Survival at low temperature of larvae of the pine processionary moth Thaumetopoea pityocampa from an area of range expansion

1 Larvae of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) develop throughout the winter, although their feeding activity and survival can be impaired by adverse climatic factors. The present study investigated the survival at low temperature of larvae originating from a population with range expansion in an alpine valley in Northern Italy.
2 The supercooling point of individually analysed larvae averaged at −7 °C. This value insufficiently described the cold hardiness of the larvae; 39% of the tested larvae were alive when returned to room temperature immediately after freezing. When larval colonies inside their nest were exposed to −17 °C for 1 h after gradual temperature decrease, survival was 70.4%.
3 Rearing of larvae in the laboratory at different day/night temperatures indicated an effect of cumulative chill injury on larvae. A logistic regression explained the relationship between negative thermal sum (h°C below 0 °C) received in the laboratory experiment and larval survival. A similar relationship was demonstrated between negative thermal sum and survival of larval colonies in the field.
4 In the laboratory experiment, some tested larvae were able to survive for up to 8 weeks without feeding depending on rearing temperature. As expected, feeding occurred only when larvae were reared at temperatures of 9 °C day/0 °C night.
5 We classify the larvae of T. pityocampa as being moderate freezing tolerant. The winter behaviour allows this species to track climate warming by a rapid expansion into those areas that become compatible with the insect's development.     

Wood ants are wood ants: deforestation causes population declines in the polydomous wood ant Formica aquilonia

Abstract.  1. One of the main themes in ecology is adaptation for survival in different habitats and the potential of the environment to regulate populations.
2. The effects of clear-cutting on nest-abandonment rate and local population sizes in the polydomous wood ant Formica aquilonia was studied, using uncut forest stands as controls.
3. The nest-abandonment rate was clearly higher in clear-cuts than in forest interiors. In clear-cuts, 39% of pre-deforestation nests and 73% of new bud-nests were abandoned 4–5 years after deforestation, whereas in forest interiors fewer than 2% of nests were abandoned at the same time period. Local population size decreased 30% in clear-cuts, but fewer than 2% in forest interiors.
4. The results demonstrate that despite modern logging practices in which mechanical harming of nest mounds is reduced, nest mounds are abandoned at high rate, and despite frequent establishment of new bud-nests, populations start to decline.
5. The likely reason for the high nest-abandonment rate in clear-cuts is a combination of changed abiotic conditions, resource limitation, and disturbed reproduction.
6. Species that are sensitive to changes in the size of habitat patch, such as F. aquilonia , likely are harmed by logging, even employing biodiversity oriented management practices. Hence there is a need for conservation actions that are based on the size of protection areas.     

Fate of Salmonella in dry confectionery raw materials

Aims:  To study the behaviour of salmonellae inoculated in the dry, raw materials, related to chocolate confectionery manufacture, as affected by the strain, cell preparation method and storage temperature.
Methods and Results:  Outbreak and non outbreak-associated salmonellae were used for the inoculation of cocoa butter oil, crushed cocoa and hazelnut shells, cocoa beans and almond kernels. Dry matrices were inoculated with lawn-collected and broth-grown cells and were stored at 5 and 21°C for 21 days. Results demonstrated that all strains survived in all dry matrices. Lawn-collected cells survived considerably better than broth-collected cells, at either temperature, and outbreak-associated strains of Salmonella serotype Enteritidis PT30 and Salmonella serotype Oranienburg appeared to be among the best surviving strains.
Conclusions:  The work demonstrated that salmonellae can survive storage for 3–4 weeks in dry raw materials and that survival is dependent on the source of strains, cell preparation and inoculation methodology, and storage temperature.
Significance and Impact of the Study:  The data contributes to understanding the parameters to consider when assessing the risk of dry raw materials as the most likely source of salmonellae in chocolate processing plants. It also demonstrates the importance of implementing effective lethal processes and segregation procedures to prevent cross-contamination to ensure the safety of confectionery products regarding Salmonella .     

