Electrophysiological characterisation of the infrared organ of the Australian “Little Ash Beetle” <Emphasis Type="Italic">Acanthocnemus nigricans</Emphasis> (Coleoptera,Acanthocnemidae)

This study characterises the response properties of the sensilla located on the prothoracic disc organ of the beetle Acanthocnemus nigricans, such as intensity response functions and temporal coding properties. Warming the sensilla by a red laser accelerated their ongoing spiking activity, cessation of the stimulus suppressed their firing as revealed by extracellular recordings. Convective heat sources also increased sensillum activity, but stimuli of other modalities failed to elicit responses. The response threshold was between 11 and 25 mW/cm² and latencies ranged between 20 and 40 ms. Repeating stimuli with frequencies between 5 and 20 Hz were reliably resolved by the sensilla. This temporal resolution enables the disc sensilla to represent behaviourally relevant changes in heat stimuli in a thermally patchy environment. These findings complement our knowledge on the sensory physiology of pyrophilous insects by hinting at two different, elementary orientation strategies evolved in the three pyrophilous beetle species described. A. nigricans seems to be best adapted to short-range orientation on freshly burnt areas.     

Responses of eight boreal flat bug (Heteroptera: Aradidae) species to clear-cutting and forest fire

Boreal flat bugs include a high proportion of species that are considered negatively affected by forestry. Knowledge on the biology and habitat demands of individual species is generally limited. We examined the influence on flat bugs of stand-age and clear-cutting, comparing five classes of spruce stands. The five classes were: clear-cut, unthinned, and thinned (all three products of current clear-cutting forestry), mature managed and old-growth stands (these two had never been clear-cut). We also compared unburned and recently burned mature pine forest. Fire, but not stand age, had a pronounced effect on species richness and total abundance. Aradus depressus showed a significant association with older forest stands. Aradus betulae occurred only in clear-cuts and burned forest indicating that this species is favored by disturbance in general. Aradus lugubris, Aradus crenaticollis and Aradus brevicollis were found only in the burned forest. Aradus brevicollis has not previously been shown to be associated with fire.     

The analysis of the mechanosensory origin of the infrared sensilla in Melanophila acuminata (Coeloptera; Buprestidae) adduces new insight into the transduction mechanism

The thoracic infrared (IR) sensilla of the pyrophilous jewel beetle Melanophila acuminata most likely have evolved from hair mechanoreceptors (sensilla trichodea). To further elucidate the sensory transduction mechanism, the morphology of IR sensilla and of neighbouring hair mechanoreceptors was investigated by using conventional electron microscopical techniques (SEM, TEM) in combination with focused ion beam milling (FIB). It was assumed that any deviation from the bauplan of a sensillum trichodeum is of particular concern for the transduction of IR radiation into a mechanical stimulus. Thus, the structures supposed to be relevant for stimulus uptake and transduction were homologized. Compared to a hair mechanoreceptor, an IR sensillum shows the following special features: (i) the formation of a complex cuticular sphere instead of the bristle; the sphere consists of an outer exocuticular shell as well as of an inner porous mesocuticular part. (ii) The enclosure of the dendritic tip of the mechanosensitive neuron inside the sphere in a fluid-filled inner pressure chamber which is connected with a system of microcavities and nanocanals in the mesocuticular part. Hence we propose that an IR sensillum most probably acts as a microfluidic converter of infrared radiation into an increase in internal pressure inside the sphere which is measured by the mechanosensitive neuron.     

