Male Antennae Research Articles

A new Blepharosis species from China (Lepidoptera, Noctuidae).

In 2017 the second author encountered a rather small Noctuidae species in western Sichuan (China) with unicolorous brown forewings and ochre reniform stigmata. Initially the six males collected resembled the taxa of the genus Cerapteryx Curtis, 1833, but the more gracile body, the finely serrate (and not bipectinated) male antennae and the late flight period indicated the need of further study. Dissection of the male genitalia revealed that the peculiar species belongs to the genus Blepharosis Boursin, 1964. The most recent review with descriptions of new Blepharosis taxa is available from Hreblay, Ronkay Plante (1998). Comparison of external and genitalia features of the newly found taxon with the known species confirmed that it represents an undescribed species, which is very different externally from all but one of the members of Blepharosis. Regarding the configuration of the male genitalia, the only similar species is Blepharosis anachoretoides (Alphéraky, 1892), displaying only surprisingly small differences between the two species. The large difference between their barcodes (13.5% difference in the COI sequences) indicate however their specific distinctness despite their similar male genitalia structures.

Ultrastructure of the antennal sensilla of Alabama argillacea (Hübner, 1823) (Lepidoptera: Erebidae)

Insects have several types of sensilla, the characterization of which has been fundamental to understanding the mechanisms of sensory perception in different species. This study aimed to describe the ultrastructure of the sensilla present on the antennae of Alabama argillacea (Hübner, 1823) (Lepidoptera: Erebidae), an important pest of cotton (Gossypium hirsutum L.) crops, as well as their possible variation between sexes. To do this, the antennae of males and females of A. argillacea were analyzed using scanning electron microscopy. Sensilla morphometry was assessed using photomicrographs, from which the lengths and basal and apical diameters of sensilla were measured using the ImageJ program. Seven types of sensilla were identified on the antennae of A. argillacea: sensilla trichodea, sensilla chaetica, sensilla auricillica, sensilla coeloconica, sensilla styloconica, sensilla basiconica, and sensilla Böhm bristles. Differences between the sensilla of males and females were found in their lengths and basal diameters in the distal and proximal regions. This suggests that sensilla functionality may not only vary from one species to another, but also between sexes within the same species. Thus, further transmission electron microscopy and single sensillum recording studies may provide more detailed information on the sensilla of A. argillacea and their functions.

Expression and Functional Analysis of Two Odorant-Binding Proteins from Bradysia odoriphaga (Diptera: Sciaridae).

Two OBP genes, BodoOBP1 and BodoOBP2, were cloned from Bradysia odoriphaga, a major agricultural pest of Chinese chives. The amino acid sequence alignment of both BodoOBPs showed high similarity. Fluorescence competitive binding assays revealed that both BodoOBPs have a moderate binding affinity to dipropyl trisulfide. Tissue expression profiles indicated that both BodoOBPs are antennae-specific and more abundant in the male antennae than in the female antennae. Developmental expression profile analysis indicated that expression levels of both BodoOBPs were higher in the male adult stage than in the other developmental stages. Both BodoOBPs also showed differential expression in pre- and postmating adults. RNAi assays indicated that ability of dsOBPs-treated males to detect females was significantly reduced compared to controls. Attraction of plant volatile dipropyl trisulfide to dsOBPs-treated adults was also significantly lower than in the control. Our findings indicate that both BodoOBPs are involved in host-seeking behavior and in detecting sex pheromones.

An Unstable Monoterpene Alcohol as a Pheromone Component of the Longhorned Beetle Paranoplium gracile (Coleoptera: Cerambycidae).

