Susceptibility of Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) to Sulfur

The parasitic mite Acarophenax lacunatus (Cross & Krantz) is a potentially important biocontrol agent of stored grain insect pests, but its presence in insect mass rearing is undesirable. This study was carried out to evaluate the susceptibility of A. lacunatus to sulfur. The experimental units were petri dishes containing 30 g of whole wheat grains infested with 30 adults of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae). The treatments consisted of pulverizing the wheat grains with sulfur, at 0, 0.15, 0.3, 0.6, 0.9 and 1.2 mg a.i./g, in five replicates. Three inoculations of A. lacunatus were carried out in each petri dish at five, ten and fifteen days after infestation with R. dominica. The petri dishes were stored for 60 days at 30 +/- 1 degree Celsius, 60 +/- 5% R.H. and 24h scotophase. The parasitic mite was susceptible to all sulfur doses used in the test. The number of eggs of R. dominica parasitized by A. lacunatus showed a decreasing trend with the increase in doses of sulfur, as did the number of physogastric females of the mite. The mite showed a negative correlation of their instantaneous rate of increase with sulfur dose. No mites developed at sulfur doses higher than 0.3 mg a.i./g. The susceptibility of A. lacunatus to sulfur is an important aspect to consider in the control of this parasitic mite in colonies of R. dominica. In addition, this control method has low cost and is easy to use.     

Interaction of the temperature with the parasite mite Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) on the development of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae)

The objective of this study was to evaluate the effect of different temperatures with the association of the mite Acarophenax lacunatus (Cross & Krantz) on the population suppression of Rhyzopertha dominica (Fabricius). The experimental units were petri dishes containing 40 g of whole wheat grains (13% moisture content) infested with 10 adults of R. dominica, under the temperatures of 20, 25, 30 and 35 masculineC, with or without A. lacunatus, in five replicates. Relative humidity of 60 +/- 5% and escotophase of 24h were used for all temperatures. Five days after the infestation, five mites were inoculated in each experimental unit. The evaluations were carried out at 20, 40, 60, 80, 100 and 120 days after R. dominica infestation. The interaction of the temperature with the parasite A. lacunatus was an important tool for the population suppression of R. dominica. In temperatures higher than 25 masculineC, however, despite the reduction of the immature stages of R. dominica, there was a high grain weight loss after 120 days. The maintenance of the temperature of the wheat grains stored at 20 masculineC can be used to complement the biological control of R. dominica with A. lacunatus.     

Interaction between Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) and Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) on Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae)

The interaction between Acarophenax lacunatus (Cross & Krantz) and Anisopteromalus calandrae (Howard) may be a promising tool for the integrated pest management of stored grain insect pests. The objective of this study was to evaluate the compatibility of these two natural enemies on Rhyzopertha dominica (Fabricius). The experimental units were petri dishes (140 x 10 mm) containing 30 g of whole wheat grains (13% water content) infested with 20 adults of R. dominica. The treatments consisted of inoculation of A. lacunatus and A. calandrae, separately and associated, in eight replicates. Three inoculations of five adult females of the natural enemies were carried out in each petri dish at five, ten and fifteen days after the infestation of R. dominica. All treatments were stored during 60 days in environmental chamber at 30 +/- 1 degrees C, 60 +/- 5% relative humidity and 24 h scotophase. The smallest numbers of physogastric females of A. lacunatus and of adults of A. calandrae were obtained when the natural enemies were in association. The use of A. calandrae alone demonstrated a low instantaneous rate of increase (r(i)) of R. dominica and a high protection of the wheat grains. The association of A. calandrae with A. lacunatus led to the lowest number of immatures of R. dominica. These results demonstrate the importance of this interaction as a tool of for the integrated management of R. dominica in stored wheat grains.     

