Pupal weights and fecundities of spruce budworm from Minnesota had different means, coefficients of variation, and frequency distributions than spruce budworm from New Hampshire. The two variables were correlated in one of the populations but not the other

Bauer, Leah S

Lorimer, Nancy

English

Nancy Lorimer

Leah S Bauer

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Spruce Budworm Weight and Fecundity: Means, Frequency Distributions, and Correlations for Two Populations (Lepidoptera: Tortricidae)

ValpoScholar

The Great Lakes Entomologist 
Volume 16 
Number 4 - Winter 1983 Number 4 - Winter 
1983 
Article 10 
December 1983 
Spruce Budworm Weight and Fecundity: Means, Frequency 
Distributions, and Correlations for Two Populations (Lepidoptera: 
Tortricidae) 
Nancy Lorimer 
USDA Forest Service 
Leah S. Bauer 
USDA Forest Service 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Lorimer, Nancy and Bauer, Leah S. 1983. "Spruce Budworm Weight and Fecundity: Means, Frequency 
Distributions, and Correlations for Two Populations (Lepidoptera: Tortricidae)," The Great Lakes 
Entomologist, vol 16 (4) 
Available at: https://scholar.valpo.edu/tgle/vol16/iss4/10 
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. 
1983 THE GREAT LAKES ENTOMOLOGIST 153 
SPRUCE BUDWORM WEIGHT AND FECUNDITY; MEANS, 

FREQUENCY DISTRIBUTIONS, AND CORRELATIONS FOR TWO 

POPULATIONS (LEPIDOPTERA: TORTRICIDAE) 

