirty-six thousand female specimens of 12 necrophagous taxa were sampled as a possible groundwork for establishing a prediction tool for the activity of certain forensically relevant taxa. The most abundant taxon was Lucilia sericata (n = 19,544), followed by Lucilia caesar (n = 8025), Calliphora vicina (n = 5224), and Lucilia ampullacea (n = 1834). Up to six environmental parameters were statistically significant predictors of fly presence, leading to unique patterns of seasonal and daily activity for all four species. In detail, our analysis proved that L. sericata is a sun-loving, high-summer species that dominates the warmer months and is mostly influenced by mean day temperature. In contrast, L. caesar seems to be a shade-loving species that dominates in autumn resp. late-season and is mainly influenced by mean day temperature and wind speed. The activity of L. ampullacea was highly related to mean day temperature and relative humidity. In contrast to all other species, C. vicina behaved differently, particularly due to its occurrence throughout the entire sampling interval and the higher tolerance limits for the measured abiotic parameters, especially temperature. The present study is groundwork for establishing a prediction tool for the flight and oviposition activity of forensically relevant taxa.