Biology of Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) on Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae)

The aim of the present study was to assess the effect of six different temperatures on the development of Acarophenax lacunatus (Cross & Krantz) using eggs of Tribolium castaneum (Herbst) and Cryptolestes ferrugineus (Stephens) as hosts. The temperature affected the development of A. lacunatus. The largest values for the progeny (19 mites in T. castaneum and 15 mites in C. ferrugineus) were obtained at about 30 degrees C, as also observed for the net reproductive rate (Ro), which revealed that the A. lacunatus population increased 18 times in T. castaneum and 14 times in C. ferrugineus in a generation. The intrinsic rate of increase (r m) gradually increased with temperature, reaching the maximum value at 35 degrees C in T. castaneum (1,608) and C. ferrugineus (1,289). The generation time was negatively correlated with temperature, ranging from 1,60 to 4,85 days in T. castaneum and from 1,96 to 5,34 days in C. ferrugineus. These results suggest that the mite A. lacunatus may be used in programs of biological control of T. castaneum and C. ferrugineus in the tropics.     

Dispersion of Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) in stored wheat, under artificial conditions

Ability to disperse is fundamental for a successful natural enemy in a stored grain environment. The objective of the present work was to assess whether the mite Acarophenax lacunatus (Cross & Krantz) disperses in a grain mass to locate its host Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae). The experiment was based on the release of physogastric females of A. lacunatus on the surface of glass containers containing Petri dishes with 20 adults of R. dominica at different depths (4, 8, 12, 16 and 20 cm). The Petri dishes were covered with voil to prevent insect escape. Dispersion of the progeny of these physogastric females was assessed 10, 20 and 30 days after the beginning of the experiment. The mites were able to disperse and they were observed at every depth and at every period of assessment. Nonetheless, the number of A. lacunatus decreased with the increasing depth, with highest values observed at the lowest depths after 20 and 30 days of storage. It is possible that evaluations conducted in periods longer than 30 days of the parasite release could demonstrate an increase in parasitism at higher depths. The results indicated that A. lacunatus actively disperse for up to 20 cm on its own, without the assistance of its host for phoresy.     

Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia Mello-Leitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae)

In this study, the maximum and minimum lethal temperatures (LT₅₀) of L. intermedia and L. laeta were determined in two treatments: gradual heating (25–50°C) and cooling (25°C to −5°C), and 1 h at a constant temperature. In gradual temperatures change, L. intermedia mortality started at 40°C and the LT₅₀ was 42°C; for L. laeta, mortality began at 35°C and the LT₅₀ was 40°C. At low temperatures, mortality was registered only at −5°C for both species. In the constant temperature L. intermedia showed a maximum LT₅₀ at 35°C and L. laeta at 32°C; the minimum LT for both species was −7°C.     

Survival of the mite Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) under starvation

The ability of a natural enemy to tolerate starvation increases its chances to survive in the absence of food, what is an important factor for its success in storage grain environment. The objective of the present work was to assess the survival of Acarophenax lacunatus (Cross & Krantz) in the absence of food. The experiment used individualized physogastric females of A. lacunatus placed in petri dishes (5 cm diameter) and maintained at 20, 25, 28, 30 and 32 degrees C, 50+/-5 % R.H. and 24h scotophase. The number of live mites was recorded every 6h thus assessing the progeny survival without food at different temperatures. The mites died within 60h at the temperatures 30 degrees C and 32 degrees C, while they survived for up to 108h at 20, 25 and 28 degrees C. The mean lethal time for death was 58.6h for the lowest temperatures and 39.3h for the highest temperatures. Thus, A. lacunatus subjected to starvation lived longer under lower temperatures, what is probably due to its lower metabolism. In contrast, the mites survived for about 90h at 28 degrees C, temperature commonly observed in tropical and subtropical climates, what may favor their use as control agents of stored product insects in these regions.     

Temperature-dependent Development of Four Egg Parasitoid Trichogramma Species (Hymenoptera: Trichogrammatidae)