Nancy Lorimer and Leah S. Bauer l 
ABSTRACT 
Pupal weights and fecundities of spruce budworm from Minnesota had different means, 
coefficients of variation, and frequency distributions than spruce budworm from New 
Hampshire. The two variables were correlated in one of the populations but not the other. 
We 
collected pupal weight and fecundity information on spruce budworm 
(Choristoneura!umiferana (Clemens)) as part of a larger project to measure and document 
population differences in this economically important insect (Lorimer 1982, in press; 
Lorimer and Bauer 1983). We were interested in trait variabilities: how the weight and 
fecundity values were distributed about their means. and whether the distributions were 
different by population. Because size and egg number are commonly correlated in 
Lepidoptera and other insects, we also examined this relation. 
MATERIALS AND METHODS 
Spruce budworm late instar larvae were collected from Minnesota (MN) and New 
Hampshire (NH) in 1981, weighed within 24 h of pupation, and mated s newly emerged 
adults in single pairs. We counted all eggs at the end of the oviposition (Lorimer and 
Bauer 1983). Statistical analyses were performed with the MULTREG program at the 
University of Minnesota Computing Center. 
RESULTS AND DISCUSSION 
The mean values for weight and fecundity in the two populations corresponded rather 
well. Mean pupal weight of MN females was 24% greater than for NH females; MN mean 
egg number was greater by 21 % (Table 1). 
Frequency distributions for the two variables in the two popUlations were also dissimilar 
(Fig. 1). The frequency distributions for the MN data were both leptokurtic, i.e., more of 
the values were in the center and the tails than the intervening areas of the normal curve. 
All four bar graphs showed some skewness. Overall variation was greater in the NH data 
than in the MN data. The coefficients of variation for weight and eggs in MN were 16.9 
and 33.1, respectively, as compared with 25.3 and 42.8 in NH. 
The relation between the variables was also different by population (Table 1, Fig. 2). 
Only the females from NH displayed a strong correlation. Correlation coefficents for 
pupal weight and egg number in MN and NH were DAD and 0.78, respectively. 
Regression statistics were different (Table I), but this is a nearly meaningless comparison 
because of the insignificant correlation between weight and egg number in MN. 
The data do not suggest a reason for the lack of size-fecundity correlation for females 
from one of the populations. Correlations have been reported in the literature for this 
INorth Forest Experiment Station, USDA Forest Service, 1992 Folwell Avenue, St. Paul, 
MN 55108. 
1
Lorimer and Bauer: Spruce Budworm Weight and Fecundity: Means, Frequency Distributio
Published by ValpoScholar, 1983
154 THE GREAT LAKES ENTOMOLOGIST VoL 16, No.4 
Table I. Statistics for pupal weight and fecundity of females from Minnesota a d New Hamp­
shire. 
Mean weight (mg) 
standard deviation 
Mean egg number 
standard deviation 
Correlation 
Slope 
Intercept 
105.7 
17.9 
148.2 
49.0 
0.40 
1.1 
32.4 
85.5 
21.6 
122.3 
52.4 
0.78 
1.9 -3 .2 
species. Campbell (1962) also explored the possibility that fecundity-pupal weight 
relations differed by population in the spruce bud worm. He found no significant 
differences among populations from Kenora, Cochrane, and Port Arthur, Ontario in 1950 
(Campbell 1962). The overall correlation coefficient 
was 0.72. Separate population 
coefficients were not reported. Thomas et al. (1980) listed fecundity-forewing length 
correlations of 0.65-0.82 from two populations of spruce budworrn in New Brunswick in 
1977 and 1979. Regression statistics for females collected from the same host species did 
not appear to differ significantly by population (Thomas et al. 1980). Mattson et al. (1982) 
found differences in spruce budworrn pupal weight-adult dry weight relations that 
apparently depended on the source of the insects. 
As in 
all insects, traits such as size and fecundity are variable 
in the spruce budworm, 
and th ir means, distributions, and relations commonly vary unpredictably from popula­
tion to population. 
MN Females 
,----------------------, ,------------------------, 
Weight (mg) Eggs 
Fig. 1. Frequency distributions of pupal weight and numbers of eggs per female for spruce budworm 
collected as late instar larvae from Minnesota (MN) and New Hampshire (NH). 
2
The Great Lakes Entomologist, Vol. 16, No. 4 [1983], Art. 10
https://scholar.valpo.edu/tgle/vol16/iss4/10
• 
• 
•• • 
•• 
• • • • 
• • 
• •• • 
•• 
• • 
• • •• • 
• • 
1983 THE GREAT LAKES ENTOMOLOGIST 155 
•
•225f­
MN 
2 • 
~ 150i­ •
•• 2 •••~ 
• 
•
• 
75f­
• 
• 
• 
60 80 100 120 140 
Weight (mg) 
300 
NH • 
200 
100 
• ••
• 
• 
• 
2 •
• • •• 
•• • ••
•• 2 
• 2 • • 
• 
• 
• 
• 
•
• •
• • • 
• 
• ••
• 
• 
• 
25 50 
Weight (mg) 
Fig. 2. The relation between pupal weight and fecundity (number of eggs laid) in spruce budworm 
from Minnesota (MN) and New Hampshire (NH). Each • represents a single female. 
3
Lorimer and Bauer: Spruce Budworm Weight and Fecundity: Means, Frequency Distributio
Published by ValpoScholar, 1983
156 THE GREAT LAKES ENTOMOLOGIST Vol. 16, No.4 
ACKNOWLEDGMENTS 
This study was partially funded by the Canada-United States Spruce Budworm Program 
(CAN USA-E). 
LITERATURE CITED 
Campbell, L M. 1962. Reproductive capacity in the genus Choristonera Led. (Lepidop­
tera: Tortricidae). L Quantitative inheritance and genes as controllers of rates. Canadian 
J. 
Genet. Cyto\' 4:272-288. 
Lorimer, Nancy. 1982. Morphological variation by population, host, and sex in spruce 
budworm. Environ. Entomo\. 11:493-496. ___
. (in press). Sex ratios of two forest defoliators, 
M. Disstria and C. jllm(ferana, 
Ann. Entomo\. Soc. Amer. 
Lorimer, Nancy and Leah S. Bauer. 1983. Reproductive compatibility among spruce 
budworm popUlations. Great. Lakes Entomo!. 16:149-152. 
Mattson, W. 1., K. N. Koller, S. Slocum. 1982. Adult female spruce budworm dry weight 
in relationship to pupal fresh weight and case diameter. Great Lakes Entomo!. 
15:185-187. 
Thomas, A. W., S. A. 	 Borland, and D. O. Greenbank. 1980. Field fecundity of the 
spruce bud worm as determined from regression relationships between egg complement, 
forewing length, and body weight. Canadian 1. Zoo1. 58:1608-1611. 
4
The Great Lakes Entomologist, Vol. 16, No. 4 [1983], Art. 10
https://scholar.valpo.edu/tgle/vol16/iss4/10


