Masking ability of CAD-CAM resin-matrix ceramics with different translucencies and thicknesses combined with four cement shades against varying background colors when facing veneer restorations.

BACKGROUND: To evaluate the comprehensive effect of translucency, thickness, cement shades, and background color on the masking ability of resin-matrix ceramic veneer restorations. METHODS: Resin-matrix ceramic specimens with 2 translucencies (LT, HT) and 3 thicknesses (0.5, 1.0, and 1.5 mm) were made of Upcera Hyramic (A2 shade). Cement specimens were made of Variolink N in 4 shades (yellow, white, transparent, and bleach XL). Five background specimens were made of IPS Natural Die Material in 5 shades (ND1, ND2, ND3, ND4, and ND5). Color coordinates of 120 subgroups (n = 5) of combined specimens composed of different ceramic, cement, and background specimens were obtained using a spectroradiometer. Color difference (ΔE00) compared with a 4-mm thick specimen of LT and HT ceramics was calculated and four-way ANOVA was used for statistical analysis (α = 0.05). RESULTS: Translucency, thickness, cement shade, background color, and their interaction had significant effects on ΔE00 (p < 0.001). ΔE00 values of HT groups were always higher than that of LT groups and were greater than 1.8 against all background colors. ΔE00 values of LT groups could be achieved to be less than 1.8 with appropriate thickness and cement shade. ΔE00 value decreased with increasing ceramic thickness. The effect of cement shade on ΔE00 had no obvious regularity, but ΔE00 values of bleach XL cement shade group were always lower than other cement shade groups under ND3 and ND5 background color. CONCLUSIONS: The masking ability of CAD-CAM resin-matrix ceramics can be simultaneously affected by translucency, thickness, cement shade, and background color. Resin-matrix ceramics with low translucency has a better masking ability than that with high translucency. The masking ability of CAD-CAM resin-matrix ceramics increase with increasing thickness. Cement shade has less impact on the final color of resin-matrix ceramic restorations.

Red Backgrounds Enhance Dominance in Human Faces and Shapes.

Red color signals dominance in both animals and humans. This study investigated whether a red background color influences the perception of dominance in human faces and geometric shapes. The facial stimuli consisted of computer-generated faces, quantitatively morphed into nine levels of dominance, ranging from less dominant to more dominant. This included East-Asian female faces in Experiment 1 and male faces in Experiment 2. The face stimuli were presented against three background colors: red, green, and gray. Participants were instructed to categorize the faces as either obedient or dominant by pressing the corresponding labeled keys. The results showed that faces were more likely to be perceived as dominant when presented against a red background than against green or gray backgrounds, for both female and male faces. Additionally, two questionnaire surveys showed that the perception of dominance also increased for shapes presented against a red background. However the effect of red diminished in the absence of the actual perception of the color red. These results suggest that the perception of dominance in both human faces and objects is enhanced by the presence of red, possibly due to evolutionary factors related to the perception of red.

Effects of Water Temperature on the Body Color and Expression of the Genes Related to Body Color Regulation in the Goldfish.

Melanin-concentrating hormone (MCH), melanocyte-stimulating hormone (MSH), and somatolactin (SL) in the hypothalamus-pituitary axis are associated with body color regulation in teleost fish. Although these hormones' production and secretion respond well to light environments, such as background color, little is known about the effects of different water temperatures. We investigated the effects of water temperature, 10°C, 20°C, and 30°C, on body color and the expression of these genes and corresponding receptor genes in goldfish. The body color in white background (WBG) becomes paler at the higher water temperature, although no difference was observed in black background (BBG). Brain mRNA contents of proMCH genes (pmch1 and pmch2) increased at 30°C and 20°C compared to 10°C in WBG, respectively. Apparent effects of background color and temperature on the pituitary mRNA contents of a POMC gene (pomc) were not observed. The pituitary mRNA contents of the SLα gene were almost double those on a WBG at any temperature, while those of the SLß gene (slb) at 30°C tended to be higher than those at 10°C and 20°C on WBG and BBG. The scale mRNA contents of the MCH receptor gene (mchr2) in WBG were higher than those in BBG at 30°C. The highest scale mRNA contents of MSH receptor (mc1r and mc5r) on BBG were observed at 20°C, while the lowest respective mRNA levels were observed at 30°C on WBG. These results highlight the importance of temperature for the endocrinological regulation of body color, and darker background color may stabilize those endocrine functions.

