The influence of climate change on the lifecycle of an invasive forest pest Dendroctonus micans (Kug.) and that of its natural enemy, Rhizophagus grandis (Gyll.)

Abstract

The bark beetle Dendroctonus micans (Kugelann) (Scolytinae) is one of the mosteconomically important pest species of spruce forests in Europe. Dendroctonus micans feeds on the phloem of healthy trees, and can kill a tree within a few generations. It was first discovered in the UK in 1982, and despite attempts to halt its spread, it can now be found from Devon to Dumfries and Galloway. When new outbreaks are discovered, the biocontrol agent Rhizophagus grandis (Coleoptera: Rhizophaginae) is released as the primary means of control.As insect lifecycles are directly affected by environmental temperature, forest insect outbreaks are expected to increase and intensify under climate change. Very little is known about how this will affect the fine balance between pests and their natural enemies. This study investigates the possible effects climate change may have on the lifecycles of D. micans and R. grandis, and how this might influence their ecologicalinteractions.The two species of beetle were reared in the laboratory to attain developmentalparameters for the beetles’ life stages. Microhabitat temperatures within spruce stands were also recorded so that future climatic predictions (from the UKCP09 Weather Generator) could be translated into more appropriate microclimatic predictions. Using these data, phenology models for both D. micans and R. grandis were developed in R (R Core Team 2013).A two year lifecycle was the most common lifecycle predicted for D. micans, whilst R. grandis was found to have a partially bivoltine lifecycle. Under climate change, the reduction in generation time predicted for D. micans was not matched by that of R. grandis, and lifecycles appeared less synchronized. Under these conditions, D. micans outbreaks are very likely to occur. The phenology models can be used to inform decisions regarding the pest management of D. micans. In particular, they could help provide more targeted biocontrol.

Thesis is embargoed until 30th April 2016

Date of Award	Apr 2014
Original language	English
Sponsors	Department for Employment and Learning (DEL) & Co-operative Awards in Science and Technology (CAST)
Supervisor	KEITH DAY (Supervisor) & Dario Fornara (Supervisor)