Effect of straw on the behaviour of growing pigs

The effects of straw on the behaviour of young growing pigs were studied in two experiments. In Experiment 1, groups of three pigs, aged about 7 weeks, were housed in raised decks with or without straw bedding. Time-lapse video recording showed no major differences between treatments in the amount or daily pattern of overall activity and feeding. Detailed observations showed that bedding reduced the incidence of rooting and chewing on pen-mates, but had little effect on other social activities such as mounting and aggressive biting. Experiment 2 compared groups of eight growing pigs aged about 10 weeks, housed in floor pens with or without a small amount of straw provided daily in a rack. Pigs with straw concentrated more of their daily activity into the period when straw was fresh, but the total amount of overall activity and time spent feeding were not affected. Rooting and chewing of pen-mates were the only social activities reduced by the provision of fresh straw. In these studies, where straw was not required to compensate for deficiencies such as low temperatures or hunger, the one major function of straw was to provide a stimulus and outlet for rooting and chewing, with a resulting reduction in such activities directed at pen-mates.     

Floor temperature preference of sows at farrowing

A preference testing apparatus was used to provide sows with continuous access to three identical farrowing crates, each with a different floor temperature. The concrete floor under each crate contained copper pipe through which temperature-controlled water was circulated to achieve unoccupied floor temperatures of 22 degrees C (+/-3.5), 29 degrees C (+/-1) and 35 degrees C (+/-1). Eighteen sows were tested in the apparatus. Video recording was used to determine sow position from 7 days before farrowing (Days -7 to -1) to 14 days after (Days 1 to 14). On Days -7 to -1, sows showed no significant preference among the three temperatures when selecting a resting area. Once farrowing had begun, there was a significant increase (P<0.01) in the use of the 35 degrees C floor and it became the most preferred resting area for Days 1 to 3. After this interval, use of the 35 degrees C floor declined significantly (P<0.01), and use of the cooler floors increased, resulting in no significant thermal preference during Days 4 to 6. There was a further decline in the use of the 35 degrees C floor after Days 4 to 6 (P<0.01) to the extent that the coolest floor (22 degrees C) became the most preferred from Days 7 to 14. In summary, sows showed a pronounced increase in preference for a warm floor during the 3 days after the start of farrowing. This change in preference may explain how free-living sows select a suitable thermal environment for their young, and why sows try to avoid metal flooring at the time of farrowing.     

Effect of straw amount on feed intake and weight gain in growing pigs housed in pens with partly slatted floor

The provision of straw to pigs kept in conventional pens with concrete floor improves animal welfare, but the effects of straw on pigs’ performance are unclear. In two steps, we investigated the relationship between amount of straw provided to pigs and measures of performance in a set-up maintaining constant space allowance and controlled room temperature. From approximately 30- to 85-kg BW, pigs were housed in groups of 18 in pens (5.48 m × 2.48 m) with concrete floor (1/3 solid, 1/3 drained and 1/3 slatted). The pens were cleaned manually twice a week, and the designated amount of fresh uncut wheat straw was provided daily onto the solid part of the floor. In the first step, 48 pens were assigned to 10-, 500- or 1000-g straw per pig per day, while in the second step, 90 pens were assigned to 10-, 80-, 150-, 220-, 290-, 360-, 430- or 500-g straw per pig per day. Pigs were weighed at the start of the experimental period at approximately 30 kg and again at approximately 85-kg BW. The average daily gain increased 8.1 g (SEM 17) for every extra 100-g straw added daily (P < 0.001) resulting in 40 g higher average daily gain with 500 compared to 10-g straw per pig per day. The feed conversion ratio was not affected by the amount of straw provided, as the feed intake tended to be higher with increasing amounts of straw. Thus, between 10 and 500 g, the more straw provided, the higher the daily weight gain. As the nutritional value of straw is considered minimal, this result is likely due to improved gut health from the increasing amounts of straw ingested and increased feed intake due to increased stimulation of exploratory behaviour with increasing amounts of straw available, or a combination of these. The observed tendency for a higher feed intake supports this suggestion, but studies are needed to establish the impact of these two contributing factors.     

