Acrobasis shoot moth infestations were evaluated in a young black walnut progeny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest trees in the fourth and fifth year after plantation establishment, and were declining by the sixth year. Acrobasis infestation appears to be a problem primarily on young trees less than 2.5 m in height. There was no evidence for genetic resistance to Acrobasis infestation in black walnut

Baines, D. Michael

Funk, David T

Rink, George

Weber, Barbara C

English

Valparaiso University

The Great Lakes Entomologist Volume 24 Number 1 - Spring 1991 Number 1 - Spring 1991 Article 4 March 1991 Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation George Rink USDA Forest Service Barbara C. Weber USDA Forest Service D. Michael Baines USDA Forest Service David T. Funk USDA Forest Service Follow this and additional works at: https://scholar.valpo.edu/tgle Part of the Entomology Commons Recommended Citation Rink, George; Weber, Barbara C.; Baines, D. Michael; and Funk, David T. 1991. "Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation," The Great Lakes Entomologist, vol 24 (1) Available at: https://scholar.valpo.edu/tgle/vol24/iss1/4 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1991 THE GREAT LAKES ENTOMOLOGIST 21 A CROBASIS SHOOT MOTH (LEPIDOPTERA: PYRALIDAE) INFESTATION-TREE HEIGHT LINK IN A YOUNG BLACK WALNUT PLANTATION George Rinkl, Barbara C. Weber2, D. Michael Baines3, and David T. Funk4 ABSTRACT Acrobasis shoot moth infestations were evaluated in a young black walnut prog­eny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest trees in the fourth and fifth year after plantation establishment, and were declining by the sixth year. Acrobasis infestation appears to be a problem primarily on young trees less than 2.5 m in height. There was no evidence for genetic resistance to Acrobasis infestation in black walnut. Black walnut (Jug/ans nigra) is commonly grown for production of high-quality veneer logs. Only trees with stems free of form defects, such as forks or crooks in the first 3 to 5 m, qualify as veneer logs. Stem defects in black walnut often result from loss of apical dominance due to damage or mortality of the terminal bud, often associated with late spring frosts. More recently, case bearer moths (Acrobasi spp.) have been shown to damage terminal shoots and buds of young black walnut trees when larvae tunnel into them. Our study was designed as a survey to assess damage to trees in a young plantation with a relatively serious Acroba is infestation. Insect identification techniques followed those of McKeague and Simmons (1979). METHODS Open-pollinated seeds from 54 walnut trees were used to produce 1-0 seedlings for a progeny test. Parent trees were selected from within a 250-mile semi-circular radius south of the Shawnee National Forest in southern Illinois. This included an area bounded by southern Illinois, western Kentucky, western Tennessee, and southeast Kansas. However, most of the seed collections were from western Kentucky and western Tennessee. In most cases seed was collected from one tree per stand. Although trees of better than average form were sought at the time of collection, no rigid minimum selection criteria were applied. Seedling progeny resulting from these seed collections were planted in 5-tree row plots at a spacing of 1.8 m within rows and 3.7 m between rows, in a randomized complete block design with 10 blocks; upon establishment the plantation contained 2,700 trees. The progeny test was established in early spring 1973 on a Haymond silt loam on the floodplain f Sexton Creek, on the Shawnee National Forest in Alexander IUSDA Forest Service, North Central Forest Experiment Station, Carb dale, IL 62901. 2USDA Forest Service. Washington. DC 20090. 3USDA Forest Service, Allegheny National Forest, Marienville, PA 16239. 4USDA Forest Service, Northeastern Forest Experiment Station, Durham, NH 03824. 1Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Published by ValpoScholar, 199122 THE GREAT LAKES ENTOMOLOGIST Vol. 24, No. I County, Illinois. The site was an abandoned pasture on which 1.2 m strips were machine sprayed with a simazine, dalapon, 2,4-0 mix before planting and spot sprayed in spring 1974 and 1975. In addition the plantation was mowed annually. In 1976, after three growing seasons, we observed that many of the walnut trees were growing slowly, some were crooked o forked, and a few had died back and sprouted from near the base. We suspected insect attack as a possible cause of the poor form and began surveys for the following insects: Acrobasis juglandis (LeBaron), the pecan leaf casebearer; A. demotella Grote, the walnut shoot moth (Martinat and Wallner 1980); and Xylosandrus germanus (Blandf.), an ambrosia beetle. The ambrosia beetle was later associated with canker and dieback but not with crook or forking problems related to