M. A. Carrillo

University of Minnesota Morris, Saint Paul, Minnesota, United States

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Publications (18)17.49 Total impact

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    ABSTRACT: Supercooling points (SCP) of adult Diamesa mendotae Muttkowski, 1915 (Diptera: Chironomidae) were determined at 3, 5, 9, 12 and 17 days post-collection. Supercooling points were recorded using surface contact thermometry and a cooling rate of ca. 1°C min−1. Female SCPs averaged −22.81, −23.76, −23.85, −23.65, and −20.87°C on each date post-collection and did not differ significantly. Male SCPs were statistically similar and averaged −21.75, −23.53, −23.68, −23.66, and −22.92°C on each date post-collection. Paired comparisons of female/male SCPs on each date post-collection did not show significant differences over time. The overall mean SCP of D. mendotae (−23.05°C) is substantially lower than values of −5.3°C and −5.7°C published for adults and larvae of Belgica antarctica Jacobs 1900 collected at Palmer Station (Antarctica) and −14.2°C for larvae of Paraclunio alaskensis Coquillett 1900 collected at Vancouver Island, British Columbia. In addition, the SCP of this species appears to be lower than that of other winter-active insect species reported in the literature. Although no adults survived after the SCP was recorded, further studies are necessary to determine if D. mendotae is a freeze-intolerant insect. Nevertheless, our results suggest that a low SCP could be used as a mechanism to facilitate emergence and adult activity of this species during winter conditions.
    Aquatic Insects 02/2010; September–December 2004(3-4-Vol. 26):243-251. DOI:10.1080/0165-0420400000320 · 0.43 Impact Factor
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    ABSTRACT: Integrated pest management (IPM) programs for the bean leaf beetle, Cerotoma trifurcata (Förster), could benefit from an ability to forecast the magnitude and timing of early-season infestations. The objectives of this study were to examine the supercooling point (SCP) of adult C. trifurcata as an index of its cold hardiness, monitor overwintering survival, and revise an existing model used to predict the overwintering survival of this pest in wooded areas as a function of low-temperature accumulation. Within a year, the mean SCP of C. trifurcata ranged from −8.9 to −6.0°C. Soil temperatures dropped below the lowest mean SCP (i.e., −8.9°C) in only 2 of 11 yr (1994–2004). In-field survivorship studies showed that adult C. trifurcata successfully overwintered in Minnesota (34–59% survival). This species survived well in years when the existing model predicted zero or low survival. In contrast, our revised model predicted more closely the overwintering survival of this species in southern Minnesota. However, other overwintering mortality factors should be studied to improve our understanding of how well C. trifurcata overwinters in temperate regions.
    Environmental Entomology 10/2009; 34(Dec 2005):1395-1401. DOI:10.1603/0046-225X-34.6.1395 · 1.42 Impact Factor
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    ABSTRACT: A model for predicting mortality of Indianmeal moth larvae [Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)] under fluctuating low-temperature conditions was developed. The time and temperature combinations required to achieve 100% mortality of field-collected, cold-acclimated P. interpunctella larvae obtained from laboratory mortality experiments were used to develop the mortality model. Accumulation of mortality rate over time was called the cumulative lethality index (CLI). Complete mortality of insect populations would occur when CLI equals 1. Observed mortality of field-collected, cold-acclimated P. interpunctella larvae in five 76.2-T (3,000-bu) shelled corn bins located in Rosemount, MN, during the winters of 2003-2004 and 2004-2005 were used to validate the CLI model (i.e., mortality model). Excellent agreement between predicted and measured time to 100% larval mortality was observed. The CLI model would be useful for developing low-temperature aeration management strategies for controlling overwintering P. interpunctella in grain bins. In addition, this model will be useful when determining if additional control measures will be required as a result of above-seasonal ambient temperatures.
