Susceptibility of Weevil Resistant Spruce to Damage by Other Insect Pests

Susceptibility of weevil resistant spruce to damage by other insect pests.

FII project No. Y051225

Summary Report

Submitted by: René Alfaro and Lara vanAkker Abstract

Sitka and interior spruce with demonstrated resistance to the white pine weevil (Pissodes strobi) have been identified and are being used in breeding programs. However, some trees that are resistant to weevil may also be resistant to other pests, while other trees may be more susceptible. In order to determine the susceptibility of weevil resistant spruce to other insect pests, ground surveys were conducted in genetic trials established by the BC Ministry of Forests. Data were collected from the top ten weevil resistant and susceptible families or clonal lines at three Sitka spruce plantations as well as one white and one interior spruce plantation. At all sites weevil resistant trees had superior stem form and height growth compared to weevil susceptible trees. Incidence of damage by insect pests other than weevil was not influenced by the trees’ weevil resistance status at any of the sites.

A number of tree variables were correlated with insect damage. These relationships will be useful in the selection of reforestation material to minimize damage due to these pests and are summarized as follows:

• Trees with poor stem form had a higher frequency of aphid galls. • Trees that are slightly chlorotic had less Z. canadensis damage. • Trees from the CDF, ICH and Washington biogeoclimatic zones had less Z. canadensis damage. • Trees from the Washington sources had the lowest levels of needle spotting.

Observations at the family and clonal line level indicated variation in performance with respect to specific insect pests. Individual weevil resistant families and clonal lines with good height growth and stem form as well as better than average performance with respect to insect pests were identified at some of the sites. This information will be useful in selecting weevil resistant material for inclusion breeding programs and seed orchards. Introduction

The white pine weevil (Pissodes strobi) is the most serious threat to spruce reforestation in BC, in both coastal Sitka spruce and interior white spruce, causing millions of dollars in losses to industry. Host resistance is a method of pest control, where natural resistant genotypes are utilized to reduce pest incidence and damage. Recently, by means of an extensive screening program, a set of Sitka and interior spruce parents with demonstrated resistance to the weevil has been identified (Kiss and Yanchuk 1991; Alfaro et al. 2001; King et al. 2004). The resistant genotypes are being used in advancing the breeding program for BC (King 1994), in establishing seed orchards, and are being planted by industry.

While the implementation of weevil resistant genotypes in spruce regeneration programs will reduce damage by the white pine weevil, there are a number of other insect pests that also have an impact on spruce regeneration. For example, the green spruce aphid is a very important defoliator of Sitka spruce in BC and the UK. Lately, this insect is causing severe damage to white spruce in western USA. The spruce bud moth, Zeiraphera canadensis, and Cooley spruce gall aphid (Adelges cooleyi) can produce stunted and deformed trees (Peterson et al. 1997).

A given suite of mechanisms that confer resistance to weevil may or may not confer resistance to other pests. As a result, some genotypes that are resistant to weevil may also be resistant to other pests, while others may be more susceptible (Mattson et al. 1997; Lewis et al. 1999). In order to protect the investment made in identifying and propagating weevil resistant spruce, and to effectively use these genotypes in reforestation programs, it is necessary to determine the susceptibility of weevil resistant spruce to incidence of damage by other insect pests.

The objectives of this study were to survey weevil resistant stock for damage by other insect pests, in order to provide guidelines for the selection of weevil resistant material for inclusion in breeding programs and seed orchards.

Methodology

The BC Ministry of Forests (BC MoF) has established a number of Sitka and interior spruce progeny trials throughout BC, that are monitored annually by the Canadian Forest Service (CFS) for the purpose of screening for weevil resistance. (See webpage: http://www.pfc.forestry.ca/entomology/weevil/resistance/resistance_e.html). These trials consist of a well replicated set of either half or full sibling families, or clonal lines. The trials have been surveyed extensively for weevil damage and weevil resistance rankings have been generated for the material in each trial. There are several individual genotypes (for example Haney 898) and families (descendants from specific parents) that have performed exceptionally well, showing very few weevil attacks under the extreme weevil pressure applied during the screening program. Ground surveys at five trial sites were conducted to explore the following hypothesis: The weevil-resistant status of a tree influences incidence of damage by other insect pests.

For this study we used three Sitka spruce and two interior spruce trials, established between 1984 and 1999 (Table 1). The top ten weevil-resistant families or clonal lines at each site, as well as the ten most weevil-susceptible, were selected based on the proportion of trees in each family/clonal line that had sustained at least one weevil attack during the screening process. Seven trees from each family/clonal line at each site were randomly selected to be surveyed. Ground surveys were conducted and the information that was collected is described in Table 2.

Table 1. BC Ministry of Forests Sitka and interior spruce progeny trials monitored for the purpose of establishing the susceptibility of weevil- resistant spruce to incidence of damage by other insect pests.

Species and Site Year Material No. families planted at site Sitka spruce Jordan River 1991 half sib 75 Espinosa Creek, Zeballos 1991 clonal 151 Harrison Mills 1999 half sib 126 Interior and white spruce Camp Creek, Clearwater 1984 half sib 139 Kalamalka Research Stn 1995 full sib 42

Table 2. Data collected from each tree to determine the susceptibility of weevil-resistant families and clonal lines to damage by other insect pests.

