Three ages of alfalfa weevil, Hypera postica (Gyllenhal) eggs were exposed to repeated exposures of -15 and -20°C. Fresh-laid eggs were quite susceptible and 3- and 5day old eggs were relatively resistant to -15\u27C, but all ages of eggs showed considerable susceptibility to -20°C, with an average LT50 of 2.2 days. Comparison of this data with similar studies utilizing constant low temperature exposures showed the effect to be independent of temporal interruptions

Armbrust, E. J

Crain, L. J

English

ValpoScholar

The Great Lakes Entomologist 
Volume 11 
Number 1 - Spring 1978 Number 1 - Spring 1978 Article 8 
April 1978 
The Effect of Repeated Low Temperature on Eggs of the Alfalfa 
Weevil (Coleoptera: Curculionidae) 
L. J. Crain 
Illinois Natural History Survey and Illinois Agricultural Experiment Station 
E. J. Armbrust 
Illinois Natural History Survey and Illinois Agricultural Experiment Station 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Crain, L. J. and Armbrust, E. J. 1978. "The Effect of Repeated Low Temperature on Eggs of the Alfalfa 
Weevil (Coleoptera: Curculionidae)," The Great Lakes Entomologist, vol 11 (1) 
Available at: https://scholar.valpo.edu/tgle/vol11/iss1/8 
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 ENTOMOLOGlST 
THE EFFECT OF REPEATED LOW TEMPERATURE ON EGGS 
OF THE ALFALFA WEEVIL (COLEOPTERA: CURCULIONIDAE)~ 
L. J. Crain and E. J. Armbrust2 
ABSTRACT 
Three ages of alfalfa weevil, Hypera postica (Gyllenhal) eggs were exposed to repeated 
exposures of -15 and -20°C. Fresh-laid eggs were quite susceptible and 3- and 5 d a y  old 
eggs were relatively resistant to  -15'C, but all ages of eggs showed considerable 
susceptibility to -20°C, with an average LT50 of 2.2 days. Comparison of this data with 
similar studies utilizing constant low temperature exposures showed the effect to be 
independent of temporal interruptions. 
The alfalfa weevil, Hypera postica (Gyllenhal), is the principal pest of alfalfa in the 
United States. In many areas, once adults reach sexual maturity in the fall, they have the 
capability to oviposit throughout the winter whenever temperatures reach ca. 10°C 
(Hamlin et al., 1949). Fall- and winter-laid eggs may account for 50% of the spring larval 
populations (Evans, 1959), while the remainder of the larvae hatch from spring-laid eggs. 
The importance of temperature as a mortality factor of overwintering eggs has been 
discussed by several workers (Drea, 1969; Hsieh and Armbrust, 1974; Miller and Shaw, 
1967; Niemczyk and Flessel, 1970; Roberts et al., 1970; and Streams and Fuester, 1966), 
most of whom based their observations on field sampling data. 
Armbrust et al. (1969) found the supercooling point of exposed eggs to be as low as 
25 .2"C and Morrison and Pass (1974) tested the survival of eggs of various ages at  a 
wide range of temperatures and constant exposure times. These researchers provided 
temperature mortality thresholds, but did not consider the effect of repeated exposures 
to  low temperatures interspersed with sublethal temperatures, conditions which often 
occur naturally. This study was undertaken to study the effect of repeated low 
temperature exposures on alfalfa weevil egg mortality and to provide parameter values for 
simulation and predictive models of alfalfa weevil biology. 
METHODS AND MATERIALS 
Eggs used in this study were obtained from fall-collected adults from Washington 
County, Illinois. Adults were stored at a constant 4 + 2°C until needed for oviposition, at 
which time they were held at 15 t 3OC, 30 + 5% relative humidity with bouquets (10 
stems) of fresh greenhouse alfalfa. Eggs were extracted from stems daily using a 
modification of the blender method developed by Pass and Van Meter (1966). For 
temperature testing, eggs were placed on filter paper in inverted glass petri dishes with a 
thin plaster of paris layer on the bottom. The plaster was saturated with a ,001 aqueous 
solution of benzalkonium chloride for mold inhibition. The inside edge of the dish was 
ringed with cotton dental wicks. Both cotton wicks and filter paper were saturated with 
the benzalkonium chloride solution to inhibit mold during incubation. When the 
l ~ h i s  publication was supported by the Illinois Natural History Survey, the Illinois 
Agricultural Experiment Station, National Science Foundation, and the United States 
Environmental Protection Agency, through a grant (NSF GB-34718) to the University of 
California. The findings, opinions and recommendations expressed herein are those of the 
authors and not necessarily those of the University of California, the National Science 
Foundation or the Environmental Protection Agency. 