Bimodal innervation of the infrared organ of Merimna atrata (Coleoptera,Buprestidae) by thermo- and mechanosensory units

The pyrophilous Australian “fire-beetle” Merimna atrata approaches forest fires and possesses abdominal infrared (IR) organs. Each round IR organ is centrally innervated by a sensory complex showing two different units: one thermoreceptive multipolar neuron and one mechanosensitive chordotonal organ (CO) consisting of two scolopidia. We investigated the CO and found that the scolopidia are mononematic (the scolopale cap remains below the cuticle) and monodynal (one sensory cell per scolopidium). The dendrites of the scolopidia extend anteriorly and are attached by their caps to the cuticle about in the middle of the absorbing area. Structural features at the site of innervation suggest that the CO measures minute thermal deformations caused by IR absorption. Therefore, an additional photomechanic component which has been described for the IR receptors of pyrophilous jewel beetles of the genus Melanophila can be proposed for the IR organ of Merimna. Because scolopidia can measure displacements in the subnanometer range, the CO may enhance the sensitivity of the IR organ. The sensory complex of the Merimna IR organ shows the same units and similar cuticular modifications as the tympanal organs of some noctuid moths. Therefore, a parallel evolution of insect ears and the Merimna IR organ is discussed.     

Antennal sensilla in five Psychodini moth flies (Diptera: Psychodidae: Psychodinae) pollinators of Arum spp. (Araceae)

The pollination of the genus Arum (Araceae) is mainly achieved by deception, the floral odour mimicking the pollinator ovipositing site. In order to discover the sensory organs involved in this attraction, we have studied the antennae of five species of psychodine moth-flies (former Psychoda sensu lato=Psychodini), pollinators of Arum spp. The antennae of the five Psychodini reveal seven types of sensilla: multiporous tribranched sensilla basiconica (sensilla ascoidea), multiporous sensilla basiconica, multiporous sensilla coeloconica, multiporous sensilla auricillica, uniporous sensilla basiconica, aporous sensilla chaetica, aporous Böhm’s sensilla. Each species possesses three, five or six of these sensillum types. All the multiporous sensilla are probably olfactory receptors while the uniporous sensilla basiconica must possess a contact chemoreceptive function. The multiporous tribranched sensilla basiconica (s. ascoidea), present in all the species, are the best candidates for the reception of the odours given off by the ovipositing sites and the inflorescences of Arum. The multiporous sensilla basiconica and the multiporous sensilla coeloconica may be involved respectively as CO₂ receptors or thermoreceptors. Psychoda phalaenoides, which is the main pollinator of A. maculatum, is the species which possesses the largest number of antennal sensilla. The sexual dimorphism, studied only in Psycha grisescens, as concerns the number of sensilla and the absence of a sensillum type which differ according to sex, is difficult to interpret.     

Hirschmanniella pomponiensis n. sp. (Nemata: Pratylenchidae), Parasitic on Bulrush,Scirpus robustus Pursh

A new species of Hirschmanniella was found in bulrush roots; LM and SEM morphological studies revealed that it is distinct from other species in the genus. Therefore, it is designated Hirschmanniella pomponiensis n. sp. Six lips are fused to form a hexagonal labial plate, six inner sensilla encircle the stoma opening, and four cephalic sensilla open in the corners of subdorsal and subventral lips. Cephalic lip region consists of six or seven annuli. The female has incomplete areolation in the lateral field, the intestine overlaps the rectum, the tail tip is pointed and without annulation.     

Ultrastructure of sensilla on the maxillary and labial palps of three species (Coleoptera: Staphylinidae: Staphylininae)

Most species of Staphylinidae are predators in an agroecosystem. They acquire prey information from their environment through receptors. In this study, the sensilla on maxillary and labial palps of Philonthus kailiensis, Philonthus lewisius and Quedius robustus were examined with scanning electron microscopy to identify and analyse the external morphology and distribution of the sensilla to enhance our knowledge of the sensilla of Staphylinidae and provide a rationale of taxonomical studies on the two genus. Results showed that the sensilla are classified into six types: Böhm bristles, sensilla chaetica, sensilla furcate, sensilla coeloconica, sensilla placodea and sensilla basiconica. No sexual dimorphism exists among the three species. The relationships and functions of sensilla on maxillary and labial palps were also speculated. There may be a certain correlation between the sensilla on maxillary and labial palps of the staphylinid and its habitat.     