Body composition estimates using a 2D image analysis system across different environmental conditions: An agreement study.

PURPOSE: This study examined the agreement between %Fat measurements using a smartphone-based application (IMAGE) across different environmental conditions. METHODS: A single reference image was obtained using an 8 MP smartphone camera under Ambient Light in front of a white background. Additional photos were obtained using a 0.7 MP, 5 MP, and 12 MP smartphone cameras; low-, moderate-, and bright-lighting conditions; and various color backgrounds including black, green, orange, and gray. RESULTS: %Fat measured using the 0.7 MP camera (27.8 ± 6.2 %Fat) was higher than the reference (26.8 ± 6.1 %Fat) (p < 0.001). The black (32.0 ± 12.0 %Fat), green (27.5 ± 6.3 %Fat), and gray (27.8 ± 6.3 %Fat) backgrounds yielded higher %Fat than the white (p = 0.03, 0.01, and 0.001). All camera, lighting, and background conditions were strongly correlated with the reference (all intraclass correlation coefficient [ICC] >0.98, all standard error of the estimate [SEE] <1.5 %Fat, all p < 0.001), except the black background which yielded poorer agreement with the white background (ICC = 0.69, SEE = 4.5%, p < 0.001). CONCLUSION: %Fat from IMAGE were strongly correlated across various environmental conditions.

Transcriptome analysis reveals candidate miRNAs involved in skin color differentiation of juvenile Plectropomus leopardus in response to different background colors.

Red skin color in Plectropomus leopardus is important to its ornamental and economic value. However, the color of P. leopardus can change during the rearing process, darkening and turning black due to the influence of environmental background color. The underlying molecular mechanisms that regulate this phenomenon remain unclear. MicroRNAs (miRNAs) are endogenous, small non-coding RNAs that play important roles in numerous biological processes, such as skin differentiation and color formation in many animals. Therefore, we performed miRNA sequencing of P. leopardus skin before (initial) and after rearing with three different background colors (white, black, and blue) using Illumina sequencing to identify candidate miRNAs that may contribute to skin color differentiation. In total, 154,271,376 clean reads were obtained, with over 92 % of them successfully mapped to the P. leopardus reference genome. The miRNA length distributions of all samples displayed peaks around a typical length of 22 nt. Within these sequences, 243 known and 287 novel miRNAs were identified. A total of 65 significantly differentially expressed miRNAs (DEMs) were identified (P < 0.05), including 40 known DEMs and 25 novel DEMs. These DEMs included novel_561, miR-141-3p, and miR-129-5p, whose target genes were primarily associated with pigmentation related processes, including tyrosine metabolism, melanogenesis, and the Wnt signaling pathway. These findings shed light on the potential roles of miRNAs in the darkening of skin color in P. leopardus, thus enhancing our understanding of the molecular mechanisms involved in skin pigmentation differentiation in this species.

Red biases sex categorization of human bodies.

Color is associated with gender information (e.g., red-female). However, little has been known on the effect of color on sex recognition of human bodies. This study aimed to investigate whether the color red could influence the categorization of human bodies by sex, and the effect of contextual information. Visual stimuli were created using body silhouettes varying along the waist-to-hip ratio from female to male shapes. These stimuli were presented in conjunction with red, green, and gray colors, which were used either as body color (Experiment 1) or background color (Experiment 2). Participants were instructed to categorize the sex of the body stimuli as either male or female by pressing labeled keys. The results showed that when red was used as a body color, it induced a bias toward feminine body perception, while when used as a background color, it induced a bias toward masculine body perception. Thus, the color red influenced the sex categorization of human bodies, which being modulated by contextual information. These findings provided novel insights into the effect of contextual color cues in sex recognition of human bodies.

Weighted correlation network analysis of the genes in the eyes of juvenile Plectropomus leopardus provide novel insights into the molecular mechanisms of the adaptation to the background color.