Trichogramma species have been successfully utilized for biocontrol of several lepidopteran pests worldwide. The development, survival and progeny production of two Kenyan species' Trichogramma bournieri Pintureau & Babault and Trichogramma sp. nr. mwanzai Schulten & Feijen (collected from Kenya), Trichogramma evanescens Westwood (Germany) and Trichogramma chilonis Ishii (India) was studied at four constant temperatures (13, 18, 25 and 34°C) with the 011 aim of assessing the relative biotic potential of the two native species for 011 biocontrol of Helicoverpa armigera and Plutella xylostella in Kenya. The study was conducted at the Institute 011 for Biological Control (BBA), Darmstadt, Germany. The Trichogramma species tested showed variations 011 in fertility, developmental time, percent emergence, progeny production and sex ratio 011 at the four temperature regimes. Fertility decreased as temperature increased from 25 to 34°C. 011 T. chilonis and T. evanescens completed development at all temperatures tested, but T. 011 bournieri and T. sp. nr. mwanzai failed to complete development at 13°C. The developmental 011 period for all the species decreased as the temperature increased. The duration of development from 011 oviposition to adult emergence varied from 8 days to 12 weeks shorter at 34°C than at 011 13°C for T. chilonis and T. evanescens . For the various temperatures tested, a linear model was 011 satisfactory for egg to adult development at P = 0.05 for T. chilonis and T. evanescens . The 011 lower temperature thresholds for development and duration in degree-days were 8.83°C and 188 for 011 T. chilonis and 9.23°C and 192 for T. evanescens , respectively. For all temperatures tested, 011 T. sp. nr. mwanzai had the highest preimaginal survivorship. Adult emergence was lower at 13°C and 34°C than at 011 18 and 25°C. The highest fertility (mean ±SE) (50.37 ±2.32 adult 011 female -1 ) and progeny production (44.03 ±2.02 adult female -1 ) was recorded at 25°C for 011 T. evanescens . Sex ratio was biased towards female at all temperatures in T. bournieri and T. chilonis . 011 At all temperatures tested, T . sp. nr. mwanzai produced more males than females. For all species tested, 011 favourable parasitism was between 18 and 25°C. The results from this study will be useful for mass rearing purposes as well as for future field release programmes.     

Influence of temperature on life-table parameters of Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae) fed on Tetranychus urticae Koch

The influence of temperature on life-table parameters, fecundity and survivorship of the predatory ladybird, Stethorus gilvifrons , fed on Tetranychus urticae was determined at seven constant temperatures of 15°C, 20°C, 25°C, 28°C, 30°C, 35°C and 40°C. No development was observed at 40°C, thus being regarded as the threshold for the development of S. gilvifrons . The results indicate a significant decrease in male and female longevity with increasing temperature from 15°C to 35°C. The longest and shortest longevity were 18.40 and 12.75 days for males and 17.40 and 8.80 days for females, respectively. The intrinsic rate of natural increase ( r _m ) and the net reproductive rate ( R ₀) of S. gilvifrons linearly increased with increasing temperatures from 15°C to 35°C, while the mean generation time ( T ) and doubling time (DT) decreased linearly within this temperature range. The highest values of r _m (0.240 females/female/day) and R ₀ (59.27 females/female) and the lowest mean generation time (17.01 days) and DT (2.88 days) were recorded at 35°C. The maximum (185.50 eggs) and minimum (25.50 eggs) measurement of total fecundity was also recorded at 35°C and 15°C, respectively. The results indicate that temperature greatly affected fecundity, survivorship and life-table parameters of S. gilvifrons , and that 35°C is a suitable temperature for population growth of this predator.     

Effect of temperature on developmental time and longevity of Psyttalia cosyrae (Hymenoptera: Braconidae)

Psyttalia cosyrae (Wilkinson) (Hymenoptera: Braconidae) is a koinobiont, solitary larval-pupal parasitoid of Ceratitis cosyra (Walker) (Diptera: Tephritidae), and possibly other tephritid fruit flies. The effect of temperature on developmental time and longevity of this parasitoid was investigated and the thermal requirement at six constant temperatures (15±0.5, 20±0.5, 25±0.5, 27±0.5, 30±0.5, and 33±0.05°C) and 60-70% R.H was determined. The developmental rate increased with an increase in temperature. Females took a longer time to complete development than males at all temperatures tested. Development from egg to adult emergence required 244 degree-days (DD) above a thermal threshold of 11.9°C for both sexes pooled, 233 DD above 12.0°C for males and 256 DD above 11.6°C for females. Adult longevity was affected by temperature, and females lived longer than males at all temperatures tested.     

