CRYPTORHYNCHUS LAPATHI (L.) (COLEOPTERA: CURCULIONIDAE) on Sallx SPP
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DISTRIBUTION AND IMPACT OF CRYPTORHYNCHUS LAPATHI (L.) (COLEOPTERA: CURCULIONIDAE) ON SALlX SPP. IN BRITISH COLUMBIA Cynthia L. Broberg B. Sc. (Plant Biology), University of British Columbia, 1997 THESIS SUBMllTED IN PARTIAL FULFILLMENT FOR THE DEGREE OF MASTER OF PEST MANAGEMENT in the Department of Biological Sciences O Cynthia L. Broberg 1999 SIMON FRASER UNIVERSITY October 1999 All rights reserved. This work may not be repmduced in whole or in part. by photocopy or other means. without permission of the author. National Library Bibliothèque nationale du Canada Acquisitions and Acquisitions et Bibliographie Services sewices bibliographiques 395 Wdüngîori Street 395, rue Wellington ûtîawaON KIAON4 ûttawa ON KIA ON4 Cariada Canadtt The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or seil reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/nlm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othenivise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract The poplar and willow borer, Cryptorhynchus lapathi (L.), known to be present in British Columbia since 1923, primarily attacks species of Salk and Populus. Larvae bore into stems, causing them to break easily. Its impact has been increasing in recent years due to the increasing importance of poplar and willow from both economic and ecological perspectives. I conducted a survey to document the distribution and prevalence of C. lapathi in B.C. within different biogeoclimatic subzones and Salix hosts, and to describe the between-tree and within- tree dynamics of C. lapathi. The sunrey spanned five biogeoclimatic zones, 15 subzones, 45 locations, 135 sites, and 3360 trees, 675 of which were measured in detail. The range of C. lapathi has at least doubled since 1963. The weevil was present in 38 locations and 14 subzones. The intensity of attack and the number of individual weevils were positively related to the prevalence of attacked trees (f= 0.701 and 0.562, respectively). The prevalence of weevil- attacked trees was significantly lower in cold than in warm subzones. Using available climatic data, three different regression models were derived using: number of months with mean ternperature >1 O°C (mode1 1); number of months with mean ternperature >lO°C, mean annual ternperature (OC), and number of frost tee days (model 2); and elevation (m), mean temperature warmest month (OC), and accumulated day degrees >5'C (model 3) to predict the proportion of attacked trees, al1 with ? XI.8. There were 11 new host records, but no evidence of host preference. In general, attacked trees were larger, had more dead wwd and stems, more adventitious branches per stem, more total breaks per stem, and more naturally-caused breaks per stem than their attack-free neighbours. Breaks caused by C. lapathi tended to be slightly larger in diameter and lower on the stem than naturally-caused breaks. Bases of stems were preferentially attacked, and C. lapathi selected large stems in which to oviposit. As large attack- free trees becorne less abundant, weevils apparendy start to attack small-diameter stems. Although C. lapethi is advenely affecting the health of willows in B.C., there is no evidenm that any Salix species is threatened by weevil-caused extinction. iii Well grandpa, here's to given'er snoose. Acknowledgements I thank Kim Hardacker and Alton Harestad for helping develop the methodology used in the study; John Borden for his support and supervision; Margaret Gajecki for her unfailing enthusiasm and help in collecting most of the data; Kim Hardacker, Ryan Comber, John Borden, Morgan Jones, and Nicole Jeans-Williams for their help in the field; rny parents for their help and encouragement; Lee Humble for his help starting this project; George Argus and Anna Roberts for help with willow identification; Del Meidinger for allowing me access to the dimate data; lan Bercovitz for his help with PROC MIXED; and John Borden, Alton Harestad and Lee Humble for review of this manuscript. This research was supported by the Natural Sciences and Engineering Research Council of Canada, the Canadian Forest Sewice, Forest Renewal B.C., Ainsworth Lumber Co. Ltd., B.C. Hydro Power Authority, Bugbusters Pest Management Inc., Canadian Forest Products Ltd., Crestbrook Forest lndustries Ltd., Finlay Forest lndustries Inc., Gorrnan Bros. Ltd,, International Forest Products Ltd., Lignum Ltd., Manning Oiversified Forest Products Ltd., MB Research, Northwood Pulp and Timber ttd., Pacific Forest Products Ltd., Phero Tech Inc., Riverside Forest Products Ltd., Slocan Forest Products Ltd., TimberWest Ltd,, Tolko lndustries Ltd., Weldwood of Canada Ltd., West Fraser Mills Ltd., Western Forest Products Ltd., Weyerhaeuser Canada Ltd. Table of Contents .i Approval .................... .... ............................................................ 11 Abstract ...........................................................................................iii Acknowledgements ......................................................................... v .. List of Tables ............................................................................ VII List of Figures ............................ .....................................................ix Introduction Materials and Methods .......................m........m..........m.mmm.............mm...10 SELECTION OF SAMPLING UNITS ................................................................................................... 10 SAMPLINGTREES .........................................................................................................................15 SALIXIDENTIFICATION .................................................................................................................16 STATISTICALANALYSES ................................................................................................................17 Results and Discussion .................... .......................21 DISTRIBUTION AND ABUNDANCE .............................. ... ......................S.......2f GEOGRAPHICRANGE ................................................................................................................ 21 EFFECTOF BIOGEOCLIMATIC SUBZONE ON THE PROPORTION OF ArrACKED TREES ..........................24 RELATIONSHIPBETWEEN THE PREVALENCE OF ArrACKED TREES AND MEVIL ABUNDANCE ............. 30 INFESTATION DYNAMICS AND IMPACT ..............................................................33 HOST PREFERENCE ..................................................................................................................... 33 DlFFERENCES BETWEN ATTACKED AND AITACK-FREE TREES .......................................................35 Size related factors .............................................................................................................. 35 Dead wood ........................................................................................................................... 37 Stem breakage .................................................................................................................... 42 WITHIN-TREE DISTRIBUTION OF C. UPATHl ................................................................................... 45 Conclusions ....................m..mm.m..mm..mmm.m....................m..m...m...m...........mm52 Appendix ........................................................................................ 57 References Cited .............................m...m........................mm..m............76 List of Tables 'able 1. Biogeoclirnatic description, sampling date, and coordinates of the 45 locations in this study in decreasing order of mean annual temperature ("C). Latitude and longitude are from the most central of the thrw possible sites. Table 2. Components of regression equations used to predict the proportion of attacked trees in any biogeocfimatic subzone. The intercepts and cfirnate variables are tested with the null hypothesis that they, or their modifying parameters, are equal to zero. Residuals are tested against the null hypothesis that they are nomally distributed. See text for explanation of mode1 components. Table 3. Results of correlation analysis between the mean proportions of trees with attack and dimatic factors. Table 4. Ranked percentages of attack by C. lapathi on willow in various taxa. Some species presented in groups because of inability to distinguish benHeen specirnens collected. Othen pooled because of taxonornic affinity within a section. Sarnples were excluded if species could not be determined. Table 5. Comparison between attacked and attack-free willows with respect to 14 rneasured characteristics. Values pooled for each site so that each site with both attacked and attack-free trees is a replicate. Table 6. Ranked summaries of causes of stem death in willows assessed by visual observations in the field, comparing stems attacked by C. lapsthi with attack-free stems. Table 7. Predicted proportions