Search

Newly developed light-emitting materials and device structure achieved a highly efficient long-lived white tandem OLED with saturated RGB spectra for a wider color gamut. By combining the OLED devices with a color filter and top emission structure, we successfully fabricated a full-specification 8K AMOLED panel with the BT.2020 color gamut.

We developed a deep-blue fluorescent organic light-emitting diode (OLED) that is long-lived and thermally stable. This blue OLED accommodates the BT.2020 color gamut for the first time in the world, and enables a longer lifetime than a conventional one while maintaining comparable power consumption in a full-color OLED panel.

We developed a deep-red phosphorescent organic light-emitting diode (OLED) with (x, y) chromaticity coordinates of (0.709, 0.290), high external quantum efficiency of 27.4%, and higher stability than a conventional red OLED. This device realizes an OLED display with a color-gamut ratio of 101% to the BT.2020 standard.

A top-emission organic light-emitting diode (OLED) with a microcavity structure combined with a blue/yellow tandem structure was developed. A high-resolution active-matrix OLED display with the world's lowest level of power consumption using the tandem OLED with red, green, blue, and yellow subpixels was fabricated.

A top-emission organic light-emitting diode (OLED) with a a microcavity structure combined with a blue/yellow tandem structure was developed. A high-resolution active-matrix OLED display with the world's lowest level of power consumption using the tandem OLED with red, green, blue, and yellow subpixels was fabricated.

It has long been hypothesized that the flower-like appearance of the juvenile orchid mantis is used as visual camouflage to capture flower-visiting insects, although it is doubtful whether such morphological resemblance alone could increase their success in hunting. We confirmed that juvenile female orchid mantes often succeed in capturing oriental honeybees, while adult females often fail. Since most of the honeybees approached the juveniles from the front, we hypothesized that juvenile orchid mantes might attract honeybees by emitting some volatile chemical cues. Gas chromatography-mass spectrometry analyses revealed that the mantes' mandibular adducts contained 3-hydroxyoctanoic acid (3HOA) and 10-hydroxy-(E)-2-decenoic acid (10HDA), both of which are also features of the pheromone communication of the oriental honeybee. We also successfully detected 3HOA emitted in the head space air only at the time when the juvenile mantes were attempting to capture their prey. Field bioassay showed that the Oriental Honeybee predominantly preferred to visit dummies impregnated with a mixture of the appropriate amounts and ratios of 3HOA and 10HDA. We therefore conclude that the juvenile mantes utilize these as allelochemicals to trick and attract oriental honeybees.

In this study, the device structure of a white tandem organic light-emitting diode (OLED) was changed to control the emission area and thereby achieve less luminance decay. A long-life 13.5-inch 4 K flexible c-axis-aligned crystal oxide semiconductor (CAAC-OS) active-matrix OLED with less color shift and high resolution was fabricated using this long-life white OLED, transfer technology, and a CAAC-OS field-effect transistor.

Hydrogen production through steam reforming of ethanol was investigated with conventional supported nickel catalysts and a Ni-containing smectite-derived catalyst. The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition. Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite. The Ni-containing smectite-derived catalyst contains, after H-2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H-2.

In this study, the device structure of a white tandem OLED is changed to control the emission area to achieve less luminance decay. A long-life 13.5-inch 4K flexible CAAC-OS AMOLED with less color shift and high resolution is fabricated using this long-life white OLED, transfer technology, and a CAAC-OS FET.

Caterpillars of the parasitic lycaenid butterfly are often adopted by host ants. It has been proposed that this adoption occurs because the caterpillars mimic the cuticular hydrocarbons of the host ant. This study aimed to examine whether caterpillars of the Japanese lycaenid butterfly Niphanda fusca induce adoption by mimicking their host ant Camponotus japonicus. Behavioral observations conducted in the laboratory showed that most second-instar caterpillars were not adopted, whereas most third-instar caterpillars were successfully adopted by host workers. A chemical comparison detected no characteristic differences in the cuticular hydrocarbon profiles between second- and third-instar caterpillars. However, morphological features of the caterpillars differed between the second and third instars; third-instar caterpillars developed exocrine glands (ant organs) such as tentacle organs and a dorsal nectary organ. These results suggest that multiple chemical signatures, not only cuticular hydrocarbons, may be important for invasion of the host ant nest.

