Methodologies for the identification of historic forest pathogen dynamics

The scale, severity, and synchronicity of recent outbreaks of forest pests such as bark beetles (Coleoptera, Scolytinae) and defoliators (Lepidoptera, Choristoneura) within coniferous forest ecosystems of North America, Europe, and Asia are widely regarded as ‘unprecedented’. Despite such devastating outbreak occurrence in recent times, very little is known about historic outbreak occurrence. Traditional methods of reconstructing historic outbreak dynamics, including dendroecology, pollen analysis, and the identification of fossilised pest remains, all have critical weaknesses in their ability to reconstruct such outbreaks accurately, notably non-standardised methodologies, varying parameters for identifying outbreak periods within proxy records, and a bias towards the detection of large-scale, highly destructive outbreaks only. The development of a more accurate detection tool to reconstruct historic outbreak dynamics within the palaeoecological record has been prioritised as one of the top 50 areas of research within Quaternary science. This paper assesses the current methodologies, before presenting the potential role of DNA-based methodologies can play in overcoming some of these limitations and providing more comprehensive reconstructions, and critically, direct detection of historic forest pathogen outbreaks.