Insect Behavior in Fossil Wood: Linking Wood-Boring Activity to Resin Formation in Baltic Amber Deposits

Insects have played an important role in an understanding of the fossil records of plants, revealing insights into their past ecological interactions (Labandeira et al., 2001; Hulcr et al., 2015). This case study presents the results of the examination of a unique conifer xylite specimen from the Baltic amber-bearing deposits, showing evidence of insect behaviour and its connection to resin production. The specimen contains a system of cylindrical borings, likely created by xylophagous beetles, characterised by longitudinal tunnels connected by cross tunnels and chambers. These structures, filled with a fossilised resin that preserves fungal hyphae and singular coprolites, indicate a complex interaction between plants, insects, and fungi (Franceschi et al., 2005; Nagy et al., 2022).

Specimen analysis included imaging using stereoscopic microscopy, UV light photography, and Fourier Transform Infrared (FT-IR) spectroscopy to confirm the resin as succinite, the most abundant fossil resin of Baltic amber deposits (Kosmowska-Ceranowicz, 2015). The results suggest that the borings represent insect habitation and feeding traces, which triggered a plant defense mechanism involving extensive resin production. This finding suggests that wood-boring insects could have had a significant impact on resin secretion and amber formation (Cognato & Grimaldi, 2009).

This study provides new insights into the ichnotaxonomy of trace fossils in xylic substrates and the paleoecology of amber-producing forests. The research further highlights lignite deposits as valuable data sources on fossil resin preservation and taphonomy.