A global risk assessment for the success of bird introductions

1.  Concern over the impact of invasive species has led to the development of risk assessment methodologies to identify potential invaders and prevent future ecological and economic problems. However, developing a risk assessment tool is challenging because of the difficulties of accurately predicting the outcome of species introductions.
2.  In this study, we develop a global risk assessment for birds. We integrate two approaches, generalized linear mixed models (GLMM) and hierarchical tree models, to help identify those introductions with the highest risk of establishment success.
3.  Past work has shown that the number of individuals released is the main factor influencing establishment success in animals, a conclusion that was supported in our analyses. Establishment success was also higher for species with broader ecological niches and larger brains relative to body size. These features should increase the likelihood of finding an appropriate niche in the region of introduction.
4.  The GLMM and tree model predicted the probability of establishment success of birds in Europe and Australia with high accuracy (over 80% of introductions correctly classified). This highlights that establishment risk can be reasonably assessed with information on general habitat use, brain size and the size of the founder population. When compared with an alternative risk assessment tool based on a qualitative ranking, our quantitative approaches achieved higher accuracy with less information.
5.   Synthesis and applications. Quantitative risk assessments based on traits related to establishment success are difficult but feasible, providing a useful tool for guiding preventive polices aimed at mitigating the impact of invasive species.     

Survival of enteric bacteria and coliphage MS2 in pure human urine

Aims:  The survival of Escherichia coli , Salmonella enterica serovar Typhimurium, Enterococcus faecalis and coliphage MS2 was studied in stored, fresh and diluted (1 : 1) human urine at 15 and 30°C.
Methods and Results:  Survival rate was studied by the plate count method. All the organisms showed rapid inactivation in stored urine, but they survived better in diluted and fresh urine. The high pH level and temperature were the major factors found to influence the survival of the micro-organisms with the survival rate being higher at 15°C than at 30°C.
Conclusions:  The destruction of all micro-organisms in stored urine required <1 week at 30°C. Thus, the storage of urine is a useful way to reduce the risk of contamination while using urine as a fertilizer.
Significance and Impact of the Study:  The urine fertilization is aimed for the developing countries and the high temperatures in these countries may hasten the destruction of micro-organisms in urine. On the contrary, a higher survival rate of these organisms in fresh and diluted urine is a public health concern because the dilution of urine with water is likely to happen during flushing.     

Effect of production conditions on the stability of a human bifidobacterial species Bifidobacterium longum in yogurt

Aims:  Human bifidobacteria are more sensitive to external environmental factors than animal bifidobacteria, and it is difficult to ensure their stable survival in yogurt. The purpose of this investigation was to observe the survival of human bifidobacteria in yogurts produced under various production conditions.
Methods:  Frozen or lyophilized bifidobacteria starters containing Bifidobacterium longum BB536 originally isolated from an infant, and commercial lyophilized yogurt starters were used for yogurt preparation. After producing yogurts under various conditions, the survival of bifidobacteria in these yogurts over various storage periods was observed.
Results:  Although there were some differences in bifidobacterial survival in yogurt between various production conditions, more than 1·0 × 10⁷ CFU g⁻¹ of Bif. longum survived in yogurt after 35 days' storage at 5°C. Lower fermentation temperature (37°C) and inclusion of Lactococcus lactis in the starter significantly ( P  < 0·05) improved survival of Bif. longum in the yogurt.
Conclusion:  In this investigation, the human bifidobacterial strain Bif. longum survived adequately in yogurt, although the fermentation temperature and starter composition affect bifidobacterial survival.
Significance and Impact of the Study:  This investigation indicates that stable probiotic yogurt using human bifidobacteria can be produced by choosing optimal production conditions.     

Rapid cold-hardening in a Karoo beetle, Afrinus sp.

Abstract.  In the insect rapid cold-hardening response, survival at subzero temperatures is greatly improved by a brief pre-exposure at a milder temperature. It is predicted that insects with minimal cold tolerance capabilities living in variable environments should use rapid cold-hardening to survive sudden cold snaps. This is tested in Afrinus sp., a beetle that lives in an exposed habitat on rock outcrops in the Karoo Desert, South Africa, where microclimate temperatures drop infrequently to below freezing. Afrinus sp. shows a significant rapid cold-hardening response: survival of a 2-h exposure to −6.5 °C is much improved after pre-exposure to −2 °C, to 0 °C with a 2-h return to the rearing temperature, and to 40 °C, but not after pre-exposure to 0 °C. Little is known about the mechanism of the rapid cold-hardening response, although the data suggest that rapid cold-hardening may be mediated via several different mechanisms.     