terminal buds (Weber and McPherson 1984). During 1977-1979, we made two types of surveys, using the same sampling scheme for both. The surveys were done on a pilot basis in 1976 and repeated 1977-1979. First, during the dormant season, we counted I mm-Iong hibernacula containing overwintering larvae of A. juglandis; the hibernaculum is the overwinter­ing case for the first instar larva. First instar larvae develop from eggs hatched in late summer; they spin hibernacula in preparation for overwinter hibernation. Pres­ence of hibernacula on a tree was considered an indicator of susceptibility of the tree to Acrobasis infestation. Second, in the early summer, we counted infested growing shoots as a measure of damage by A. demotella; A. juglandis is a defoliator but does not tunnel into shoots (Martin at and Wilson 1979). One tree per family-row plot per block was randomly chosen (using a random number generator) for infestation evaluation each fall; the same tree was evaluated the following spring. All insect and infested shoot count data were square root transformed to increase normality. Tree height was measured to the nearest em during the dormant season. Data were analyzed by analysis of variance and covariance and correlation tech­niques. Family heritabilities were calculated using the H2 = (1-IIF) formula of Kung and Bey (1979) in which F is t e variance ratio for families. RESULTS AND DISCUSSION During our 4-year evaluation of this plantation, height growth averaged 0.36 m annually. Mean total tree height was 1.5 m in 1976 and the plantation average was 2.9 m by the end of the 1980 growing season. Infestation as reflected by the number of hibernacula per tree increased from 1.4 in 1976 to a high of 2.6 in 1978 and declined to 2.0 hibernacula per tr e in 1979. Demographic trends established by Acrobasis hibernacula were mirrored by the number of infested twigs per tree, which increased from 1.3 in 1976 to 2.3 in 1978 and then declined to 1.7 in 1979 (table 1). However, during the 1976-1979 period, the number of trees with hibernacula increased from 20 percent in 1976 to 33 percent in 1977,44 percent in 1978, and 57percent in 1979. Similarly, the number of trees with infested twigs increased from 20 percent in 1976 to 30 percent in 1977, 58 percent in 1978, and 63 percent in 1979. Analyses of variance or covariance failed to disclose any significant family effects. Heritability of susceptibility to infestation by Acrobasis was less than 0.15, confirming that genetic resistance to Acrobasis damage is extremely low or nonexist­ent. Similarly there was no correlation between either number of hibernacula or number of infested twigs and latitude or longitude of family origin. Correlation analysis disclosed a pattern of very high positive correlations between the number of hibernacula per tree and the number of infested twigs (0.87 < r < 0.97). These high correlations were expected and suggest that the parameters mea­sure similar attributes of Acrobasis infestation and that future surveys probably need to measure only one of these parameters. The high correlations also suggest that overwintering survival rates were high and parasitism/predator levels were low. 2The Great Lakes Entomologist, Vol. 24, No. 1 [1991], Art. 4https://scholar.valpo.edu/tgle/vol24/iss1/41991 THE GREAT LAKES ENTOMOLOGIST 23 Table 1. - Average height (m), height growth (m), number of hibernacula per tree (no.) and number of infested twigs Variable Mean Minimum Maximum Height 76 1.5 0.2 2.9 Height 77 1.8 0.4 3.6 Height 78 2.1 0.4 4.4 Height 79 2.4 0.6 5.5 Height 80 2.9 0.8 6.1 Ht. Gr. 76-77 0.35 -0.63 1.39 Ht. Gr. 77-78 0.26 -1.15 1.67 Ht. Gr. 78-79 0.35 -0.90 2.78 Ht. Gr. 79-80 0.46 -2.55 2.02 Hib.76 1.4 1.0 7.0 Hib.77 2.0 1.0 14.Hib.78 2.6 1.0 16.0 Hib.79 2.0 1.0 3.0 Infest. 76 1.3 1.0 15.0 Infest. 77 1.7 1.0 3.0 Infest. 78 2.3 1.0 14.0 Infest. 79 1.7 1.0 9.0 Table 2. - Correlations of number of hibernacula and infested shoots with total tree height (m) in current and subsequent years (ns = not stati tically significant; •• = significant at P < 0.05) Measurement Tree height in Tree height in Tree height in Tree height in year current year subsequent year current year subsequent year Number of hibernacu/a Number of infested shoots 1976 0.15 ns 0.18 ns 0.04 ns 0.07 ns 1977 1978 0.22 •• 0.40 ** 0.23 •• 0.41 .