The group postural behaviour of growing pigs in relation to air velocity,air and floor temperature

In three experiments with 6 piglets each (3 males, 3 females), given access to a pen with 4 plates having different surface temperatures and an air-velocity gradient, the group postural behaviour was recorded and analyzed.The results indicate that temperature control of the floor surface can realize the preferred comfort zone of growing pigs, as a function of age and air temperature.In the case of a constant floor temperature which was higher than the air temperature, as a function of age the pigs preferred a lying area with an enhanced air velocity (0.3 m s⁻¹) when the air temperature was 14–25°C.Hence, the animals' preference for a well-defined combination of air and floor temperature, as well as of air velocity, can be used as a trigger within the engineering and control system of the house environment to avoid behaviour-related problems.     

The effect of long or chopped straw on pig behaviour

In the EU, pigs must have permanent access to manipulable materials such as straw, rope, wood, etc. Long straw can fulfil this function, but can increase labour requirements for cleaning pens, and result in problems with blocked slatted floors and slurry systems. Chopped straw might be more practical, but what is the effect on pigs’ behaviour of using chopped straw instead of long straw? Commercial pigs in 1/3 slatted, 2/3 solid pens of 15 pigs were provided with either 100 g/pig per day of long straw (20 pens) or of chopped straw (19 pens). Behavioural observations were made of three focal pigs per pen (one from each of small, medium and large weight tertiles) for one full day between 0600 and 2300 h at each of ~40 and ~80 kg. The time spent rooting/investigating overall (709 s/pig per hour at 40 kg to 533 s/pig per hour at 80 kg), or directed to the straw/solid floor (497 s/pig per hour at 40 kg to 343 s/pig per hour at 80 kg), was not affected by straw length but reduced with age. Time spent investigating other pigs (83 s/pig per hour at 40 kg), the slatted floor (57 s/pig per hour) or pen fixtures (21 s/pig per hour) was not affected by age or straw length. Aggressive behaviour was infrequent, but lasted about twice as long in pens with chopped straw (2.3 s/pig per hour at 40 kg) compared with pens with long straw (1.0 s/pig per hour at 40 kg, P=0.060). There were no significant effects of straw length on tail or ear lesions, but shoulders were significantly more likely to have minor scratches with chopped straw (P=0.031), which may reflect the higher levels of aggression. Smaller pigs showed more rooting/investigatory behaviour, and in particular directed towards the straw/solid floor and the slatted floor than their larger pen-mates. Females exhibited more straw and pen fixture-directed behaviour than males. There were no effects of pig size or sex on behaviour directed towards other pigs. In summary, pigs spent similar amounts of time interacting with straw/solid floor when long and chopped straw were provided, and most aspects of pig-directed behaviour and injuries were not affected by straw length. There was an increase in pigs with minor shoulder lesions with chopped straw, perhaps because of increased aggression. The use of chopped straw as an enrichment material for pigs warrants further investigation in larger and more detailed studies.     

The effects of weight asymmetry and resource distribution on aggression in groups of unacquainted pigs

The relationship between weight asymmetry and aggression when mixing groups of unacquainted pigs in two different environments was investigated. Ten groups of 4 female (LandracexYorkshire), unacquainted pigs with a weight asymmetry of 3.1+/-0.2 kg (mean weight: 16.6+/-0.6 kg) between each pig, and another 10 groups with a weight asymmetry of 1.2+/-0.1 kg (mean weight: 14.1+/-0.1 kg), were mixed at the age of 7 weeks. Ten of the groups (five of each) were mixed in an experimental pen with a heterogeneous distribution of straw. The pen consisted of two main compartments with straw in one of them, and a passage area with concrete floor in between. The other 10 groups were mixed in the same pen, but with a homogenous distribution of straw (straw spread all over the pen).The results showed that fighting duration was significantly shorter in groups with large weight asymmetry than in groups with small weight asymmetry irrespective of the environment. The number of bites delivered during the fights in the heterogeneous environment was lower in groups with large weight asymmetry than in groups with small weight asymmetry. In the homogenous environment, however, there was no significant difference between groups with large and small weight asymmetries regarding the number of bites. The combination of a limited straw area and a small weight asymmetry resulted in the greatest number of bites. In groups with large weight asymmetry, the largest pig won around 50% of the fights, and 25% of the variation in the percentage of fights won was explained by the weight asymmetry.In groups with small weight asymmetry, less than 10% of the variation in the percentage of fights won could be explained by weight asymmetry. The two largest pigs delivered significantly more bites and spent significantly more time fighting than the smallest pig. The second largest pig received significantly more bites and body lesions than the smallest pig in the groups. Fights between the two largest pigs had a significantly longer duration than when other pigs were involved. The results were discussed in relation to sequential assessment theory and resource defence theory.     

