Sensory neurons that respond to sex and aggregation pheromones in the nymphal cockroach.

In the common pest cockroach, Periplaneta americana, behavioural responses to the sex and aggregation pheromones change in an age-dependent manner. Nymphs are attracted by the aggregation pheromone periplanolide-E (PLD-E) but not by the sex pheromone periplanone-B (PB) in faeces. Adults display prominent behaviours to PB but not to PLD-E. Despite the significant behavioural differences depending on postembryonic developmental stages, peripheral codings of the sex and aggregation pheromones have not been studied in the nymph of any insects as far as we know. In this study, we morphologically and electrophysiologically identified antennal sensilla that respond to PB and PLD-E in nymphal cockroaches. Although nymphs lacked the sex pheromone-responsive single-walled B (sw-B) sensilla identified in adult males, we found PB-responsive sensory neurons (PB-SNs) within newly identified sw-A2 sensilla, which exhibit different shapes but have the same olfactory pores as sw-B sensilla. Interestingly, PLD-E-responsive sensory neurons (PLD-E-SNs) were also identified in the same sensillar type, but PB and PLD-E were independently detected by different SNs. Both PB-SNs and PLD-E-SNs showed high sensitivity to their respective pheromones. The hemimetabolous insect nymph has an ability to detect these pheromones, suggesting that behaviours elicited by pheromones might be established in brain centres depending on postembryonic development.

Biocommunication between Plants and Pollinating Insects through Fluorescence of Pollen and Anthers.

Flowering plants attract pollinators via various stimuli such as odor, color, and shape. Factors determining the foraging behavior of pollinators remain a major theme in ecological and evolutionary research, although the floral traits and cognitive ability of pollinators have been investigated for centuries. Here we show that the autofluorescence emitted from pollen and anthers under UV irradiation may act as another attractant for flower-visiting insects. We have identified fluorescent compounds from pollen and anthers of five plant species as hydroxycinnamoyl derivatives. The fluorescent compounds are also shown to quench UV energy and exhibit antioxidant activity, indicating a function as protectants of pollen genes from UV-induced damage. A two-choice assay using honeybees in the field demonstrated that they perceived the blue fluorescence emitted from the fluorescent compounds and were attracted to it. This result suggested that the fluorescence from pollen and anthers serves as a visual cue to attract pollinators under sunlight.

Coherent array of branched filamentary scales along the wing margin of a small moth.

In butterflies and moths, the wing margins are fringed with specialized scales that are typically longer than common scales. In the hindwings of some small moths, the posterior margins are fringed with particularly long filamentary scales. Despite the small size of these moth wings, these scales are much longer than those of large moths and butterflies. In the current study, photography of the tethered flight of a small moth, Phthorimaea operculella, revealed a wide array composed of a large number of long filamentary scales. This array did not become disheveled in flight, maintaining a coherent sheet-like structure during wingbeat. Examination of the morphology of individual scales revealed that each filamentary scale consists of a proximal stalk and distal branches. Moreover, not only long scales but also shorter scales of various lengths were found to coexist in each small section of the wing margin. Scale branches were ubiquitously and densely distributed within the scale array to form a mesh-like architecture similar to a nonwoven fabric. We propose that possible mechanical interactions among branched filamentary scales, mediated by these branches, may contribute to maintaining a coherent sheet-like structure of the scale array during wingbeat.

Kinetic resolution of racemic carboxylic acids through asymmetric protolactonization promoted by chiral phosphonous acid diester.

Chiral phosphonium salts induce the kinetic resolution of racemic α-substituted unsaturated carboxylic acids through asymmetric protolactonization. Both the lactones and the recovered carboxylic acids are obtained with high enantioselectivities and high S (= kfast/kslow) values. Asymmetric protolactonization also leads to the desymmetrization of achiral carboxylic acids. Notably, chiral phosphonous acid diester not only induced the enantioselectivity but also promoted protolactonization.

Photo-orientation regulates seasonal habitat selection in the two-spotted spider mite, Tetranychus urticae.

Non-diapausing spider mites (Tetranychus urticae) live on the undersurface of host leaves during summer, but diapausing mites overwinter in dark hibernacula. The light environments of these habitats differ: visible radiation (VIS) but not ultraviolet radiation (UV) reaches the undersurface of leaves, but neither enters dark hibernacula. Thus, mites of either seasonal form could locate their preferred habitat by photo-orientation responses to UV and VIS. To investigate this possibility, we analysed the mites' locomotion behaviour on a virtual field with a programmed chequered pattern of light and dark patches in a micro-locomotion compensator. Both non-diapausing and diapausing mites moved away from UV-illuminated patches into dark patches. Non-diapausing mites moved towards VIS-illuminated patches, whereas diapausing mites did not show a preference. Our results show that non-diapausing mites avoid UV and are attracted to VIS, suggesting that this can guide them beneath a leaf. Diapausing mites simply avoid UV. The lack of a preference for VIS during diapause could be due to changes in carotenoid metabolism, which also involve orange pigmentation of diapausing mites. We consider that a diapause-mediated switch of the response to VIS, together with regular avoidance of UV, plays a key role in the seasonal change of habitat selection in this species. This seasonal polyphenism involves alterations in not only reproductive state and pigmentation, but also in photo-spectral responses.

Chiral Lewis base-assisted Brønsted acid (LBBA)-catalyzed enantioselective cyclization of 2-geranylphenols.

Chiral Lewis base-assisted Brønsted acids (Chiral LBBAs) have been designed as new organocatalysts for biomimetic enantioselective cyclization. A salt of a chiral phosphonous acid diester with FSO(3)H catalyzes the enantioselective cyclization of 2-geranylphenols to give the desired trans-fused cyclized products with high diastereo- and enantioselectivities (up to 98:2 dr and 93% ee).

An odor stimulator controlling odor temporal pattern applicable in insect olfaction study.

The olfactory system of an insect brain codes for information about odorant quality and quantity using the temporal pattern of neural activity as well as neurons' firing. Although an accurate odor temporal pattern is indispensable for investigations of olfactory systems, it is difficult to control in conventional odor stimulators. To overcome this problem, we fabricated an odor stimulator that can control the odor temporal pattern. The stimulator has 3 major parts: an "odor conditioner," with odor-laden air prepared with known concentrations of odorants; a Pitot tube; and a small wind tunnel of laminar flow. Using this stimulator, we realized not only timing control of the odor stimulation with millisecond order but also constant odor concentrations or intensity of stimulation, with error of 2.4% in replicated trials.

Oligosaccharide composition and pheromonal activity of male tergal gland secretions of the German cockroach, Blattella gennanica (L.).

In the sequential courtship behavior of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae), females feed on the tergal gland secretions from the male tergites. The phagostimulative components in the male secretions were composed of a complex mixture of oligosaccharides and phospholipids. Besides seven oligosaccharides previously identified, two new trisaccharides, O-alpha-D-glucopyranosyl-(1 --> 6)-alpha-D-glucopyranosyl alpha-D-glucopyranoside and O-alpha-glucopyranosyl-(1 --> 4)-O-alpha-glucopyranosyl-(1 --> 1)-myo-inositol, were characterized as the sugar components of the secretions. The activity of the sugar components was compared in combination with the lipid fraction. Individual oligosaccharides exhibited the activity either alone or synergistically with the phospholipids. A complex mixture of these primary substances in the tergal gland secretions, thus, serves as a pheromonal phagostimulant in the precopulatory behavior, strongly eliciting feeding response in the female cockroach.