(excerpt)
Successful protection of elm trees can only be accomplished by means of thorough understanding of the feeding behavior of the smaller European elm bark beetle, Scolytus multistriatus (Marsham). Wolfenbarger and Buchanan (1939) and Whitten (1958) noted that most feeding occurred in the outer portion of the upper crown region, but offered no quantitative data. Therefore, this study was initiated to investigate the regional distribution of feeding injuries along a vertical and horizontal gradient in native American elm, Ulmus americana L

Butcher, J. W

Riedl, H

English

H Riedl

J. W Butcher

Crossref

 (Marsham) (Scoltytidae: Coleoptera) and Implications for Control

Valparaiso University

The Great Lakes Entomologist Volume 8 Number 3 - Fall 1975 Number 3 - Fall 1975 Article 8 October 1975 Aspects of the Feeding Behavior of Scolytus Multistriatus (Marsham) (Scoltytidae: Coleoptera) and Implications for Control H Riedl J. W. Butcher Michigan State University Follow this and additional works at: https://scholar.valpo.edu/tgle Part of the Entomology Commons Recommended Citation Riedl, H and Butcher, J. W. 1975. "Aspects of the Feeding Behavior of Scolytus Multistriatus (Marsham) (Scoltytidae: Coleoptera) and Implications for Control," The Great Lakes Entomologist, vol 8 (3) Available at: https://scholar.valpo.edu/tgle/vol8/iss3/8 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. THE GREAT LAKES ENTOMOLOGIST ASPECTS OF THE FEEDING BEHAVIOR OF SCOLYTUS MUL TISTRIATUS (MARSHAM) (SCOLYTI DAE: COLEOPTERA) AND IMPLICATIONS FOR CON'rROL1 H. Riedl and J. W. ~utcher ' Successful protection of elm trees can only be accomplished by means of thorough understanding of the feeding behavior of the smaller European elm bark beetle, Scolytus multistriatus (Marsham). Wolfenbarger and Buchanan (1939) and Whitten (1958) noted that most feeding occurred in the outer portion of the upper crown region, but offered no quantitative data. Therefore, this study was initiated to investigate the regional distribution of feeding injuries along a vertical and horizontal gradient in native American elm, Ulmus americana L. Another objective of this study concerned a detailed analysis of feeding scars in order to correlate specific physical characteristics of twig crotches with feeding injuries. Chemical aspects of feeding stimulation have received considerable attention (Baker and Norris, 1967), but the importance of physical characteristics of the twig crotch of the feeding process was not fully researched. Information of this kind could be valuable in the selection of elms with twig crotch characteristics which would not induce feeding attack. However, as Heybroek (1969) pointed out, an elm resistant to feeding by mullistri~tzts could still be attacked by other vectors. MATERIALS AND METHODS Six elm trees henceforth designated A to F were sampled at three height levels: 5, 10 and 15 meters. The elms were park trees and had not been sprayed at any time during the previous five years. In this respect the natural feeding pattern was not disturbed. Tree height ranged from 15 to 18 meters. Random samples of 50-70 twig crotches were taken from five points in each height level (from four compass points and the interior of the crown). A light-weight aluminum pole pruner, extendable to 16 m was used to sample elm twigs. The total number of twig crotches and t h e number of feeding injuries were recorded from each sample. The number of scars in places other than twig crotches (mainly in leaf axils) was not included in the figure for total attack. The average feeding attack for each height level was computed from the percentage feeding at the five sample points (Table 1). Also, the position of the sample branches at the three height levels was recorded as: (a) pointing upwards, (b) projecting horizontally, and (c) pointing downwards. For a study of feeding preference for vertical quarters, each sample tree was subdivided into five sections: N (north), S (south), E (east), W (west), and C (center). In order to demonstrate the consistency of the horizontal feeding pattern over the three height levels, the twig-crotch injury data for each tree was subjected to Friedman's ANOVA according to rank (Siegel, 1956, p. 166). Tree A was deleted from this analysis because of the low attack rate at all levels. I n order to study the association of certain morphological features of twig crotches to feeding, 300 samples from tree B and 400 samples from tree D were analyzed. The following characteristics were recorded: 1. Angle between the two lateral members of crotch. This was measured by placing the twig crotch on polar coordinate graph paper (accurate to 5'). 2. Crotch base: either rounded or acute (Fig. 1). 3. Injuries by vector feeding. 