Effect of temperature on life history of the predatory mite Amblyseius (Neoseiulus) californicus (Acari: Phytoseiidae)

Amblyseius (Neoseiulus) californicus is an indigenous mite in Japan that feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of A. californicus on a diet of eggs of Tetranychus urticae (red form). More than 97.3% of A. californicus eggs hatched and more than 81.6% of newly hatched larvae attained maturity at temperatures between 15 and 35 degrees C. Females oviposited at 37.5 degrees C, but no eggs hatched. At 40 degrees C, no females laid eggs. The lower threshold temperature from egg to oviposition was 10.3 degrees C and the thermal constant was 86.2 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between 21 and 28. At 25 degrees C, females laid a mean of 41.6 eggs during a mean oviposition period of 19.4 days. The intrinsic rates of natural increase (rm) were 0.173 at 20 degrees C, 0.274 at 25 degrees C and 0.340 at 30 degrees C.     

Life table and predation of Neoseiulus longispinosus (Acari: Phytoseiidae) on Oligonychus coffeae (Acari: Tetranychidae) infesting tea

Life table and predation of the predatory mite Neoseiulus longispinosus (Evans) on the red spider mite (RSM), Oligonychus coffeae (Nietner), a major pest of tea in India, were studied in the laboratory. Developmental time from egg to adult varied from 4 to 14 days at 30 to 15 °C, respectively; at 35 °C no larva survived. Survival of immature stages was more than 94 % at all temperatures. Threshold temperature for development of immature stages of females and males was 10 and 9.9 °C, respectively, and thermal constant was 84.03 degree-days for females and 80 for males. Sex ratio was female biased and temperature (20–30 °C) had no clear effect on sex determination. Egg hatchability was 73 % at 35 °C and >97 % at lower temperatures. Average number of eggs laid per female/day was higher at 30 °C than at 20 or 25 °C. The highest net reproductive rate (R ₀) was 40.7, at 20 °C. Mean generation time (T) decreased from 28 to 13 days with temperature increasing from 20 to 30 °C. Weekly multiplication (6.5) and intrinsic rate of natural increase (r _m ) (0.268) were highest at 30 °C. Males lived longer than females at every temperature tested. Longevity was highest at 20 °C (50 days for females and 55 for males). Survival and longevity were adversely affected by temperature above 30 °C. Daily consumption of prey increased with the advancement of predator’s life stages; adult females consumed the highest numbers of prey items, preferably larvae and nymphs.     

Environmental Effects on the Development and Survival of the Scale Insect Abgrallaspis cyanophylli (Signoret) (Homoptera: Diaspididae) with Reference to its Suitability for Use as a Host for Rearing Biological Control Agents

Developmental and survival rates of the locally important diaspidid pest, Abgrallaspis cyanophylli (Signoret) reared on Solanum tuberosum L . tubers were examined under light and dark conditions; humidities of 33, 53, 62 and 75% relative humidity (RH); varying population densities; constant temperatures in the range of 20 to 30oC and at cycling temperatures of 12 h at 14°C and 12 h at 30°C. Developmental rate was slightly lower under constant light conditions but mortality was higher in the dark, particularly amongst the males. At 26°C, there were no differences in developmental rate in relation to the various humidity levels. However, survival was significantly lower at 33% RH, with females suffering higher mortality than males. Population density was found to have no effect on developmental rate or size of the females. Overall mortality increased in line with population density although the result was poorly correlated. Within the range 20-28°C developmental rate increased with rising temperature but decreased at 30°C. Thermal summation and polynomial regression data show a theoretical lower thermal threshold for development of 12.47°C. The thermal constant was 541.7 degree days. Survival was lowest at 20°C and 30°C and highest at temperatures in the median range and under cycling conditions. Male survival was significantly higher than that of the females at 30°C and under the cycling regime of 14/30°C. The results suggest that the optimum conditions for rearing A. cyanophylli on potatoes would be at temperatures in the range 24-26°C and humidities of 55-65% RH.     