Longitudinal gait development and variability of growing pigs reared on three different floor types

Biomechanical investigation into locomotor pathology in commercial pigs is lacking despite this being a major concern for the industry. Different floor types are used in modern, intensive pig production systems at different stages of the pigs’ production cycle. The general perception holds that slatted and/or hard solid concrete surfaces are inferior to soft straw-covered floors regarding healthy musculoskeletal development. Previous studies have compared pigs housed on different floor types using clinical, subjective assessment of leg weakness and lameness. However, reliability studies generally report a low repeatability of clinical lameness scoring. The objective of this study was to quantitatively assess the long-term effect of pen floors, reflected in the biomechanical gait characteristics and associated welfare of the pigs. A cohort of 24 pigs housed on one of three different floor types was followed from 37 to 90 kg average liveweight, with gait analysis (motion capture) starting at 63 kg. The three floor types were fully slatted concrete, partly slatted concrete and deep straw-bedded surfaces, all located within the same building. Pigs underwent five repeated camera-based motion captures, 7 to 10 days apart, during which 3D coordinate data of reflective skin markers attached to leg anatomical landmarks were collected. Pigs walked on the same solid concrete walkway during captures. One-way ANOVA and repeated measures ANOVA were used to analyse the gait data. Results revealed changes over time in the spatiotemporal gait pattern which were similar in magnitude and direction for the pigs from different floor types. Significant increases in elbow joint flexion with age were observed in all pigs (P⩽0.050; +6°). There were few differences between floor groups, except for the step-to-stride ratio in the hind legs being more irregular in pigs housed on partly slatted floors (P=0.012; 3.6 times higher s.d.) compared with those on 5 to 10 cm straw-bedding in all pen areas. As the level of clinical problems was generally low in this cohort, it may be that floors elicit problems only when there is a primary predisposing factor increasing weakness in susceptible tissues.     

土著发酵床对商品猪生产性能和血液生化指标的影响

目的采集徐州当地土著微生物作为原始菌株制作发酵床,考察土著发酵床对商品猪生产性能及血液生化指标的影响。方法选择60头杜×长×大三元配套系仔猪进行实验,仔猪断奶日龄为21 d。实验组商品猪饲喂于发酵床猪舍,对照组饲喂于水泥地面猪舍。每组设3个重复,每个重复随机选取健康仔猪10头。仔猪饲喂125 d后考察土著发酵床对商品猪生产性能和血液生化指标的影响。结果土著发酵床具有一定提高商品猪日增重的效果,并可显著降低料重比（P〈0.05）,但对猪酮体品质未产生显著影响。在血液生化指标方面,实验组商品猪血液中的总蛋白、白蛋白、碱性磷酸酶含量均显著高于对照组（P〈0.05）。结论土著发酵床可以提高猪的生长性能和免疫机能。     

Preferences of sheep for different types of pen flooring

In countries where the climate makes it practical with indoor housing during cold periods of the year and access to straw is limited, e.g. Iceland and Norway, housing of sheep on slats or expanded metal floors is common practice. However, European regulations for organic farming require that all animals should have access to a lying area with solid floor. The objective of this experiment was to investigate sheep preferences for different types of pen flooring.

In Experiment 1, a total number of 16 ewes, divided into four groups, were subjected to four different treatments. In each treatment, the ewes could choose between two lying areas with one of the following flooring materials: (1) solid wood versus rubber mats, (2) expanded metal versus solid wood, (3) solid wood versus straw, (4) expanded metal versus straw. In Experiment 2, a total number of eight ewes were individually subjected to the same treatments, first fully coated and then sheared. The ewes were video taped for 48 h in each treatment period.