The crystal structure of gallium oxynitride nanowire was investigated by using scanning transmission electron microscopy. Gallium oxynitride nanowire was directly observed to have a biphasic wurtzite and zinc-blende structure. There was a stacking disorder of several atomic layers between the two phases. The new biphasic nanowire formed due to the presence of Ni in starting material because its nitride has a zinc-blende structure whereas gallium oxynitride has the wurtzite structure. Crystal growth of gallium oxynitride nanowires was studied using seed crystals. Seed crystals and amorphous gallium oxide precursors were annealed under different ammonia flow rates to grow gallium oxynitride nanowires. The nanowires grew to length of 150 μm but they did not grow laterally when the ammonia flow rate was 50 mL/min.

Intraspecific variation in mating signals and preferences can be a potential source of incipient speciation. Variable crossability betweenDrosophila melanogasterandD. simulansamong different strains suggested the abundance of such variations. A particular focus on one combination ofD. melanogasterstrains, TW1(G23) and Mel6(G59), that showed different crossabilities toD. simulans, revealed that the mating between females from the former and males from the latter occurs at low frequency. The cuticular hydrocarbon transfer experiment indicated that cuticular hydrocarbons of TW1 females have an inhibitory effect on courtship by Mel6 males. A candidate component, a C25 diene, was inferred from the gas chromatography analyses. The intensity of male refusal of TW1 females was variable among different strains ofD. melanogaster, which suggested the presence of variation in sensitivity to different chemicals on the cuticle. Such variation could be a potential factor for the establishment of premating isolation under some conditions.

We studied the ability of domestic cats to distinguish familiarity based on faecal odours. This was evaluated by comparing the sniffing duration of cats’ own, familiar, and unfamiliar faeces. We found that (1) sniffing durations differed between unfamiliar faeces and the other types of faeces, (2) sniffing durations of faeces of the same unfamiliar individuals decreased over time, and (3) sniffing durations toward unfamiliar faeces increased after change of donors. These results indicate that domestic cats can distinguish the faecal odours based on familiarity. This ability could be adaptive for domestic cats to maintain their social relationships.

Inducible behavioral defense in response to predator cue detection is a key phenomenon in predator–prey interactions. The mechanisms by which prey use chemical/visual cues to avoid predation remain little known. We hypothesized that the distance at which prey species detect predator cues would be related to avoiding detection by the predator. To test this hypothesis, we performed laboratory experiments using an anuran tadpole (Hyla japonica) and a predatory dragonfly nymph (Anax parthenope julius). Tadpole activity level was reduced as a function of exposure to chemical cues from the dragonfly predator, but activity levels did not change when tadpoles were exposed to potential visual cues from the dragonfly. The distances over which tadpoles detected predator cues were longer than those over which the dragonfly predator detected tadpoles. The differences in cue-detection ranges between tadpoles and dragonfly predators are related both to predator avoidance by tadpoles and effective foraging strategies by dragonfly predators. Chemical cue detection as a trigger of inducible defense by prey species may shape predator–prey relationships in aquatic habitats.