Antennal sensilla of the click beetle,Melanotus villosus (Geoffroy) (Coleoptera: Elateridae)

The typology, number and placement of antennal sensilla of the click beetle Melanotus villosus (Geoffroy) (Coleoptera: Elateridae) were studied using scanning electron microscopy. On both the males and females the antennae are made up of the scape, pedicel and nine flagellomeres. Two types of basiconic sensilla, three types of trichoid sensilla, one type of styloconic sensilla, one type of chetoid sensilla, dome-shaped sensilla, grooved pegs, and Böhm sensilla all appear on the antennae of the beetles of both sexes, with the exception of trichoid sensilla type II, whose large number (average of 1635 hairs per antenna) was found only in male beetles. Sensilla trichodea type II evidently respond to the sex pheromone produced by the female beetle. Unlike the other two click beetles, studied up till now, Agriotes obscurus and Limonius aeruginosus, the trichoid and basiconic sensilla of M. villosus, whose proven or assumed function is olfactory, are located predominantly on the flagellomeres ventral extensions. It is assumed that the placement of the olfactory sensilla, mainly on the ventral side of M. villosuss antennae, and their more or less even distribution on the flagellomeres, can be seen as morphological adaptation of this species of insect, whose specific behavioural reaction of olfactory searching is flying, both before and after contact with an odour plume.     

Comparative study of the antennal sensilla of five species of root maggots: Delia radicum L., D. floralis F., D. antiqua Mg., D. platura MG. (Diptera : Anthomyiidae) and Psila rosae F. (Diptera : Psilidae)

A comparative study of the antennal sensilla of Delia radicum L., D. floralis F., D. antiqua Mg., D. platura Mg. (Diptera : Anthomyiidae) and Psila rosae F. Diptera Psilidae) is undertaken. For both sexes of each species, the type, distribution, and density of sensilla are determined. All 5 species have trichoid (olfactory) and grooved (olfactory) sensilla. Basiconica I (blunt) sensilla (olfactory) are found on each of the species examined, except D. platura. Basiconica II (tapered) (olfactory) and clavate (olfactory) sensilla are found only on Delia species. Also, only Delia species have single-chambered, dorsal pits, and these contain basiconic II pit sensilla (olfactory). Common to all 5 species is a multi-chambered ventral pit (olfactory). In the ventral pit, all 5 species have grooved pit sensilla (olfactory). In addition to this type of sensillum the Delia species have smooth-walled conical pit sensilla (hygro-/thermosensitive) and P. rosae has granular pit sensilla (hygro-/thermosensitive). Smooth-walled tapered pit sensilla (hygro-/thermosensitive) are found in D. radicum. Similarities and differences in the density of surface sensilla between dorsal and ventral funicular surfaces, male and female flies, and oligophagous (D. antiqua, D. radicum, D. floralis and P. rosae) and polyphagous (D. platura) species are compared. Several differences in sensillum density between the dorsal and ventral funicular surfaces are observed, but these do not fit into a consistent trend. Except for D. radicum, there are differences in sensillum density between male and female flies. For the oligophagous species, females have a greater sensillum density, whilst for the polyphagous D. platura males have a greater sensillum density. Comparisons between species show the greatest differences between the Delia species and P. rosae, and within the 4 Delia species, differences in sensillum density do not correlate with host range or body size.     

Redescription of Robustodorus megadorus with Molecular Characterization and Analysis of Its Phylogenetic Position within the Family Aphelenchoididae

Based on a new record of the rare species Robustodorus megadorus from Utah, the generic diagnosis was amended to include the following characters: a labial disc surrounded by six pore-like sensilla; the absence of a cephalic disc; a lobed cephalic region devoid of annulation; a hexagonal inner cuticular structure of the pouch surrounding the stylet cone; large stylet knobs, rounded in outline and somewhat flattened on their lateral margins; a large spermatheca with an occluded lumen and lacking sperm; the excretory pore located between the median bulb and nerve ring. The stylet orifice consists of an open, ventral, elongate slit or groove. These characters distinguish the genus from the closely related genus Aphelenchoides. A lectotype and paralectotypes were designated. Results of phylogenetic analyses of the 18S and D2-D3 of 28S rRNA gene sequences revealed that R. megadorus occupies a basal position within one of the two main clades of the subfamily Aphelenchoidinae and shares close relationships with a species group of the genus Aphelenchoides that includes A. blastophthorus, A. fragariae, A. saprophilus, A. xylocopae, and A. subtenuis. Several specimens in our collection of R. megadorus were infected with Pasteuria sp. as were some of the paralectotypes.     