Variable Description HT - height class for the site, i.e. is the tree small, med or large compared to other trees on the site? (1=relatively small for site, 2= average for site, 3=relatively large for site) STEM - Stem form, 1= single straight dominant stem, 4=bushy, deformed, stunted tree with multiple leaders (codes 2 and 3 were given to intermediate forms) COLOR - Colour of the foliage, dark green to bright yellow (1= dark green, 4=yellow) (codes 2 and 3 were given to intermediate forms) DEFOL - Ranking of the extent of defoliator damage (not including damage to new shoots) 0=none, 1=very light, 2=light, 3=moderate, 4=severe GALLS - Ranking of the extent of galling on the tree 0=none, 1=very light (1-5 galls), 2=light (6-20 galls), 3=moderate (21-50 galls), 4=severe (>50 galls) BUDS - Ranking of the extent of bud/shoot damage due to insects. 0=no buds affected, 1=very light (1-5 buds affected), 2=light (6-20 buds affected), 3=moderate (21-50 buds affected), 4=severe (>50 buds affected)

Box plots were prepared to determine the variation in tree and insect damage variables amongst families and clonal lines at each site. Since relatively high levels of insect damage occurred at the Espinosa site, correlation analyses were conducted to identify relationships between insect damage and tree variables such as height, stem form and parent tree origin variables. Box plots were also prepared to identify differences in insect damage amongst various parent tree provenances and biogeoclimatic zones at the Espinosa site. The results of these analyses are presented in the Espinosa survey summary.

Descriptions of site and plant material

Jordan River

The Jordan River plantation was established in 1991 with 75 half-sibling Sitka spruce families represented. In 1994 three Pissodes strobi weevils were released on each tree in the southeast half of the plantation, for the purpose of screening the families for weevil resistance. The site has been monitored continuously from 1994 until 2003. The families selected for this study are listed in Table 3. Weevil attack rates (the percent of trees in each family that sustained at least one weevil attack between 1994 and 2003) for susceptible families ranged from 82.6 to 95.8%, while attack rates in resistant families ranged from 25.0 to 39.1%.

Table 3. Provenance, geographic co-ordinates, elevation and weevil resistance status of Sitka spruce families surveyed for susceptibility to other insect pests. Jordan River Trial, B.C.

Family Source LAT LONG ELEV(m) STATUS* %Attack 6 Comox1, VI 49.75 -124.98 20 R 36.4 10 Courten2, VI 49.70 -125.03 10 R 38.1 12 Royston2, VI 49.62 -124.93 20 R 29.2 16 Buckley3, VI 49.52 -124.85 20 R 31.8 18 Fanny3, VI 49.50 -124.82 10 R 29.2 24 Qualic2, VI 49.37 -124.48 5 R 34.8 25 Qualic3, VI 49.37 -124.48 5 R 39.1 32 MillBay1, VI 48.65 -123.55 20 S 82.6 43 SanJosef, VI 50.67 -128.20 40 S 95.8 47 Channel1, QCI 53.13 -132.27 70 S 95.8 48 Channel2, QCI 53.13 -132.27 70 S 95.6 49 Tlell1, QCI 53.37 -131.92 7 S 95.8 50 Tlell2, QCI 53.37 -131.92 7 S 95.6 51 Copper, QCI 53.12 -131.68 10 S 90.3 65 Dungen1, Washington 48.13 -123.20 25 S 95.2 81 Hood16, Washington 47.87 -122.67 80 S 91.7 82 Beaver21, Washington 47.97 -122.77 40 S 91.3 120 DeepBay1, VI 49.45 -124.70 20 R 29.2 121 DeepBay2, VI 49.45 -124.70 20 R 25.0 134 Gillies2, VI 49.68 -124.48 10 R 38.1 * weevil resistance status, R= resistant to white pine weevil, S= susceptible Harrison

The Harrison plantation was established in 1999 with 126 half-sibling Sitka spruce families. In October 2002, three weevils were placed on each tree to facilitate screening for weevil resistance. Parent source data for the families at this site is currently unavailable. Weevil attack rates (the percent of trees in each family that sustained at least one weevil attack between 1999 and 2003) for susceptible families ranged from 79.2 to 87.0%, while attack rates in resistant families ranged from 12.5 to 17.4%.

Table 4. Weevil resistant and susceptible Sitka spruce families selected for survey of other insect damage at Harrison, BC.

Family STATUS* %Attack 11 R 17.4 22 R 17.4 24 R 17.4 26 R 16.7 33 R 17.4 36 R 17.4 60 R 12.5 79 R 13.0 122 R 17.4 123 R 13.6 18 S 87.0 87 S 81.8 88 S 79.2 90 S 79.2 93 S 79.2 97 S 79.2 103 S 82.6 125 S 81.8 129 S 87.0 130 S 81.8 * weevil resistance status, R= resistant to white pine weevil, S=susceptible

Espinosa

The Espinosa plantation was established in 1991 with 151 clonal lines of Sitka spruce represented. The weevil population at this site was not augmented and screening for weevil resistance was conducted under natural weevil population levels. Clonal lines selected for this study are listed in Table 5. Weevil attack rates (the percent of trees in each family that sustained at least one weevil attack between 1996 and 2002) for susceptible families ranged from 57.1 to 100.0%, while none of the trees in resistant families had ever been attacked.