We report the identification of p-mentha-1,3-dien-8-ol, an unstable monoterpene alcohol, as a male-produced aggregation-sex pheromone component of the cerambycid beetle Paranoplium gracile (Leconte) (subfamily Cerambycinae, tribe Oemini), a species endemic to California. Headspace volatiles from live males contained a blend of nine cyclic terpenoids that were not detected in analogous samples from females. Volatiles produced by male Eudistenia costipennis Fall, also in the tribe Oemini, contained the same suite of nine compounds. Four compounds, dehydro-p-cymene, p-mentha-1,3-dien-8-ol, p,α,α-trimethylbenzyl alcohol, and an unidentified compound were found to elicit responses from antennae of P. gracile females in coupled gas chromatography-electroantennogram detection (GC-EAD) assays, whereas only p-mentha-1,3-dien-8-ol elicited responses from antennae of males. In field assays, p-mentha-1,3-dien-8-ol stabilized with the antioxidant butylated hydroxytoluene (BHT) attracted P. gracile of both sexes, indicating it functions as an aggregation-sex pheromone, as with other pheromones identified from its subfamily, the Cerambycinae. Adding four of the other compounds found in headspace samples to the dienol lure had no effect on attraction. Because of the instability of p-mentha-1,3-dien-8-ol, it seems likely that at least some of the compounds seen in the extracts of volatiles from both species are artefacts, rather than being components of the pheromone.

Re-description of Azygokeras columbiae Koeller amp; Littlepage, 1976 (Calanoida: Aetideidae) and musculature of the male grasping antennule.

Azygokeras columbiae from Bute Inlet, British Columbia, Canada, is re-described, correcting some details and adding information not available in the original description. Azygokeras columbiae is unique amongst male Aetideidae in having the right antennule modified for grasping but without a true knee joint (geniculation) between segments XX and XXI nor a hiatus in the musculature at this joint, typical of taxa with a geniculate male antennule. Male Azygokeras have wide pivot points and arthrodial membranes between segments XXI and XXII, XXIII and XXIV and XXV and XXVI that allow greater movement in several planes than in homologous segments of Euaugaptilus and Heterorhabdus. Modifications of the terminal antennular joints allow for extensive movement in several planes associated with a series of short muscles in segments XIX to XXVI. These muscles become progressively more massive from proximal to distal on the antennule and are paired with an antagonistic muscle also increasing in mass distally.

Detection of volatile pheromone candidates from the white-spotted longicorn beetle, Anoplophora malasiaca (Coleoptera: Cerambycidae)

Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae) is a serious pest that affects various crop trees and landscapes in Japan. We collected and analyzed volatiles from male and female A. malasiaca. 4-(n-Heptyloxy)butan-1-ol and its aldehyde, pheromone components in A. glabripennis and A. chinensis, were detected in the male volatile extracts and nonanal both in the male and female volatile extracts. Nonanal was absent from the extracts of twigs of the willow host plant. Gas chromatograph-electroantennographic responses showed that nonanal and 4-(n-heptyloxy)butan-1-ol elicited responses from both male and female antennae, but 4-(n-heptyloxy)butanal did not. Volatiles of eight artificially reared males, analyzed every 3 or 4 days for 60 days from adult emergence showed that they all produced nonanal and 4-(n-heptyloxy)butan-1-ol. The two compounds produced no short-range female attraction but in males, the short-range attraction to nonanal was dose dependent and significant in a higher dose, but did not depend on 4-(n-heptyloxy)butan-1-ol. When wounded willow twigs were added to nonanal and 4-(n-heptyloxy)butan-1-ol, the frequency of male responses was higher than in all other treatments, but the same as wounded willow twigs alone. The wounded host plant willow twigs might thus be enough for male attraction. The identified volatiles from the beetles in the present study might have a weaker function for attraction from the distance compared to their host plant volatiles.

Morphology and distribution of antennal sensilla in egg parasitoid, Ooencyrtus nezarae (Hymenoptera: Encyrtidae).