Ultrastructure of antennal sense organs of small ermine moths,Yponomeuta spp. (Lepidoptera : Yponomeutidae)

The ultrastructure of antennal sensilla was investigated in males and females of 5 European Yponomeuta species. Three types of olfactory sensilla could be distinguished, i.e. sensilla trichodea, sensilla basiconica, and sensilla coeloconica. Sexual dimorphism in the number of cells innervating sensilla trichodea could be established in 3 species. Most of these sensilla in males of Y. vigintipunctatus, Y. rorellus, and Y. cagnagellus are associated with 3 sensory cells, whereas in females of these species these sensilla contain 2 sensory cells. In both males and females of Y. padeltus and Y. malinellus, the great majority of the sensilla trichodea is innervated by 3 cells. So-called sensilla chaetica type 1 show features typical of a combined mechano/contact-chemoreceptor. No structures indicating a sensory function were found in sensilla chaetica type 11. Sensilla styloconica contain 3 cells, the dendritic outer segment of one being lamellated; most likely, these cells have a thermo- and hygroreceptive function. The findings concerning the olfactory sensilla are discussed in the context of olfactory communication and reproductive isolation in European Yponomeuta.     

Antennal morphology of the endogean carabid genus typhlocharis (Coleoptera: Carabidae: Anillini): Description of sensilla and taxonomic implications

The antennal morphology and chaetotaxy were studied in 52 species of the endogean carabid genus Typhlocharis, using scanning electron microscopy and light microscopy. The antennae are composed of 11 antennomeres (scape, pedicel, and nine flagellomeres). We found considerable variation between species in the third antennomere, with short‐stem and long‐stem forms, and flagellomere morphology, distinguishing two morphs: rounded (subovoid, subspheric and subquadrate, morph 1) and reniform shapes (morph 2). Antennal sensilla are grouped in six types of sensilla trichodea, three types of sensilla basiconica, one type of sensilla coeloconica, and one type of sensilla campaniformia. The distribution of sensilla along the antennomeres is described. The “rings” of trichoid sensilla in the antennomere body are affected by its shape and there is interspecific variation in the pattern of sensilla coeloconica in antennomere 11°, a novelty for the genus. The types of sensilla found in Typhlocharis are compared to those described in other Carabidae and the potential functionality and taxonomic interest of those variable antennal features are discussed. A correlation between the flagellomere morphology and the presence/absence of a stridulatory organ is suggested. The study also allowed comparing the observation of antennal features by SEM and light microscopy. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

The silkworm glutathione S-transferase gene noppera-bo is required for ecdysteroid biosynthesis and larval development

Insect molting and metamorphosis are tightly controlled by ecdysteroids, which are important steroid hormones that are synthesized from dietary sterols in the prothoracic gland. One of the ecdysteroidogenic genes in the fruit fly Drosophila melanogaster is noppera-bo (nobo), also known as GSTe14, which encodes a member of the epsilon class of glutathione S-transferases. In D. melanogaster, nobo plays a crucial role in utilizing cholesterol via regulating its transport and/or metabolism in the prothoracic gland. However, it is still not known whether the orthologs of nobo from other insects are also involved in ecdysteroid biosynthesis via cholesterol transport and/or metabolism in the prothoracic gland. Here we report genetic evidence showing that the silkworm Bombyx mori ortholog of nobo (nobo-Bm; GSTe7) is essential for silkworm development. nobo-Bm is predominantly expressed in the prothoracic gland. To assess the functional importance of nobo-Bm, we generated a B. mori genetic mutant of nobo-Bm using TALEN-mediated genome editing. We show that loss of nobo-Bm function causes larval arrest and a glossy cuticle phenotype, which are rescued by the application of 20-hydroxyecdysone. Moreover, the prothoracic gland cells isolated from the nobo-Bm mutant exhibit an abnormal accumulation of 7-dehydrocholesterol, a cholesterol metabolite. These results suggest that the nobo family of glutathione S-transferases is essential for development and for the regulation of sterol utilization in the prothoracic gland in not only the Diptera but also the Lepidoptera. On the other hand, loss of nobo function mutants of D. melanogaster and B. mori abnormally accumulates different sterols, implying that the sterol utilization in the PG is somewhat different between these two insect species.     