At the Espinosa site, incidence of galling and damage by Zeiraphera canadensis was significantly higher than at the other two Sitka spruce sites (Jordan and Harrison) as a result a more in-depth analysis was conducted on the data from this site. In addition to resistance we related attack by other pests to tree variables (height, stem form, foliage color) and parent tree source variables (geographic coordinates, elevation, transfer distance).

Table 5. Weevil resistant and susceptible Sitka spruce clonal lines and parent source information for trees selected for survey of other insect damage at Espinosa (Lat: 50º 01’N, Long:-126º 57’ W, Elev: 75m, BEC zone: CWHvm1). Clonal line Source LAT LONG ELEV(m) ZONE DIST(km)* STATUS** #Kills/tree %Attack 885 Wedene R. 54 08 -128 37 165 CWH vm 472 R 0.00 0.0 887 Derrick L. 55 41 -128 41 240 ICH mc 1 641 R 0.00 0.0 889 Haney 49 14 -122 36 90-300 CWH dm 326 R 0.00 0.0 898 Haney 49 14 -122 36 90-300 CWH dm 326 R 0.00 0.0 901 Blenheim Mt. 48 54 -124 57 180-240 CWH vm 1 192 S 1.57 85.7 902 Blenheim Mt. 48 54 -124 57 180-240 CWH vm 1 192 S 2.00 100.0 903 Masset Sound 53 55 -132 05 5 CWH wh 1 562 S 4.86 100.0 906 Malcolm Knapp 49 16 19 -122 34 26 136 CWH dm 327 S 1.71 100.0 919 Maple Ridge 49 14 24 -122 34 38 15 CWH dm 328 R 0.00 0.0 934 Big Qualicum R. 49 24 -124 37 5 CDF mm 181 S 0.71 71.4 953 Usk Ferry 54 38 -128 24 135 CWH ws 1 523 S 1.86 100.0 954 Usk Ferry 54 38 -128 24 135 CWH ws 1 523 S 1.86 85.7 1048 Forks (USA) 48 04 -124 18 120-150 (unknown) 291 S 2.00 57.1 1050 Hoquiam (USA) 47 05 -124 03 5 (unknown) 389 S 1.86 85.7 1053 Cedarvale 55 01 -128 19 240 ICH mc 2 565 R 0.00 0.0 1056 Haney 49 14 -122 36 90-300 CWH dm 326 R 0.00 0.0 1057 Fair Harbour 50 03 -127 02 30 CWH vm 1 8 R 0.00 0.0 1064 Fair Harbour 50 03 -127 02 30 CWH vm 1 8 S 1.29 85.7 1086 Haney 49 14 -122 36 90-300 CWH dm 326 R 0.00 0.0 1087 Squamish R. 49 53 -123 15 30 CWH dm 267 R 0.00 0.0 * transfer distance from parent tree source to Espinosa site ** weevil resistance status, R= resistant to white pine weevil, S= susceptible Kalamalka

The Kalamalka plantation was established in 1995 with 42 full sibling families of interior spruce. In October 1999, three weevils were placed on each tree in the trial for the purpose of screening the families for weevil resistance. The families selected for this study as a result of the weevil screening, are listed in Table 6. Weevil attack rates (the percent of trees in each family that sustained at least one weevil attack between 1999 and 2003) for susceptible families ranged from 82.1 to 93.2%, while attack rates for resistant families ranged from 1.5 to 20.5%.

Table 6. Weevil resistant and susceptible interior spruce families and parent source information for trees selected for survey of other insect damage at the Kalamalka Research Station.

Family LATf LONGf ELEVf (m) LATm LONGm ELEVm (m) STATUS* %Attack 1 54 04 -122 02 610 53 54 -122 02 732 R 16.9 2 54 04 -122 02 610 53 52 -122 15 762 R 20.5 4 54 04 -122 02 610 53 14 -121 30 1220 R 16.9 6 53 54 -122 02 732 53 52 -122 15 762 R 2.8 10 53 52 -122 15 762 53 01 -122 04 854 R 8.1 11 53 52 -122 15 762 53 14 -121 30 1220 R 4.3 12 53 37 -122 31 930 53 01 -122 04 854 R 19.7 13 53 37 -122 31 930 53 14 -121 30 1220 R 8.4 14 53 37 -122 31 930 45 41 -89 01 n/a R 19.4 16 53 52 -122 15 762 53 37 -122 31 930 R 1.5 19 54 04 -122 02 610 53 34 -122 03 960 S 85.3 20 54 04 -122 02 610 53 16 -122 05 960 S 82.1 21 53 01 -122 04 854 53 39 -122 11 960 S 86.5 23 53 01 -122 04 854 53 19 -122 12 1189 S 85.3 30 53 54 -122 02 732 53 19 -122 12 1189 S 81.4 37 53 39 -122 11 960 53 19 -122 12 1189 S 93.2 39 53 39 -122 11 960 53 16 -122 05 960 S 92.3 40 53 15 -121 30 1159 53 34 -122 03 960 S 83.1 41 53 26 -121 57 1021 53 19 -122 12 1189 S 86.1 42 53 15 -121 30 1159 53 19 -122 12 1189 S 89.8 f source data for female parent m source data for male parent * weevil resistance status, R= resistant to white pine weevil, S= susceptible ** the number of trees that had sustained weevil attack out of 7 trees randomly selected from each family

Clearwater

The Clearwater plantation was established in 1984 with 139 half-sibling interior spruce families represented. The weevil population at this site was not augmented and screening for weevil resistance was conducted under natural weevil population levels. Families selected for this study are listed in Table 7. Weevil attack rates (the percent of trees in each family that sustained at least one weevil attack between 1993 and 2002) for susceptible families ranged from 87.5 to 100.0%, while attack rates for resistant families ranged from 12.5 to 32.2%.