    Environmental Entomology 01/2008; 36(6):1318-27. DOI:10.1603/0046-225X(2007)36[1318:MOIMLP]2.0.CO;2 · 1.42 Impact Factor
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    ABSTRACT: Aeration management strategies were developed to control cold-acclimated and diapausing Indianmeal moth, Plodia interpunctella (Hübner), larvae in grain bins during winter in north- and east-central regions of the US. The application in this study focuses on corn because it is the dominant crop in these regions, but we believe that the analyses can be applied to other grains as well. Contour maps for hours below −10 °C for the months of December, January, and February were developed to help effective planning and management of aeration to control overwintering stored-grain insects. Two cumulative lethality index (CLI) models were developed to estimate mortality of laboratory-reared (diapausing without cold-acclimation) and field-collected (cold-acclimated, and diapausing with cold-acclimation) P. interpunctella larvae under changing temperature conditions. The CLI models were used for evaluating aeration management strategies. Simulation studies were conducted using 30 years of weather data for 12 locations in north- and east-central regions of the US to evaluate different aeration management strategies for controlling P. interpunctella larvae. For each strategy, temperatures of headspace air and grain in the top meter of the grain mass were simulated using an existing model for the period of December–February. The tested management strategies included no aeration, continuous aeration, and intermittent aeration by controlling fan operation. During aeration, air was pulled from the headspace downward through the grain with an airflow rate of 0.11 m3/min-t (0.1 cfm/bu). Simulation results indicated that a fan control strategy that turned the aeration fan on when the grain temperature at 0.4-m depth was greater than the headspace-air temperature was the best strategy for managing P. interpunctella larvae in all tested locations. For this strategy, the CLI model indicated that 100% mortality of P. interpunctella larvae could be achieved at a grain depth of 0.4 m from the top grain surface in all locations. For this strategy, the aeration fan operated about 10% of the time from December to February. The average cost of electrical energy required for aeration fan operation with this strategy for all locations was 1.3 ¢/t (0.033 ¢/bu) based on an electrical energy cost of 7 ¢/kWh.
    Journal of Stored Products Research 01/2007; 43(2):177-192. DOI:10.1016/j.jspr.2006.04.004 · 1.49 Impact Factor
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    ABSTRACT: The winter-active Diamesa mendotae Muttkowski (Diptera: Chironomidae) is freeze intolerant in the adult stage with a low mean supercooling point (SCP) of ~−20°C. However, cold-hardiness strategies for immatures of this species are unknown. In this study, we measured SCP values for D. mendotae larvae, pupae and adults using surface-contact thermometry. In addition, the lower lethal temperature (LLT) was determined for the larval stage. The mean SCPs for larvae (−7.4°C) and pupae (−9.1°C) were relatively high compared to adults (−19.7°C). Our results indicate that the larvae of D. mendotae are freeze tolerant with a LLT99 (−25.4°C), ~−10°C lower than their minimum SCP (−15.6°C). Freeze tolerance in these larvae may be a strategy to provide protection from short-term exposures to ice crystals or to permit diapause within frozen substrates. The change in cold-hardiness strategy from freeze tolerant to freeze intolerant between the larval and adult stages of this species is likely a result of the different habitats occupied by these two life stages.
    Hydrobiologia 09/2006; 568(1):403-416. DOI:10.1007/s10750-006-0200-6 · 2.21 Impact Factor
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    ABSTRACT: Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae), has been classified as one of the most cold-tolerant pests of stored grain. In this study, the supercooling point (SCP) of field-collected, cold-acclimated fifth instars was determined as an index of cold hardiness. In addition, mortality of laboratory-reared and field-collected, cold-acclimated fifth instars exposed to -10 degrees C was measured to understand the ability of P. interpunctella to survive winter conditions. Finally, the overwintering mortality of this species in southern Minnesota was measured in grain bins filled with shelled corn. The SCP of field-collected, cold-acclimated fifth instars was approximately -24 degrees C before their release in grain bins. Mortality of laboratory-reared fifth instars exposed to -10 degrees C reached 100% after only 12 h, whereas the same percentage was achieved after 312 h for field-collected, cold-acclimated individuals. Overwintering mortality of P. interpunctella under field conditions reached 100% in all locations inside the grain bins; however, depth within the grain mass, location inside the grain bin, and the duration of exposure to outdoor conditions significantly affected the rate of mortality. A mathematical model for the overwintering mortality of P. interpunctella is proposed as a first step to forecast early season infestations under field conditions.