2~esea rch  Assistant, and Associate Entomologist and Associate Professor respectively, 
at Illinois Natural History Survey and Illinois Agricultural Experiment Station, Urbana, 
Illinois 6 180 1. 
1
Crain and Armbrust: The Effect of Repeated Low Temperature on Eggs of the Alfalfa Wee
P blished by ValpoScholar, 1978
64 THE GREAT LAKES ENTOMOLOGIST VoL 11, No. 1 
incubation dishes were tested for possible insulative properties, it was found that the 
interior of the dish required 5.3 minutes to cool from 22.S°C to 2.0°C and 22.6 minutes 
to reach the chamber temperature of 0°C. When the environmental chamber was set at 
-20°C, the dish required 5.1 minutes to cool to -lS°C and 27.0 minutes to cool to 
-20°C. Thus any influence of the incubation dish on cooling data was considered 
inconsequential to the data. 
To determine the effect of repeated exposure to low temperature, 50 eKes at three 
stages of deveIopment (fresh, 3-, and 5-day old) were exposed to each test temperature of 
-15 and -20°C for either 1, 2 ,  3, 4 and 5 repetitive 6 hour periods. The test 
temperatures of -15 and -20°C were selected in light of the mortality th~esholds 
obtained by Morrison and Pass (1974). Eggs were stored at 4 + 2'C for 18 hours between 
each exposure. 
RESULTS AND DISCUSSION 
The percent hatch of three ages of alfalfa weevil eggs after repeated exposures to -15 
and -20°C is presented in Table 1 and a regression analysis is illustrated in Figure 1. At 
-lS°C, fresh eggs showed a marked drop in hatch with time; the time required to kill 
50% of the population (LT50) was 1.2 days. Eggs that had been aged for 3 and 5 days 
were relatively resistant to -lS°C. Eggs of all ages showed a steady decrease in hatch at 
-20°C although aged eggs withstood lodger exposures, as evidenced by the LT50 values 
of 2.1, 2.7, and 4.0 days for fresh, 3- and 5day-old eggs, respectively. Regression 
formuIae and correlation coefficients for Figure 1 are presented in Table 2. With the 
exception of the equations for fresh and 3-day-old eggs exposed to  -20°C, none of the r 
40 I 0-0 = FRESH -15Oc\\ *-a = FRESH - 2 0 ' ~  
-= 3-DAYS OLD - 2 0 ' ~  
---- - 5-DAYS OLD -15 '~  \ 
lo i = 5-DAYS OLD -20 '~  
(DAYS = COLD DEGREE DAYS FOR -20°C EGGS ONLY) 
Fig. 1. Percent hatch of alfalfa weevil eggs of various ages exposed to  -15 and - 2 0 " ~ .  
2
The Great Lakes Entomologist, Vol. 11, No. 1 [1978], Art. 8
https://scholar.valpo.edu/tgle/vol11/iss1/8
1978 THE GREAT LAKES ENTOMOLOGIST 65 
values were significant at the .05 level. For this reason, the data for exposures showing 
no decrease in hatch with time (3- and 5-day at -15OC) were lumped as were those 
exposures showing a decrease in hatch (15°C fresh eggs and all ages at -20°C). The 
resulting formulae are found at the bottom of Table 2 and the regression lines in Figure 
2. After lumping, the 3- and 5day-old eggs showed no significant correlation at -15OC as 
---- 
--- 
- 
- 
- 
- 
- 
--- 
- 
= - 1 5 ' ~  FRESH AND - 2 0 ' ~  FRESH, 
1 3 -  AND 5 -  DAY-OLD EGGS 
(DAYS = C O D  DEGREE DAYS FOR -20°C EGGS ONLY) 
Fig. 2. Percent hatch of 3- and 5-day old alfalfa weevil eggs exposed to  - 1 5 ' ~  and fresh 
and 3- and 5-day old eggs exposed to -20°c. 