Table 7. Weevil resistant and susceptible interior spruce families and parent source information for trees selected for survey of other insect damage at Clearwater, BC.

Family source LAT LONG ELEV(m) STATUS* %Attack 1846 SBSmw 53 03 -122 09 823 R 28.1 1853 SBSmw 52 49 -121 58 914 R 12.5 1857 SBSmw 52 51 -121 58 930 R 25.8 1871 SBSmw 52 50 -121 49 1006 R 23.3 1951 SBSmw 53 04 -122 08 823 R 30.0 1952 SBSmw 53 05 -122 10 793 R 25.0 4728 Thompson ICHmw 52 16 -119 38 1098 R 22.6 4729 ESSFwc 51 52 -120 14 700 R 32.2 4731 Thompson ICHmw 51 55 -120 04 1421 R 16.7 4782 Thompson ICHmk 52 27 -121 08 799 R 31.2 1663 Cariboo ESSFwk 52 21 -120 30 1555 S 90.6 1672 Thompson ICHmw 52 13 -119 40 1677 S 96.7 1707 Cariboo ESSFwk 52 08 -120 27 1422 S 96.8 1727 Cariboo ESSFwk 52 45 -120 34 1440 S 100.0 1737 Cariboo ESSFwk 52 46 -120 23 1515 S 93.8 1738 Cariboo ESSFwk 52 47 -120 27 1455 S 93.1 4756 Wells Gray ICHwk 52 41 -120 54 732 S 100 4769 N. Monashee ESSFwk 52 10 -119 54 1403 S 93.8 4771 Wells Gray ICHwk 52 36 -121 22 1354 S 93.8 4772 Cariboo ESSFwk 52 37 -121 13 1350 S 87.5 * weevil resistance status, R= resistant to white pine weevil, S= susceptible ** the number of trees that had sustained weevil attack out of 7 trees randomly selected from each family

Results - Overview

Other than the white pine weevil, the insects that had the greatest impact at all sites were gall aphids and the spruce bud moth Zeiraphera canadensis. We present family (or clone) and resistance class averages for relative damage caused by these agents as well as averages for height and stem form.

In general, resistant and susceptible trees performed similarly with respect to damage by other insect pests. However, at some of the sites certain families or clonal lines appeared to perform better overall than others. These observations are included as a “Note” at the end of the site survey summaries.

In effort to identify possible effects of tree vigour on incidence of insect damage, foliage colour observations were made for each tree and family/clone means calculated. There was little variation in average family/clone foliage colour at all sites (generally ranging from 1.0 to 1.7 (where 1 = dark green up to 4 = yellow)), except at Espinosa, where the range among families was slightly higher (1.0 to 2.3). Consequently this variable was not considered for further analysis except at the Espinosa site.

None of the sites had trees that had sustained significant defoliation, therefore this variable was not analyzed further.

At the Kalamalka site, the spruce cone worm Dioryctria reniculelloides was also an important pest. Family and resistance class averages for damage caused by D. reniculelloides are included in the Kalamalka site summary.

At the Espinosa site there was an unknown agent causing needle spotting on the lower foliage of the trees. However, we were unable to determine the cause for the discoloration. This spotting could be caused by a number of foliar pathogens or by aphids. The damage was very difficult to quantify, consequently the results for this variable should be considered only in a broad sense.

Jordan River - Survey Summary

On average, resistant families were taller than susceptible families and had better stem form (Figures 1 and 2).

There was a low population of galling aphids present at the Jordan River site resulting in less than half the trees surveyed having galls. The majority of trees that had galls had relatively few (1-5 galls). The spruce bud moth (Zeiraphera canadensis) was also present at this site in low numbers. Approximately 85% of trees surveyed had low levels of damage by this pest. One tree sustained medium damage levels. No other insect pests of significance were noted at this site.

Since the incidence of galling and Z. canadensis damage at this site was relatively low, statistical analyses were not conducted. There were no apparent differences in the relative frequencies of galling or Zeiraphera damage between resistant and susceptible families at this site (Figures 3 and 4).

Note: Resistant family 121 had very good stem form and height, only one tree had weevil damage, none of the trees had adelgid galls, however the family sustained a slightly above average level of Zeiraphera damage.