    Environmental Entomology 08/2006; 35(4):843-855. DOI:10.1603/0046-225X-35.4.843 · 1.42 Impact Factor
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    ABSTRACT: A model for predicting mortality of Indianmeal moth larvae [Plodia interpunctella (Hübner)] under changing low-temperature conditions was developed. The time and temperature combinations required to achieve 100% mortality of field-collected, cold-acclimated P. interpunctella larvae obtained from laboratory mortality experiments were used to develop the mortality model. Accumulation of mortality rate over time was called the Cumulative Lethality Index (CLI). Complete mortality of insect population would occur when CLI equals one. Measured mortalities of fieldcollected, cold-acclimated P. interpunctella larvae in a total of five 76.2-t (3,000 bu) shelled corn bins located in Rosemount, Minnesota during the winters of 2003-2004 and 2004-2005 were used to validate the mortality model (i.e., CLI model). Excellent agreement between predicted and measured time to 100% larval mortality was observed. The CLI model would be useful for developing lowtemperature aeration management strategies for controlling overwintering P. interpunctella in grain bins.
    2006 Portland, Oregon, July 9-12, 2006; 01/2006
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    ABSTRACT: The ectoparasitoid Habrobracon hebetor (Say) attacks stored-product infesting pyralid moths that are able to overwinter under extremely cold conditions. The extent to which H. hebetor can withstand these conditions is not known, but has important implications for the ability of H. hebetor to provide long-term suppression of these pests in temperate climates. We investigated basic cold hardiness aspects of a mutant eye-color strain of H. hebetor. Feeding larvae and adults of H. hebetor had supercooling points (SCPs) at temperatures higher than those of eggs and pupae. Mean SCPs of females and males were equivalent, as were those of naked and silk-encased pupae. Feeding on honey prior to being subjected to low temperatures significantly increased the SCP of adult females by approximately 8 degrees C. Mortality of pupae and adults increased significantly whenever the temperature dropped below the mean SCP, indicating that H. hebetor does not tolerate freezing. For pupae and adults exposed to -12 and -5 degrees C, the hourly mortality rate increased with time of exposure. Pupae and adults exposed to -12 degrees C for different time intervals showed high mortality after only 1d of exposure. At -5 degrees C, none survived 12d of exposure. A better understanding of how well this parasitoid tolerates low temperatures will be useful in evaluating its potential as a biological control agent of stored-product moths in temperate regions.
    Journal of Insect Physiology 08/2005; 51(7):759-68. DOI:10.1016/j.jinsphys.2005.03.006 · 2.50 Impact Factor
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    ABSTRACT: Indianmeal moth, Plodia interpunctella (Hübner), is classified as a freeze-intolerant organism and one of the most cold-tolerant stored-product pests. The objective of this study was to determine the relationship between mortality at low temperatures after minimum exposure and the supercooling point (SCP) for laboratory-reared P. interpunctella at different stages of development. This relationship also was analyzed for field-collected, cold-acclimated fifth instars. Mean SCP of laboratory-reared larvae (i.e., feeding stage) was consistently above approximately -16 degrees C. Mean SCP of laboratory-reared pupae and adults (i.e., nonfeeding stages) and field-collected, cold-acclimated fifth instars was consistently below approximately -21 degrees CP seemed to be the boundary between survival and death for larvae. However, it seemed that a 1-min exposure was not sufficient to cause larval mortality at the SCP. Alternatively, for both pupae and adults, the SCP seemed not to play an important role in their survival at low temperatures, with significant mortality observed at temperatures higher than the mean SCP. Adults were the most susceptible to low temperatures with no survival occurring at -20 degrees C, > 3 degrees C above its mean SCP. Results of this investigation demonstrate that P. interpunctella has a different response to low temperatures depending on stage of development and cold acclimation. Classifying P. interpunctella only as a freeze-intolerant organism disregards the occurrence of prefreeze mortality in this species. Therefore, a reclassification of this species (e.g., chill tolerant or chill susceptible) based on the extent of prefreeze mortality and the temperature and time of exposure at which it occurs is suggested.