4. Position of feeding scar; either lateral or central (Fig. 1). l ~ i c h i ~ a n Agricultural Experiment Station Journal Article Number 691 1. 2Department of Entomology and Department of Zoology, respectively, Michigan State University, East Lansing, Michigan 48824. 1Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus MultistriatusPublished by ValpoScholar, 1975THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 Table 1. Feeding attack in three height levels of six mature elm trees. Tree Height level (m) 5 10 15 a) Average per cent attack, f SE. b) Total no. attacked leaf axils. a b c d Fig. 1. Type of twig crotch base: (a) rounded, (b) acute and t)-pe of feeding: (c) lateral, (d) central. Several t-tests were performed on the angle data of attacked and unattacked twig crotches to test if multistriatus had a preference for twig crotches with certain angles. No t-value was calculated for tree B at the lowest height level because the numbers of attacked crotches was too small Combinations of type of twig crotch base and type of feeding were tested for their independence in a 2 X 2 contingency table. The combinations were round-lateral, round-central. acute-lateral and acute-central. 2The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8https://scholar.valpo.edu/tgle/vol8/iss3/81975 THE GREAT LAKES ENTOMOLOGIST 141 RESULTS AND DISCUSSION REGIONAL DISTRIBUTION OF FEEDING INJURIES ALONG A VERTICAL GRADI- ENT.- The relationship between height level and amount of feeding (Table 1) appeared t o be linear for low and high vector pressure (Fig. 2). I t appears that as most available twig crotches in the top level become attacked, newly arriving vectors have difficulty finding suitable feeding sites and move down into the middle level of the crown region. This explains the departure from the linear relationship between elevation and feeding in trees C and D. In trees where the attack rate exceeded 80%,, the beetle vectors occasionally resorted t o feeding in leaf axils. This was especially noticeable o n trees C, D, and E, bu t feeding wounds of this kind were also present o n tree F where the average attack at height level 2 was lower (27.8%). The importance of feeding in leaf axils with regard to effective disease transmission is not known. Twig crotches were sometimes attacked more than once, particularly in samples with a great number of feeding injuries. The amount of feeding was not correlated with branch position. Location of the feeding wound, in respect to upper or bottom side of the twig showed n o pattern regardless of the position of the branch. Morphological variation of twig characteristics among the six sampled elms was considerable. Some elms had long slender twigs which were very flexible. These also had few crotches (tree E and F) while others had many crotches and were more sturdy in appearance. REGIONAL DISTRIBUTION O F FEEDING INJURIES ALONG A HORlZONTAL GRADIENT.-Using Friedman's ANOVA by rank only trees B and E had greater differences in feeding attack between the five sample points consistently over all three height levels (Table 2). In tree B the percentage of feeding injuries was lowest in the S sector, but considerably higher in the N and E sectors. Tree E had the least feeding in the W sector and the highest number of injuries in the E sector. Initially it was suspected that the central sector at the lower height levels 2 and 3 would be the region with the fewest number of feeding scars, because of a reported % feeding 1 " r A 0 A 0 0 I I 5 10 15 - height level (meter) Fig. 2. Relationship between feeding by S. multistriatus and height level on six untreated elms (A to F). 3Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus MultistriatusPublished by ValpoScholar, 1975THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 Table 2. Comparison of feeding attack in four cardinal quarters and center section of elm trees using Friedman's ANOVA. Tree X i Significance Highest feeding in quarter of tree vector preference for the periphery of the crown (Wolfenbarger and Buchanan, 1939). However, this was not the case in this study. Uneven distribution of feeding wounds in the 5 vertical sections of the tree (N, S, E, W, C) was probably not the result of preferential feeding in any one of the five regions. Rather, the proximity of a beetle-producing elm tree to a particular quarter of the above sample trees might have caused this difference in attack. The question of a possible difference in the overall feeding pattern on elm trees in a closed stand and on road-side elms was also raised. Sample trees A, B, C and D were in closed stands, together with other tree species, while trees E and F were part of a road-side planting. The vertical and horizontal distribution of feeding injuries in these two groups of trees did not seem to be different. However, both road-side elms showed differences in the number