* 0.30 •• 0.43 ** 0.34 •• 0.45 ** 1979 0.08 ns 0.07 ns 0.04 ns 0.05 ns A more interesting pattern of correlations emerged between number of hiberna­cula, infestation, and total tree height (table 2) and height growth (table 3). In 1976, the first year of Acrobasis evaluation, there was no statistical correlation (r < 0.2) between either measure of insect attack and growth variables. In 1977, there were low but significant correlations (r > 0.2) of hibernacula nd infestation with total tree height. By 1978, both measures of insect attack were significantly correlated with total height and height growth. Fur ermore, the magnitude of the correlation between total height and number of hibernacula doubled. However, by 1979 neither measure of Acrobasis infestation was correlated with total height or with height growth. Such correlation patterns could result from the following circumstances: in 1976, when there was no correlation between infestation and tree size or growth, the 3Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Published by ValpoScholar, 199124 THE GREAT LAKES ENTOMOLOGIST Vol. 24, No. 1 Table 3. -Correlations of number of hibernacula and infested shoots with tree growth (m) in current and subsequent years (ns not statistically significant; ** significant at P < 0.05) Measurement Growth in Growth in Growth in Growth in year current year subsequent year current year subsequent year Number of hibernacula Number of infested shoots 1976 0.14 ns 0.08 ns 1977 0.10 ns 0.13 ns 0.18 u 0.23 ** 1978 0.18 ** 0.23 ** 0.19 ** 0.25 ** 1979 0.08 ns 0.20 ** 0.05 ns 0.04 ns plantation was only 3 years old and all trees were in approximately the same size category. The initial infestation was small and the outbreak was distributed among trees of the same size class. By 1977 the outbreak was spreading to the larger trees as evidenced by the positive corelation with tree height; by 1978, positive correlations between infestation and both total height and height growth were present. By 1979, on the basis of average number of hibernacula per tree or mean number of infested twigs per tree, th infestation seemed to be declining. Furthermore, the remaining Acrobasis no longer preferred the larger trees but infested any size trees. All statistically significant correlations between total height and insect attack were positive, suggesting that Acrobasis preferentially attacks larger trees once an infesta­tion is established in a plantation (table 2). Furthermore, it appears that in 1977 and 1978 Acrobasis also attacked the faster growing trees (table 3). The implication is that, initially, Acrobasis infests the largest trees, those with the largest crowns; however, in subsequent years when most of the trees in the plantation are in larger size classes, insect attacks are of a more random nature. The lack of negative correlations between infestation in a given year and growth in subsequent years was surprising. Acrobasis damage has been described as resem­bling frost damage where infested terminals die back. In a large infestation, negative correlations with growth in the following year might be expected. However, in infestations at this population level, negative correlations were not encountered. Instead, positive correlations imply that somehow infestations had little effect on growth and perhaps were even slightly stimulatory. Thus, it is likely that the overall infestation levels were not high enough to affect average growth rates. By 1979, when the trees averaged 2.4 m in total height (table 1), infestation appeared to be subsiding. Subsequent surveys did not disclose significant infesta­tions. Thus, we hypothesize that Acrobasis is a problem on young trees less than 2.5 m in height; stem form m'ly be affected but growth rate is not. Alternatively, a buildup of populations of natural predators of Acrobasis may have resulted in a declining Acrobasis population; unfortunately, no effort was made to monitor these predators. ACKNOWLEDGMENTS We thank David J. Polak, for assistance with statistical analyses. At the time of the study Dave Polak was a computer programmer with NCFES, Carbondale, IL. We also acknowledge the cooperation of the Shawnee National Forest on whose land the plantation was established. 4The Great Lakes Entomologist, Vol. 24, No. 1 [1991], Art. 4https://scholar.valpo.edu/tgle/vol24/iss1/41991 THE GREAT LAKES ENTOMOLOGIST 25 LITERATURE CITED Kung, F. H. and C. F. Bey. 1979. Heritability construction for provenance and family selec­tion. In: Proceedings, Thirteenth Lake States For. Tree Impr. Conf., Aug. 17-18, 1977, Univ. Minn., St. Paul, MN. USDA For. Servo Gen. Tech. Rep. NC-50, p. 136-146. Martinat, P. J. and L. F. Wilson. 1979. The life histories of Acrobasis juglandis and A. demotella on black walnut in Michigan. In: Walnut Insects and Diseases Workshop Proc., Carbondale, IL. USDA For. Servo Gen. Tech. Rep. NC-52, p. 40-43. Martinat, P. J. and W. E. Wallner. 1980. Notes on the biology and damage of two Acrobasis species (Lepidoptera: Pyralidae) on black walnut in Michigan. Great Lakes Entomol. 13:41-48. McKeague, M. A. and G. A. Simmons. 1979. Terminal bud damage on black walnut. Michi­gan State Univ. Ext. Bull. E-1321. 3 p. Weber, B. C. and J. E. McPherson. 1984. Attack on black walnut trees by th ambrosia beetle Xylosandrus german us (Coleoptera: Scolytidae). Forest Science 30:864-870. 5Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Published by ValpoScholar, 1991