    Journal of Economic Entomology 05/2005; 98(2):618-25. DOI:10.1603/0022-0493-98.2.618 · 1.61 Impact Factor
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    ABSTRACT: The soybean aphid, Aphis glycines Matsumura, has a heteroecious, holocyclic life cycle. Soybean aphids overwinter as eggs, hatch in the spring, reproduce asexually, and undergo three or more generations on buckthorn, Rhamnus spp., before migrating to a secondary host such as soybean, Glycine max (L.) Merr. The ability of different soybean aphid life stages to survive low temperatures potentially experienced during fall or winter is not known. The objectives of this study were to determine the supercooling point (SCP) of various soybean aphid life stages and to determine the annual probability that winter temperatures within the North Central region of the United States would equal or fall below the mean SCP of soybean aphid eggs. Aphid eggs are considered the most cold-hardy stage; therefore, their SCP can be used as a conservative estimate for aphid overwintering mortality. In our study, eggs had the lowest mean SCP (approximately −34°C) among all life stages, whereas gynoparae and oviparae had the highest mean SCPs (approximately −15°C). During the winter, extreme low air temperatures are likely to reach or exceed the mean SCP of soybean aphid eggs in portions of northern Minnesota, northern Wisconsin, and the upper peninsula of Michigan. Thus, widespread successful overwintering in the northern United States and southern Canada is less likely than in Illinois, Indiana, Ohio, Iowa, southern Minnesota, southern Wisconsin, and the lower peninsula of Michigan.
    Environmental Entomology 03/2005; 34(2):235-240. DOI:10.1603/0046-225X-34.2.235 · 1.42 Impact Factor
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    ABSTRACT: Survivability of Indianmeal moth, Plodia interpunctella (Hübner), larvae fed a standard laboratory diet, whole corn with 0% broken kernels, whole corn with 5 to 7% broken kernels, and 100% broken corn kernels were assessed in our laboratory at 28oC, 65% RH, and 14 h light :10 h dark photoperiod cycle. A conventional low-oil yellow dent corn (about 3.9% oil content) and a highoil corn hybrid (about 7.7% oil content) were tested. Survivability was measured as the percentage emergence of pre-pupae, pupae, and adults at the end of the rearing period. For the standard laboratory diet, a mean ± SD of 97.5% ± 2.9 larvae survived. The mean ± SD percentages of larval survival for the conventional low-oil yellow dent corn were 6.7 ± 2.9, 63.8 ± 4.8, and 80.0 ± 14.7 for 0, 7, and 100% broken kernels, respectively. The mean ± SD percentages of larval survival for the highoil corn hybrid were 28.3 ± 12.6, 81.3 ± 4.8, and 100.0 ± 0.0 for 0, 5, and 100% broken kernels, respectively. Larval growth rate for high-oil corn was faster than for low-oil corn. Results indicate that cleaning corn before storage could reduce Indianmeal moth problems. Also, Indianmeal moth problems in high-oil corn varieties might be slightly greater than in corn varieties with normal oil levels.
    2005 Tampa, FL July 17-20, 2005; 01/2005
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    ABSTRACT: The striped cucumber beetle, Acalymma vittatum (Fabricius) (Coleoptera: Chrysomelidae), is an important pest of cucurbit crops. However, the overwinter-ing capacity of this pest in temperate regions is poorly understood. In this study, the in-field survival of A. vittatum was examined during three consecutive winters. In addition, the supercooling points of A. vittatum were determined as an index of cold hardiness for adults. During each winter, the survival of adults decreased significantly through time, with no individuals surviving until spring. By compar-ing the supercooling points and in-field survival of adults to soil temperatures, it appears that winter temperatures in Minnesota are cold enough to induce freez-ing of the beetles. Moreover, a considerable amount of mortality occurred before minimum monthly soil temperatures dropped below the supercooling point of overwintering individuals, suggesting the occurrence of prefreeze mortality. An improved understanding of the response of A. vittatum to winter temperatures in temperate regions may aid in early season management of this pest.