3.0

2.5

2.0

1.5 Height class

±1.96*SE of mean 1.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

0.5 6 10 12 16 18 24 25 32 43 47 48 49 50 51 65 81 82 120 121 134 R mean S mean Family Number

Figure 1. Mean height class of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Jordan River trial (1=relatively small for the site, 3= relatively large). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3.5

3.0

2.5

2.0

Stem form 1.5

±1.96*SE of mean 1.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

0.5 6 10 12 16 18 24 25 32 43 47 48 49 50 51 65 81 82 120 121 134 R mean S mean Family number

Figure 2. Mean stem form of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Jordan River trial (1= very straight tree, 4= bushy tree without dominant leader). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

2.0

±1.96*SE of mean ±1.00*SE of mean 1.5 Mean of resistant clone Mean of susceptible clone

1.0

0.5 Frequency of galls

0.0 6 10 12 16 18 24 25 32 43 47 48 49 50 51 65 81 82 120 121 134 R mean S mean Family number

Figure 3. Mean frequency of galls in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Jordan River trial (0= no galls, 4= severe galling (>50 galls)). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

2.0

1.5 ge a

1.0

0.5

±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone

Intensity of Zeiraphera dam 0.0 Mean of susceptible clone 6 10 12 16 18 24 25 32 43 47 48 49 50 51 65 81 82 120 121 134 R mean S mean Family number

Figure 4. Mean intensity of Z. canadensis damage in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Jordan River trial (0= very light damage, 4= severe). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

Harrison - Survey Summary

There was no apparent difference in height between resistant and susceptible families at this site, perhaps because weevils had only been present at this site for one year prior to this survey (Figure 5). Since screening at this site has only just begun, it is possible that some of the families that have been selected as resistant may have been misclassified and may prove to be susceptible as the screening process progresses. Resistant families on average, had better stem form than susceptible families (Figure 6).

There was a low incidence of adelgid galls at this site with less than one third of the trees surveyed having galls. All of the trees that had galls had relatively few (1-5 galls) Z. canadensis damage levels were also low. Just over 50% of the trees were affected with only a few buds damaged, while the rest were damage free. We also noted that Mindarus aphids (unidentified species of woolly aphid feeding between the needles) were present on some of the trees at this site.

There was no difference in damage due to adelgid galling or Z. canadensis on resistant versus susceptible families (Figures 7 and 8). While presence of Mindarus aphids was recorded by only one of the two observers, and therefore only half the trees were surveyed for presence of Mindarus, there was no significant difference between resistant and susceptible trees surveyed for this pest.

Note: Surveyed trees from resistant family 123 sustained the least number of kills, had the highest average height, and the best stem form. No galls were found on any of the trees from this family and there was very little damage due to Z. canadensis. 3.5

3.0

2.5

2.0

1.5 Height class

±1.96*SE of mean 1.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

0.5 11 22 24 26 33 36 60 79 18 87 88 90 93 97 122 123 103 125 129 130 R mean S mean Family number

Figure 5. Relative height class of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Harrison trial (1= relatively small for the site, 3= relatively large). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

4.0 ±1.96*SE of mean ±1.00*SE of mean 3.5 Mean of resistant clone Mean of susceptible clone

3.0

2.5

2.0 Stem form 1.5

1.0

0.5 11 22 24 26 33 36 60 79 18 87 88 90 93 97 122 123 103 125 129 130 R mean S mean Family number

Figure 6. Mean stem form of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Harrison trial (1= very straight tree, 4= bushy tree without dominant leader). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

1.4 ±1.96*SE of mean ±1.00*SE of mean 1.2 Mean of resistant clone Mean of susceptible clone 1.0

0.8

0.6

0.4

0.2 Frequency of galls

0.0

-0.2 11 22 24 26 33 36 60 79 18 87 88 90 93 97 122 123 103 125 129 130 R mean S mean Family number

Figure 7. Mean frequency of galls in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Harrison trial (1= 1-5 galls, 4= severe galling (>50 galls)). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

1.6 ±1.96*SE of mean 1.4 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone 1.2 ge a 1.0

0.8

0.6

0.4

0.2

Intensity of Zeiraphera dam 0.0

-0.2 11 22 24 26 33 36 60 79 18 87 88 90 93 97 122 123 103 125 129 130 R mean S mean Family number

Figure 8. Mean intensity of Z. canadensis damage in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Harrison trial (1= very light damage, 4= severe). Crosshatched boxes represent means for all resistant and all susceptible trees studied. Espinosa - Survey Summary

There was no difference in relative height class between resistant and susceptible trees; however, resistant trees had better stem form (Figures 9 and 10). On average, weevil resistant clones were slightly more chlorotic than weevil susceptible clones (Figure 11)

Adelgid galls were more numerous at this site than at either of the other two Sitka spruce sites. All of the trees surveyed had galls and more than half of the trees fell into the second or third gall classes (approximately 6-50 galls). Z. canadensis damage was also more prevalent at this site, with all of the trees sustaining bud/shoot damage due to this moth, except for trees from clone 1050. There was no difference in damage intensity due to galling or bud moth between resistant and susceptible clonal lines (Figures 12 and 13).

We noted at the time of the survey, that in all of the 1050 ramets bud flush was significantly later than in the rest of the trees surveyed. The buds on the 1050 ramets were still closed at the time of the survey whereas on the rest of the trees the buds had flushed and the new shoots elongated several inches. The late bud flush likely influenced the susceptibility of the 1050 clone to Zeiraphera damage. Quiring (1992) reported that first instar larvae of Zeiraphera canadensis could not penetrate unburst white spruce buds.

The majority of the trees had low levels of needle spotting (92 out of 140 trees) which was loosely defined as a low density of spots on individual needles, with relatively few needles affected. Approximately 25% of the trees surveyed had moderate levels of needle spotting (more dense spotting on individual needles and more needles affected). While there was great variation amongst individual clonal lines, on average, resistant lines had significantly more intense needle spotting than susceptible lines, indicating that weevil resistant trees may be more susceptible to the unknown agent causing needle spotting at this site (Figure 14).

The top-performing clonal lines as a result of the survey at Espinosa are listed in Table 8.