Ambient temperature limits and stability of temperature regulation in telemetered male and female rats

Knowing the ambient temperature (T_a) limits of normothermia in laboratory rodents is important because their thermoregulatory responses are useful in studies of physiology, pharmacology and toxicology. The present study assessed the T_a limits of normothermia using radiotelemetry to monitor core temperature (T_c), heart rate (HR), and motor activity (MA) in unrestrained, male and female Long-Evans rats over a 24 h period. Rats were housed individually in acrylic cages with wire-screen tops and bottoms and maintained at T'_as ranging from 12 to 33.5°C for 24 h with food and water provided ad libitum on a 12:12 L:D photoperiod. The limits of normothermia (i.e. where there was no significant change in T_c) were <12–29.5°C for females and 14.5–29.5°C for males. T_c of males at T'_as of 12, 32, and 33.5°C increased significantly above the baseline T_c. Female rats had a lower T_c than males at the warmest and coldest T'_as. HR and MA were generally higher in females at all T'_as. Males appeared to be poorly adapted to thermoregulate at T'_as above 30°C as based on their excessively high T'_cs, low MA, and marked weight loss compared to that of the females. Within the limits of normothermia the stability of T_c regulation (i.e. [(ΔT_c/ΔT_a) × 100]/2) was ±1.3 and ± 0.9% for males and females, respectively, over a 24 h period. These data on the stability of T_c in the male and female rat provide a valuable framework to study the acute and chronic effects of drugs, chemicals and other agents that affect temperature regulation.     

A sexually dimorphic response in supercooling temperature, enhanced by starvation, in the lesser mealworm Alphitobius diaperinus (Coleoptera: Tenebrionidae)

The effect of starvation on supercooling temperature (SCP) distribution was investigated in adults and larvae of Alphitobius diaperinus (Coleoptera: Tenebrionidae).

The mean values for SCPs of adults fed at 20°C were −14.5±2.4°C (31 males) and −10.3±1.3°C (29 females). The distribution of the SCPs of these control adults was unimodal. No significant differences were observed in either mean wet weight or mean dry weight between males and females.

The mean values for SCPs of adults starved for 1 month at 20°C were found to be bimodal due to sexual dimorphism. The mean SCPs for males was lower (−17±2.6°C; 28) than that for females (−11.2±1.8°C; 26). No significant differences were observed in either mean dry weight or wet weight between males and females.

The SCPs of both fed and starved larvae, kept for 1 month at 20°C were −12.3±2.4°C (fed) and −18.0±2.6°C (starved).     

The influence of pH on the viscous behavior of starch-poly(ethylene-co-acrylic acid) complexes

Starch-poly (ethylene-co-acrylic acid) (EAA) complexes were prepared by jet-cooking mixtures of either cornstarch, waxy cornstarch or high amylose cornstarch with aqueous ammonia dispersions of EAA (4% EAA based on the weight of starch). Viscosities (η) were determined at temperatures ranging from 80°C to 22°C, and plots of log η versus 1/T (K⁻¹) were prepared. When cooked with EAA, cornstarch and waxy cornstarch showed major changes in viscous behavior between 50°C and 60°C. Above 50–60°C, viscosity increased markedly with a reduction in temperature; however, viscosity increased slowly below 50–60°C with an apparent activation energy for the process approximating that of water itself. The temperature dependence of the measured viscosity from 80°C to 60°C could be attributed to the large increase in size and complexity of the flowing particles as individual amylopectin molecules were bound together by complexed EAA. Apparently, complexing is essentially complete at 50°C. When high amylose cornstarch was cooked in the absence of EAA, retrogradation produced a sharp increase in log η at temperatures below about 50°C. However, if EAA is present, association between amylose molecules apparently takes place via complex formation rather than retrogradation, since log η increases sharply at about 70–80°C. Also, in contrast to cornstarch and waxy cornstarch, log η versus 1/T plots for high amylose cornstarch did not level off at low temperatures. In general, viscosities increased with the pH of the system, particularly when η was measured at high temperatures. This could result from improved complexing ability of EAA under high pH conditions, possibly due to reduced micelle size and maximum extension of polymer chains from micelle surfaces.     

