Tamara Richardson

MSc (NRES) Candidate

University of Northern British Columbia

Population dynamics and factors influencing host selection in Leptoglossus occidentalis in BC seed orchards

Photo: T. Richardson

The western conifer seed bug, Leptoglossus occidentalis Heidemann (Hemiptera: Heteroptera: Coreidae) is an economically pest in seed orchards in south interior British Columbia and is responsible for varying degrees of seed damage in several conifer species. Although pesticides are used several times per season to combat L. occidentalis, substantial seed loss still occurs in lodgepole pine (Pinus contorta var. latifolia Engelmann) and Douglas-fir (Pseudotsuga menziesii Mirb. Franco) and less significant seed loss occurs in numerous other conifer species such as spruce and larch (Picea and Larix spp.)(Strong at al. 2001, Bates et al. 2000, Hedlin et al. 1980).

BC Ministry of Forests seed orchards produce high quality seed from so called “plus trees” which have been bred for attributes such as rapid growth, stem form and stem diameter. Currently orchard produced seed represents approximately 55% the seed used in reforestation in BC and this percentage is expected to increase to 75% by 2012 (Forest Genetics Council, 2007). The main impediment to attaining this goal is sub-optimal seed yield in orchards caused by seed feeding insects like L. occidentalis

Photo: T. Richardson

The goal of my research is to help with the development of effective management of L. occidentalis in seed orchards. Specifically, my research focuses on spring dispersal processes and spatial patterns of L. occidentalis, factors influencing host plant selection and the development of accurate population census methods. Describing the spring dispersal processes and spatial patterns of L. occidentalis will help to determine optimal timing of for early season intervention, when highest level of seed damage occurs. Determining the mechanisms underlying L. occidentalis host selection has implications for the development of insect trap baits, trap crops and orchard design. Finally, relating standardized field survey insect counts to absolute population abundance estimates will make the development of accurate and efficient population census methods possible and will ultimately be used to develop economic damage thresholds.

Photo: W. Strong

Literature cited:

Bates, S.L., Borden, J.H., Kermode, A.R., Bennett, R.G. 2000. Impact of Leptoglossus occidentalis on Douglas fir seed production. Journal of Economic Entomology. 93 (5):1441-1451.

Forest Genetics Council of British Columbia Annual Report 2007/2008. Available from http://www.fgcouncil.bc.ca/FGCAnnRpt-0708-Web.pdf [accessed 2009-03-11].

Hedlin, A.F, Yates III, H.O., Tovar, D.C., Ebel, B.H., Koerber, T.W. & Merkel, E.P. 1980. Cone and Seed Insects of North American Conifers. Canadian Forestry Service, USDA and Forest Service and Secretaria de Agricultura y Recursos Hidraulicos, Mexico.

Strong, W.B., Bates, S.L., Stoehr, M.U. 2001. Feeding by Leptoglossus occidentalis (Hemiptera:Coreidae) reduces seed set in lodgepole pine (Pinaceae). The Canadian Entomologist 133:857-865