Host colonization patterns, cues mediating host selection and calibration of field surveys with estimates of population abundance of leptoglossus occidentalis in a seed orchard.

The western conifer seed bug, Leptoglossus occidentalis Heidemann (Hemiptera: Heteroptera: Coreidae) is an important pest in southern interior British Columbia seed orchards. In spite of its pest status, host colonization patterns and cues mediating host selection have not been well studied. Additionally standardized population census methods, which are essential for the development of economic damage thresholds, have not yet been established. I examined spring immigration patterns of L. occidentalis into a lodgepole pine seed orchard in 2008 and 2009. In 2008, significant spatial gradients of L. occidentalis-infested trees were found in four of seven surveys, however, they were not directionally consistent. In 2009 a significant spatial gradient was found in a single survey. Spatial gradients may have been detected more easily in 2008 than 2009, as counts of L. occidentalis were much larger. I also assessed whether L. occidentalis exhibits clonal preference, if preferences remained consistent between 2008 and 2009, and examined whether cues responsible for such preferences could be identified. I found that clone preference remained consistent between 2008 and 2009 and that predefined clone preference classes had significantly different levels of the monoterpenes [α]-pinene, [δ]-3 carene, and p-cymene. Additionally, L. occidentalis was found more frequently on clones with cones of greater diameter and weight. Finally, in 2009 I conducted mark-release-recapture studies with corresponding walk-through surveys for L. occidentalis both in lodgepole pine and Douglas-fir seed orchards. I was unable to establish mathematical relationships between population estimates and walk-through surveys in either location. Data from these surveys indicated that the walk-through survey were unreliable, at least at low populations. Studies exploiting cues attractive to L. occidentalis for trap design and additional studies to establish standardized survey methods are recommended as L. occidentalis continues to cause dam