Effect of body size, temperature, and salinity on the routine metabolism of larval and juvenile spotted seatrout

Routine oxygen consumption rates of young spotted seatrout Cynoscion nebulosus (Sciaenidae) were measured over a range of temperatures (24, 28, 30 and 32° C) and salinities (5, 10, 20, 35 and 45). Larvae and juveniles, 4·1–39·5 mm standard length ( L _S), ranging several orders of magnitude in dry body mass were used to estimate the mass–metabolism relationship. Oxygen consumption (μl O₂ larva⁻¹ h⁻¹) scaled isometrically with body mass for larvae <5·8 mm L _S(phase I, slope = 1·04) and allometrically thereafter (phase II, slope = 0·78). The inflection in the mass–metabolism relationship coincided with the formation of the hypural plate and an increase in the relative tail size of larvae. Salinity did not have a significant effect on routine metabolism during phase I. Temperature and salinity significantly affected routine metabolism during phase II of the mass–metabolism relationship. The effect of salinity was temperature dependent, and was significant only at 30° C. Response surfaces describing the environmental influences on routine metabolism were developed to provide a bioenergetic basis for modelling environmental constraints on growth.     

The survival of Salmonella enterica serovar Typhimurium DT104 and total viable counts on beef surfaces at different relative humidities and temperatures

Aims:  The aim of this study was to investigate changes in Salmonella and total viable count (TVC) survival on beef carcass surfaces stored for 72 h under different combinations of relative humidity (i.e. RH 75% or 96%) and temperature (5°C or 10°C).
Methods and Results:  The influence of low water activity ( a _w) and temperature on the survival and growth of Salmonella enterica serovar Typhimurium DT104 and the aerobic mesophilic flora on meat pieces from different sites on beef carcasses was investigated, under controlled conditions (75% or 96% RH; 5 or 10°C) in an environmental cabinet. Salmonella counts declined during storage at low a _w (75% RH) conditions at 5°C or 10°C. Salmonella counts increased during storage at high a _w (96% RH) at 10°C only. At 5°C, TVCs increased during storage at high a _w, but not at low a _w. TVCs increased on all samples from carcasses stored at high or low a _w at 10°C, except those samples taken from areas of surface fat.
Conclusions:  This suggests that substrate composition dictates growth rates under low a _w conditions. The results are discussed in terms of the possible protective effects of substrate osmolyte accumulation in bacterial survival and/or growth.
Significance and Impact of the Study:  The data obtained in this study provides useful insights on the influence of a _w and temperature on pathogen survival on meat surfaces at chill temperature.     

Waterborne metals impair inducible defences in Daphnia pulex: morphology, life-history traits and encounters with predators

1.  Inducible defences may be temporary and favoured where predation is intermittent and have been demonstrated in several invertebrates and vertebrates when prey detect chemical cues (kairomones) released by predators. Daphnia pulex (a water flea) exposed to Chaoborus (midge larvae) kairomones produce small neckteeth on the dorsal surface of the head as a defence against this gape-limited predator and survive better in the presence of Chaoborus . Recent studies have shown that waterborne copper (Cu) impairs the induction of neckteeth which could lead to lower survival.
2.  Here, we examined the effects of Cu on morphological changes and shifts in life-history traits in D. pulex exposed to kairomone from Chaoborus americanus . We exposed D. pulex mothers to chemical cues of C. americanus fed on either D. pulex neonates or on brine shrimp Artemia salina , the same Chaoborus cues combined with an environmentally relevant concentration of copper (10 μg L⁻¹), or dechlorinated tap water. We examined several morphological characteristics of neonates and life-historical characteristics of adults as well as assessing survival of neonates by staging encounters with predators.
3.  Neonates from mothers exposed to kairomone plus copper had fewer and shorter neckteeth than neonates from mothers exposed to kairomone alone. Moreover, neonates exposed to Cu had lower survival during encounters with predators than neonates exposed to kairomone without Cu.
4.  Adult female Daphnia exposed to kairomones released more neonates within the first 24 h of brood release and emptied their brood pouches quicker than mothers not exposed to kairomones, irrespective of the presence of Cu.
5.  Impairment by metals of morphological defences in zooplankton could lead to a decline in population density and alter community structure.     