In Experiment 1, the first animal that lay down after feeding preferred to lie down on straw or wood to expanded metal and straw to wooden floor (P < 0.05), but this first choice did not reflect the overall flooring preference for unsheared ewes. The groups of unsheared ewes showed no significant preferences for lying area.

In Experiment 2, single housed, unsheared ewes preferred wooden floor to rubber mats (P < 0.05), and tended to prefer expanded metal floor to straw (P = 0.08). There were no significant preferences in the two other treatments. After shearing, the ewes’ preferred wooden floor to expanded metal (P < 0.05), straw to wooden floor (P < 0.05), and straw to expanded metal floor (P< 0.0001). There were no significant preferences between rubber mats and wooden floor. Mean lying time (% of observations) for all treatments was 64.7% for unsheared ewes, and there were no significant differences between treatments. Mean lying time (% of observations) for all treatments the first 2–3 days after shearing was 43%. Significant differences in pre-shearing versus post-shearing lying times (% of observations) existed when the ewes were housed in pens with no straw (P < 0.05), this was not the case when the ewes had access to straw.

In conclusion, sheared but not unsheared ewes, preferred softer floors with low thermal conductivity (straw and wood). The less dramatically reduction in lying time (% of observations) after shearing when the ewes had access to straw, suggest that access to straw the first weeks after shearing may improve animal welfare.     

Postprandial thermophily,transit rate,and digestive efficiency of juvenile cornsnakes,Pantherophis guttatus

We measured substrate temperature preference of juvenile cornsnakes in a linear thermal gradient during a fast and after feeding. After feeding the snakes selected temperatures approximately 6 °C warmer than those chosen by fasting snakes. We measured transit rates, the time from feeding to defecation, in snakes maintained at 22 or 32 °C or during ecdysis. Snakes at 32 °C had a significantly faster transit rate than those at 22 °C and during ecdysis snakes retained feces. The digestive efficiency ranged from 87% to 95% for individual snakes.     

Effect of rubber mats and perforation in the lying area on claw and limb lesions of fattening pigs

Claw and leg lesions are frequently observed in finishing pigs and are likely to compromise their welfare. Providing softer than the usual concrete flooring may reduce both the frequency and severity of these lesions. Therefore, this study evaluated the influence of rubber mats and floor perforation in the lying area on claw and leg health of finishing pigs. A total of 240 Swiss Large White finishing pigs from on average 24.9 kg until 102.3 kg were used in four batches, with six groups of 10 animals per batch. The six experimental pens initially measured 1.85×3.55 m and were enlarged after 6 weeks to 1.85×5.25 m. In all pens, one third of the floor space was built as a defecating area consisting of a concrete floor with 15% perforation. The remaining two thirds of the pen were designed as a lying area whose floor quality differed between the pens. It either consisted of concrete elements or was covered with rubber mats, and perforation of both floor types was either 0%, 5% or 10%. All individuals were scored for claw and leg lesions at the beginning, in the middle and at the end of the 12-week fattening period. Lesions were summarised in scores based on the results of a principal component analysis. The influence on lesion scores of floor material, amount of perforation in the lying area, assessment time, and sex was examined using mixed-models. The total claw lesion score and the total limb lesion score as well as the claw angle increased from the beginning to the end of the fattening period. The values for both scores were slightly lower for animals kept on rubber mats compared with animals kept on concrete floor. There was no effect of the percentage of perforation on the examined outcome variables. In conclusion, our results indicate that rubber mats in the lying area bring about improvements in some aspects of claw and leg health in fattening pigs, whereas there is no effect of floor perforation.     

Thermal preferences of subtropical Aedes aegypti and temperate Ae. japonicus mosquitoes