Nanowires of gallium oxynitride with wurtzite type structure were grown using seed crystals obtained by ammonia nitridation of an amorphous gallium oxide precursor containing 3 at% nickel additive. The seed crystals on a silica substrate were annealed with the amorphous gallium oxide precursor under ammonia flow to grow gallium oxynitride nanowires. The nanowires grew to lengths of about 150 μm along the seed crystals parallel to the hexagonal c -plane at 750 and 800 °C but they did not grow in the lateral direction. When the growth temperature was increased above 900 °C, the growth direction gradually changed to become parallel with the c -axis with a copresenting of gallium-nitride-like crystals. Room-temperature cathodoluminescence spectra of nanowires grown at 800 °C exhibited strong blue emission at 2.69 eV along with weak band-edge emission at 3.39 eV, similar to those of GaN. The latter emission was intense for nanowires grown at 1000 °C, which had an improved crystallinity and a higher nitride/oxide ion ratio. Nanowires grown at 750 and 900 °C exhibited persistent photoconductivity under UV irradiation at 393 nm.

In eusocial Hymenoptera, workers usually cannot mate but can lay male-destined haploid eggs. In contrast, in many species, worker reproduction is regulated by means of worker policing, which consists of two behavioral categories: aggression towards workers that have developed ovaries, and the destruction of worker-laid eggs. We focused on the latter behavior in the ant Diacamma sp. from Japan, in which a mated worker (gamergate) serves as the functional queen in each colony. An experiment in which we introduced both worker-laid eggs and gamergate-laid eggs from foreign colonies showed that workers preferentially destroyed the worker-laid eggs. This indicates that workers can discriminate worker-laid eggs from gamergate-laid eggs. In contrast, gamergates destroyed all introduced eggs that they discovered. Our chemical analysis of egg surface substances revealed that the worker-laid eggs clearly differed from gamergate-laid eggs in their surface hydrocarbons (SHCs), with the former containing more long-chain components. However, a bioassay to test whether specific components of the SHCs trigger the observed discrimination behavior by workers remains to be done.

We identified the soldier-specific compounds in the Japanese subterranean termite, Reticulitermes speratus, to clarify their ethological roles. Silica gel column chromatography separated one major soldier-specific compound in the hexane fraction accounting for 70-80% of the total amount of the fraction, while cuticular hydrocarbons constituted the rest. We identified the compound as β-selinene by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy. Comparative GC analyses of the major exocrine glands detected the compound in the soldier's frontal gland. Both soldiers and workers made aggregation to the hexane fraction, as well as to the crushed heads and head extract of the soldiers. They did not aggregate to cuticular hydrocarbons, making it likely that β-selinene was the aggregation pheromone in this species. The opportunistic predator of this termite, Lasius japonicus, was also attracted to the compounds. The ant workers, therefore, would use the termite aggregation pheromone as a kairomone for hunting them.

SUMMARY In ants, including Formica japonica, trophallaxis and grooming are typical social behaviors shared among nestmates. After depriving ants of either food or nestmates and then providing them with either food or nestmates, a behavioral change in type and frequency of social interactions was observed. We hypothesized that starvation and isolation affected levels of brain biogenic amines including dopamine (DA) and octopamine (OA) – neuromediators modifying various insect behaviors – and tested the relationship between brain biogenic amines and social behaviors of stressed ants. Ants starved for 7 days contained lower brain DA levels and they did not perform trophallaxis toward nestmates. Feeding starved ants sucrose solution re-established trophallaxis but not brain DA levels. The performance of trophallaxis induced recovery of brain DA content to the level of untreated ants. Ants that were isolated for 2 days displayed markedly increased OA levels, which following nestmate interactions, returned to levels similar to those of control (non-isolated) ants and ants isolated for 1 h. We conclude that: (1) starvation reduced brain DA level but had no significant effect on brain OA (trophallaxis recovered the brain DA levels), and (2) isolation increased brain OA level but had no effect on brain DA (trophallaxis and grooming events recovered the brain OA levels). We suggest that social interactions with nestmates influenced brain biogenic amine homeostasis in stressed F. japonica.