Staphylorchis cymatodes (Gorgoderidae: Anaporrhutinae) from carcharhiniform, orectolobiform and myliobatiform elasmobranchs of Australasia: Low host specificity, wide distribution and morphological plasticity

Anaporrhutine gorgoderids (Digenea: Gorgoderidae: Anaporrhutinae) found in the body cavity of six species of elasmobranchs from the orders Carcharhiniformes, Myliobatiformes and Orectolobiformes from Australian waters were found to belong to the genus Staphylorchis. Although these specimens were morphologically variable, sequences of ITS2 and 28S ribosomal DNA from specimens from three host families and two host orders were identical. Based on morphological and molecular data these specimens were identified as the type-species of the genus, Staphylorchis cymatodes. New measurements are provided for S. cymatodes, and for the first time genetic data are presented for this species. In addition to providing new morphological and molecular data for S. cymatodes, the previously described species S. gigas, S. parisi and S. scoliodonii, are here synonymised with S. cymatodes. This implies that S. cymatodes, as conceived here, has remarkably low host-specificity, being recorded from eight elasmobranch species from four families and three orders, has a wide geographical distribution in the Indo-west Pacific from off India, in the Bay of Bengal, to Moreton Bay in the Coral Sea, and is morphologically plastic, with body size, size of specific organs and body shape differing dramatically between specimens from different host species. The genus Staphylorchis now contains only two valid species, S. cymatodes and S. pacifica.     

Observations on post-fire black morel ascocarp development in an Israeli burnt forest site and their preferred micro-sites

Morchella species ascocarps (morels) are sought-after edible mushrooms that exhibit pyrophilous behavior, proliferating in fire-affected soils of certain types of forests. The factors governing fruiting in this habitat are poorly understood. An observational approach was used to determine the spatial distribution on preferred micro-sites of black morel fruiting in a forest after a summer fire, subjected to different post-fire forestry management activities. Clearing the burnt tree stumps from the site, compaction of the burnt soil by heavy machinery (bulldozers) and covering the soil with chopped wood created preferred micro-sites for black morel fruiting. Fewer fruit bodies developed on untouched burnt soil, and almost none on non-burnt soil at the same site. These observations enhance understanding the ecological principles underlying the distribution and abundance of morel ascocarp development in natural habitats; such an understanding could contribute to conservation and management of morel fruiting in the wild.     

Vision in click beetles (Coleoptera: Elateridae): pigments and spectral correspondence between visual sensitivity and species bioluminescence emission

Among lampyrids, intraspecific sexual communication is facilitated by spectral correspondence between visual sensitivity and bioluminescence emission from the single lantern in the tail. Could a similar strategy be utilized by the elaterids (click beetles), which have one ventral abdominal and two dorsal prothoracic lanterns? Spectral sensitivity [S(λ)] and bioluminescence were investigated in four Brazilian click beetle species Fulgeochlizus bruchii, Pyrearinus termitilluminans, Pyrophorus punctatissimus and P. divergens, representing three genera. In addition, in situ microspectrophotometric absorption spectra were obtained for visual and screening pigments in P. punctatissimus and P. divergens species. In all species, the electroretinographic S(λ) functions showed broad peaks in the green with a shoulder in the near-ultraviolet, suggesting the presence of short- and long-wavelength receptors in the compound eyes. The long-wavelength receptor in Pyrophorus species is mediated by a P540 rhodopsin in conjunction with a species-specific screening pigment. A correspondence was found between green to yellow bioluminescence emissions and its broad S(λ) maximum in each of the four species. It is hypothesized that in elaterids, bioluminescence of the abdominal lantern is an optical signal for intraspecifc sexual communication, while the signals from the prothoracic lanterns serve to warn predators and may also provide illumination in flight.     