Plectropomus leopardus is a valuable marine fish whose skin color is strongly affected by the background color. However, the influence of the visual sense on the skin color variation of P. leopardus remains unknown. In the present study, transcriptome analysis was used to examine the visual response mechanism under different background colors. Paraffin sections of the eyes showed that the background color caused morphological changes in the pigment cells (PCs) and outer nuclear layer (ONL) and the darkening of the iris color. The transcriptome analysis results indicated that the gene expressions in the eyes of P. leopardus were significantly different for different background colors. We identified 4845, 3069, 5874, and 6309 differentially expressed genes (DEGs) in the pairwise comparisons of white vs. initial, blue vs. initial, red vs. initial, and black vs. initial groups, respectively. Some hub genes and key pathways regulating the adaptive mechanism of P. leopardus's eyes to the background color were identified, i.e., the JAK-STAT, mTOR, and Ras signaling pathways, and the ndufb7, slc6a13, and novel.3553 gene. This adaptation was achieved through the synthesis of stress proteins and energy balance supply mediated by hub genes and key pathways. In addition, the phenylalanine metabolism, tyrosine metabolism, and actin cytoskeleton-related processes or pathways and genes were responsible for iris and skin color adaptation. In summary, we inferred that stress protein synthesis, phenylalanine metabolism, and energy homeostasis were critical stress pathways for P. leopardus to adapt its skin color to the environment. These new findings indicate that the P. leopardus skin color variation may have been caused by the environmental adaption of the eyes. The results provide new insights into the molecular mechanisms underlying the skin color adaptation of P. leopardus.

Evaluating the interactive effects of artificial light at night and background color on tadpole crypsis, background adaptation efficacy, and growth.

Artificial light at night (ALAN) is a global pollutant of rising concern. While alterations to natural day-night cycles caused by ALAN can affect a variety of traits, the broader fitness and ecological implications of these ALAN-induced shifts remain unclear. This study evaluated the interactive effects of ALAN and background color on traits that have important implications for predator-prey interactions and fitness: crypsis, background adaptation efficacy, and growth. Using three amphibian species as our models, we discovered that: (1) Exposure to ALAN reduced the ability for some species to match their backgrounds (background adaptation efficacy), (2) Crypsis and background adaptation efficacy were enhanced when tadpoles were exposed to dark backgrounds only, emphasizing the importance of environmental context when evaluating the effects of ALAN, (3) ALAN and background color have a combined effect on a common metric of fitness (growth), and (4) Effects of ALAN were not generalizable across amphibian species, supporting calls for more studies that utilize a diversity of species. Notably, to our knowledge, we found the first evidence that ALAN can diminish background adaptation efficacy in an amphibian species (American toad tadpoles). Collectively, our study joins others in highlighting the complex effects of ALAN on wildlife and underscores the challenges of generalizing ALAN's effect across species, emphasizing the need for a greater diversity of species and approaches used in ALAN research.

Neuronal responses of melanin-concentrating hormone and corticotropin-releasing hormone to background color in the self-fertilizing fish, Kryptolebias marmoratus.

We examined neuronal responses of hypothalamic melanin-concentrating hormone (MCH) and corticotropin-releasing hormone (CRH) to background color in the self-fertilizing fish, Kryptolebias marmoratus. Fish were individually reared in lidless white or black cylindrical plastic containers for 15 days. The number of MCH-immunoreactive (ir) cell bodies in the nucleus lateralis tuberis (NLT) of the hypothalamus was significantly greater in the white-acclimated fish, while no significant differences were observed in the nucleus anterior tuberis (NAT) of the hypothalamus. Significant differences were not seen in the number of CRH-ir cell bodies in the NLT between the groups. The body of the white- and black-acclimated fish appeared lighter and darker, respectively, compared with the baseline color. In the black-acclimated fish, feeding activity was significantly greater with a tendency toward higher specific growth rate compared with the observations in white-acclimated fish. No significant inter-group cortisol level differences were observed. These results indicate that background color affects MCH neuronal activity in the NLT as well as body color adaptation but does not affect CRH neuronal activity in K. marmoratus.

What coloration brings: Implications of background adaptation to oxidative stress in anurans.

