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Types of antennal sensilla found on the antenna of New Zealand alpine grasshoppers (Acrididae; Catantopinae). Chaeticum (a, b), basiconicum (c, d), trichodeum (e), coeloconicum (f), cavity sensillum (g) and cavity sensillum with internal tissue visible (h). f flexible socket, i inflexible socket, ap apical pore, wp wall pore
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Brachaspis nivalis, Sigaus australis and Paprides nitidus are grasshopper species endemic to Aotearoa, New Zealand where they are sympatric in several regions of South Island. On mountains of Kā Tiritiri o te Moana (Southern Alps), B. nivalis is more abundant on scree/rock habitat, whereas S. australis and P. nitidus are prevalent in alpine tussock...
Citations
... Sensillum shape, size, presence and absence of pores, socket type, among other characteristics, can be used to infer its function (Nakano et al. 2023), which is of great importance for understanding insect bioecology and establishing pest control strategies. For instance, the antenna is a fundamental organ for investigations associated with the screening of molecules responsible for the chemical communication of insects based on semiochemicals (Schal & Wada-Katsumata 2021;Nakano et al. 2023). ...
... Sensillum shape, size, presence and absence of pores, socket type, among other characteristics, can be used to infer its function (Nakano et al. 2023), which is of great importance for understanding insect bioecology and establishing pest control strategies. For instance, the antenna is a fundamental organ for investigations associated with the screening of molecules responsible for the chemical communication of insects based on semiochemicals (Schal & Wada-Katsumata 2021;Nakano et al. 2023). Pest control based on semiochemicals, with emphasis on the pheromones, has become a fundamental method (Schneider 1957(Schneider , 1962Ma et al. 2017). ...
In the present study, we investigated the antennal morphology and the distribution and typology of sensilla in antennae of male and female Caligo illioneus illioneus Cramer (Lepidoptera: Nymphalidae), examined by scanning electron microscopy—SEM. The insect was identified by morphological and molecular means, and the COI gene of this subspecies was sequenced and deposited in GenBank. The SEM results showed that antennae of both sexes do not present dimorphism, as they cannot be distinguished from each other in terms of morphology. In addition, the ventral region of the flagellum has longitudinal carinae. In both sexes, seven types of sensilla were identified along the scape, pedicel and flagellum: Böhm’s bristles and sensilla auricillica, basiconica, chaetica, coeloconica, squamiformia, and trichodea. Subtypes I and II were characterized for Böhm's bristles and sensilla basiconica and chaetica according to the length, because morphometric result was statistically different among individuals of the same sex. In addition, the flagellum contains the vast majority of sensilla and their subtypes, except for Böhm’s bristles, present only in the basal region. This study provides valuable information about the antennal morphology and sensilla typology in C. i. illioneus, contributing with morphological evidence on the sensory system of butterflies, mainly in the genus Caligo, which is helpful to assist behavioral and electrophysiological studies.
... Sympatric species of New Zealand alpine grasshoppers, Sigaus nivalis (Hutton 1897), Sigaus nitidus (Hutton 1897) and Sigaus australis (Hutton 1897) ; Fig. 1), feed on a variety of plant species including rushes, grasses, dicot herbs, shrubs, ferns and mosses, but have preference towards dicots over monocots (Nakano 2024;Watson 1970). The abundance of different morphological types of antennal sensilla in these grasshoppers are similar, but male S. australis have significantly more olfactory sensilla than conspecific females (Nakano et al. 2023;Fig. 1). ...
... We analyzed the chemical composition of these food plants using GC-MS and recorded electrophysiological responses of each Sigaus species to the smells of potential food plants. Due to similarity in the abundance and types of sensilla found in these three species of Sigaus (Nakano et al. 2023) and observed similarity in their diets (Nakano 2024;Watson 1970), we expected similar olfactory responses to the smells of food plants. We also expected S. australis males to respond more strongly than conspecific females due to the higher abundance of sensilla on their antenna (Nakano et al. 2023). ...
... Due to similarity in the abundance and types of sensilla found in these three species of Sigaus (Nakano et al. 2023) and observed similarity in their diets (Nakano 2024;Watson 1970), we expected similar olfactory responses to the smells of food plants. We also expected S. australis males to respond more strongly than conspecific females due to the higher abundance of sensilla on their antenna (Nakano et al. 2023). ...