A laboratory experiment was conducted to evaluate temporal and spatial effects of predator chemicals and visual stimuli on the behavioral responses of the Rana japonica tadpoles. Nymphs of the dragonfly Anax parthenope Julius were used as the predator model. Tadpoles exhibited defensive responses by reducing tail movement time associated with their activity when exposed to chemicals from the nymphs. These responses tended to be quicker and stronger as distance from the nymphs decreased. Tadpoles exposed to visual stimuli from the nymphs also exhibited similar but weaker behavioral responses. Our results suggest that in a short distance encounter defensive responses of the R. japonica tadpole are induced more quickly by chemical cues of the predator than by its visual cues. For the tadpole, detecting the dragonfly nymph by chemical cues may function as a trigger for effective predator-avoidance strategy in tadpole-dragonfly nymph interactions.

The exploitation of parental care is common in avian and insect ‘cuckoos’ and these species engage in a coevolutionary arms race. Caterpillars of the lycaenid butterfly Niphanda fusca develop as parasites inside the nests of host ants ( Camponotus japonicus ) where they grow by feeding on the worker trophallaxis. We hypothesized that N. fusca caterpillars chemically mimic host larvae, or some particular castes of the host ant, so that the caterpillars are accepted and cared for by the host workers. Behaviourally, it was observed that the host workers enthusiastically tended glass dummies coated with the cuticular chemicals of larvae or males and those of N. fusca caterpillars living together. Cuticular chemical analyses revealed that N. fusca caterpillars grown in a host ant nest acquired a colony-specific blend of cuticular hydrocarbons (CHCs). Furthermore, the CHC profiles of the N. fusca caterpillars were particularly close to those of the males rather than those of the host larvae and the others. We suggest that N. fusca caterpillars exploit worker care by matching their cuticular profile to that of the host males, since the males are fed by trophallaxis with workers in their natal nests for approximately ten months.

Here we show that larvae of the lycaenid butterfly Niphanda fusca secrete droplets containing trehalose and glycine. These droplets attract the larva's host ants Camponotus japonicus, which collect and protect the larvae. We comparatively investigated gustatory preference for trehalose, glycine or a mixture of the two between host (C. japonicus) and non-host (Camponotus obscuripes) species of ants in behavioral and electrophysiological experiments. Glycine itself induced no taste sensation in either host or non-host ants. The mixture of trehalose plus glycine was chosen as much as pure trehalose by non-host ants. However, the host ants clearly preferred the mixture of trehalose plus glycine to trehalose alone. When we used sucrose instead of trehalose, the mixture of sucrose plus glycine was chosen as much as sucrose alone, in both species. These behavioral data are supported by the electrophysiological responsiveness to sugars and/or glycine in the sugar-taste receptor cells of the ants. Considering that lycaenid butterflies' secretions have species-specific compositions of sugar and amino acid; our results clearly showed that such species-specific compositions of larval secretions are precisely tuned to the feeding preferences of their host ant species, in which the feeding preferences are synergistically enhanced by amino acid.

When predator chemical cues are present, low activity of prey is a commonly seen defensive behavior. However, few studies have explored the functional implications of the defensive behaviors and, thus, elucidated the possible linkages between behavioral responses and its consequences. In this study, we experimentally investigated how behavioral responses of Hyla japonica tadpoles to predator chemical cues affect vulnerability to a dragonfly nymph Anax parthenope julius. The frequency of tadpoles attacked by dragonfly nymphs was lower with chemical cues of predator was present than without chemical cues, and most of attacks occurred when tadpoles were mobile. When tadpoles were exposed to chemical cues, on the other hand, their swimming speed was quicker and swimming distance was longer, respectively, and the rates of being approached of the swimming tadpoles by dragonfly nymph was lower than those not exposed to chemical cues. We found that the tadpoles are induced by predator chemical cues not only to generally lower activity but also to swim in bursts as additional behavior and that the suite of their behavioral responses reduce the vulnerability against dragonfly nymph. Tadpoles can receive information about the predation risks by chemical cues and adjust their defensive behavior accordingly.