BACKGROUND: Urban development results in habitat destruction, affecting populations of amphibians, the most fragile group of vertebrates. With changes in the environment, these animals become more exposed to light and predators. To enhance their chances of survival, they display plasticity of body coloration. Aside from adaptive benefits, animals exhibiting background matching meet the energetic costs and restrictions of changing body tones. To study the physiological consequences of Hyla arborea tadpole adaptation to background color, we followed oxidative stress parameters after rearing larvae on a constant background (black/white) and after changing the background color. RESULTS: Larvae cultivated for 20 days on constant substrate color exhibited differences in body coloration but without differences in lipid peroxidation (LPO) concentration between dark and pale individuals, suggesting that coloration investment during this period did not induce higher oxidative damage in darker tadpoles. Prolonged exposure of larvae (37 days) to a dark habitat increased antioxidative system defense and LPO concentrations, compared to animals reared permanently in the white surroundings. The positive correlation of oxidative damage with color intensity of individuals points to the physiological consequences of higher investment in the number of pigment cells necessary for dark pigmentation. In individuals faced with non-matching background and change in body coloration, defense system declined and LPO occurred relative to individuals cultivated in white habitat. CONCLUSION: Here, we have pointed to consequences related to background matching and stress that amphibians experienced during chromatic adaptations. Background color change causes a complex physiological response affecting the antioxidative defense parameters. This investigation elucidates the accompanying cost of amphibians' adjustment to an altered environment.

The Effect of Background Color on Skin Color Variation of Juvenile Plectropomus leopardus.

Fish skin color is usually strongly affected by the background color of their environment. The study investigated the effects of five different background colors on the skin color of leopard coral groupers (Plectropomus leopardus). More than 450 juveniles were reared in Blue, Red, Black, White, and Transparent background tanks for 56 days. The paraffin section showed that the skin melanin zone of fish in the White group was smaller, whereas the Black and Red groups (especially Black) were nearly the largest. The apparent skin color of P. leopardus was red on the white background, which darkened in response to the other color backgrounds. The Black group revealed the blackest skin color, followed by the transparent group. Moreover, the White group had the highest L*, a*, and b* values. The melanin content and tyrosinase activity in the dorsal and ventral skin of the Black group were significantly higher than those in the other groups (p < 0.05), and the serum α-MSH level was higher in the Black group as well. The carotenoid and lutein contents showed completely different trends among the experimental groups, as carotenoid content was higher in the Red and White groups, while lutein content was higher in the Transparent group. The expression level of scarb1 was highest in the Blue and White groups, followed by the Transparent group, and lowest in the Black group (p < 0.05). The expression trend of scarb1 was similar to the skin color in different backgrounds, indicating that the background color regulated scarb1 expression level through visual center, then influenced the uptake and transport of carotenoids, then influenced the skin color formation of P. leopardus. Moreover, lighter colors inhibited the formation of melanocytes and had a significant effect on carotenoid and lutein contents. Pigment-related genes were involved in the regulation of fish skin color, and they were affected by background color in P. leopardus. These results indicate that a white background is more conducive to maintaining red skin color in juvenile P. leopardus.

Combining gain-loss frame and background color to increase the effectiveness of online oral health messages: Differences among decision stages.

BACKGROUND: Gain-loss framing is one of the most popular verbal techniques for increasing message persuasiveness. Color is believed to be a compelling visual cue for persuasion purposes. The verbal and visual elements of online health messages are often studied and applied independently of each other, although they may be mutually supportive in a communication process. OBJECTIVE: Drawing on the protection motivation theory, this study aims to examine the effects of the gain-loss frame and background color of online messages as well as their combination on users' threat appraisal and coping appraisal in the context of oral health. The health action process approach, a theoretical model of behavior change, is further introduced to test whether the decision stage moderates the effects of message design on readers' protection motivation. METHODS: An online experiment involving 258 participants, including 119 non-intenders, 47 intenders, and 92 actors, was conducted based on a 2 × 2 between-subject design. Each participant was instructed to read an online oral health message that was communicated with either gain- or loss-framing and displayed on a either red or blue background. The change in one's protection motivation was elicited with the reading task and measured with the differences between the ratings in the pretest and posttest. RESULTS: While there was no significant main effect of gain-loss frame on the participants' oral health protection motivation, the red background was more effective in increasing the participants' coping appraisal than the blue background. In particular, displaying the loss-framed message on a red background was effective in increasing the non-intenders' coping appraisal, but not effective for intenders or actors. CONCLUSIONS: Humans' automous and rapid responses to visual elements (e.g., background color) of messages can be enhanced with the combination of verbal elements and harnessed to achieve message effectiveness. It is also necessary to tailor message visual/verbal design to suit individual decision stage.

Transcriptome Analysis Reveals the Complex Regulatory Pathway of Background Color in Juvenile Plectropomus leopardus Skin Color Variation.