\u3ci\u3eAcrobasis\u3c/i\u3e Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

ValpoScholar

The Great Lakes Entomologist 
Volume 24 
Number 1 - Spring 1991 Number 1 - Spring 1991 Article 4 
March 1991 
Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree 
Height Link in a Young Black Walnut Plantation 
George Rink 
USDA Forest Service 
Barbara C. Weber 
USDA Forest Service 
D. Michael Baines 
USDA Forest Service 
David T. Funk 
USDA Forest Service 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Rink, George; Weber, Barbara C.; Baines, D. Michael; and Funk, David T. 1991. "Acrobasis Shoot Moth 
(Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation," The Great Lakes 
Entomologist, vol 24 (1) 
Available at: https://scholar.valpo.edu/tgle/vol24/iss1/4 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
1991 THE GREAT LAKES ENTOMOLOGIST 21 
A CROBASIS SHOOT MOTH (LEPIDOPTERA: PYRALIDAE) 

INFESTATION-TREE HEIGHT LINK IN A YOUNG BLACK 

WALNUT PLANTATION 

George Rinkl, Barbara C. Weber2, D. Michael Baines3, and David T. Funk4 
ABSTRACT 
Acrobasis shoot moth infestations were evaluated in a young black walnut prog­
eny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest 
trees in the fourth and fifth year after plantation establishment, and were declining 
by the sixth year. Acrobasis infestation appears to be a problem primarily on young 
trees less than 2.5 m in height. There was no evidence for genetic resistance to 
Acrobasis infestation in black walnut. 
Black walnut (Jug/ans nigra) is commonly grown for production of high-quality 
veneer logs. Only trees with stems free of form defects, such as forks or crooks in the 
first 3 to 5 m, qualify as veneer logs. Stem defects in black walnut often result from 
loss of apical dominance due to damage or mortality of the terminal bud, often 
associated with late spring frosts. More recently, case bearer moths (Acrobasi spp.) 
have been shown to damage terminal shoots and buds of young black walnut trees 
when larvae tunnel into them. Our study was designed as a survey to assess damage 
to trees in a young plantation with a relatively serious Acroba is infestation. Insect 
identification techniques followed those of McKeague and Simmons (1979). 
METHODS 
Open-pollinated seeds from 54 walnut trees were used to produce 1-0 seedlings for 
a progeny test. Parent trees were selected from within a 250-mile semi-circular radius 
south of the Shawnee National Forest in southern Illinois. This included an area 
bounded by southern Illinois, western Kentucky, western Tennessee, and southeast 
Kansas. However, most of the seed collections were from western Kentucky and 
western Tennessee. In most cases seed was collected from one tree per stand. 
Although trees of better than average form were sought at the time of collection, no 
rigid minimum selection criteria were applied. Seedling progeny resulting from these 
seed collections were planted in 5-tree row plots at a spacing of 1.8 m within rows 
and 3.7 m between rows, in a randomized complete block design with 10 blocks; 
upon establishment the plantation contained 2,700 trees. 
The progeny test was established in early spring 1973 on a Haymond silt loam on 
the floodplain f Sexton Creek, on the Shawnee National Forest in Alexander 
IUSDA Forest Service, North Central Forest Experiment Station, Carb dale, IL 62901. 