Table 8. Top performing Sitka spruce clonal lines at the Espinosa site with respect to tree height, form and insect damage variables (least damaged clones listed). Number in brackets indicates clone performance rank. Bold numbers indicate weevil resistant clones.

height stem form galls Zeiraphera Needle spotting 889 (1) 889 (1) 887 (1) 1050 (1) 1064 (1) 934 (1) 1053 (1) 1050 (1) 887 (2) 1050 (1) 898 (2) 1057 (2) 889 (2) 1053 (3) 1048 (2) 1057 (2) 898 (3) 919 (2) 889 (4) 953 (2) 919 (2)

3.5

3.0

2.5

2.0

1.5

1.0

Relative height class ±1.96*SE of mean 0.5 ±1.00*SE of mean Mean of resistant clone 0.0 Mean of susceptible clone 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 9. Mean height class of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce clones at the Espinosa trial (1=relatively small for the site, 3= relatively large). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

±1.96*SE of mean 3.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

2.5

2.0

1.5 Stem form

1.0

0.5 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 10. Mean stem form of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Espinosa trial (1= very straight tree, 4= bushy tree without dominant leader). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3 ±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

2 Foliage color

1 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 11. Average foliage colour class of weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Espinosa trial (1= dark green, 4= bright yellow). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3.5 ±1.96*SE of mean ±1.00*SE of mean 3.0 Mean of resistant clone Mean of susceptible clone 2.5

2.0

1.5

1.0 Frequency of galls 0.5

0.0 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 12. Mean frequency of galls in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce families at the Espinosa trial (0= no galls galls, 4= severe galling (>50 galls)). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3.5

3.0 ge

a 2.5

2.0

1.5

1.0

±1.96*SE of mean 0.5 ±1.00*SE of mean Mean of resistant clone Intensity of Zeiraphera dam 0.0 Mean of susceptible clone 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 13. Mean intensity of Z. canadensis damage in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce clones at the Espinosa trial (1= very light damage, 4= severe). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

2.5

2.0

1.5

1.0

0.5 ±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone Intensity of needle spotting 0.0 Mean of susceptible clone 885 887 889 898 919 901 902 903 906 934 953 954 1053 1056 1057 1086 1087 1048 1050 1064 R mean S mean Clone number

Figure 14. Mean intensity of needle spotting in weevil resistant (dark boxes) and susceptible (light boxes) Sitka spruce clones at the Espinosa trial (1= very light damage, 4= severe). Crosshatched boxes represent means for all resistant and all susceptible trees studied. There was a weak but significant positive correlation between the relative frequency of galls and stem form. This is likely due to a greater number of branch terminals available to be infested on trees with less than perfect stem form (greater than stem form class 1). There was a significant negative correlation between the relative intensity of bud moth damage and foliage color (Table 9). The more yellow the foliage, the less bud damage there was (Figure 15). This indicates that Z. canadensis may avoid trees that are slightly chlorotic. Correlation analysis also indicated a significant positive relationship between needle spotting and the latitude, elevation and transfer distance of the parent tree (Table 9), suggesting that trees from more northerly locations and higher elevations are more susceptible to the agent(s) causing needle spotting.

Table 9. Pearson Product-Moment correlation matrix describing the relationships between tree and site variables and insect damage variables. Bold correlations are significant at p<0.05.

variable GALLS ZEIRAPHERA NEEDLE SPOTTING HT 0.06 0.16 -0.04 STEM 0.17 0.12 -0.11 COLOR -0.08 -0.35 0.10 LAT 0.12 0.15 0.23 LONG 0.09 0.05 0.08 ELEV 0.07 0.07 0.23 DIST -0.02 0.03 0.19

2.4 ±1.96*SE of mean n=110 ±1.00*SE of mean 2.0 Mean

n=34

1.6

n=9 1.2 n=1

0.8

0.4 Intensity of Zeiraphera damage Increasingly chlorotic 0.0 1234 Foliage colour category

Figure 15. Relative intensity of Z. canadensis damage in Sitka spruce clones at the Espinosa site, that fall into four foliage colour categories (1= dark green, 4= bright yellow). There were six biogeoclimatic subzones represented by the sampling design for this site. Each subzone was represented by from one to four parent sources. The number of clonal lines sampled from each parent source also varied from one to four (See Table 5). While some parent sources appeared to have less insect damage than others, there was considerable variation among clonal lines within parent sources (Figures 12 and 13). For example, the average relative intensity of Zeiraphera damage in the Haney clones (889, 898, 1056 and 1086) averaged 1.8 and ranged from 1.3 (light damage) to 2.8 (moderate to high damage) (Figure 13). There was also considerable variation in insect damage among parent sources within biogeoclimatic subzones, permitting only generalizations of our results based on biogeoclimatic zone classification.

While average gall frequency varied among parent sources, there did not appear to be a relationship between biogeoclimatic subzone of the parent and average gall frequency (Figure 16). Mean damage by Z. canadensis also varied amongst parent sources, however, trees from the CDFmm, ICHmc and Washington subzones on average, appear to have sustained less Zeiraphera damage than trees from the other subzones (Figure 17). While intensity of needle spotting varied among parent sources, on average trees from the ICHmc subzone appeared to have higher than average levels of needle spotting while trees from the Washington area had, on average, lower levels (Figure 18).