Fish skin color is often strongly affected by background color. We hypothesized that the regulatory mechanism of variations in skin color in P. leopardus is linked to the background color. In this study, we conducted transcriptome analysis of Plectropomus leopardus cultured under different background colors to compare gene expression levels and the important signaling pathways. The RNA-seq analysis yielded 26,675 known mRNAs, 3278 novel mRNAs, and 3179 differentially expressed genes (DEGs). The DEGs related to melanin synthesis were screened out. Some key melanin-related genes were identified, specifically tyr, slc7a11, mc1r, ednrb, dct, tat, and wnt1. These DEGs were mainly involved in melanogenesis, including tyrosine metabolism, the Wnt signaling pathway, and the cAMP signaling pathway. The expression levels of some key genes were upregulated when background color deepened, such as α-msh, wnt, and gf. The α-MSH/cAMP-dependent, Wnt/ß-catenin, and PI3K/Akt signaling pathways were activated, resulting in the accumulation of intracellular mitf. mitf promoted melanin production by binding to the tyr/tyrp1/dct promoter region. In the present study, we explored the molecular mechanism underlying the darkened skin color pattern of P. leopardus, providing a theoretical basis for the molecular mechanism underlying pigmentation in P. leopardus.

Evaluation of drug seeking behavior on nicotine conditioned place preference in zebrafish.

Seeking of drugs is commonly evaluated in a specific environment for assessing drug preference. However, cognitive strategies involved in drug seeking are mostly unknown. To assess the strength of environmental cues that can be associated with nicotine in the zebrafish brain reward circuitry, we have designed herein a modified conditioned place preference (CPP) paradigm. This task was devised to identify salient environmental cues relevant for strong nicotine-environment association and drug seeking induction. During test sessions, background colors of the CPP tank chambers were shifted and preference for colors associated to nicotine was assessed. We have compared several tank designs and different compartment colors. Our findings indicated that zebrafish seeking behavior was strongly dependent on compartment color shades. Combination of red and yellow environments, which were preferred and avoided compartments, respectively, was the most effective design presenting the highest CPP-score. Interestingly, animals that stayed for longer periods in the environment conditioned to nicotine during a first testing interval were also able to follow the background color shade conditioned to nicotine to the other compartment immediately after background colors were relocated between compartments. During a second testing period, zebrafish also stayed for longer periods in the colored compartment paired to nicotine during conditioning. These findings suggest that under salient environmental conditions, zebrafish voluntarily followed a shifting visual cue previously associated with nicotine delivery. Furthermore, our findings indicate that zebrafish exhibit spatial associative learning and memory, which generates a repertoire of conspicuous locomotor behaviors induced by nicotine preference in the CPP task.

Taisho-Sanshoku koi have hardly faded skin and show attenuated melanophore sensitivity to adrenaline and melanin-concentrating hormone.

Introduction: Koi carp, an ornamental fish derived from the common carp Cyprinus carpio (CC), is characterized by beautiful skin color patterns. However, the mechanism that gives rise to the characteristic vivid skin coloration of koi carp has not been clarified. The skin coloration of many teleosts changes in response to differences in the background color. This change in skin coloration is caused by diffusion or aggregation of pigment granules in chromatophores and is regulated mainly by sympathetic nerves and hormones. We hypothesized that there would be some abnormality in the mechanism of skin color regulation in koi carp, which impairs skin color fading in response to background color. Methods: We compared the function of melanin-concentrating hormone (MCH), noradrenaline, and adrenaline in CC and Taisho-Sanshoku (TS), a variety of tri-colored koi. Results and Discussion: In CC acclimated to a white background, the skin color became paler and pigment granules aggregated in melanophores in the scales compared to that in black-acclimated CC. There were no clear differences in skin color or pigment granule aggregation in white- or black-acclimated TS. The expression of mch1 mRNA in the brain was higher in the white-acclimated CC than that in the black-acclimated CC. However, the expression of mch1 mRNA in the brain in the TS did not change in response to the background color. Additionally, plasma MCH levels did not differ between white- and black-acclimated fish in either CC or TS. In vitro experiments showed that noradrenaline induced pigment aggregation in scale melanophores in both CC and TS, whereas adrenaline induced pigment aggregation in the CC but not in the TS. In vitro administration of MCH induced pigment granule aggregation in the CC but not in the TS. However, intraperitoneal injection of MCH resulted in pigment granule aggregation in both CC and TS. Collectively, these results suggest that the weak sensitivity of scale melanophores to MCH and adrenaline might be responsible for the lack of skin color change in response to background color in the TS.