Table 1. Percent hatch of three different ages of alfalfa weevil eggs after repeated exposure 
to -15 and -20°C. 
Age of eggs (days) and exposure temperature ("C) 
Number of 0-1 3 5 
repeated exposuresa -15 -20 -15 -20 -15 -20 
aOne exposure consisted of 6 hours at -15 or -20' and the remaining 18 hours at 4 + 2 ' ~ .  
3
Crain and Armbrust: The Effect of Repeated Low Temperature on Eggs of the Alfalfa Wee
Published by ValpoScholar, 1978
66 THE GREAT LAKES ENTOMOLOGIST Vol. 11, No. 1 
Table 2. Alfalfa weevil egg mortality regression equations. 
Temperature (OC) Age (days) Equation 
Fresh y = .5776 - , 0 4 9 7 ~  -.3613 
3 y = .8332 - .0001x -.4245 
5 y = .8021 - .0132x -.5793 
Fresh y = .8964 - , 1 8 9 5 ~  -.9280a 
3 y = .8543 - .1297x -.7633a 
5 y = .7139 - , 0 5 2 9 ~  -.6306 
-15' Fresh 
-2Oc Fresh, 3 & 5 y =  .7610 - .1174x -.6861a 
aSignificant at .05 level. 
!'combined mortality values for 3- and 5-day-old eggs at -15 '~ .  
CCombined mortality values for fresh at -15O~ with fresh 3- and 5-day-old eggs a t  - 2 0 " ~ .  
would be expected with such a low slope value. All the remaining values combined 
showed significant correlation at .05 and an LT50 of 2.2 days. If this LT50 value is 
converted into hours of constant exposure it becomes 13.2 hours. Treating data presented 
by Morrison and Pass (1974) in a similar manner resulted in an LT50 of 12.8 hours for 
eggs of comparable age exposed to -15 and -20°C for constant pcriods. This LT50 was 
97% of the value obtained in the repeat exposure study. 
The results of the present study are quite comparable with those of Monison and Pass 
(1974) and it appears that the effect of low temperature on alfalfa weevil egg mortality is 
an additive phenomenon; i.c., the effect of cold on egg mortality with time is 
independent of any temporal interruption during the low temperature exposure. This 
finding suggests that if the rate of accumulation of low temperatures in nature could be 
determined, laboratory studies involving constant temperature exposures could be de- 
signed to simulate natural conditions more efficiently. 
LITERATURE CITED 
Armbrust, E. J., C. E. White and J. R. DeWitt. 1969. Lethal h i t s  of lour temperatures 
for the alfalfa weevil in Illinois. J. Econ. Entomol. 62:464-7. 
Drea, J .  J.  1969. Fecundity, hatch of eggs and duration of oviposition of mated, isolated, 
female alfalfa weevils. J. Econ. Entomol. 62 : 1523-4. 
Evans, W. G. 1959. The biology and control of the alfalfa weevil in Virginia. Va. Agric. 
Exp. Sta. Bull. 502. 
Hamlin, J.  C., F. V. Lieberman, R. W. Bunn, W. C. McDuffie, R. C. Newton and L. J. 
Jones. 1949. Field studies of the alfalfa weevil and its environment. USDA Teach. 
Bull. 975. 
Hsieh, H. F. and E. J. Ammbrust. 1974. Temperature limits of alfalfa weevil oviposition 
and egg density in Illinois. J. Econ. Entomol. 67:203-6. 
Miller, M. C. and F. R. Shaw. 1967. Overwintering of alfalfa weevil eggs in Massachusetts. 
Co-op Econ. Ins. Rep. 17:168-70. 
Morrison, W. P. and B. C. Pass. 1974. The effect of subthreshold temperatures on eggs of 
the alfalfa weevil. Environ. Entomol. 3: 35 3-5. 
Niemczyk, H. D. and J .  K. Flessel. 1970. Population dynamics of alfalfa weevil eggs in 
Ohio. J. Econ. Entomol. 63:242-7. 
Pass, B. C. and C. L. Van Meter. 1966. A method for extracting eggs of the alfalfa 
weevil from stems of alfalfa. J .  Econ. Entomol. 59:1294. 