Valparaiso University

The Great Lakes Entomologist Volume 16 Number 4 - Winter 1983 Number 4 - Winter 1983 Article 10 December 1983 Spruce Budworm Weight and Fecundity: Means, Frequency Distributions, and Correlations for Two Populations (Lepidoptera: Tortricidae) Nancy Lorimer USDA Forest Service Leah S. Bauer USDA Forest Service Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Lorimer, Nancy and Bauer, Leah S. 1983. "Spruce Budworm Weight and Fecundity: Means, Frequency Distributions, and Correlations for Two Populations (Lepidoptera: Tortricidae)," The Great Lakes Entomologist, vol 16 (4) Available at: https://scholar.valpo.edu/tgle/vol16/iss4/10 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. 1983 THE GREAT LAKES ENTOMOLOGIST 153 SPRUCE BUDWORM WEIGHT AND FECUNDITY; MEANS, FREQUENCY DISTRIBUTIONS, AND CORRELATIONS FOR TWO POPULATIONS (LEPIDOPTERA: TORTRICIDAE) Nancy Lorimer and Leah S. Bauer l ABSTRACT Pupal weights and fecundities of spruce budworm from Minnesota had different means, coefficients of variation, and frequency distributions than spruce budworm from New Hampshire. The two variables were correlated in one of the populations but not the other. We collected pupal weight and fecundity information on spruce budworm (Choristoneura!umiferana (Clemens)) as part of a larger project to measure and document population differences in this economically important insect (Lorimer 1982, in press; Lorimer and Bauer 1983). We were interested in trait variabilities: how the weight and fecundity values were distributed about their means. and whether the distributions were different by population. Because size and egg number are commonly correlated in Lepidoptera and other insects, we also examined this relation. MATERIALS AND METHODS Spruce budworm late instar larvae were collected from Minnesota (MN) and New Hampshire (NH) in 1981, weighed within 24 h of pupation, and mated s newly emerged adults in single pairs. We counted all eggs at the end of the oviposition (Lorimer and Bauer 1983). Statistical analyses were performed with the MULTREG program at the University of Minnesota Computing Center. RESULTS AND DISCUSSION The mean values for weight and fecundity in the two populations corresponded rather well. Mean pupal weight of MN females was 24% greater than for NH females; MN mean egg number was greater by 21 % (Table 1). Frequency distributions for the two variables in the two popUlations were also dissimilar (Fig. 1). The frequency distributions for the MN data were both leptokurtic, i.e., more of the values were in the center and the tails than the intervening areas of the normal curve. All four bar graphs showed some skewness. Overall variation was greater in the NH data than in the MN data. The coefficients of variation for weight and eggs in MN were 16.9 and 33.1, respectively, as compared with 25.3 and 42.8 in NH. The relation between the variables was also different by population (Table 1, Fig. 2). Only the females from NH displayed a strong correlation. Correlation coefficents for pupal weight and egg number in MN and NH were DAD and 0.78, respectively. Regression statistics were different (Table I), but this is a nearly meaningless comparison because of the insignificant correlation between weight and egg number in MN. The data do not suggest a reason for the lack of size-fecundity correlation for females from one of the populations. Correlations have been reported in the literature for this INorth Forest Experiment Station, USDA Forest Service, 1992 Folwell Avenue, St. Paul, MN 55108. 