Figure 16. Average gall frequency in Sitka spruce clones from various parent sources and biogeoclimatic subzones (Espinosa).

Figure 17. Average intensity of Zeiraphera damage in Sitka spruce clones from various parent sources and biogeoclimatic subzones (Espinosa).

Figure 18. Average intensity of needle spotting caused by an unknown agent in Sitka spruce clones from various parent sources and biogeoclimatic subzones (Espinosa). Kalamalka Survey Summary

Resistant trees were taller on average and had better stem form than susceptible trees (Figures 19 and 20).

Only six trees at this site did not have any galls at all. More than half the trees fell into the first gall class (1-5 galls) while approximately 20% of the trees fell into the second gall class (6-25 galls). On average trees in the resistant class had more galls, however there was a lot of variability amongst the families of both classes (Figure 21).

The spruce cone worm Dioryctria reniculelloides was present at this site. Approximately half the trees with cones had cone worm damage with the number of infested cones varying from 1 to 25. More of the resistant trees had cones and on average individual resistant trees had more cones, than susceptible trees. Also, more resistant trees had infested cones (Figure 22). This finding is not surprising considering the likelihood that trees with more cones are more likely to be infested by cone worm (trees with more cones are more easily detected as hosts).

Damage due to the spruce bud moth (Z. canadensis) was not observed at this site.

±1.96*SE of mean 3.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone 2.5

2.0

1.5

Relative height class 1.0

0.5 1 2 4 6 10 11 12 13 14 16 19 20 21 23 30 37 39 40 41 42 R mean S mean Cross number

Figure 19. Mean height class of weevil resistant (dark boxes) and susceptible (light boxes) interior spruce derived from controlled crosses and planted at the Kalamalka trial (1=relatively small for the site, 3= relatively large). Crosshatched boxes represent means for all resistant and all susceptible trees studied. ±1.96*SE of mean 3.5 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone 3.0

2.5

2.0

Stem form 1.5

1.0

0.5 1 2 4 6 10 11 12 13 14 16 19 20 21 23 30 37 39 40 41 42 R mean S mean Cross number

Figure 20. Mean stem form of weevil resistant (dark boxes) and susceptible (light boxes) interior spruce derived from controlled crosses and planted at the Kalamalka site (1= very straight tree, 4= bushy tree without dominant leader). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3.5 ±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone 3.0 Mean of susceptible clone

2.5

2.0

1.5

1.0 Frequency of galls

0.5

0.0 1 2 4 6 10 11 12 13 14 16 19 20 21 23 30 37 39 40 41 42 R mean S mean Cross number

Figure 21. Mean frequency of galls in weevil resistant (dark boxes) and susceptible (light boxes) interior spruce derived from controlled crosses, at the Kalamalka site (1= 1-5 galls, 4= severe galling). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

7 Resistant crosses resistant cross with cones suseptible cross with cones 6 resistant cross with infested cones susceptible cross with infested cones 5

4 Susceptible crosses

Number of trees with cones 1

1 2 4 6 10 11 12 13 14 16 19 20 21 23 30 37 39 40 21 42 Cross number

Figure 22. Number of trees with cones and number of trees with Dioryctira reniculelloides infested cones out of seven interior spruce trees surveyed from each of twenty families derived from controlled crosses (Kalamalka site).

Clearwater Survey Summary

Resistant trees were taller on average and had better stem form than susceptible trees (Figures 23 and 24).

On average, the relative frequency of aphid galls at this site was higher than at the other interior spruce site (Kalamalka). Only one tree had no galls at all while 65% of the trees fell into the second gall class (6-25 galls) and 20% fell into the third gall class (26-50 cones). There was no significant difference in average galls class between resistant and susceptible trees (Figure 25).

Damage levels by Z. canadensis were relatively high at this site with all of the trees affected and more than half the trees falling into the second damage class (approximately 6-25 branch terminals affected). There was no significant difference in Z. canadensis damage between resistant and susceptible trees (Figure 26).

±1.96*SE of mean 3.0 ±1.00*SE of mean Mean of resistant clone Mean of susceptible clone

2.5

2.0

Relative height class 1.5

1.0 1846 1853 1857 1871 1951 1952 4728 4729 4731 4782 1663 1672 1707 1727 1737 1738 4756 4769 4771 4772 R mean S mean Family number

Figure 23. Mean height class of weevil resistant (dark boxes) and susceptible (light boxes) interior spruce families at the Clearwater site (1=relatively small for the site, 3= relatively large). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

3.5

±1.96*SE of mean ±1.00*SE of mean 3.0 Mean of resistant clone Mean of susceptible clone

2.5

2.0

1.5 Stem form

1.0

0.5 1846 1853 1857 1871 1951 1952 4728 4729 4731 4782 1663 1672 1707 1727 1737 1738 4756 4769 4771 4772 R mean S mean Family number

Figure 24. Mean stem form of weevil resistant (dark boxes) and susceptible (light boxes) interior spruce families at the Clearwater site (1= very straight tree, 4= bushy tree without dominant leader). Crosshatched boxes represent means for all resistant and all susceptible trees studied. 3.5 ±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone 3.0 Mean of susceptible clone

2.5

2.0

1.5 Frequency of galls

1.0

0.5 1846 1853 1857 1871 1951 1952 4728 4729 4731 4782 1663 1672 1707 1727 1737 1738 4756 4769 4771 4772 R mean S mean Family number

Figure 25. Mean frequency of galls in weevil resistant (dark boxes) and susceptible (light boxes) interior spruce families at the Clearwater site (0= no galls, 4= severe galling (>50 galls)). Crosshatched boxes represent means for all resistant and all susceptible trees studied.