Temperature is an important determinant affecting the capacity of disease vectors like mosquitoes (Culicidae) to transmit disease agents. Although the impact of temperature on vector-borne disease dynamics has been studied intensively, the actual temperature encountered by the vector in a heterogeneous landscape is rarely taken into account. If disease vectors have temperature preferences and therefore select specific microhabitats, this would substantially influence key life history traits that determine transmission intensity. The thermal preferences of subtropical Aedes aegypti and temperate Ae. japonicus mosquitoes were investigated in a temperature gradient set-up consisting of a Plexiglas box on top of an aluminium plate on two thermal regulators. Blood-fed (one day after feeding) and unfed (non-blood-fed) mosquitoes were released in small (15–20 °C, 20–25 °C, 25–30 °C) and large (15–30 °C, 30–45 °C) temperature gradients to assess their thermal preferences after 15 min. Additionally, the effect of humidity was investigated in a two-choice chamber setup. Both mosquito species avoided higher temperatures, pronouncedly dangerously high temperatures in the 30–45 °C gradient. At lower temperatures, blood-fed mosquitoes preferred the cooler sides of the 20–25 °C and 25–30 °C gradient, which were all below their rearing temperature. In the lowest gradient of 15–20 °C, no preferences were found. The thermal preference of unfed mosquitoes was similar to that of the blood-fed mosquitoes. No humidity preference or effect of humidity on temperature preferences was observed within the tested range (40–90%). The set-up allows for assessing the thermal preference of mosquitoes under controlled conditions. The observed preference of mosquitoes for cooler temperatures would increase their longevity and slow down pathogen development. If similar microhabitat selection is observed in the field, vector borne disease models should be adjusted accordingly.     

Open-field test behavior of growing swine maintained on a concrete floor and a pasture

Open-field test behaviors of 5 barrows and 5 gilts from each of two housing treatments (N = 20) were recorded for 5-min periods. The hogs had been housed in their respective systems (pasture or concrete floor) for 6 weeks and averaged 18 weeks old at the time of the experiment. The 38 × 198-m pasture (P) contained approximately 70% grass of grazeable length and housed 49 pigs. The 3.7 × 7.6-m concrete feeding floor (FF) was located in an open-front building and housed 34 pigs. The open-field tests were conducted in a 3 × 12-m enclosure on pasture. Data collected include time spent chewing, grazing, nudging, sniffing or rooting, number of vocalizations, and time spent lying, standing walking or trotting. FF pigs spent more time grazing and chewing than did P pigs. Standing time was also greater for FF pigs. Only P pigs lay down during the test period. These findings suggest an increased specific-action potential for grazing behaviors resulted from maintaining the hogs in an indoor housing facility.     

Zur fortpflanzungsbiologie von mesostoma ehrenbergii (Focke, 1836) (Turbellaria)

1. At temperature levels from 10 to 25°C animals from resting eggs produce subitaneous eggs independent on temperature. In contrast animals from subitaneous eggs produce subitaneous eggs dependent on temperature. At a high rate subitaneous eggs are only formed at temperature levels above 20°C.
2. Below 10°C no development occurs in the juveniles. At temperatures of 30/22°C (24.7°C) the first subitaneous eggs are formed after 6–9 days, at 14/9°C (10.7°C) they are formed after 34 days. At different temperature levels the developmental rate of the young is from 10.5 to 42 days. One generation extends over 16.5 (30/22°C) to 75 days (14/9°C). The average egg production is 10–20 subitaneous eggs or 30–60 resting eggs. The maximum egg production of one individual is 50 subitaneous eggs or 84 resting eggs. 50% of the animals have just formed resting eggs, before the juveniles are hatched. Resting eggs in the first egg-batch are formed 6–20 days later than subitaneous eggs. The duration of life is between 65 (30/22°C) and 140 days (19/13°C).
3. Young worms in resting eggs have a dormance period of at least 15–30 days.