The alpine grasshoppers Sigaus nivalis, Sigaus australis and Sigaus nitidus are sympatric in the central mountains of South Island, Aotearoa New Zealand. These grasshoppers feed on a range of alpine plants but show preference towards dicots over monocots. Because herbivorous insects often use smell and taste to locate and recognize food plants it was expected that these grasshoppers would show sensitivity to their favorite foods and potential sensitivity to nonhost plants. Here, we determined feeding preference in captivity allowing each of these three sympatric grasshoppers the same choice of six native alpine plant species. We analyzed the chemical compositions of the plants used in these experiments using gas-chromatograph coupled with mass-spectrometry (GC-MS) and then recorded olfactory responses in the grasshoppers to plant-derived smells (with synthetic compounds) using electroantennogram (EAG). The grasshoppers were able to distinguish between the potential food plants and ate the shrub Coriaria sarmentosa but not the grass Chionochloa pallens, however, the chemicals we detected in the six plant species were very similar. High sensitivity to fatty acid derived aldehydes (decanal, (E,Z)-2,6-nonadienal, hexanal) and a 6-carbon alcohol ((Z)-2-hexen-1-ol) compared to terpenoids (α-phellandrene, β-myrcene, β-ocimene, eucalyptol, (S)-(-)-limonene, (1S)-(-)-α-pinene) or an aromatic compound (2-phenylethanol) was recorded in the antennae of all three grasshopper species and no species- or sex-specific sensitivity to particular compounds was observed. As aldehydes and alcohols are emitted upon plant damage, it is possible that these generalist grasshoppers are sensitive to the smells of damaged plants rather than species-specific plant smells.
... This classification of māwhitiwhiti Aotearoa simplifies the taxonomy, leaving the distinct ecological, behavioural and morphological features (e.g. Schori et al. 2020;Meza-Hoya et al. 2022;Nakano et al. 2022) of each species lineage to be explored without the distraction of relationships implied by artificial and unnecessary partitions that do not reflect their evolutionary ancestry. ...
Aotearoa New Zealand has a fauna of endemic alpine grasshoppers, consisting of thirteen species distributed among four genera. The many re-classifications of species within this group and the presence of species complexes highlight the uncertainty that surrounds relationships within and between these genera. High-throughput Next Generation Sequencing was used to assemble the complete mitochondrial genomes, 45S ribosomal cassettes and histone sequences of New Zealand’s four endemic alpine genera: Alpinacris, Brachaspis, Paprides and Sigaus. Phylogenetic analysis of these molecular datasets, as individual genes, partitions and combinations returned a consistent topology that is incompatible with the current classification. The genera Sigaus, Alpinacris, and Paprides all exhibit paraphyly. A consideration of the pronotum, epiphallus and terminalia of adult specimens reveals species-specific differences, but fails to provide compelling evidence for species groups justifying distinct genera. In combination with phylogenetic, morphological and spatial evidence we propose a simplified taxonomy consisting of a single genus for the māwhitiwhiti Aotearoa species radiation.
... For example in Hemideina crassidens (Blanchard, 1851), males have larger mandibles (Kelly 2005). In many grasshopper species, the types of antennal sensilla have no difference between males and females, but the number of antennal sensilla of males was significantly greater than females (Li et al. 2007;Nakano et al. 2022a). The reason for sexual dimorphism is complex. ...
... The function of each sensillum is extrapolated from its shape, size, porosity, and socket type. For example, sensilla without pores and a flexible socket are typically mechanoreceptors (Altner and Prillinger 1980;Nakano et al. 2022a). Sensilla without pores can be also responsible for thermoreception and hygroreception (Steinbrecht 1997;Hallberg et al 2003;Nowińska and Brożek 2017). ...
... Sensilla with pores are chemoreceptors. These sensilla can have a terminal pore (uniporous) or have many pores (multiporous or wall-pored), and they are considered gustatory receptors (contact chemoreception) or olfactory receptors (distance chemoreception) respectively (Klein 1981;Ring et al. 2008;Schneider and Römer 2016;Fea et al. 2019;Nakano et al. 2022a). The diversity of the sensory systems is linked to the ecological causes, and the specific ecology (e.g., habitats and sex roles) may influence the number and distribution of sensilla (Nakano et al. 2022b). ...
Morphological sexual dimorphism occurs in most insect species. Caves are relatively independent habitats with high levels of endemic insect species. The cave crickets are one of the most common insects in many caves and play an important role in the nutrient cycling of cave ecosystems. Sexual difference in sensilla has rarely been studied in cave crickets. We explore the types, number, and distribution of sensilla on the labial palps of both sexes of the cave cricket Tachycines plumiopedella Li, Feng & Luo, 2021 for the first time. Seven sensilla types were recorded on the labial palps in both sexes, including sensilla chaetica (Sc. 1–2), sensilla trichodea (St. 1–3), sensilla palmatum (Sp), Böhm bristles (Bb), sensilla campaniformia (Sca), sensilla basiconica (Sb. 1–3), and sensilla coeloconica (Sco. 1–2). The sensilla are mostly situated on the third palpomere of the labial palps, particularly on its middle to end part. Of sensilla on the labial palps, types and distribution were similar in males and females, but different in length, diameter, and number. The potential functional roles of sensilla were discussed.