Survival of Salmonella on refrigerated chicken carcasses and subsequent transfer to cutting board

Objective:  To determine the effect of refrigeration time and temperature on Salmonella cell numbers on inoculated chicken carcasses and their transfer to a plastic cutting board.
Methods and Results:  The survival of Salmonella on chicken skin and the transfer to a plastic cutting board when exposed to different refrigeration temperatures (2, 6 or 8°C) for 9 days were the two main issues on which this work focused. Two scenarios were carried out to ascertain these effects: carcasses treated with a decontaminating acetic acid solution and untreated carcasses. All of the contaminated carcasses remained contaminated after 9 days of refrigeration. However, on untreated samples, while Salmonella numbers increased almost 1·5 log at 8°C, the pathogen numbers decreased about 1 log at 2 and 6°C. On acid-treated samples, cell numbers slightly decreased at all of the temperatures studied. Temperature did not affect salmonellae transfer to the cutting board, but time did. Acid decontamination increased cell numbers transferred to the cutting board compared with untreated samples.
Conclusion:  Proper refrigeration at low temperatures did not allow Salmonella numbers to rise, regardless of which carcasses had been, or had not been, acid treated. Despite the fact that the rate of transfer was not affected by temperature, the acid treatment detached Salmonella cells from the chicken skin and, therefore, the probability of greater cross-contamination should be studied further.
Significance and Impact of the Study:  The results of this study may provide better information about the refrigeration conditions for fresh chicken storage and also determine if these, along with acetic acid decontamination of broiler chicken, would affect the pathogen transfer to a cutting board.     

Contact with the host plant enhances aphid survival at low temperatures

1. The hypothesis, suggested by previous studies, that host plant contact reduces the cold tolerance of anholocyclic aphids was tested under laboratory conditions. Adult and first-instar Rhopalosiphum padi (L.) were exposed to temperatures of 0, –5 and –10 °C on intact plants, excised leaves and in the absence of contact with plant material.
2. Median lethal time (LT₅₀) values at all three temperatures indicate that aphids exposed in association with plant material survive longer than aphids that have no contact with their host plant. The difference in survival was most pronounced at –10 °C. Therefore, the above hypothesis is rejected for aphids on cereals because host plant contact apparently enhances cold tolerance.
3. Exposure on excised leaves also enhanced aphid survival at low temperature but was less effective than the intact plant. This suggests that plant quality as well as the presence or absence of plants is important in the cold tolerance of aphids on cereals.     

Resistance of Enterobacter sakazakii (Cronobacter spp.) to environmental stresses

Aim:  To gain a better understanding of the survival and persistence of Enterobacter sakazakii in severe environments.
Methods and Results:  We evaluated the resistance of Ent. sakazakii to various environmental stresses, including heating, drying, water activity ( a _w), and pH. The resistance of Ent. sakazakii to heat varies widely among strains. Most tested strains of Ent. sakazakii exhibited unusual resistance to dry stress, which depends on drying media. Growth of most strains occurred within 24 h at 37°C when the initial a _w of the medium was adjusted to 0·94 with sucrose or sodium chloride. The minimum pH for growth within 24 h at 37°C was 3·9 or 4·1 for most strains tested. Additionally, there did not appear to be any relationship between resistance to stresses and biofilm-forming ability in Ent. sakazakii planktonic cells.
Conclusions:  These results indicate that Ent. sakazakii is much more resistant than other Enterobacteriaceae to environmental stresses. Moreover, it is likely that Ent. sakazakii has cross-resistance to dry and thermal stresses.
Significance and Impact of the Study:  The findings of this study will contribute to an improved understanding of the survival and behaviour of Ent. sakazakii , which will lead to improved strategies for preventing outbreaks of Ent. sakazakii infection.     