    Great Lakes Entomologist 01/2005;
  • M. A. Carrillo, C. A. Cannon
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    ABSTRACT: Factors affecting the supercooling point (SCP) of the Indian meal moth, Plodia interpunctella (Hübner), were investigated under various conditions. The effects of geographic origin, time under laboratory conditions, laboratory diet, stage of development, age within stage, and season on P. interpunctella SCP were examined. Overall, SCPs ranged from −28.6 to −2.4°C. At the times of collection, differences in SCP between field-collected individuals and individuals from laboratory sources were negligible. The minimum observed SCP for most of the cultures tested soon after collection was below −20°C. After 7 months under laboratory conditions, the mean SCP of field-collected and laboratory-reared cultures remained unchanged. No particular trend in SCP was observed when comparing cultures from northern and southern regions. Differences in laboratory diets did not affect mean SCP. Mean SCP for 1- and 4-d-old eggs was similar. Eggs (−24.4°C), first instars (−23.5°C), pupae (−22.2°C), and adults (−22.4°C) had lower mean SCPs than later instar larvae (−14.4 to −11.6°C). When confined in the laboratory for 8 months under conditions which were not controlled, monthly mean SCP for the same culture varied by as much as 5.7°C. Plodia interpunctella appeared to regulate its SCP as the season changed, with a relatively high mean SCP during summer and a marked decline of more than 10°C in fall. The SCPs obtained in this study suggest that very low temperatures may be needed for disinfestation of P. interpunctella at all stages of development.
    Journal of Stored Products Research 01/2005; 41(5):556-564. DOI:10.1016/j.jspr.2004.10.002 · 1.49 Impact Factor
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    ABSTRACT: A classical biological control agent, Harmonia axyridis (Pallas), is having both beneficial and detrimental impacts in North America. The objective of this study was to evaluate the cold hardiness of H. axyridis in North America. Supercooling points and survival at subzero temperatures of field-collected and insectary-reared H. axyridis were examined. The mean (±SE) supercooling points for eggs and pupae (i.e., nonfeeding stages) were −27.0 ± 0.18°C and −21.3 ± 0.52°C, respectively. The mean supercooling points for larvae and adults (i.e., feeding stages) were −14.17 ± 0.33 and −11.9 ± 0.53°C, respectively. Sex and color morph (i.e., red: f. succinea versus black: f. spectabilis) had no effect on the supercooling point of H. axyridis adults. Mean supercooling points of H. axyridis adults from Minnesota and Georgia were significantly lower during winter months than summer months. The mortality of H. axyridis increased significantly after individuals were exposed to temperatures below the mean supercooling point of the population. Supercooling point was a good predictor of cold hardiness. However, the cold hardiness of H. axyridis appears to be a poor predictor of its northern distribution.
    Environmental Entomology 07/2004; 33(4):815-822. DOI:10.1603/0046-225X-33.4.815 · 1.42 Impact Factor
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    ABSTRACT: Aeration management strategies were developed to control cold-acclimated and diapausing Indian meal moth larvae in grain bins in north- and east-central regions of the U.S during winter. Contour maps showing hours below –10 oC for the months of December, January, and February were developed to help effective planning and management of aeration to control insects that normally survive the winter. Two cumulative lethality index (CLI) models were developed to estimate mortality of laboratory-reared (diapausing without cold-acclimation) and field-collected (coldacclimated, and diapausing with cold-acclimation) Indian meal moth larvae under changing temperature conditions. The CLI models were found to be useful for evaluating aeration management strategies. Simulation studies were conducted using 30 years of weather data for twelve locations in north- and east-central regions of the U.S. to evaluate different aeration management strategies for controlling Indian meal moth larvae. Temperatures of headspace-air and grain in the top meter of grain were simulated using an existing model for the period of December to February. The tested management strategies included no aeration, continuous aeration, and intermittent aeration by controlling fan operation. During aeration, air was pulled from the headspace downward through the grain (downward airflow). Among the tested management strategies, a fan control strategy that turned the aeration fan on when the temperature of grain at 0.4 m depth was greater than the headspace-air temperature was found to be the best aeration management strategy for managing Indian meal moth larvae in all tested locations. For this strategy, the CLI model indicated that 100% mortality of Indian meal moth larvae could be achieved at a grain depth of 0.4 m from the top grain surface in all locations. For this strategy, the aeration fan operated about 10% of the time from December to February. The average cost of electrical energy required for aeration fan operation with this strategy for all locations was 1.3 ¢/t (0.03 ¢/bu) based on an electrical energy cost of 7 ¢/kWh.