Morphology of antennal sensilla and their distribution were investigated in adults of Ooencyrtus nezarae, an egg parasitoid of Riptortus pedestris, using scanning electron microscopy. Male antennae was found to be significantly greater in overall length than female antennae. The antenna of O. nezarae was composed of the radicula, scape, pedicel, funicle and clava in both sexes, with seven types of sensilla identified: sensillum trichodea; s. finger-like; s. placoidea; s. chaetica; s. basiconica; s. coeloconica, and s. campaniform. They occur in varying number and distribution along the antennae. Two sensillum types were further categorized into additional subtypes, with two subtypes in s. trichodea and three in s. chaetica. Among all characterized sensilla, s. trichodea subtype 1 and s. placoidea were multiporous, indicating that the primary function of these sensilla is olfactory. Sensillum trichodea was the most abundant sensillum type on the antennae of both sexes. Sexual dimorphism was only observed from the subtype 1 sensilla of s. trichodea in males and the subtype 3 sensilla of s. chaetica in females. The morphological information established in our study may provide useful information for further investigations in sensory physiological function of each morphological type of sensilla and their related behavior in this egg parasitoid.

A comparative morphometric study of sensory capacity in geometrid moths

Diet breadth and the degree of capital breeding have been established as major determinants of species-specific ecology of herbivorous insects. Both of these variables are related to resource foraging and therefore can be expected to have effects on sensory capacity. However, such effects have remained poorly studied, let alone in phylogenetically explicit multi-species comparisons. We contribute to filling this gap in a study of 60 species of geometrid moths (Lepidoptera: Geometridae), using adult head measures (eye size, antennal length and shape, forehead width) as indices of sensory capacity. When controlled for body size, eyes of the more capital breeding species (i.e. those with low contribution of adult feeding to reproduction) were found to be smaller, and female antennae shorter, than in income breeders. Feathery (vs simple filiform) male antennae were more frequently present in the capital breeders and in larger species. Regarding diet breadth, generalist species were found to have relatively wider male foreheads than specialists. The results suggest that (a) breeding strategy rather than diet breadth predicts sensory capacity in geometrids, (b) capital breeding (vs income breeding) is related to low sensory capacity in females, and (c) in contrast, males of the capital breeding species have evolved towards elevated olfactory capacity.

Identification and Expression Profiling of Odorant Receptor Protein Genes in Sitophilus zeamais (Coleoptera: Curculionoidea) Using RT-qPCR.

This study aimed to identify ORs (odorant receptors) and Orco (odorant receptor coreceptor) genes in Sitophilus zeamais Motschulsky (Coleoptera: Curculionoidea), to explore the relative expression levels of these genes in different adult tissues and obtain information on highly expressed receptor proteins. Putative OR and Orco genes were identified from transcriptomic data previously obtained for S. zeamais using bioinformatics methods. Quantitative real-time PCR was used to compare the differences in expression in seven adult tissues (male antennae, female antennae, heads, thoraxes, abdomens, wings, and legs). The candidate OR and Orco gene sequences were analyzed, and the protein physicochemical properties were predicted. We identified 64 OR genes including the Orco gene. Forty-seven OR genes, including Orco, were over expressed in male or female antennae. Seventeen OR genes appeared to be expressed at elevated levels in male antennae. Twenty-nine genes were expressed at significantly elevated levels in female antennae. In total, 11 OR genes were selected for further sequence analysis. The selected proteins were structurally characterized, and bioinformatics analysis was performed. Overall, in this study, candidate ORs of S. zeamais have been identified for the first time, and these ORs could be molecular targets for interference in the insect olfactory system.

Antennal Morphology and Sexual Dimorphism of Antennal Sensilla in Callitettix versicolor (Fabricius) (Hemiptera: Cercopidae).