of feeding injuries in the five sectors of the tree. Whether this is a general trend among road-side trees can only be speculated upon since the sample was too small. These findings suggest that the whole upper tree region requires particular attention during spraying operations. Differential hazard regions for fungus infection must be considered as well. Fungal infections originating from feeding wounds in the lower part of an elm tree are more likely to cause quicker mortality because of the shorter distance the fungus has to travel to the main trunk (Zentmper e t aL, 1946). As a consequence, spray application methods should be judged in respect to their performance on the whole tree. ASSOCIATION OF PHYSICAL TWIG CROTCH CHARACTERISTICS Q'ITH FEED- ING.-No relation was observed between crotch angle and feeding (Table 3). Of interest is the fact that the angle means of the height level samples for tree B, with 87.3O, 83.0" and 84.5" were considerably higher than the means for tree D, with 64.6O, 66.8" and 69.1". The great difference in angle means between these two trees is an example of the morphological variability one can find among elm trees. Ouelette (1962) noted that lateral feeding resulted in a higher infection rate than did central feeding. Presumably during lateral feeding the beetle vector with the spores attached to its body exterior establishes better contact with the conductive tissue. The contingency table (Table 4) suggested that twig crotches with a rounded base are more likely to induce lateral rather than central feeding responses. Therefore, the probability of fungal infection is higher on trees with a greater proportion of twig crotches with a rounded base because of the preferred lateral type of feeding. SUMMARY Extensive sampling of untreated elm trees revealed that Scolytus rnultistriatus feed preferentially in the whole upper tree region. Feeding attack rate increased linearly from the bottom to the top. This behavior must be considered for the proper choice and evaluation of a spray application method in order to achieve maximum protection. Differences in attack in vertical sections of a tree were observed but were believed to be more directly related to the close proximity of a beetle-producing tree than to a particular 4The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8https://scholar.valpo.edu/tgle/vol8/iss3/81975 THE GREAT LAKES ENTOMOLOGIST 143 Table 3. T-comparisons of angle means of attacked and unattacked twig crotches. Height level Tree (m) n Mean angle Sx tcalc B 5 Att. 5 85 .O 3.16 Unatt. 95 87.3 .85 not calc 10 Att. 3 2 84.1 2.63 Unatt. 68 82.4 1.50 ,575 15 Att. 3 2 81.7 3.12 Unatt. 68 85.7 2.0 1 1.11 5 Att. 18 63.9 2.72 Unatt 82 64.7 1.28 .299 10 Att. 120 66.5 .94 Unatt. 30 67.3 2.15 .364 15 Att. 118 68.5 1.04 Unatt. 32 71.4 2.01 1.277 t = 1.980 (a = .05, d f = 98) t = 1.960 (a = .05, d f = 148) Table 4. Association between type of feeding and type of twig crotch base. Twig crotch base Type of feeding Round Acute Total Lateral 124 60 184 Central 83 7 2 155 - - -Total 207 132 399 XZ calc = 6.78 XZ tab = 3.84 (a = 0.05, d f = 1) quarter of a sample tree. Several physical twig crotch characteristics were investigated with respect to their association with vector feeding. The size of the angle between the main and lateral member of a twig crotch had no influence on feeding. However, there was a significant relation between a more rounded twig crotch base and lateral feeding. Lateral feeding re- portedly results in more successful inoculations than does central feeding. These findings pointed out a possible resistance mechanism against feeding by rnultistriatus. LITERATURE CITED Baker, J. E., and D. M. Norris. 1967. A feeding stimulant for Scolytus rnultistriatus (Coleoptera: Scolytidae) isolated from bark of Ulmus americana. Ann. Entomol. Soc. Am. 60: 1213-5. Heybroek, H. M. 1966. Dutch elm disease abroad. Am. Forests. 72(6):26-9. Ouellete, G. B. 1962. Studies on the infection process of Ceratocystis ulrni (Buism.) C. Moreau in American elms. Can. J. Botany. 40: 1567-75. Siegel, S. Non-parametric statistics: for the behavioral sciences. McGraw-Hill, New York, Toronto, London. 3 12 pp. 5Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus MultistriatusPublished by ValpoScholar, 1975144 THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 Whitten, R. R. 1958. The Dutch elm disease and its control. U.S.D.A. Agric. Info. Bull. No. 193. Wolfenbarger, D. O., and W. D. Buchanan. 1939. Notes on elm twig crotch injuries produced by Scolytus mltistriatzts Marsham. J . Econ. .Entomol. 32:377-81. Zentmyer, G. A., J. A. Horsfall and P. Wallace. 1946. Dutch elm disease and its chemotherapy. Conn. Agric. Exp. Sta. Bull. No. 498. 6The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8https://scholar.valpo.edu/tgle/vol8/iss3/8

