Development of a pheromone-based detection and monitoring technique for the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst) (Lepidoptera: Geometridae)

A two component pheromone blend containing a 1:l ratio of isomeric 5,ll-dimethylheptadecane and 2,5-dimethylheptadecane was used in high-capacity, non-sticky Unitraps to monitor populations of the western hemlock looper, Lambdina f i s c e l l a r i a lugubrosa (Hulst) (Lepid0ptera:Geometridae) at 27 sites (1992) and 34 sites (1993) throughout the Coastal Western Hemlock and Interior Cedar Hemlock biogeoclimatic zones of British Columbia. Rubber septa were loaded via hexane solution with 10, 100, 1000, and 10000 pg (1992) and 1 and 10 pg (1993) of the blend. One trap of each dose plus an unbaited control were suspended from trees in random order at each site, 1-2 m above the ground and 100 m apart. Immature stages of the western hemlock looper (eggs, larvae and pupae) were sampled and related to male moths captured in pheromonebaited traps at each study site. Pheromone-baited traps captured significantly more male moths than unbaited control traps. Catches in traps baited with 10 pg lures caught male western hemlock loopers throughout the three-month (August through October) flight season in both years; the seasonal trends in trap catches were not closely related to temperature. Male moths demonstrated a dose-dependent response to pheromone-baited traps except that response to the two highest doses (1000 and 10000 pg) was the same. In a trap-comparison experiment in 1993, Unitraps captured significantly more male moths than similarly baited sticky iv traps in the control and 10 pg-baited traps at the beginning of the flight and in 1 and 10 pg-baited traps at mid-flight. In 1993, a declining trend in lure potency was evident but not significant for the 1 pg lures. No such trend was observed for the 10 pg lures. Male moth catches in 10 pg-baited traps were correlated with larval and pupal counts within the same generation and were predictive of egg counts in the subsequent generation, suggesting that pheromone-baited traps could be used to monitor populations and predict future outbreaks. Acknowledgements This project was made possible by the contributions of many people. Firstly, I would like to thank Dr, J.H. Borden for his tremendous enthusiasm, support and advice in all aspects of this work from its inception to completion. He has provided a stimulating and enjoyable learning environment throughout my involvement in the M.P.M. program. I would also like to thank Drs. G.A. Van Sickle and G. Gries for advice and support throughout this project, I am indebted to the Forest Insect and Disease Survey of the Canadian Forest Service, and in particular, Messrs. R. Erickson, N. Humphreys, P. Koot, A. Stewart, R. Turnquist and C.S. Wood, who were instrumental in site establishment, sampling of immature stages, and providing me with sticky traps. I would also like to thank Dr. J. Li for synthesizing the pheromone components tested, Ms. R. Gries for loading the lures, Ms. L.J. Chong for logistic support and Mr. F. Bellevance for statistical advice. Fellow M.P.M. students and members of the Borden/Winston lab provided invaluable technical and moral support throughout this project, I am grateful to the many friends, relatives and colleagues who accompanied me during my field work. Finally, I would like to thank my family, Steven, Len, Polly, Kirstin and Matthew for their support, understanding, assistance in field and lab work and overall enthusiasm and interest in this work. This work was funded by the Canadian Forest Service (Green Plan), Simon Fraser University and the Natural Sciences and Engineering Research Council of Canada. Table of