2USDA Forest Service. Washington. DC 20090. 

3USDA Forest Service, Allegheny National Forest, Marienville, PA 16239. 

4USDA Forest Service, Northeastern Forest Experiment Station, Durham, NH 03824. 

1
Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-
Published by ValpoScholar, 1991
22 THE GREAT LAKES ENTOMOLOGIST Vol. 24, No. I 
County, Illinois. The site was an abandoned pasture on which 1.2 m strips were 
machine sprayed with a simazine, dalapon, 2,4-0 mix before planting and spot 
sprayed in spring 1974 and 1975. In addition the plantation was mowed annually. 
In 1976, after three growing seasons, we observed that many of the walnut trees 
were growing slowly, some were crooked o forked, and a few had died back and 
sprouted from near the base. We suspected insect attack as a possible cause of the 
poor form and began surveys for the following insects: Acrobasis juglandis 
(LeBaron), the pecan leaf casebearer; A. demotella Grote, the walnut shoot moth 
(Martinat and Wallner 1980); and Xylosandrus germanus (Blandf.), an ambrosia 
beetle. The ambrosia beetle was later associated with canker and dieback but not 
with crook or forking problems related to terminal buds (Weber and McPherson 
1984). 
During 1977-1979, 
we made two types of surveys, using the same sampling 
scheme for both. The surveys were done on a pilot basis in 1976 and repeated 
1977-1979. First, during the dormant season, we counted I mm-Iong hibernacula 
containing overwintering larvae of A. juglandis; the hibernaculum is the overwinter­
ing case for the first instar larva. First instar larvae develop from eggs hatched in 
late summer; they spin hibernacula in preparation for overwinter hibernation. Pres­
ence of hibernacula on a tree was considered an indicator of susceptibility of the tree 
to Acrobasis infestation. Second, in the early summer, we counted infested growing 
shoots as a measure of damage by A. demotella; A. juglandis is a defoliator but does 
not tunnel into shoots (Martin at and Wilson 1979). One tree per family-row plot per 
block was randomly chosen (using a random number generator) for infestation 
evaluation each fall; the same tree was evaluated the following spring. All insect and 
infested shoot count data were square root transformed to increase normality. Tree 
height was measured to the nearest em during the dormant season. 
Data were analyzed by analysis of variance and covariance and correlation tech­
niques. Family heritabilities were calculated using the H2 = (1-IIF) formula of 
Kung and Bey (1979) in which F is t e variance ratio for families. 
RESULTS AND DISCUSSION 
During our 4-year evaluation of this plantation, height growth averaged 0.36 m 
annually. Mean total tree height was 1.5 m in 1976 and the plantation average was 
2.9 m by the end of the 1980 growing season. Infestation as reflected by the number 
of 
hibernacula per 
tree increased from 1.4 in 1976 to a high of 2.6 in 1978 and 
declined to 2.0 hibernacula per tr e in 1979. Demographic trends established by 
Acrobasis hibernacula were mirrored by the number of infested twigs per tree, which 
increased from 1.3 in 1976 to 2.3 in 1978 and then declined to 1.7 in 1979 (table 1). 
However, during the 1976-1979 period, the number of trees with hibernacula 
increased from 20 percent in 1976 to 33 percent in 1977,44 percent in 1978, and 57
percent in 1979. Similarly, the number of trees with infested twigs increased from 20 
percent in 1976 to 30 percent in 1977, 58 percent in 1978, and 63 percent in 1979. 
Analyses of variance or covariance failed to disclose any significant family 
effects. Heritability of susceptibility to infestation by Acrobasis was less than 0.15, 
confirming that genetic resistance to Acrobasis damage is extremely low or nonexist­
ent. Similarly there was no correlation between either number of hibernacula or 