Aspects of the Feeding Behavior of \u3ci\u3eScolytus Multistriatus\u3c/i\u3e (Marsham) (Scoltytidae: Coleoptera) and Implications for Control

ValpoScholar

The Great Lakes Entomologist 
Volume 8 
Number 3 - Fall 1975 Number 3 - Fall 1975 Article 8 
October 1975 
Aspects of the Feeding Behavior of Scolytus Multistriatus 
(Marsham) (Scoltytidae: Coleoptera) and Implications for Control 
H Riedl 
J. W. Butcher 
Michigan State University 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Riedl, H and Butcher, J. W. 1975. "Aspects of the Feeding Behavior of Scolytus Multistriatus (Marsham) 
(Scoltytidae: Coleoptera) and Implications for Control," The Great Lakes Entomologist, vol 8 (3) 
Available at: https://scholar.valpo.edu/tgle/vol8/iss3/8 
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. 
THE GREAT LAKES ENTOMOLOGIST 
ASPECTS OF THE FEEDING BEHAVIOR OF SCOLYTUS 
MUL TISTRIATUS (MARSHAM) (SCOLYTI DAE: COLEOPTERA) 
AND IMPLICATIONS FOR CON'rROL1 
H. Riedl and J. W. ~utcher ' 
Successful protection of elm trees can only be accomplished by means of thorough 
understanding of the feeding behavior of the smaller European elm bark beetle, Scolytus 
multistriatus (Marsham). Wolfenbarger and Buchanan (1939) and Whitten (1958) noted 
that most feeding occurred in the outer portion of the upper crown region, but offered 
no quantitative data. Therefore, this study was initiated to investigate the regional 
distribution of feeding injuries along a vertical and horizontal gradient in native American 
elm, Ulmus americana L. 
Another objective of this study concerned a detailed analysis of feeding scars in order 
to correlate specific physical characteristics of twig crotches with feeding injuries. 
Chemical aspects of feeding stimulation have received considerable attention (Baker and 
Norris, 1967), but the importance of physical characteristics of the twig crotch of the 
feeding process was not fully researched. Information of this kind could be valuable in 
the selection of elms with twig crotch characteristics which would not induce feeding 
attack. However, as Heybroek (1969) pointed out, an elm resistant to feeding by 
mullistri~tzts could still be attacked by other vectors. 
MATERIALS AND METHODS 
Six elm trees henceforth designated A to F were sampled at three height levels: 5, 10 
and 15 meters. The elms were park trees and had not been sprayed at any time during 
the previous five years. In this respect the natural feeding pattern was not disturbed. Tree 
height ranged from 15 to 18 meters. Random samples of 50-70 twig crotches were taken 
from five points in each height level (from four compass points and the interior of the 
crown). A light-weight aluminum pole pruner, extendable to 16 m was used to sample elm 
twigs. The total number of twig crotches and t h e number of feeding injuries were 
recorded from each sample. The number of scars in places other than twig crotches 
(mainly in leaf axils) was not included in the figure for total attack. The average feeding 
attack for each height level was computed from the percentage feeding at the five sample 
points (Table 1). Also, the position of the sample branches at the three height levels was 
recorded as: (a) pointing upwards, (b) projecting horizontally, and (c) pointing downwards. 
For a study of feeding preference for vertical quarters, each sample tree was 
subdivided into five sections: N (north), S (south), E (east), W (west), and C (center). In 
order to demonstrate the consistency of the horizontal feeding pattern over the three 
height levels, the twig-crotch injury data for each tree was subjected to Friedman's 