We examined the contribution of diurnal and nocturnal pollination to male and female reproductive success in Lilium auratum. Plants were bagged for either 12 h during the day or at night to allow either only nocturnal or only diurnal visitors to forage throughout the flowering period. We found that there was no significant difference in the seed:ovule ratio among diurnally pollinated, nocturnally pollinated, or control flowers. However, in terms of male reproductive success, it was more advantageous for the plants to be pollinated both diurnally and nocturnally: the numbers of pollen grains remaining in diurnally pollinated or nocturnally pollinated flowers were significantly greater than those in control flowers. The total amount of floral volatiles of L. auratum was significantly higher at night than during the day. The constituents of floral scent of all time series examined were mostly monoterpenoids, many of which serve as attractants for nocturnal hawkmoths. Such nocturnally biased floral scent emission of L. auratum might achieve male reproductive success by attracting nocturnal visitors, which may suggest that the relative contribution of floral scent in this species is biased towards male reproductive success.

In freshwater systems, little is known about the characteristics of chemical cues derived from predators which induce defensive responses in prey species. To elucidate traits of predator chemical cues, we examined chemical cues originating from water incubated by the nymph of the dragonfly Anax parthenope julius, which induces low activity as predator-avoidance behavior in tadpoles of two anuran species, the Japanese tree frog Hyla japonica and the winkled frog Rana (Rugosa) rugosa. H. japonica exhibited a reduction in tail movement time as low activity in response to both untreated incubation water and incubation water that had volatile substances removed by freeze-drying. The response threshold of R. rugosa to chemical cues was determined to be one dragonfly nymph in a water volume between 500 and 5,000 ml. We found that chemical cues inducing predator-avoidance behavior in anuran tadpoles have water-soluble non-volatile characteristics. In this study, we devised both the bioassay to assess the effects of chemical cues and the method to enrich the cues by freeze-drying, which can serve as a tool in the process of identification of unknown chemical cues in freshwater predator-prey interaction.

The role of cuticular chemicals in mating behavior and their chemical components were studied in two sympatric flower-visiting longicorn beetles, Pidonia grallatrix and P. takechii. Mating experiments revealed that female cuticular chemicals elicit male mating behavior and that males can discriminate between conspecific and heterospecific females on the basis of contact chemicals. GC-MS analyses of whole-body extracts in the two species and both sexes determined that extracts contained a series of hydrocarbons including n-alkanes, n-alkenes, and methylalkanes. The relative abundance of some hydrocarbons differed between species and sexes, and canonical discriminant analysis showed discrimination of species and sex could be made unambiguously with several compounds. These results imply that the difference in cuticular hydrocarbons facilitates the premating isolation of sympatric Pidonia species.

The flowers of different plant species have diverse scents with varied chemical compositions. Hence, every floral scent does not uniformly affect insect feeding preferences. The blowfly, Phormia regina, is a nectar feeder, and when a fly feeds on flower nectar, its olfactory organs, antennae, and maxillary palps are exposed to the scent. Generally, feeding preference is influenced by food flavor, which relies on both taste and odor. Therefore, the flies perceive the sweet taste of nectar and the particular scent of the flower simultaneously, and this olfactory information affects their feeding preference. Here, we show that the floral scents of 50 plant species have various effects on their sucrose feeding motivation, which was evaluated using the proboscis extension reflex (PER). Those floral scents were first categorized into three groups, based on their effects on the PER threshold sucrose concentration, which indicates whether a fly innately dislikes, ignores, or likes the target scent. Moreover, memory of olfactory experience with those floral scents during sugar feeding influenced the PER threshold. After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects. Considering such empirical effects of scents on the PER threshold, we categorized the effects of the 50 tested floral scents on feeding preference into 16 of all possible 27 theoretical types. We then conducted the same experiments with flies whose antennae or maxillary palps were ablated prior to PER test in a fly group naïve to floral scents and prior to the olfactory experience during sugar feeding in the other fly group in order to test how these organs were involved in the effect of the floral scent. The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences. Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.