The rice spittlebug Callitettix versicolor (Fabricius) is an important pest of rice and maize in South Asia and causes severe economic damage. To provide background information for chemical ecology studies, the fine morphology of antennae and the types and distribution of the sensilla on the male and female antennae of Callitettix versicolor (Fabricius) are investigated by means of scanning electron microscopy (SEM). Results show that the antenna is filiform and composed of three segments: a scape, a pedicel, and a flagellum. The female antennae are slightly shorter than the male antennae. In both sexes, four types and nine subtypes of sensilla were observed: sensilla basiconica (SB1, SB2), sensilla campaniformia (SCa1, SCa2 and SCa3), sensilla coeloconica (SCo1, SCo2 and SCo3) and sensilla trichodea (ST). In addition, sensilla coeloconica (SCo1) are observed on the membrane of the top of the pedicel in Cercopidae for the first time. Sexual dimorphism mainly occurs in variation in the number of sensilla coeloconica (SCo2, SCo3) on the bulb-shaped portion of the flagellum and in the shape of sensilla basiconica (SB2). There are significantly more sensilla coeloconica in males than in females. The external structure and distribution of these sensilla are compared to those of other cercopids and possible functions of the antennal sensilla are discussed.

Fifteen new species of Chilicola (Oroediscelis) (Hymenoptera: Colletidae: Xeromelissinae) with illustrated keys to the males and females of the subgenus.

Fifteen new species of Chilicola subgenus Oroediscelis are described and illustrated. The following 11 species are from Argentina recording a remarkable diversity and the first records of the subgenus in the country: Chilicola capillitas Packer and Dumesh, new species, C. abrebotellas, Packer and Dumesh, new species; C. goloboffi Packer and Dumesh, new species; C. fritzi, Packer and Dumesh, new species; C. rozeni Packer and Dumesh, new species; C. roigi Packer and Dumesh, new species; C. carpenteri Packer Dumesh, new species; C. calchaqui Packer and Dumesh, new species; C. jaguense Packer and Dumesh, new species; C. cuyense Dumesh Packer, new species; and C. huarpe Packer and Dumesh, new species. Chilicola pustulata Packer and Dumesh, new species, and Chilicola luna Dumesh, and Packer new species, are described from Peru; C. boharti Packer and Dumesh, new species, and C. ashei Dumesh and Packer, new species, are described from Bolivia, where C. carpenteri also occurs. An unusual feature of the male antennae is described: long setae on F2 and F3 (less commonly F4) that are appressed to, and occasionally longer than, the succeeding flagellomere. Additional records for previously described species are listed and a revised key to males is provided as well as a provisional complete key for all females.

Characterization and expression profiling of odorant-binding proteins in Anoplophora glabripennis Motsch

In insects, olfaction plays a critical role in locating hosts, recognizing mates, and selecting oviposition sites. The Asian long-horned beetle (Anoplophora glabripennis Motschulsky) feeds on 43 species of trees in 15 families, but its chemosensory mechanisms are poorly understood. Herein, genes encoding 61 odorant-binding proteins (OBPs) were identified from the published genome and our previous A. glabripennis transcriptomic data. To investigate their physiological functions, we performed expression profiling of all AglaOBPs in the antennae, legs, and maxillary palps of both sexes. Phylogenetic analysis clustered A. glabripennis OBPs into four subgroups, comprising 29 Minus-C OBPs, 15 Antennae-binding proteins (ABPIIs), 10 Classic OBPs, and one Plus-C OBP. 12 AglaOBP genes were expressed specifically in antennae, and AglaOBP3, AglaOBP18, AglaOBP21, AglaOBP33, AglaOBP41, AglaOBP45, and AglaOBP47 were particularly highly expressed in male antennae. These proteins may function in the detection of female sex pheromones. AglaOBP23 and AglaOBP44 were preferentially expressed in maxillary palps. Expression profiling suggests that many OBPs may be involved in olfaction and gustation, in addition to carrying hydrophobic molecules. The AglaOBPs family has acquired functional diversity concurrently with functional constraints, and further investigation could provide insight into the roles of OBPs in chemoreception.