ANOVA according to rank (Siegel, 1956, p. 166). Tree A was deleted from this analysis 
because of the low attack rate at all levels. 
I n order to study the association of certain morphological features of twig crotches to 
feeding, 300 samples from tree B and 400 samples from tree D were analyzed. The 
following characteristics were recorded: 
1. Angle between the two lateral members of crotch. This was measured by placing 
the twig crotch on polar coordinate graph paper (accurate to 5'). 
2. Crotch base: either rounded or acute (Fig. 1). 
3. Injuries by vector feeding. 
4. Position of feeding scar; either lateral or central (Fig. 1). 
l ~ i c h i ~ a n Agricultural Experiment Station Journal Article Number 691 1. 
2Department of Entomology and Department of Zoology, respectively, Michigan State 
University, East Lansing, Michigan 48824. 
1
Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus Multistriatus
Published by ValpoScholar, 1975
THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 
Table 1. Feeding attack in three height levels of six mature elm 
trees. 
Tree 
Height level (m) 
5 10 15 
a) Average per cent attack, f SE. 
b) Total no. attacked leaf axils. 
a b c d 
Fig. 1. Type of twig crotch base: (a) rounded, (b) acute and t)-pe of feeding: (c) lateral, 
(d) central. 
Several t-tests were performed on the angle data of attacked and unattacked twig 
crotches to test if multistriatus had a preference for twig crotches with certain angles. No 
t-value was calculated for tree B at the lowest height level because the numbers of 
attacked crotches was too small 
Combinations of type of twig crotch base and type of feeding were tested for their 
independence in a 2 X 2 contingency table. The combinations were round-lateral, 
round-central. acute-lateral and acute-central. 
2
The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8
https://scholar.valpo.edu/tgle/vol8/iss3/8
1975 THE GREAT LAKES ENTOMOLOGIST 141 
RESULTS AND DISCUSSION 
REGIONAL DISTRIBUTION OF FEEDING INJURIES ALONG A VERTICAL GRADI- 
ENT.- The relationship between height level and amount of feeding (Table 1) appeared 
t o be linear for low and high vector pressure (Fig. 2). I t appears that as most available 
twig crotches in the top level become attacked, newly arriving vectors have difficulty 
finding suitable feeding sites and move down into the middle level of the crown region. 
This explains the departure from the linear relationship between elevation and feeding in 
trees C and D. 
In trees where the attack rate exceeded 80%,, the beetle vectors occasionally resorted 
t o feeding in leaf axils. This was especially noticeable o n trees C, D, and E, bu t feeding 
wounds of this kind were also present o n tree F where the average attack at height level 
2 was lower (27.8%). The importance of feeding in leaf axils with regard to effective 
disease transmission is not known. Twig crotches were sometimes attacked more than 
once, particularly in samples with a great number of feeding injuries. 
The amount of feeding was not correlated with branch position. Location of the 
feeding wound, in respect to upper or bottom side of the twig showed n o pattern 
regardless of the position of the branch. Morphological variation of twig characteristics 
among the six sampled elms was considerable. Some elms had long slender twigs which 
were very flexible. These also had few crotches (tree E and F) while others had many 
crotches and were more sturdy in appearance. 
REGIONAL DISTRIBUTION O F FEEDING INJURIES ALONG A HORlZONTAL 