Cold shock and cold tolerance in larvae and pupae of the blow fly, Lucilia sericata

Abstract.  Understanding the effects of low winter temperatures on mortality is essential in the development of a full understanding of the long-term population dynamics of any insect. The present study aims to examine the survival of pupae and larvae of the blow fly, Lucilia sericata , at overwintering temperatures. Groups of pupae and diapausing and nondiapausing third-stage larvae of L. sericata are maintained in cooled incubators at either 3 °C and 6 °C. Groups are removed from the incubators at 3–4-day intervals and transferred either to−8 °C or to 25 °C. After 1 h in the freezer, the larvae and pupae exposed to this cold-shock are also transferred to 25 °C. Larvae and pupae are then allowed to continue development and the number of adults emerging from each group is counted. The results demonstrate that survival decreases linearly with the period of exposure at both 3 °C and 6 °C. Mortality is higher at 3 °C than at 6 °C and, in groups that receive the cold shock, cold-shock reduces emergence by over 50%. However, there is no consistent tendency for diapausing larvae to survive prolonged cold or cold shock better than other life-cycle stages. The results suggest that the facultative development of an overwintering diapause stage in L. sericata does not appear to be an adaptation to enhance cold tolerance or resistance to cold shock. It is concluded that the survival of overwintering L. sericata is likely to be relatively less affected by low temperatures than it is by, for example, biotic factors, particularly given the buffered soil environment and short time-scales over which periods of cold act.     

Persistence of Shiga toxin-producing Escherichia coli O26 in various manure-amended soil types

Aims:  To evaluate the behaviour of Shiga toxin-producing Escherichia coli (STEC) O26 strains inoculated in manure-amended soils under in vitro conditions.
Methods and Results:  Four green fluorescent protein (GFP)-labelled STEC O26 strains were inoculated in duplicate (at 10⁶ CFU g⁻¹) in three different manure-amended soil types, including two loam soils (A and B) and one clay loam soil (C), and two incubation temperatures (4 and 20°C) were tested. STEC counts and soil physical parameters were periodically monitored. STEC O26 cells were able to persist during extended periods in soil even in the presence of low moisture levels, i.e. less than 0·08 g H₂O g⁻¹ dry soil. At 4 and 20°C, STEC could be detected in soil A for 288 and 196 days, respectively, and in soils B and C for at least 365 days postinoculation at both temperatures. The ambient temperature (i.e. 20°C) was significantly associated with the highest STEC count decline in all soils tested.
Conclusions:  The temperature and soil properties appear to be contributory factors affecting the long-term survival of STEC O26 in manure-amended soils.
Significance and Impact of the Study:  This study provides useful information regarding the ecology of STEC O26 in manure-amended soils and may have implications for land and waste management.     

Dry mass–length relationships for benthic insects: a review with new data from Catamaran Brook, New Brunswick, Canada

1.___We summarized previously published mass–length relationships for aquatic insects, and determined the relationship between dry body mass and body length for eight genera and seven families of benthic insects from Catamaran Brook, New Brunswick, Canada.
2.___A power function was the most commonly used model in the earlier studies and best described the observed mass–length relationship for taxa from Catamaran Brook.
3.___Predicted mass at length was highly variable (coefficient of variation_≥ 25%) among models developed in different studies for the same family group. This variability presumably resulted from both variation in the methods used to construct the models, and in the natural spatio-temporal and taxonomic variation in mass at length, although the relative contributions of these two sources cannot be determined from existing data.
4.___Several recommendations are made for the development and application of mass–length equations in future studies.     

Effects of temperature on the establishment potential in the U.K. of the non-native glasshouse biocontrol agent Macrolophus caliginosus

Abstract This study investigated the effect of temperature on the development and winter survival of the predatory mirid Macrolophus caliginosus Wagner, recently introduced into the U.K. as a biocontrol agent for glasshouse whitefly Trialeurodes vaporariorum . The developmental threshold for M. caliginosus calculated by three methods was between 7.3 and 8.4 °C, with a day-degree requirement per generation varying between 472 and 524 day-degrees. It was estimated that under outdoor conditions M. caliginosus could complete two generations per year in the U.K. All life stages of M. caliginosus had supercooling points around −20 °C, with some pre-freeze mortality evident in both acute and chronic low temperature exposures. Acclimation increased survival of nymphal M. caliginosus from approximately 24–52 days when exposed to a constant 0 °C. Provision of prey extended survival of nymphs in the laboratory at a constant 5 °C from 39 to 64 days and in the field by c . 150 days. The results are discussed in the context of the occurrence and establishment of M. caliginosus in the U.K. and the need to develop a reliable risk assessment system for non-native species used in glasshouse biocontrol.     