2.5

2.0

1.5

1.0

±1.96*SE of mean ±1.00*SE of mean Mean of resistant clone

Intensity of Zeiraphera damage 0.5 Mean of susceptible clone 1846 1853 1857 1871 1951 1952 4728 4729 4731 4782 1663 1672 1707 1727 1737 1738 4756 4769 4771 4772 R mean S mean Family number

Figure 26. Mean intensity of Z. canadensis damage in weevil resistant (dark boxes) and susceptible (light boxes) interior spruce families at the Clearwater site (1= very light damage, 4= severe). Crosshatched boxes represent means for all resistant and all susceptible trees studied. Conclusions

At all sites weevil resistant trees had superior stem form and height growth compared to weevil susceptible trees. This is expected due to the nature of weevil damage. Incidence of damage by insect pests other than weevil was not influenced by the trees’ weevil resistance status at any of the sites. While higher levels of needle spotting in resistant trees were observed at the Espinosa site, the agent causing weevil spotting was not identified and therefore the potential impact of this agent is unknown.

A number of tree variables were found to be correlated with insect damage. These relationships will be useful in the selection of reforestation material to minimize damage due to these pests. The correlations are summarized as follows:

While incidence of insect damage, other than damage due to weevil, was not influenced by weevil resistance status (Table 9), observations at the family and clonal line level indicated variation in performance with respect to specific insect pests. Individual weevil resistant families and clonal lines with good height growth and stem form as well as better than average performance with respect to insect pests were identified at some of the sites. This information will be useful in selecting weevil resistant material for inclusion breeding programs and seed orchards.

Table 9. Summary of mean height class and stem form and mean relative damage due to galling aphids, Zeiraphera canadensis and weevil, in weevil-resistant and susceptible spruce at five sites in British Columbia.

Weevil attack rate Height class Stem form Galling Zeiraphera Site R S R S R S R S R S Jordan River 33.1 93.0 2.43 1.83 1.71 2.44 0.36 0.54 1.11 0.94 Harrison 16.0 81.9 2.36 2.14 1.43 2.59 0.30 0.29 0.64 0.57 Espinosa 0.0 87.1 1.87 1.80 1.36 2.04 1.66 1.87 1.80 1.78 Kalamalka 11.9 86.5 2.06 1.89 1.27 1.78 1.43 0.91 - - Clearwater 24.7 94.6 2.57 1.93 1.30 2.26 1.93 1.95 1.44 1.56

References

Alfaro, R.I., J.N. King, Y.A. El-Kassaby, R.G. Brown and K. Lewis. 2001. Use of artificial infestations in the selection of Sitka spruce genotypes for resistance to the white pine weevil in British Columbia, Canada. In Alfaro, R.I., Day, K., Salom, S., Nair, K.S.S., Evans, H., Leibhold, A., Leutier, F., Wagner, M., Futai, K. and Suzuki, K. (Eds.), Protection of World Forests from Insect Pests: Advances in Research. Papers presented at the XXI IUFRO World Congress, 7-12 August 2000, Malaysia. IUFRO World Series Vol. 11. pp 13-17.

King, J.N. 1994. Delivering durable resistant Sitka spruce for plantations. In: Alfaro, R.I. Kiss, G., Fraser, R.G. (Eds.), The White Pine Weevil: Biology, Damage and Management. Proceedings of a symposium held January 19-21, 1994 in Richmond, B.C. Can. For. Serv. Victoria, B.C., FRDA Rep. 226, pp.134-149.

King, J.N., R.I. Alfaro and C. Cartwright. 2004. Genetic resistance of Sitka spruce (Picea sitchensis) populations to the white pine weevil (Pissodes strobi): distribution of resistance. Forestry. 77(4): 269-278.

Kiss, G.K. and A.D. Yanchuk. 1991. Preliminary evaluation of genetic variation of weevil resistance in interior spruce in British Columbia. Can. J. For. Res. 21: 230-234.

Lewis, K.G., R.I. Alfaro and D. Andrucko. 1999. Variation in Elatobium abietinum attack on Picea glauca and its relation to Pissodes strobi resistance. Scand. J. For. Res. 14(4): 334-340.

Mattson, W.J., A. Yanchuk, G. Kiss and B. Birr. 1997. Resistance to galling adelgids varies among families of Engelmann spruce (Picea engelmani P.). In Leutier, F., W.J. Mattson and M.R. Wagner eds. Physiology and Genetics of Tree-Phytophage Interactions. Gujan (France), Aug.31- Sept. 5, 1997. Ed. INRA, Paris (Les Colloques, no90). 51-64.

Peterson, E.B., N.M. Peterson, G.F. Weetman and P.J. Martin. 1997. Ecology and Management of Sitka Spruce Emphasizing Its Natural Range in British Columbia. UBC Press. Vancouver 336 pp.

Quiring, D.T. 1992. Rapid change in suitability of white spruce for a specialist herbivore, Zeiraphera canadensis, as a function of leaf age. Canadian Journal of Zoology. 70: 2132-2138. http://www.pfc.forestry.ca/entomology/weevil/resistance