GRADIENT.-Using Friedman's ANOVA by rank only trees B and E had greater 
differences in feeding attack between the five sample points consistently over all three 
height levels (Table 2). In tree B the percentage of feeding injuries was lowest in the S 
sector, but considerably higher in the N and E sectors. Tree E had the least feeding in 
the W sector and the highest number of injuries in the E sector. 
Initially it was suspected that the central sector at the lower height levels 2 and 3 
would be the region with the fewest number of feeding scars, because of a reported 
% feeding 
1 " r 
A 0 A 0 
0 I I 
5 10 15 
- 
height level (meter) 
Fig. 2. Relationship between feeding by S. multistriatus and height level on six untreated 
elms (A to F). 
3
Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus Multistriatus
Published by ValpoScholar, 1975
THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 
Table 2. Comparison of feeding attack in four cardinal quarters 
and center section of elm trees using Friedman's ANOVA. 
Tree X i Significance Highest feeding in quarter of tree 
vector preference for the periphery of the crown (Wolfenbarger and Buchanan, 1939). 
However, this was not the case in this study. 
Uneven distribution of feeding wounds in the 5 vertical sections of the tree (N, S, E, 
W, C) was probably not the result of preferential feeding in any one of the five regions. 
Rather, the proximity of a beetle-producing elm tree to a particular quarter of the above 
sample trees might have caused this difference in attack. 
The question of a possible difference in the overall feeding pattern on elm trees in a 
closed stand and on road-side elms was also raised. Sample trees A, B, C and D were in 
closed stands, together with other tree species, while trees E and F were part of a 
road-side planting. The vertical and horizontal distribution of feeding injuries in these two 
groups of trees did not seem to be different. However, both road-side elms showed 
differences in the number of feeding injuries in the five sectors of the tree. Whether this 
is a general trend among road-side trees can only be speculated upon since the sample 
was too small. These findings suggest that the whole upper tree region requires particular 
attention during spraying operations. Differential hazard regions for fungus infection must 
be considered as well. Fungal infections originating from feeding wounds in the lower 
part of an elm tree are more likely to cause quicker mortality because of the shorter 
distance the fungus has to travel to the main trunk (Zentmper e t aL, 1946). As a 
consequence, spray application methods should be judged in respect to their performance 
on the whole tree. 
ASSOCIATION OF PHYSICAL TWIG CROTCH CHARACTERISTICS Q'ITH FEED- 
ING.-No relation was observed between crotch angle and feeding (Table 3). Of interest is 
the fact that the angle means of the height level samples for tree B, with 87.3O, 83.0" 
and 84.5" were considerably higher than the means for tree D, with 64.6O, 66.8" and 
69.1". The great difference in angle means between these two trees is an example of the 
morphological variability one can find among elm trees. 
Ouelette (1962) noted that lateral feeding resulted in a higher infection rate than did 
central feeding. Presumably during lateral feeding the beetle vector with the spores 
attached to its body exterior establishes better contact with the conductive tissue. 
The contingency table (Table 4) suggested that twig crotches with a rounded base 
are more likely to induce lateral rather than central feeding responses. Therefore, the 