    2004, Ottawa, Canada August 1 - 4, 2004; 01/2004
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    ABSTRACT: The innate capacity to withstand exposure to low temperatures (i.e., cold hardiness) and the condi-tions experienced at an overwintering site deter-mine whether an insect will survive the winter. In general, insects survive low temperatures through freeze tolerance or freeze avoidance (Lee 1991). Insects that cannot survive freezing use one or more mechanisms to avoid freezing (e.g., by moving to physically protected areas, or by supercooling). Su-percooling is the depression of the freezing point of body fluids to levels where crystallization is avoided (Lee 1991). The temperature at which spon-taneous freezing of the body fluids occurs has been called the supercooling point (SCP) and can be eas-ily detected using simple surface contact thermom-etry (e.g., Carrillo et al. 2004). By definition, freeze-intolerant insects do not survive when temperatures are at or below the SCP. The SCP, along with mortality at different low tem-peratures, has been widely used as an index of cold hardiness (e.g., Watanabe 2002, Koch et al. 2004). Information on insect cold hardiness may help re-searchers predict the possible geographic range and the probability of outbreaks for a particular spe-cies (Bale 2002). The multicolored Asian lady beetle, Harmonia axyridis (Pallas), is currently present in much of the United States and southern Canada (Koch 2003). The potential geographic range of this ex-otic coccinellid may depend on its overwintering behavior and cold hardiness. Adult H. axyridis have been reported to overwinter close to promi-nent objects on the horizon (e.g., buildings or moun-tains) (Koch 2003), which may confer a degree of protection from low temperatures. In addition, Watanabe (2002) and Koch et al. (2004) have shown that H. axyridis acquires cold hardiness by cold acclimation and protects itself against low tem-peratures by supercooling. Furthermore, Watanabe (2002) observed a degree of chill tolerance for this species, with adult H. axyridis of a Japanese strain surviving up to 200 d at –5ºC. Recently, we evaluated several aspects of the cold hardiness of H. axyridis in North America (Koch et al. 2004). The SCP and mortality at low tem-peratures of field-collected and insectary-reared H. axyridis were measured as indices of cold hardi-ness. Sex and color morph (i.e., red: f. succinea versus black: f. spectabilis) had no effect on the SCP of adult H. axyridis (Koch et al. 2004). How-ever, the mean SCP of adult H. axyridis changed significantly with season. Adults from Minnesota froze at significantly lower temperatures during winter (≈ –23ºC) versus summer (≈ –8ºC) months. The mean SCP of adults from Georgia had a simi-lar seasonal trend, but with less change between seasons. This observed seasonal trend corrobo-rated reports from Japan about this species (Watanabe 2002). We also found that the mean SCPs for eggs and pupae occurred at lower temperatures than for lar-vae and adults (Koch et al. 2004). These results suggest that food in the digestive tract may induce ice nucleation and increase the SCP. Therefore, by clearing their guts (Iperti and Bértrand 2001), adult H. axyridis may reduce their SCP in preparation for overwintering. In addition, Watanabe (2002) found a negative correlation between the SCP and the concentration of a cryoprotectant, myo-inosi-tol, and he speculated that this compound may also contribute to the increased cold hardiness of H. axyridis during winter. Although the SCP has been used frequently as an index of cold hardiness because it is relatively easy to measure, its ecological significance may be unclear. The analysis of mortality at low tempera-tures appears to be a more robust index of cold hardiness. Mortality of adult H. axyridis increased signifi-cantly after exposure to temperatures below the mean SCP of the population (Koch et al. 2004). However, mortality of adult H. axyridis did not occur immediately at the SCP but increased with time after the SCP was reached. Similar results have been observed for other chill-tolerant/freeze-intol-erant insects in which mortality was proportional to