Integrated forest management of hylobius

 

Annual Summary of Research
1 April 2002–31 March 2003

Population Dynamics and Migration of Hylobius abietis (R Moore)

Prior to 2002 this project was primarily aimed at understanding the population dynamics of Hylobius from the commencement of clearfelling to a number of years post-fell as well as the relationship between Hylobius densities and damage to transplants. The data collection for this part of the work declined sharply in 2001–02 and the detailed ‘dynamics’ monitoring taking place was completed by the autumn of 2002. The project began to enter a new phase in 2001–02, in collaboration with FE Forest Districts, with greater emphasis on determining whether patterns of population development that had been recorded were similar across a range of sites in northern Britain. This part of the programme was also designed to determine our ability to predict damage in advance. In addition to this, work was started in 2002 to determine the importance of size and separation distances between clearfells in terms of the ability of Hylobius populations to migrate between them. The latter work will continue during 2003 and attempt to further quantify the effects of clearfell separation distance and size on subsequent population density and, by implication, transplant damage.

The work that has taken place in this programme has shown that there are consistent and predictable patterns of population development and damage following clearfelling. It has also shown that there is a strong relationship between populations and transplant damage. Work is continuing to build predictive models that forecast population trajectories and transplant damage on a site-specific basis and with this objective in mind a new ‘Management Support System’ (MSS) will be trialled from 2003 onwards. The information collected will be used to deliver management options and advice to FD staff on the Hylobius threat to transplants.

Other work in progress in this project includes experiments to determine the effects of Continuous Cover Forestry on Hylobius.

Publications

A paper entitled ‘The effect of time of year on the development of immature stages of the Large Pine Weevil (Hylobius abietis L.) in stumps of Sitka spruce (Picea sitchensis Carr.) and the influence of felling date on their growth, density and distribution’ has been accepted for publication. Another paper ‘The use of dye markers as a method of reducing herbicide use and potential environmental impacts’ has been published.

Plant Quality (D Wainhouse)

The ability of young conifer transplants to resist or tolerate feeding by the pine weevil, Hylobius abietis, has an important influence on the amount of insecticide needed to protect them during the establishment phase. Little is known about natural levels of resistance in Corsican pine and Sitka spruce and how its expression is affected by the mass-production techniques currently used for production of planting stock. Transplants vary in a number of different ways but physical size is often considered to be important in resistance or tolerance of attack. Within the IFM programme, greenhouse and laboratory studies are in progress to identify the mechanism of resistance to weevils and its relationship to plant size. Bioassay of individual plants has revealed large differences in the amount of bark eaten that appears to be related to the amount of resin produced in stem bark. In general, resin concentration was higher in larger stems. Preliminary bioassay of 2-year-old cell-grown Corsican pine from nurseries suggests that they are highly susceptible to weevil damage. Field trials of experimentally manipulated plants are currently being planned.