At room temperatures (20°C) no juvenile in resting eggs hatches from water. By combining room and refrigerator (3.5°C) temperatures the hatching rate increases to a maximum of 85%. To reach a hatching rate of 50–65% the influence of low temperatures must be at least 30 days. At room temperatures 60% of the young in resting eggs hatch from mud covered with water. Combining high and low temperatures the hatching success is between 67 and 81%, where the highest percentage of the young may hatch at room temperature. Up to 90 days low temperatures cause a maximum hatching rate of 79%. It decreases to approximately 30% after 180 days. At high temperatures resting eggs preserved in 100% moist mud, survive for two months. By adding a period of low temperatures the hatching rate increases to a maximum of 52%. Low temperatures are survived for more than 6 months. Up to 30 days preservation at 3.5°C causes a maximum hatching rate of 61%, up to 12o days it decreases to 30%. At room temperature the young in resting eggs are not resistant against air-dried mud (30–40% rel. air moisture). Combining high and low temperatures air-dried mud is endured 1 month (hatching rate 5–14%). Preservation of 30–120 days at 3.5°C and 70% rel. air moisture result in a hatching rate of 43–61%. li]4. In the open air in Middle-Europe there occur 5–6 generations of M. ehrenbergii per life-cycle. The first generation hatches from resting eggs in May, where the production of subitaneous eggs is independent on temperature. All other generations up to October hatch from subitaneous eggs. The egg-production of those worms is dependent on environmental factors. In summer subitaneous egg production prevails, in autumn resting egg production. The abundance during the life-cycle is dependent on the number of animals which produce subitaneous eggs. Resting eggs are predestinated to endure periods of dryness and cold. The life-cycles of the species M. lingua and M. productum are different from those of M. ehrenbergii in length and in the number of generations. In both species 7 generations occur over 8 to 8.5 respectively 5.5 months. M. nigrirostrum only forms resting eggs. The life-cycle consists of one generation from February/March to May/June.     

The welfare of growing pigs in five different production systems: assessment of feeding and housing

Ninety-one farms were visited over a 2-year period to assess the welfare of growing pigs in five different production systems found either in France or in Spain using the Welfare Quality® protocol. This study focused on animal-based measures as indicators of ‘good feeding’ and ‘good housing’. Multiple Generalized Linear Mixed Models were performed for each measure to evaluate the differences between production systems and to detect possible causal factors. Pigs in the conventional system presented the lowest prevalence of poor body condition, whereas extensive Mallorcan Black pigs and extensive Iberian pigs were associated with a decreased prevalence of bursitis and pig dirtiness. The straw-bedded system presented a lower prevalence of bursitis, but poorer hygiene and more susceptibility of poor body condition than the conventional system. The age of the animals had a significant effect on the appearance of bursitis in the three intensive systems studied. The type of floor was a significant causal factor of bursitis and pig dirtiness in the conventional system and among intensive Iberian pigs. The feeding system was another causal factor of pig dirtiness on more than 50% of the body in the conventional system, whereas pig dirtiness on less than 50% of the body was influenced by the age of the animals. The prevalence of huddling animals in the conventional system was associated with the highest stocking densities and the lowest environmental temperatures. The results indicate that there were important differences between production systems based on animal-based indicators of the good feeding and housing principles. The recording of the age of the animals, type of floor, feeding system, stocking density and environmental temperature can be useful to predict the appearance of a given welfare measure of ‘good housing’ on a farm.     

Further studies on acclimatization to low temperatures in the grain weevils Sitophilus oryzae (L.) and Sitophilus granarius (L.)

The effect of thermal acclimatization on the resting metabolism of adult grain weevils was examined by closely restraining the weevils during respirometry. Sitophilus oryzae (L.) acclimatized to 15°C consumed less oxygen over 11–23°C than 27°C-acclimatized weevils but like amounts over 25–35°C. Similar results were observed with S. granarius (L.). Respiration R–T curves of unrestrained S. oryzae and S. granarius showed no evidence of rotation at temperatures close to their chill-coma thresholds but warm- and cold-acclimatized weevils consumed similar amounts of oxygen when both categories of weevils were in chillcoma. Acclimatizing S. oryzae from 27 to 13.5°C through four, weekly 4.5°C step-transfers lowered the median chill-coma thresholds of the weevils from 8.9 to 6.2°C, increased their life span at 9°C, an unfavourable temperature for this species, from 2 to 8 weeks and lowered their oxygen uptake at 9°C by 19%.     

Thermal preferences in upstream migrating glass-eels of Anguilla anguilla (L.)