number of infested twigs and latitude or longitude of family origin. 
Correlation analysis disclosed a pattern of very high positive correlations between 
the number of hibernacula per tree and the number of infested twigs (0.87 < r < 
0.97). These high correlations were expected and suggest that the parameters mea­
sure similar attributes of Acrobasis infestation and that future surveys probably 
need to measure only one of these parameters. The high correlations also suggest 
that overwintering survival rates were high and parasitism/predator levels were 
low. 
2
The Great Lakes Entomologist, Vol. 24, No. 1 [1991], Art. 4
https://scholar.valpo.edu/tgle/vol24/iss1/4
1991 THE GREAT LAKES ENTOMOLOGIST 23 
Table 1. - Average height (m), height growth (m), number of hibernacula per tree (no.) and 
number of infested twigs 
Variable Mean Minimum Maximum 
Height 76 1.5 0.2 2.9 
Height 77 1.8 0.4 3.6 
Height 78 2.1 0.4 4.4 
Height 79 2.4 0.6 5.5 
Height 80 2.9 0.8 6.1 
Ht. Gr. 76-77 0.35 -0.63 1.39 
Ht. Gr. 77-78 0.26 -1.15 1.67 
Ht. Gr. 78-79 0.35 -0.90 2.78 
Ht. Gr. 79-80 0.46 -2.55 2.02 
Hib.76 
1.4 1.0 7.0 
Hib.77 
2.0 1.0 14.Hib.78 
2.6 1.0 16.0 Hib.79 
2.0 1.0 3.0 
Infest. 
76 1.3 1.0 15.0 
Infest. 77 1.7 1.0 3.0 
Infest. 78 2.3 1.0 14.0 
Infest. 79 1.7 1.0 9.0 
Table 2. - Correlations of number of hibernacula and infested shoots with total tree height 
(m) in current and subsequent years (ns = not stati tically significant; •• = significant at P < 
0.05) 
Measurement Tree height in Tree height in Tree height in Tree height in 
year current year subsequent year current year subsequent year 
Number of hibernacu/a Number of infested shoots 
1976 0.15 ns 0.18 ns 0.04 ns 0.07 ns 
1977 
1978 
0.22 
•• 
0.40 ** 
0.23 •• 
0.41 .* 
0.30 
•• 
0.43 ** 
0.34 •• 
0.45 ** 
1979 0.08 ns 0.07 ns 0.04 ns 0.05 ns 
A more interesting pattern of correlations emerged between number of hiberna­
cula, infestation, and total tree height (table 2) and height growth (table 3). In 1976, 
the first year of Acrobasis evaluation, there was no statistical correlation (r < 0.2) 
between either measure of insect attack and growth variables. In 1977, there were 
low but significant correlations (r > 0.2) of hibernacula nd infestation with total 
tree height. By 1978, both measures of insect attack were significantly correlated 
with total height and height growth. Fur ermore, the magnitude of the correlation 
between total height and number of hibernacula doubled. However, by 1979 neither 
measure of Acrobasis infestation was correlated with total height or with height 
growth. 
Such correlation patterns could result from the following circumstances: in 1976, 
when there was no correlation between infestation and tree size or growth, the 
3
Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-
Published by ValpoScholar, 1991
24 THE GREAT LAKES ENTOMOLOGIST Vol. 24, No. 1 
Table 3. -Correlations of number of hibernacula and infested shoots with tree growth (m) in 
current and subsequent years (ns not statistically significant; ** significant at P < 0.05) 
Measurement Growth in Growth in Growth in Growth in 
year current year subsequent year current year subsequent year 
Number of hibernacula Number of infested shoots 
1976 0.14 ns 0.08 ns 
1977 
0.10 
ns 0.13 ns 0.18 u 0.23 ** 
1978 
0.18 
** 0.23 ** 0.19 ** 0.25 ** 
1979 
0.08 
ns 0.20 ** 0.05 ns 0.04 ns 
plantation was only 3 years old and all trees were in approximately the same size 
category. The initial infestation was small and the outbreak was distributed among 
trees of the same size class. By 1977 the outbreak was spreading to the larger trees as 
evidenced by the positive corelation with tree height; by 1978, positive correlations 
between infestation and both total height and height growth were present. By 1979, 
on the basis of average number of hibernacula per tree or mean number of infested 