the amount of ice formed inside the body (e.g., Salt 1953). Although the SCP appeared to be a good indicator of adult mortality at minimum ex-posure (i.e., 1 min), Watanabe (2002) found that some pre-freeze mortality occurred when adult H. axyridis where exposed to subzero temperatures for a longer period of time (i.e., 24 h). Within the current North American range of H. axyridis, minimum air temperatures can exceed the minimum mean SCP of adult H. axyridis (i.e., ≈ –23ºC) (Fig. 1), and should be lethal for this coccinellid. Thus, local air temperature alone ap-pears to be a poor predictor of the distribution of this species. Consequently, adult H. axyridis most likely survive extreme winter conditions by finding microclimates that provide protection from lethal temperatures. Therefore, the capacity of H. axyridis to survive winter conditions in northern locations may be more related to the availability of quality overwintering sites than to its capacity to increase cold hardiness.
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    ABSTRACT: A simple method to obtain predetermined constant cooling rates for insect supercooling point (SCP) determination is described. A transient heat transfer equation was used to design polystyrene cubes of different sizes to yield constant rates of cooling at their centers when held at a constant surrounding temperature. Cubes of 0.29 x 0.29 x 0.29 m and 0.19 x 0.19 x 0.19 m were found to produce cooling rates of about -0.5 and -1 degree C per min, respectively, from 0 to -40 degree C. The observed temperature variations at the geometrical center of the cubes were similar to those predicted by the equation. Temperature plots showed a nearly constant rate of cooling. Supercooling points of Tribolium castaneum (Herbst) at different stages of development were recorded using polystyrene cubes. These SCPs compared favorably with published values. This method of obtaining cooling rates is economical, flexible, and allows for multiple simultaneous SCP measurements.
    Cryo letters 01/2004; 25(3):155-60. · 0.64 Impact Factor
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    ABSTRACT: To develop practical weather-based headspace ventilation management strategies to control Indian meal moth in stored shelled corn (Zea mays L.) bins for locations in the north- and east-central states of the U.S., historical weather data were analyzed to estimate the mean number of hours below certain critical threshold temperatures for the months of December, January, and February and they were presented as contour maps. Minneapolis - St. Paul, MN weather data were analyzed to estimate the mean frequency of occurrences of consecutive hours of temperatures below certain threshold values for the months of December, January, and February. The application of these two weather parameters for the control of stored grain insects was discussed. An existing temperature prediction model was modified to simulate the temperatures of headspace-air and grain in the upper surface during mechanically ventilated and unventilated conditions. The model was used to simulate the temperatures of corn stored in Minneapolis- St. Paul, MN during December, January, and February. Predicted temperatures of headspace-air and grain near the top surface were analyzed to estimate the mean temperatures, mean number of hours and mean frequency of consecutive hours occurrences below –10 and –20oC during the simulation period. The results suggest that in Minneapolis- St. Paul, MN, cold-acclimated diapausing Indian meal moth larvae could easily be controlled by mechanical ventilation of headspace during winter months. Further research is warranted to develop site-specific headspace ventilation strategies to control Indian meal moth and other stored grain insects.
    2003, Las Vegas, NV July 27-30, 2003;

Publication Stats

161 Citations
17.49 Total Impact Points

Institutions

  • 2004–2010
    • University of Minnesota Morris
      Saint Paul, Minnesota, United States
  • 2006–2008
    • Saint Mary's University of Minnesota
      Minneapolis, Minnesota, United States
  • 2005–2007
    • University of Minnesota Duluth
      Duluth, Minnesota, United States