Antennal and ovipositor sensilla of Pseudoligosita yasumatsui (Hymenoptera: Trichogrammatidae)

Abstract Pseudoligosita yasumatsui Viggiani and Subba Rao 1978 (Hymenoptera: Trichogrammatidae) is a common egg parasitoid of rice insect pests. The surface morphology of the antenna and ovipositor on P. yasumatsui was examined using scanning electron microscopy. The antenna of P. yasumatsui is geniculate in shape, hinged at the scape-pedicel joint, approximately 190 μm in length and consists of seven antennomeres. In total, the male and female antennae have ten different types of sensilla: trichoid sensilla type 1, 2, 3, 4, 5, 6, campaniform sensilla, basiconic sensilla, and placoid sensilla type 1 and 2. The flagellum of the female antenna is covered with cuticular pores, which are absent on the male antennal flagellum. The distal extremity of its ovipositor stylet has campaniform sensilla and styloconic sensilla. Trichoid sensilla found on its apical abdomen part may play a role in the host detection and egg placement. The types and distribution of antennal and ovipositor sensilla on the parasitoid were discussed.

Antennal sensilla of the weaver ant Oecophylla Smaragdina (F.)-Males and Females sense differently?

Antenna of males and female insects are distinct in morphology and function, and such differences exist in the weaver ant Oecophylla smaragdina (F.). In this ant, behaviour is predominantly olfactory driven. Foraging, nursing, feeding, defense etc., are the predominant female behaviour. Males are in less numbers and are seldom in the colony. This study explores the sexual dimorphism in O. smaragdina with respect to antennal morphology, morphometry and sensilla profile, which are often considered key components of the peripheral sensory system. Scanning electron microscopic (SEM) studies revealed that the sensilla profile on the antenna probably reflects the sensitivity. Antennal morphology and sensilla profile differ in males and females. Sensilla repertoire of the females (major worker) is different in the number and types of chemosensilla. Sensilla basiconica type1 and type 2, sensilla trichoidea curvata, sensilla ampullacea and sensilla coeloconica were the abundant ones observed on the female antenna. Males have sparse sensilla, and its putative sensilla basiconicais strikingly different. The results suggest that the sensilla profile can be reflective of the behavioral repertoire in these ants.

Morphometrics of Trichogramma spp. released in sugarcane

Trichogramma populations were collected from sugarcane fields from four districts of Punjab. Important taxonomic characters such as body length, head length, head width, female antennae, fore wings, hind wings, male antennae and genitalia were studied and a morphometric analysis was performed. Descriptive analysis of ratios of characters (flagellar width/length, club width/length, fore wing length/width, genital capsule length/width) was also undertaken. Results revealed that females were bigger than males, and head was wider than long. Despite slight variations in size, all specimens were found to belong to T. chilonis.

Expression patterns and colocalization of two sensory neurone membrane proteins in Ectropis obliqua Prout, a geometrid moth pest that uses Type-II sex pheromones.

Sensory neurone membrane proteins (SNMPs) function as essential cofactors for insect sex pheromone detection. In this study, we report two SNMPs in Ectropis obliqua Prout, a serious geometrid pest that produces typical Type-II sex pheromones. Sequence alignments and phylogenetic analyses showed that EoblSNMP1 and EoblSNMP2 belong to two distinct SNMP subfamilies. Quantitative real-time PCR suggested that EoblSNMP1 was male antennae-biased, whereas EoblSNMP2 was highly expressed on male antennae but was also expressed on female antennae and other chemosensory tissues. Additionally, EoblSNMP1 and EoblSNMP2 differed in their developmental expression profiles. In situ hybridization revealed that EoblSNMP1 was sensilla trichodea I specific, whereas EoblSNMP2 was expressed in sensilla trichodea I and the sensilla basiconica; furthermore, EoblSNMP1 and EoblSNMP2 were co-expressed in sensilla trichodea I but in different cells. This study suggests that EoblSNMP1 is functionally distinct from EoblSNMP2 in E.obliqua; EoblSNMP1 may specifically contribute to the recognition of sex pheromones, whereas EoblSNMP2 exhibits multiple olfactory roles. Our findings comprehensively reveal the expression patterns of SNMPs in a lepidopteran species that uses Type-II sex pheromones, providing new insights into the functional evolution of SNMPs from lepidopteran moths with Type-I sex pheromones to those with Type-II sex pheromones.