We experimentally examined the anti-predator behaviors of tadpoles of the Japanese tree frog, Hyla japonica, to chemical cues released by a cyprinid fish, Gnathopogon elongatus elongatus, and a dragonfly nymph, Anax parthenope julius. Tadpoles exposed to these chemical cues exhibited a similar reduction in activity level. In the presence of the fish chemical cues, however, the tadpoles spent more time in the bottom water layer compared to controls, but did not change their microhabitat choice in the presence of dragonfly nymph chemical cues. These findings suggest that tadpoles of H. japonica have predator-specific behaviors in response to chemical cues from different predators with differential foraging strategies.

Inflorescences of beetle-pollinated plants, such as Araceae, show temporal heat generation, the role of which varies among plants. Homalomena propinqua is a common understory herb in the lowland dipterocarp forests of Borneo. Two species of beetle, Parastasia bimaculata Guerin (Scarabaeidae) and Dercetina sp. (Chrysomelidae), are known to visit inflorescences of this species and subsequently transfer its pollen. In this study, to examine the role of heat generation by inflorescences of H. propinqua, especially as an attractant of pollinators, measurements of the temperature of spadices, behavioral experiments with beetles and chemical analyses of floral scents were carried out. As a result, spadices of H. propinqua exhibited heat generation from 06:30 hours (dawn) until 09:30 hours on both the first and second days of flowering, and this paralleled the arrival of the beetle pollinators. Behavioral tests showed that both beetle pollinators were attracted to spadices significantly more than spathes. Floral scents of H. propinqua were composed of 18 compounds, the main one being 2-butanol, a highly volatile low molecule compound. The amount of floral scents increased temporally between 07:00 hours and 08:00 hours on the first day of flowering, which was consistent with the arrival of pollinators and heat generation by the spadices. These results indicate that the heat generated by spadices may promote temporal volatilization of floral scents, especially highly volatile compounds such as 2-butanol, and as a result temporally attracting beetle pollinators.

Termite feeding behavior and the chemoreception of plant extracts were evaluated to investigate the water extracts from akamatsu (Pinus densiflora), neem (Azadirachta indica), and their equivalent mixture using pseudoergates of Zootermopsis nevadensis. In behavioral assays, termite preference was akamatsu > akamatsu plus neem > neem. Electrophysiological recordings from the taste hairs on labial palps showed vigorous impulse discharge to akamatsu extract but much lower response to neem extract. The response to akamatsu plus neem was mostly the same as that to neem alone, suggesting the neem extracts inhibited the responses to akamatsu extracts. In the present article, we discuss the correlations between the feeding behaviors and the responses at their taste cells to these different extracts.

The pre-calling behavior of female adults of the common cutworm, Spodoptera litura (Lepidoptera: Noctuidae) collected in southern Japan and southeastern Asian coun- tries was investigated. Most females started calling on days 1-4 after adult emergence. In three populations obtained in Saga prefecture in Kyushu mainland, Japan, two different patterns of pre-calling period (PCP) were observed: one was the above-mentioned pattern shown by most individuals, and the other was a pattern in which females sexually matured within several hours after emergence. Diel periodicity was shown in the time of calling activity, and its pattern varied among the populations. Pre-calling period was stable over successive generations in the laboratory.