probability of fungal infection is higher on trees with a greater proportion of twig 
crotches with a rounded base because of the preferred lateral type of feeding. 
SUMMARY 
Extensive sampling of untreated elm trees revealed that Scolytus rnultistriatus feed 
preferentially in the whole upper tree region. Feeding attack rate increased linearly from 
the bottom to the top. This behavior must be considered for the proper choice and 
evaluation of a spray application method in order to achieve maximum protection. 
Differences in attack in vertical sections of a tree were observed but were believed to be 
more directly related to the close proximity of a beetle-producing tree than to a particular 
4
The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8
https://scholar.valpo.edu/tgle/vol8/iss3/8
1975 THE GREAT LAKES ENTOMOLOGIST 143 
Table 3. T-comparisons of angle means of attacked and unattacked twig crotches. 
Height level 
Tree (m) n Mean angle Sx tcalc 
B 5 Att. 5 85 .O 3.16 
Unatt. 95 87.3 .85 not calc 
10 Att. 3 2 84.1 2.63 
Unatt. 68 82.4 1.50 ,575 
15 Att. 3 2 81.7 3.12 
Unatt. 68 85.7 2.0 1 1.11 
5 Att. 18 63.9 2.72 
Unatt 82 64.7 1.28 .299 
10 Att. 120 66.5 .94 
Unatt. 30 67.3 2.15 .364 
15 Att. 118 68.5 1.04 
Unatt. 32 71.4 2.01 1.277 
t = 1.980 (a = .05, d f = 98) 
t = 1.960 (a = .05, d f = 148) 
Table 4. Association between type of feeding and type of twig 
crotch base. 
Twig crotch base 
Type of feeding Round Acute Total 
Lateral 124 60 184 
Central 83 7 2 155 
- - -
Total 207 132 399 
XZ calc = 6.78 
XZ tab = 3.84 
(a = 0.05, d f = 1) 
quarter of a sample tree. Several physical twig crotch characteristics were investigated with 
respect to their association with vector feeding. The size of the angle between the main and 
lateral member of a twig crotch had no influence on feeding. However, there was a significant 
relation between a more rounded twig crotch base and lateral feeding. Lateral feeding re- 
portedly results in more successful inoculations than does central feeding. These findings 
pointed out a possible resistance mechanism against feeding by rnultistriatus. 
LITERATURE CITED 
Baker, J. E., and D. M. Norris. 1967. A feeding stimulant for Scolytus rnultistriatus 
(Coleoptera: Scolytidae) isolated from bark of Ulmus americana. Ann. Entomol. Soc. 
Am. 60: 1213-5. 
Heybroek, H. M. 1966. Dutch elm disease abroad. Am. Forests. 72(6):26-9. 
Ouellete, G. B. 1962. Studies on the infection process of Ceratocystis ulrni (Buism.) C. 
Moreau in American elms. Can. J. Botany. 40: 1567-75. 
Siegel, S. Non-parametric statistics: for the behavioral sciences. McGraw-Hill, New York, 
Toronto, London. 3 12 pp. 
5
Riedl and Butcher: Aspects of the Feeding Behavior of Scolytus Multistriatus
Published by ValpoScholar, 1975
144 THE GREAT LAKES ENTOMOLOGIST Vol. 8, No. 3 
Whitten, R. R. 1958. The Dutch elm disease and its control. U.S.D.A. Agric. Info. Bull. 
No. 193. 
Wolfenbarger, D. O., and W. D. Buchanan. 1939. Notes on elm twig crotch injuries 
produced by Scolytus mltistriatzts Marsham. J . Econ. .Entomol. 32:377-81. 
Zentmyer, G. A., J. A. Horsfall and P. Wallace. 1946. Dutch elm disease and its 
chemotherapy. Conn. Agric. Exp. Sta. Bull. No. 498. 
6
The Great Lakes Entomologist, Vol. 8, No. 3 [1975], Art. 8
https://scholar.valpo.edu/tgle/vol8/iss3/8

https://scholar.valpo.edu/cgi/viewcontent.cgi?article=1256&amp;context=tgle

Aspects of the Feeding Behavior of \u3ci\u3eScolytus Multistriatus\u3c/i\u3e (Marsham) (Scoltytidae: Coleoptera) and Implications for Control

Abstract

Similar works

Full text

Available Versions

Crossref

Valparaiso University

ValpoScholar