1Lorimer and Bauer: Spruce Budworm Weight and Fecundity: Means, Frequency DistributioPublished by ValpoScholar, 1983154 THE GREAT LAKES ENTOMOLOGIST VoL 16, No.4 Table I. Statistics for pupal weight and fecundity of females from Minnesota a d New Hamp­shire. Mean weight (mg) standard deviation Mean egg number standard deviation Correlation Slope Intercept 105.7 17.9 148.2 49.0 0.40 1.1 32.4 85.5 21.6 122.3 52.4 0.78 1.9 -3 .2 species. Campbell (1962) also explored the possibility that fecundity-pupal weight relations differed by population in the spruce bud worm. He found no significant differences among populations from Kenora, Cochrane, and Port Arthur, Ontario in 1950 (Campbell 1962). The overall correlation coefficient was 0.72. Separate population coefficients were not reported. Thomas et al. (1980) listed fecundity-forewing length correlations of 0.65-0.82 from two populations of spruce budworrn in New Brunswick in 1977 and 1979. Regression statistics for females collected from the same host species did not appear to differ significantly by population (Thomas et al. 1980). Mattson et al. (1982) found differences in spruce budworrn pupal weight-adult dry weight relations that apparently depended on the source of the insects. As in all insects, traits such as size and fecundity are variable in the spruce budworm, and th ir means, distributions, and relations commonly vary unpredictably from popula­tion to population. MN Females ,----------------------, ,------------------------, Weight (mg) Eggs Fig. 1. Frequency distributions of pupal weight and numbers of eggs per female for spruce budworm collected as late instar larvae from Minnesota (MN) and New Hampshire (NH). 2The Great Lakes Entomologist, Vol. 16, No. 4 [1983], Art. 10https://scholar.valpo.edu/tgle/vol16/iss4/10• • •• • •• • • • • • • • •• • •• • • • • •• • • • 1983 THE GREAT LAKES ENTOMOLOGIST 155 ••225f­MN 2 • ~ 150i­ ••• 2 •••~ • •• 75f­• • • 60 80 100 120 140 Weight (mg) 300 NH • 200 100 • ••• • • 2 •• • •• •• • •••• 2 • 2 • • • • • • •• •• • • • • ••• • • 25 50 Weight (mg) Fig. 2. The relation between pupal weight and fecundity (number of eggs laid) in spruce budworm from Minnesota (MN) and New Hampshire (NH). Each • represents a single female. 3Lorimer and Bauer: Spruce Budworm Weight and Fecundity: Means, Frequency DistributioPublished by ValpoScholar, 1983156 THE GREAT LAKES ENTOMOLOGIST Vol. 16, No.4 ACKNOWLEDGMENTS This study was partially funded by the Canada-United States Spruce Budworm Program (CAN USA-E). LITERATURE CITED Campbell, L M. 1962. Reproductive capacity in the genus Choristonera Led. (Lepidop­tera: Tortricidae). L Quantitative inheritance and genes as controllers of rates. Canadian J. Genet. Cyto\' 4:272-288. Lorimer, Nancy. 1982. Morphological variation by population, host, and sex in spruce budworm. Environ. Entomo\. 11:493-496. ___. (in press). Sex ratios of two forest defoliators, M. Disstria and C. jllm(ferana, Ann. Entomo\. Soc. Amer. Lorimer, Nancy and Leah S. Bauer. 1983. Reproductive compatibility among spruce budworm popUlations. Great. Lakes Entomo!. 16:149-152. Mattson, W. 1., K. N. Koller, S. Slocum. 1982. Adult female spruce budworm dry weight in relationship to pupal fresh weight and case diameter. Great Lakes Entomo!. 15:185-187. Thomas, A. W., S. A. 	 Borland, and D. O. Greenbank. 1980. Field fecundity of the spruce bud worm as determined from regression relationships between egg complement, forewing length, and body weight. Canadian 1. Zoo1. 58:1608-1611. 4The Great Lakes Entomologist, Vol. 16, No. 4 [1983], Art. 10https://scholar.valpo.edu/tgle/vol16/iss4/10

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Spruce Budworm Weight and Fecundity: Means, Frequency Distributions, and Correlations for Two Populations (Lepidoptera: Tortricidae)

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