The alarm pheromone of the ant Camponotus obscuripes (Formicinae) was identified and quantified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Comparisons between alarm pheromone components and extracts from the major exocrine gland of this ant species revealed that the sources of its alarm pheromone are Dufour's gland and the poison gland. Most components of Dufour's gland were saturated hydrocarbons. n-Undecane comprised more than 90% of all components and in a single Dufour's gland amounted to 19 microg. n-Decane and n-pentadecane were also included in the Dufour's gland secretion. Only formic acid was detected in the poison gland, in amounts ranging from 0.049 to 0.91 microl. This ant species releases a mixture of these substances, each of which has a different volatility and function. When the ants sensed formic acid, they eluded the source of the odor; however, they aggressively approached odors of n-undecane and n-decane, which are highly volatile. In contrast, n-pentadecane, which has the lowest volatility among the identified compounds, was shown to calm the ants. The volatilities of the alarm pheromone components were closely related to their roles in alarm communication. Highly volatile components vaporized rapidly and spread widely, and induced drastic reactions among the ants. As these components became diluted, the less volatile components calmed the excited ants. How the worker ants utilize this alarm communication system for efficient deployment of their nestmates in colony defense is also discussed herein.

Communication by means of pheromones plays predominant roles in colony integration by social insects. However, almost nothing is known about pheromone processing in the brains of social insects. In this study, we successfully applied intracellular recording and staining techniques to anatomically and physiologically characterize brain neurons of the ant Camponotus obscuripes. We identified 42 protocerebral neurons that responded to undecane and/or formic acid, components of alarm pheromones that evoke attraction or evasive behavior, respectively. Notably, 30 (71%) of these neurons were efferent (output) or feedback neurons of the mushroom body, and many of these exhibited different responses to formic acid and undecane. Eight of the remaining 12 neurons had arborizations in the lateral and/or medial protocerebrum, which receive terminations of efferent neurons of the mushroom body and from which premotor descending neurons originate. The remaining four neurons were bilateral neurons that connect lateral accessory lobes or dorsal protocerebrums of both hemispheres. We suggest that the mushroom body of the ant participates in the processing of alarm pheromones. Seventeen (40%) of 42 neurons exhibited responses to nonpheromonal odors, indicating that the pheromonal and nonpheromonal signals are not fully segregated when they are processed in the protocerebrum. This may be related to modulatory functions of alarm pheromones, i.e., they change alertness of the ant and change responses to a variety of sensory stimuli.

In humans, appetite is affected by food experiences and food flavors. In the blowflyPhormia regina, we found that feeding threshold to sugar increased in the presence of the odor ofd-limonene and decreased in the presence of the odor of dithiothreitol (DTT). Using these odors as representative nonappetitive and appetitive flavors, we demonstrated the role played by tyramine (TA) in appetite regulation by experiences of food flavors. When fed with sucrose flavored withd-limonene for 5 d after emergence, flies showed subsequent decreased appetite to plain sucrose, whereas when they were fed with sucrose flavored by DTT they showed increased appetite. However, mushroom body (MB)-ablated flies did not show these patterns. This suggests that MB, one of the primary memory centers of the insect brain, is necessary for the flies to apply previous experiences of food flavors to appetitive learning behaviors. In addition, flies' previously acquired decreased or increased appetites showed parallel changes with both octopamine (OA) and tyramine levels in the brain. However, injection experiments with OA, TA, or their agonist and antagonist indicated that TA more directly mediates feeding threshold determination, which was affected by acquired memories of food flavors.

In animal societies, chemical communication plays an important role in conflict and cooperation. For ants, cuticular hydrocarbon (CHC) blends produced by non-nestmates elicit overt aggression. We describe a sensory sensillum on the antennae of the carpenter ant Camponotus japonicus that functions in nestmate discrimination. This sensillum is multiporous and responds only to non-nestmate CHC blends. This suggests a role for a peripheral recognition mechanism in detecting colony-specific chemical signals.

In this paper we report on the chemical basis for trail recognition in Lasius nipponensis. On and near trails in the field, workers became aggressive against conspecific intruders and succeeded in protective contests, while intruders usually avoided confrontation. Such asymmetric interactions were also observed in the laboratory when two non-nestmate workers were sequentially placed in a clean glass dish, while mutual aggression was observed when they were placed simultaneously. Asymmetric aggression was also observed when the workers were placed in a dish previously conditioned by other workers, or when the dish was treated with the hexane rinse of the conditioned dish. The rinse contained a series of hydrocarbons, in which components and proportion were almost identical to those of the cuticular hydrocarbons of the workers, except for a lack of n-alkanes. Amounts of the hydrocarbons that remained on the dish were very small when all the tarsi of the workers were incapacitated. We therefore consider that the hydrocarbons are not adhesion of the cuticular hydrocarbons but secretion from the tarsi of workers, and serve as a key signal for trail recognition in this ant.