The effect of temperature on the migratory behaviour of European glass-eels, Anguilla anguilla, during the first stages of their ascent into inland waters has been investigated. Very little research has documented the thermal preferences of glass-eels, most being directed instead to the study of their thermal resistance and survival. The experimental method adopted aimed at acquiring information on short- and long-term thermal choices and sought to provide evidence of the influence of preceding experiences on choices made during the tests. The results obtained in short-term choices (acute preferendum tests) show a clear preference for flows of water at temperature equal to acclimation temperature rather than for flows at temperatures lower or higher by 3° C. It is sufficient for the glass-eels to remain for about 1 h at a different temperature (acclimation temperature ± 3–4°C) for their subsequent choices to be influenced. When choosing between flows warmer or colder than acclimation water, glass-eels prefer the lower temperature. When the temperature presented is very low (about 3° C) the preference is inverted. There is evidence that the temperature gradient represents one of the main orienting cues. In long-term choices (final preference tests) the experimental apparatus allowed prolonged observation (from 24 to 52 h) of the choices between three shelters, the only difference between these being their internal temperatures. In this situation the glass-eels show a clear preference for temperatures higher than that of the environment. For both intervals of environmental temperature considered (11.0–12.6°C and 14.3–17.3° C) a linear correlation exists between temperature difference and number of choices made for the shelters at higher temperatures. The number of glass-eels choosing a higher temperature is greater in the case of lower environmental temperature. In acute preference tests the thermal stimulation is added to a rheotactic response. The glass-eels find themselves in an analogous situation to that during the ascent. On the other hand, in the second experimental situation the choices are an expression of a pure thermal preference.     

Some effects of light and heat on the feeding and resting behaviour of tsetse flies,Glossina morsitans Westwood

A laboratory investigation was carried out into the effects of light and heat on the feeding and resting behaviour of Glossina morsitans morsitans Westwood. Flies placed in small cages on the ears of rabbits were tested for feeding responsiveness at light intensities of 0, 10, 100, 1000 and 25 000 lux. Feeding occurred at the same rate in darkness as it did in light at up to 1000 lux, but at 25 000 lux was largely inhibited. At 26° C, flies flew to and settled in the light end of a 1.2 m-long choice chamber. As the temperature was raised (by 10° C/hour) they eventually took off and flew directly to the dark end. The temperature at which this skototaxis occurred was strongly negatively correlated with the light intensity: each log unit increase in light intensity (in lux) caused a 2.2° C fall in take-off temperature. Skototaxis occurred at higher temperatures in recently fed female flies than in starved ones.     

Competitive saprophytic colonization of wheat straw

Using the ‘Cambridge method’, the effect of temperature on the colonization of wheat straw by Fusarium culmorum, Gibberella zeae, Cochliobolus sativus and C. spicifer was studied. Within the range 10–30 °C, saprophytic colonization by the four fungi was favoured by lower temperatures. This could not be attributed to the effect of temperature on the growth of the fungi in pure culture, but was probably caused by increased antagonism at higher temperatures from the general soil microflora. Contrary to previous indications, C. sativus strongly colonized straw under suitable environmental conditions.     

Temperature coupling of mate attraction signals and female mate preferences in four populations of Enchenopa treehopper (Hemiptera: Membracidae)

Variation in temperature can affect the expression of a variety of important fitness‐related behaviours, including those involved with mate attraction and selection, with consequences for the coordination of mating across variable environments. We examined how temperature influences the expression of male mating signals and female mate preferences—as well as the relationship between how male signals and female mate preferences change across temperatures (signal–preference temperature coupling)—in Enchenopa binotata treehoppers. These small plant‐feeding insects communicate using plantborne vibrations, and our field surveys indicate they experience significant natural variation in temperature during the mating season. We tested for signal–preference temperature coupling in four populations of E. binotata by manipulating temperature in a controlled laboratory environment. We measured the frequency of male signals—the trait for which females show strongest preference—and female peak preference—the signal frequency most preferred by females—across a range of biologically relevant temperatures (18°C–36°C). We found a strong effect of temperature on both male signals and female preferences, which generated signal–preference temperature coupling within each population. Even in a population in which male signals mismatched female preferences, the temperature coupling reinforces predicted directional selection across all temperatures. Additionally, we found similar thermal sensitivity in signals and preferences across populations even though populations varied in the mean frequency of male signals and female peak preference. Together, these results suggest that temperature variation should not affect the action of sexual selection via female choice, but rather should reinforce stabilizing selection in populations with signal–preference matches, and directional selection in those with signal–preference mismatches. Finally, we do not predict that thermal variation will disrupt the coordination of mating in this species by generating signal–preference mismatches at thermal extremes.