Bioinspired Color Elastomers Combining Structural, Dye, and Background Colors.

Organisms that alter body color undergo color change in response to environmental variations and stimuli by combining chromatophores that develop colors by various mechanisms. Inspired by their body color changes, we can develop sensors and optical materials that change colors in response to multiple stimuli, such as mechanical and light stimuli. In this study, we report on bioinspired composite elastomers that exhibit various color changes as the pigment color, structural color, and background color change. These composite elastomers exhibit structural colors due to their fine structures in which fine silica particles form colloidal crystals, and the structural colors reversibly change as the elastomers elongate. Furthermore, photochromic dyes can reversibly change color depending on the wavelength of irradiated light when they are introduced to the composite elastomers. Since the structural color is one of the three primary colors of light and the pigment color is the color that corresponds to the three primary colors of a pigment, each color becomes vivid when the background color is black or white. Thus, we clarify that the composite elastomers exhibit various color changes due to the combination of structural color change in response to the mechanical stimulus, pigment color change in response to light irradiation, and background color change.

Effects of background color and feeding status on the expression of genes associated with body color regulation in the goldfish Carassius auratus.

Alpha-melanocyte-stimulating hormone (α-MSH), a peptide derived from proopiomelanocortin (POMC), and melanin-concentrating hormone (MCH), act as neuromodulators and regulate food intake in vertebrates. In teleosts, these peptides are also involved competitively in body color regulation; α-MSH induces a dark body color, while MCH induces a pale body color. Similarly, members of the growth hormone (GH) family, somatolactin (SL) and prolactin (PRL), which are involved in the regulation of energy metabolism, are also associated with body color regulation in teleosts. Since these hormones are involved in both body color regulation and energy metabolism, it is possible that feeding status can affect body color. Here, we examined the effects of fasting on the response of goldfish body coloration to changes in background color. Goldfish were acclimated for one week in tanks with a white or black background under conditions of periodic feeding or fasting. The results showed that body color and expression levels of pmch1 and pomc were affected by background color, irrespective of feeding status. Expression levels of sla were higher in fish maintained in tanks with a black background than in tanks with a white background, and higher in the fasted fish compared to the fed fish. However, the pattern of slb expression was almost the opposite of that observed in sla expression. The expression levels of gh and prl in the pituitary, and pmch2a and pmch2b in the brain, were not affected by background color. These results suggest that MCH, α-MSH, SLα, and SLß might be involved in body color regulation and that they are affected by background color in goldfish. The results also suggest that feeding status may affect body color regulation via SLα and SLß, although these effects might be limited compared to the effect of background color.

Electrophysiological Correlates of Processing Warning Signs With Different Background Colors: An Event-Related Potentials Investigation.

Warning signs, as a type of safety signs, are widely applied in our daily lives to informing people about potential hazards and prompting safe behavior. Although previous studies have paid attention to the color of warning signs, they are mostly based on surveys and behavioral experiments. The neural substrates underlying the perception of warning signs with different background colors remain not clearly characterized. Therefore, this research is intended to address this gap with event-related potentials (ERPs) technique. Warning signs with three different background colors (i.e., white, yellow, and blue) were used in the experiment. The results showed that the perceptual differences between different warning signs were present in the form of differential ERPs components (P1, N1, P2, N2, and P3) though subjects were not required to explicitly attend to the warning signs.

Factors Affecting Thanatosis in the Braconid Parasitoid Wasp Heterospilus prosopidis.

Thanatosis, also called death feigning, is often an antipredator behavior. In insects, it has been reported from species of various orders, but knowledge of this behavior in Hymenoptera is insufficient. This study examined the effects of sex, age (0 or 2 days old), temperature (18 or 25 °C), and background color (white, green, or brown) on thanatosis in the braconid parasitoid wasp Heterospilus prosopidis. Thanatosis was more frequent in 0-d-old individuals and in females at 18 °C. The duration of thanatosis was longer in females, but this effect of sex was weaker at 18 °C and in 0-d-old individuals. The background color affected neither the frequency nor duration. These results were compared with reports for other insects and predictions based on the life history of this species, and are discussed from an ecological perspective.