The Caloscyphaceae (Pezizomycetes, Ascomycota), with a new genus

The family Caloscyphaceae with a single genus, Caloscypha, has been considered to include a single species, C. fulgens. Study of an overlooked second species, Caloscypha incarnata from North Africa and Italy, using SSU, LSU rDNA, and morphology allows placement of this species in a new genus, Kallistoskypha, in the Caloscyphaceae. This fungus is found in association with Eucalyptus species. The species was recently redescribed from Spain under the name Marcelleina parvispora. Caloscypha fulgens, the type species of the genus Caloscypha, shows sequence variation from across its range.     

Sensilla on antennae,ovipositor and tarsi of the larval parasitoids,Cotesia sesamiae (Cameron 1906) and Cotesia flavipes Cameron 1891 (Hymenoptera: Braconidae): a comparative scanning electron microscopy study

Two braconid parasitoids of cereal stemborers in eastern Africa, Cotesia sesamiae and Cotesia flavipes, have been shown to display a similar hierarchy of behavioural events during host recognition and acceptance. In order to understand the mechanisms underlying host recognition and acceptance, the morphology of antennal sensilla on the last antennomeres, on the ovipositor, and on the fifth tarsomere and pretarsus of the prothoracic legs tarsi were studied using scanning electron microscopy followed by selective silver nitrate staining. It appeared that female C. sesamiae and C. flavipes shared the same types and distribution of sensory receptors, which enable them to detect volatiles and contact chemical stimuli from their hosts. In both parasitoids, four types of sensilla were identified on the three terminal antennomeres: (i) non-porous sensilla trichodea likely to be involved in mechanoreception, (ii) uniporous sensilla chaetica with porous tips that have gustatory functions, (iii) multiporous sensilla placodea, which are likely to have olfactory function, and (iv) sensilla coeloconica known to have thermo-hygroreceptive function. The tarsi of both parasitoids possessed a few uniporous sensilla chaetica with porous tips, which may have gustatory functions. The distal end of the ovipositor bore numerous dome-shaped sensilla. However, there were no sensilla coeloconica or styloconica, known to have gustatory function in other parasitoid species, on the ovipositors of the two braconid wasps.     

The antennae of damselfly larvae

The larval antennal sensilla of two Zygoptera species, Calopteryx haemorroidalis (Calopterygidae) and Ischnura elegans (Coenagrionidae) are investigated with SEM and TEM. These two species have different antennae (geniculate, setaceous) and live in different environments (lotic, lentic waters). Notwithstanding this, similarities in the kind and distribution of sensilla are outlined: in both species the majority of sensilla types is located on the apical portion of the antenna, namely a composed coeloconic sensillum (possible chemoreceptor), two other coeloconic sensilla (possible thermo-hygroreceptors) and an apical seta (direct contact mechanoreceptor). Other mechanoreceptors, such as filiform hairs sensitive to movements of the surrounding medium or bristles positioned to sense the movements of the flagellar segments, are present on the antenna. Similarities in the antennal sensilla types and distribution are observed also with other dragonfly species, such as Onychogomphus forcipatus and Libellula depressa. A peculiar structure with an internal organization similar to that of a gland is observed in the apical antenna of C. haemorroidalis and I. elegans and it is present also in O. forcipatus and L. depressa. The possible function of this structure is at the moment unknown but deserves further investigations owing to its widespread presence in Odonata larvae.