Roberts, S. J., J. R. DeWitt and E. J. Arrnbrust. 1970. Predicting spring hatch of the 
alfalfa weevil. J. Econ. Entomol. 63:92103. 
Streams, F. A. and R. W. Fuester. 1966. Patasson luna in overwintering eggs of the alfalfa 
weevil. J. Econ. Entomol. 59:331-3. 
4
The Great Lakes Entomologist, Vol. 11, No. 1 [1978], Art. 8
https://scholar.valpo.edu/tgle/vol11/iss1/8


The Effect of Repeated Low Temperature on Eggs of the Alfalfa Weevil (Coleoptera: Curculionidae)

Valparaiso University

The Great Lakes Entomologist Volume 11 Number 1 - Spring 1978 Number 1 - Spring 1978 Article 8 April 1978 The Effect of Repeated Low Temperature on Eggs of the Alfalfa Weevil (Coleoptera: Curculionidae) L. J. Crain Illinois Natural History Survey and Illinois Agricultural Experiment Station E. J. Armbrust Illinois Natural History Survey and Illinois Agricultural Experiment Station Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Crain, L. J. and Armbrust, E. J. 1978. "The Effect of Repeated Low Temperature on Eggs of the Alfalfa Weevil (Coleoptera: Curculionidae)," The Great Lakes Entomologist, vol 11 (1) Available at: https://scholar.valpo.edu/tgle/vol11/iss1/8 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 ENTOMOLOGlST THE EFFECT OF REPEATED LOW TEMPERATURE ON EGGS OF THE ALFALFA WEEVIL (COLEOPTERA: CURCULIONIDAE)~ L. J. Crain and E. J. Armbrust2 ABSTRACT Three ages of alfalfa weevil, Hypera postica (Gyllenhal) eggs were exposed to repeated exposures of -15 and -20°C. Fresh-laid eggs were quite susceptible and 3- and 5 d a y  old eggs were relatively resistant to  -15'C, but all ages of eggs showed considerable susceptibility to -20°C, with an average LT50 of 2.2 days. Comparison of this data with similar studies utilizing constant low temperature exposures showed the effect to be independent of temporal interruptions. The alfalfa weevil, Hypera postica (Gyllenhal), is the principal pest of alfalfa in the United States. In many areas, once adults reach sexual maturity in the fall, they have the capability to oviposit throughout the winter whenever temperatures reach ca. 10°C (Hamlin et al., 1949). Fall- and winter-laid eggs may account for 50% of the spring larval populations (Evans, 1959), while the remainder of the larvae hatch from spring-laid eggs. The importance of temperature as a mortality factor of overwintering eggs has been discussed by several workers (Drea, 1969; Hsieh and Armbrust, 1974; Miller and Shaw, 1967; Niemczyk and Flessel, 1970; Roberts et al., 1970; and Streams and Fuester, 1966), most of whom based their observations on field sampling data. Armbrust et al. (1969) found the supercooling point of exposed eggs to be as low as 25 .2"C and Morrison and Pass (1974) tested the survival of eggs of various ages at  a wide range of temperatures and constant exposure times. These researchers provided temperature mortality thresholds, but did not consider the effect of repeated exposures to  low temperatures interspersed with sublethal temperatures, conditions which often occur naturally. This study was undertaken to study the effect of repeated low temperature exposures on alfalfa weevil egg mortality and to provide parameter values for simulation and predictive models of alfalfa weevil biology. METHODS AND MATERIALS Eggs used in this study were obtained from fall-collected adults from Washington County, Illinois. Adults were stored at a constant 4 + 2°C until needed for oviposition, at which time they were held at 15 t 3OC, 30 + 5% relative humidity with bouquets (10 stems) of fresh greenhouse alfalfa. Eggs were extracted from stems daily using a modification of the blender method developed by Pass and Van Meter (1966). For temperature testing, eggs were placed on filter paper in inverted glass petri dishes with a thin plaster of paris layer on the bottom. The plaster was saturated with a ,001 aqueous solution of benzalkonium