twigs per tree, th infestation seemed to be declining. Furthermore, the remaining 
Acrobasis no longer preferred the larger trees but infested any size trees. 
All statistically significant correlations between total height and insect attack were 
positive, suggesting that Acrobasis preferentially attacks larger trees once an infesta­
tion is established in a plantation (table 2). Furthermore, it appears that in 1977 and 
1978 Acrobasis also attacked the faster growing trees (table 3). The implication is 
that, initially, Acrobasis infests the largest trees, those with the largest crowns; 
however, in subsequent years when most of the trees in the plantation are in larger 
size classes, insect attacks are of a more random nature. 
The lack of negative correlations between infestation in a given year and growth in 
subsequent years was surprising. Acrobasis damage has been described as resem­
bling frost damage where infested terminals die back. In a large infestation, negative 
correlations with growth in the following year might be expected. However, in 
infestations at this population level, negative correlations were not encountered. 
Instead, positive correlations imply that somehow infestations had little effect on 
growth and perhaps were even slightly stimulatory. Thus, it is likely that the overall 
infestation levels were not high enough to affect average growth rates. 
By 
1979, when the trees averaged 2.4 m in total height (table 
1), infestation 
appeared to be subsiding. Subsequent surveys did not disclose significant infesta­
tions. Thus, we hypothesize that Acrobasis is a problem on young trees less than 2.5 
m in height; stem form m'ly be affected but growth rate is not. Alternatively, a 
buildup of populations of natural predators of Acrobasis may have resulted in a 
declining Acrobasis population; unfortunately, no effort was made to monitor these 
predators. 
ACKNOWLEDGMENTS 
We 
thank David 
J. Polak, for assistance with statistical analyses. At the time of 
the study Dave Polak was a computer programmer with NCFES, Carbondale, IL. 
We 
also acknowledge the cooperation 
of the Shawnee National Forest on whose 
land the plantation was established. 
4
The Great Lakes Entomologist, Vol. 24, No. 1 [1991], Art. 4
https://scholar.valpo.edu/tgle/vol24/iss1/4
1991 THE GREAT LAKES ENTOMOLOGIST 25 
LITERATURE CITED 
Kung, F. H. and C. F. Bey. 1979. Heritability construction for provenance and family selec­
tion. In: Proceedings, Thirteenth Lake States For. Tree Impr. Conf., Aug. 17-18, 1977, 
Univ. Minn., St. Paul, MN. USDA For. Servo Gen. Tech. Rep. NC-50, p. 136-146. 
Martinat, P. J. and L. F. Wilson. 1979. The life histories of Acrobasis juglandis and A. 
demotella on black walnut in Michigan. In: Walnut Insects and Diseases Workshop Proc., 
Carbondale, IL. USDA For. Servo Gen. Tech. Rep. NC-52, p. 40-43. 
Martinat, P. J. and W. E. Wallner. 1980. Notes on the biology and damage of two Acrobasis 
species (Lepidoptera: Pyralidae) on black walnut in Michigan. Great Lakes Entomol. 
13:41-48. 
McKeague, M. A. and G. A. Simmons. 1979. Terminal bud damage on black walnut. Michi­
gan State Univ. Ext. Bull. E-1321. 3 p. 
Weber, B. C. and J. E. McPherson. 1984. Attack on black walnut trees by th ambrosia beetle 
Xylosandrus german us (Coleoptera: Scolytidae). Forest Science 30:864-870. 
5
Rink et al.: Acrobasis Shoot Moth (Lepidoptera: Pyralidae) Infestation-
Published by ValpoScholar, 1991

George Rink

Barbara C Weber

D. Michael Baines

David T Funk

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 Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

https://scholar.valpo.edu/cgi/viewcontent.cgi?article=1725&amp;context=tgle

\u3ci\u3eAcrobasis\u3c/i\u3e Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

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