Amphoraceras rothschildi and A. jordani sp. n.: two sibling species (Lepidoptera: Erebidae)

One new species of Amphoraceras which has so far remained unrecognised and intermingled within A. rothschildi is described as A. jordani sp. n. Both species are endemic to New Guinea, where they even happen to locally coexist and overlap phenologically. Main diagnostic features between the two taxa occur in the development of the unusual amphora-shaped structure present on male antenna, which is herewith detailed morphologically, aspects of the habitus and features of the genitalia.

Sex Pheromones of Two Leafminer Species, Antispila oinophylla and Holocacista rivillei (Lepidoptera: Heliozelidae) Infesting Grapevine in Italy

Two heliozelid species, Antispila oinophylla van Nieukerken & Wagner and Holocacista rivillei (Stainton) severely infest Italian grapevines. The volatile pheromones from calling females were collected by solid phase micro extraction (SPME) and analyzed by gas chromatography with electroantennographic detection (GC-EAD). Two compounds from A. oinophylla females eliciting electrophysiological activity from the conspecific male antenna were identified as (Z)-5-tetradecenal and (Z)-7-tetradecenal by coupled gas chromatography/mass spectrometry (GC/MS) analysis. SPME collections from H. rivillei produced no GC-EAD active compounds but analysis of fatty acyl moieties in the pheromone gland, demonstrated the presence of the putative pheromone biosynthetic precursors (Z)-5-dodecenoic acid and (Z)-7-tetradecenoic acid. Field trapping experiments in Italy confirmed that (Z)-5-tetradecenal and (Z)-7-tetradecenal are essential for the attraction of male A. oinophylla in a blend ratio of 15:100 respectively, whereas (Z)-5-dodecenal and (Z)-7-tetradecenal attract male H. rivillei in a blend ratio of 100:6.

Electroantennographic responses and field attraction of an emerging invader, the red-necked longicorn beetle Aromia bungii (Coleoptera: Cerambycidae), to the chiral and racemic forms of its male-produced aggregation-sex pheromone

The red-necked longicorn beetle Aromia bungii (Faldermann) (Coleoptera: Cerambycidae) is an emerging invader in Japan and has become a major pest of cherry blossom trees, peaches, prunes and Japanese apricots. The male-produced aggregation-sex pheromone, recently identified as (E)-2-cis-6,7-epoxynonenal, has two enantiomers. Here, we determined which enantiomer the male produces and tested the responses of beetle antennae to the enantiomers using electroantennography. The male produced only the (6R,7S)-enantiomer, but both enantiomers elicited responses from the antennae of female beetles. Antennae of males also responded to both enantiomers. In field trials, the (6R,7S)-enantiomer and the racemic mixture were equally attractive to both sexes of the beetle, whereas the unnatural (6S,7R)-enantiomer did not attract any beetles.

Nine new species of Clada from Madagascar (Coleoptera, Ptinidae).

Nine new species of the genus Clada (s. str.) Pascoe, 1887 (Bostrichoidea: Ptinidae: Eucradinae) are described from Madagascar: Clada (Clada) barclayisp. n., C. (C.) dimbyisp. n., C. (C.) fasciatasp. n., C. (C.) lalaesp. n., C. (C.) madagascarensissp. n., C. (C.) mamyisp. n., C. (C.) njakaisp. n., C. (C.) obesasp. n., and C. (C.) rindraisp. n. No species of this genus were previously known from Madagascar. Photographs of the dorsal habiti and drawings the male and female antennae and aedeagi of most of these species are given.