Here we report direct evidence that cuticular hydrocarbons are responsible for nestmate recognition in Formica japonica distributing in Southern Honshu in Japan. Workers showed aggressive behavior against foreign workers but not against nestmates. A similar response was observed when a glass dummy was treated with isolated hydrocarbons from foreign workers or nestmates. Among the isolated hydrocarbons, ten hydrocarbon components were identified: five n-alkanes and five (Z)-9-alkenes with odd number of carbons from 25 to 33, in different ratios in different colonies. When synthetic hydrocarbons blended in the same ratio as natural blends were presented to workers, they showed aggressive responses against foreign blends but paid less attention to those of nestmates. Neither n-alkane nor (Z)-9-alkene blends, however, caused aggression response in foreign workers. Thus, both n-alkanes and (Z)-9-alkenes are necessary to discriminate nestmates from foreign conspecifics.

The indirect effects of goldfish chemical cues on tadpole survival and predation by other predators (e.g. dragonfly nymph and crayfish) were tested in a field experiment. Fish chemical cues were found to affect tadpole survival when dragonfly nymphs were present. In contrast, this indirect effect was not detected in the presence of crayfish. The results from the present study found that predators, even without predation, can affect the predatory efficiency of other predators, and that the degree of such an indirect effect may differ among the foraging strategies of predators.

The partnership in the Crematogaster–Macaranga ant–plant interaction is highly species-specific. Because a mutualistic relationship on a Macaranga plant starts with colonization by a foundress queen of a partner Crematogaster species, we hypothesized that the foundress queens select their partner plant species by chemical recognition. We tested this hypothesis with four sympatric Macaranga species and their Crematogaster plant-ant species. We demonstrated that foundress Crematogaster queens can recognize their partner Macaranga species by contact with the surface of the seedlings, that they can recognize compounds from the stem surface of seedlings of their partner plant species, and that the gas chromatographic profiles are characteristic of the plant species. These findings support the hypothesis that foundress queens of the Crematogaster plant-ant species select their partner Macaranga species by recognizing nonvolatile chemical characteristics of the stem surfaces of seedlings.

An aphidiid wasp, Paralipsis eikoae, was associated with both Lasius niger and L. sakagamii attending the wormwood root aphid Sappaphis piri. An L. sakagamii worker was observed carrying a winged female P. eikoae to its nest with its mandible, but it did not kill the wasp. Once accepted by the ants, the wasp often mounted and rubbed against the worker ants and sometimes teased them to regurgitate food to itself. No workers in the colony attacked the wasp. Conspecific foreign workers, however, viciously attacked the wasp when encountered. Gas chromatography-mass spectrometry analyses showed that the accepted wasp had complex cuticular hydrocarbons that were very similar to those of its host ants, whereas the winged wasps collected outside the ant nest showed only a series of n-alkanes. Additionally, the accepted wasp had a hydrocarbon profile closer to that of its host ants than to the conspecific foreign ants. We believe the wasp mimics ant cuticular hydrocarbons to integrate into the ant nest, acquiring the hydrocarbons by mounting and rubbing against the ants. In contrast, the cuticular hydrocarbons of the emerged wasp contained larval and pupal hydrocarbons of L. sakagamii that were also similar to those of L. niger. Both ant species rejected adult workers of the other species but accepted their larvae and pupae. We suggest that the emerged P. eikoae mimics the cuticular hydrocarbons of these Lasius larvae and pupae, which allows P. eikoae to be accepted by both L. sakagamii and L. niger.