chloride for mold inhibition. The inside edge of the dish was ringed with cotton dental wicks. Both cotton wicks and filter paper were saturated with the benzalkonium chloride solution to inhibit mold during incubation. When the l ~ h i s  publication was supported by the Illinois Natural History Survey, the Illinois Agricultural Experiment Station, National Science Foundation, and the United States Environmental Protection Agency, through a grant (NSF GB-34718) to the University of California. The findings, opinions and recommendations expressed herein are those of the authors and not necessarily those of the University of California, the National Science Foundation or the Environmental Protection Agency. 2~esea rch  Assistant, and Associate Entomologist and Associate Professor respectively, at Illinois Natural History Survey and Illinois Agricultural Experiment Station, Urbana, Illinois 6 180 1. 1Crain and Armbrust: The Effect of Repeated Low Temperature on Eggs of the Alfalfa WeeP blished by ValpoScholar, 197864 THE GREAT LAKES ENTOMOLOGIST VoL 11, No. 1 incubation dishes were tested for possible insulative properties, it was found that the interior of the dish required 5.3 minutes to cool from 22.S°C to 2.0°C and 22.6 minutes to reach the chamber temperature of 0°C. When the environmental chamber was set at -20°C, the dish required 5.1 minutes to cool to -lS°C and 27.0 minutes to cool to -20°C. Thus any influence of the incubation dish on cooling data was considered inconsequential to the data. To determine the effect of repeated exposure to low temperature, 50 eKes at three stages of deveIopment (fresh, 3-, and 5-day old) were exposed to each test temperature of -15 and -20°C for either 1, 2 ,  3, 4 and 5 repetitive 6 hour periods. The test temperatures of -15 and -20°C were selected in light of the mortality th~esholds obtained by Morrison and Pass (1974). Eggs were stored at 4 + 2'C for 18 hours between each exposure. RESULTS AND DISCUSSION The percent hatch of three ages of alfalfa weevil eggs after repeated exposures to -15 and -20°C is presented in Table 1 and a regression analysis is illustrated in Figure 1. At -lS°C, fresh eggs showed a marked drop in hatch with time; the time required to kill 50% of the population (LT50) was 1.2 days. Eggs that had been aged for 3 and 5 days were relatively resistant to -lS°C. Eggs of all ages showed a steady decrease in hatch at -20°C although aged eggs withstood lodger exposures, as evidenced by the LT50 values of 2.1, 2.7, and 4.0 days for fresh, 3- and 5day-old eggs, respectively. Regression formuIae and correlation coefficients for Figure 1 are presented in Table 2. With the exception of the equations for fresh and 3-day-old eggs exposed to  -20°C, none of the r 40 I 0-0 = FRESH -15Oc\\ *-a = FRESH - 2 0 ' ~  -= 3-DAYS OLD - 2 0 ' ~  ---- - 5-DAYS OLD -15 '~  \ lo i = 5-DAYS OLD -20 '~  (DAYS = COLD DEGREE DAYS FOR -20°C EGGS ONLY) Fig. 1. Percent hatch of alfalfa weevil eggs of various ages exposed to  -15 and - 2 0 " ~ .  2The Great Lakes Entomologist, Vol. 11, No. 1 [1978], Art. 8https://scholar.valpo.edu/tgle/vol11/iss1/81978 THE GREAT LAKES ENTOMOLOGIST 65 values were significant at the .05 level. For this reason, the data for exposures showing no decrease in hatch with time (3- and 5-day at -15OC) were lumped as were those exposures showing a decrease in hatch (15°C fresh eggs and all ages at -20°C). The resulting formulae are found at the bottom of Table 2 and the regression lines in Figure 2. After lumping, the 3- and 5day-old eggs showed no significant correlation at -15OC as ---- --- - - - - - --- - = - 1 5 ' ~  FRESH AND - 2 0 ' ~  FRESH, 1 3 -  AND 5 -  DAY-OLD EGGS (DAYS = C O D  DEGREE DAYS FOR -20°C EGGS ONLY) Fig. 2. Percent hatch of 3- and 5-day old alfalfa weevil eggs exposed to  - 1 5 ' ~  and fresh and 3- and 5-day old eggs exposed to -20°c. Table 1. Percent hatch of three different ages of alfalfa weevil eggs after repeated exposure to -15 and -20°C. Age of eggs (days) and exposure temperature ("C) Number of 0-1 3 5 repeated exposuresa -15 -20 -15 -20 -15 -20 aOne exposure consisted of 6 hours at -15 or -20' and the remaining 18 hours at 4 + 2 ' ~ .  