Influence of photoreactivating light intensity and incubation temperature on photoreactivation of Escherichia coli following LP and MP UV disinfection

Aims:  To investigate the effects of fluorescent light intensity, sunlight intensity and temperature on photoreactivation of Escherichia coli after low-pressure (LP) and medium-pressure (MP) ultraviolet (UV) disinfection.
Methods and Results:  Two E. coli strains were irradiated with LP and MP UV lamps, and exposed to various fluorescent light (0–23 kLux) and sunlight intensities (1–80 kLux), and temperatures (4–50°C). Escherichia coli concentrations were enumerated at hourly intervals to determine photoreactivation rates and final photoreactivation levels. Higher photoreactivation rates and levels were observed with increasing fluorescent light intensities, while high sunlight intensity (>12 kLux) caused a one-log decrease in E. coli concentrations. When exposed to near-optimum growth temperatures (23–37°C), photoreactivation levels were higher than those with too high (50°C) or too low (4°C) temperatures. Overall, photoreactivation following MP UV disinfection was lower than that following LP UV disinfection.
Conclusions:  Photoreactivation of bacteria following UV disinfection can be a problem in tropical countries where sunlight is abundant and temperatures are high, unless high sunlight intensity is present or if MP UV disinfection is employed.
Significance and Impact of the Study:  With the increased use of UV disinfection, it is imperative that photoreactivation be taken into account in the design of reactors based on site-specific conditions of temperature and light intensity exposure.     

Influence of pregnancy on the thermal biology of the lizard, Sceloporus jarrovi: why do pregnant females exhibit low body temperatures?

1. Selected body temperatures of female lizards, Sceloporus jarrovi , were measured on a photothermal gradient during late pregnancy and again when postpartum, and pregnant females were subjected to one of three fluctuating temperature regimes that simulated body temperatures of (1) pregnant females, (2) postpartum females or (3) allowed normal thermoregulation.
2. Overall, females selected lower body temperatures when pregnant (mean = 32·0°C) than when postpartum (mean = 33·5°C).
3. Females regulated body temperature more precisely when pregnant than when postpartum as judged by their smaller variances in body temperature throughout the day.
4. When pregnant, females selected a lower mean maximum body temperature (mean: pregnant = 32·8°C; postpartum = 34·5°C) than when postpartum, but selected mean minimum body temperatures did not differ.
5. None of the experimental temperature treatments was detrimental to pregnant females. Female body length increased during pregnancy but the rate of increase did not differ among treatments. Moreover, length-adjusted body mass of postpartum females did not differ among treatments.
6. Pregnant females that experienced postpartum body temperatures produced neonates that were smaller in body mass and length than pregnant females that experienced pregnant body temperatures and females that were allowed to thermoregulate.
7. For neonates resulting from the postpartum body temperature treatment, the disparity in the body length, but not mass, was still observed at 9 days of age, although survival and growth of neonates was high and did not differ among treatments.
8. The results demonstrate that pregnant females could maintain higher postpartum body temperatures without compromising their physical condition, but select relatively low body temperatures, presumably to avoid decrements in offspring fitness.     

Shaking a leg and hot to trot: the effects of body size and temperature on running speed in ants

Abstract.  1. Data were compiled from the literature and our own studies on 24 ant species to characterise the effects of body size and temperature on forager running speed.
2. Running speed increases with temperature in a manner consistent with the effects of temperature on metabolic rate and the kinetic properties of muscles.
3. The exponent of the body mass-running speed allometry ranged from 0.14 to 0.34 with a central tendency of approximately 0.25. This body mass scaling is consistent with both the model of elastic similarity, and a model combining dynamic similarity with available metabolic power.
4. Even after controlling for body size or temperature, a substantial amount of inter-specific variation in running speed remains. Species with certain lifestyles [e.g. nomadic group predators, species which forage at extreme (>60 °C) temperatures] may have been selected for faster running speeds.
5. Although ants have a similar scaling exponent to mammals for the running speed allometry, they run slower than predicted compared with a hypothetical mammal of similar size. This may in part reflect physiological differences between invertebrates and vertebrates.