The effect of temperature and light conditions on diapause induction in a Korean population of Neoseiulus womersleyi Schicha (Acari: Phytoseiidae)

To determine the condition for diapause induction of a Korean population of Neoseiulus womersleyi, combinations of constant temperatures (14, 16, 18, 20 and 25 °C) and photoperiods (0, 8, 10, 12, 14, 16 and 24 h photophase) were used from egg to adult emergence. Diapause induction was determined by reproductive cessation of adult females. Lower temperature and shorter photophase resulted in higher diapause induction. Critical photophases for diapause induction were 10 and 12 h at 18 and 16 °C, respectively. Diapause-induced N. womersleyi adult females consumed significantly fewer eggs of the two-spotted spider mite, Tetranychus urticae, than non-induced females. Field monitoring of N. womersleyi showed that there was no egg-bearing female after 282 Julian date, while a model estimated complete diapause induction at 288 Julian date. Diapause of this predatory mite occurred approximately 2 weeks before diapause of its main prey, T. urticae, in Korean apple orchards. Further study perspectives are discussed relative to the spider mite biological control system in fruit orchards.     

Thermal requirement for development of Sancassania rodionovi (Acari: Acaridae) on mushrooms

The free-living mite species Sancassania rodionovi (Zachvatkin) (Acari: Acaridae), is a serious pest of mushrooms in Iran. Studies were conducted to examine the development of this mite in relation to temperature on two mushroom species: Agaricus bisporus Lange (button mushroom) and Pleurotus ostreatus Kummer (oyster mushroom). The developmental time of this acarid mite was studied at eight constant temperatures, ranging from 5 to 40 degrees C, and developmental rates were modeled as a function of temperature. Sancassania rodionovi completed immature development in 17.35 +/- 0.58 and 20.17 +/- 0.88 d at 25 degrees C on button and oyster mushrooms, respectively. When the mite fed on button mushroom, the rate of development increased gradually from 10 to 35 degrees C. Using a linear model, the developmental zero was estimated to be 3.50 degrees C with a thermal constant of 357.14 degree-days. The Logan 10, Briere 1, and Thermodynamic models adequately described the data for this mite and yielded R2 values >0.95; these models provided estimates of optimum temperature for development of 33.244, 32.145, and 32.148 degrees C, respectively. Understanding the influence of temperature on development of S. rodionovi is discussed with respect to pest management in mushroom production.     

Effects of temperature and exposure time on mortality of stored-product insects exposed to low pressure.

The prospects of using low pressure that creates a low-oxygen atmosphere to control stored-product insects were investigated in the laboratory. Eggs, larvae, and pupae of Tribolium castaneum (Herbst), Plodia interpunctella (Hübner), and Rhyzopertha dominica (F.) were exposed to 32.5 mmHg in glass chambers at 25, 33, 37, and 40 degrees C for times ranging from 30 min to 144 h. Time-mortality data were subjected to probit analyses and lethal dose ratios were computed to determine differences in lethal time (LT) values among all species-life stage combinations across the four temperatures. Eggs of each species were the life stage most tolerant to low pressure. Pupae of T. castaneum and R. dominica were more tolerant to low pressure than larvae. In all life stages, mortality increased with increasing exposure time to low pressure and also with increasing temperature. Immature stages of R. dominica were more tolerant to low pressure than immature stages of the other two species. The LT99 for R. dominica eggs was 176.32 h at 25 degrees C and that for P. interpunctella eggs was 28.35 h at the same temperature. An increase in temperature to 33 degrees C resulted in a LT99 < of 85.98 h for R. dominica and 6.21 h for P. interpunctella. Higher temperatures resulted in further significant reduction in lethal time values. Low pressure represents a simple, nonchemical alternative to fumigants such as methyl bromide and phosphine for controlling pests of stored-products or other commodities.     

Effects of Menstrual Cycle and Room Temperature on Color Preference

This study investigated the effects of menstrual cycle on color preference in nine normally menstruating female subjects. They were instructed to choose their preferred color out of 45 Munsell hues every 5 min at ambient temperatures (T_a) of 28°C (630-800 h), from 28°C to 23°C (800-900 h) and at 23°C (900-930 h). Warmer color hues were preferred during the luteal phase than the follicular phase at 28°C, while there did not exist any significant differences at other T_as. The findings that a preference for warmer colors occurred in the luteal phase at 28°C is discussed in terms of the load error between actual core temperature and its setpoint.