3Crain and Armbrust: The Effect of Repeated Low Temperature on Eggs of the Alfalfa WeePublished by ValpoScholar, 197866 THE GREAT LAKES ENTOMOLOGIST Vol. 11, No. 1 Table 2. Alfalfa weevil egg mortality regression equations. Temperature (OC) Age (days) Equation Fresh y = .5776 - , 0 4 9 7 ~  -.3613 3 y = .8332 - .0001x -.4245 5 y = .8021 - .0132x -.5793 Fresh y = .8964 - , 1 8 9 5 ~  -.9280a 3 y = .8543 - .1297x -.7633a 5 y = .7139 - , 0 5 2 9 ~  -.6306 -15' Fresh -2Oc Fresh, 3 & 5 y =  .7610 - .1174x -.6861a aSignificant at .05 level. !'combined mortality values for 3- and 5-day-old eggs at -15 '~ .  CCombined mortality values for fresh at -15O~ with fresh 3- and 5-day-old eggs a t  - 2 0 " ~ .  would be expected with such a low slope value. All the remaining values combined showed significant correlation at .05 and an LT50 of 2.2 days. If this LT50 value is converted into hours of constant exposure it becomes 13.2 hours. Treating data presented by Morrison and Pass (1974) in a similar manner resulted in an LT50 of 12.8 hours for eggs of comparable age exposed to -15 and -20°C for constant pcriods. This LT50 was 97% of the value obtained in the repeat exposure study. The results of the present study are quite comparable with those of Monison and Pass (1974) and it appears that the effect of low temperature on alfalfa weevil egg mortality is an additive phenomenon; i.c., the effect of cold on egg mortality with time is independent of any temporal interruption during the low temperature exposure. This finding suggests that if the rate of accumulation of low temperatures in nature could be determined, laboratory studies involving constant temperature exposures could be de- signed to simulate natural conditions more efficiently. LITERATURE CITED Armbrust, E. J., C. E. White and J. R. DeWitt. 1969. Lethal h i t s  of lour temperatures for the alfalfa weevil in Illinois. J. Econ. Entomol. 62:464-7. Drea, J .  J.  1969. Fecundity, hatch of eggs and duration of oviposition of mated, isolated, female alfalfa weevils. J. Econ. Entomol. 62 : 1523-4. Evans, W. G. 1959. The biology and control of the alfalfa weevil in Virginia. Va. Agric. Exp. Sta. Bull. 502. Hamlin, J.  C., F. V. Lieberman, R. W. Bunn, W. C. McDuffie, R. C. Newton and L. J. Jones. 1949. Field studies of the alfalfa weevil and its environment. USDA Teach. Bull. 975. Hsieh, H. F. and E. J. Ammbrust. 1974. Temperature limits of alfalfa weevil oviposition and egg density in Illinois. J. Econ. Entomol. 67:203-6. Miller, M. C. and F. R. Shaw. 1967. Overwintering of alfalfa weevil eggs in Massachusetts. Co-op Econ. Ins. Rep. 17:168-70. Morrison, W. P. and B. C. Pass. 1974. The effect of subthreshold temperatures on eggs of the alfalfa weevil. Environ. Entomol. 3: 35 3-5. Niemczyk, H. D. and J .  K. Flessel. 1970. Population dynamics of alfalfa weevil eggs in Ohio. J. Econ. Entomol. 63:242-7. Pass, B. C. and C. L. Van Meter. 1966. A method for extracting eggs of the alfalfa weevil from stems of alfalfa. J .  Econ. Entomol. 59:1294. Roberts, S. J., J. R. DeWitt and E. J. Arrnbrust. 1970. Predicting spring hatch of the alfalfa weevil. J. Econ. Entomol. 63:92103. Streams, F. A. and R. W. Fuester. 1966. Patasson luna in overwintering eggs of the alfalfa weevil. J. Econ. Entomol. 59:331-3. 4The Great Lakes Entomologist, Vol. 11, No. 1 [1978], Art. 8https://scholar.valpo.edu/tgle/vol11/iss1/8

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The Effect of Repeated Low Temperature on Eggs of the Alfalfa Weevil (Coleoptera: Curculionidae)

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