2024

Jump to: 2023, 2022, 2021, 2020

17 pages, 7819 KiB

Open AccessArticle

Morphological Characterization of the Antenna and Scent Patch of Three Danaus Species (Papilionoidea: Nymphalidae, Danainae)

by Yaqi Yang, Linyun Ding, Tong Wang, Huaijian Liao and Chufei Tang

Insects 2024, 15(2), 121; https://doi.org/10.3390/insects15020121 - 07 Feb 2024

Viewed by 1127

Abstract

The scent system of Danaus is important for the study of butterfly sexual communication and relevant investigations in biomimetics due to its involvement with mimicry. Using light, scanning, and transmission electron microscopy, the morphological characteristics of Danaus’ antennae and scent patches of [...] Read more.

The scent system of Danaus is important for the study of butterfly sexual communication and relevant investigations in biomimetics due to its involvement with mimicry. Using light, scanning, and transmission electron microscopy, the morphological characteristics of Danaus’ antennae and scent patches of the scent system for three species, D. chrysippus, D. genutia, and D. plexippus, were investigated herein. Their apical clubs of the flagellums contain sensilla trichodea, sensilla chaetica, and sensilla coeloconica. The scent patch scales typically have a tree-like structure in its lumen at the nano-scale. Comparisons were made between the androconial scales and the other scales in scent patches. Rank sum tests showed significant differences in scent patch scales’ characteristics between the species, as well as in the ultrastructure of antennal segments between species and sexes. Spearman’s correlation tests showed significant correlations between the morphological characteristics of androconial scales in scent patches. Moreover, the antennal characteristics were significantly correlated. The morphological characteristics of the females’ antennae were significantly correlated with those of the males’ antennae and androconial scales. However, the significance and coefficient of these correlations were inconsistent across species and sexes. This study provides fundamental morphological information that helps in understanding the pheromone recognition system of Danaus. Full article

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2023

Jump to: 2024, 2022, 2021, 2020

22 pages, 3089 KiB

Open AccessArticle

Chemosensory Receptor Expression in the Abdomen Tip of the Female Codling Moth, Cydia pomonella L. (Lepidoptera: Tortricidae)

by William B. Walker III, Alberto M. Cattaneo, Jennifer L. Stout, MacKenzie L. Evans and Stephen F. Garczynski

Insects 2023, 14(12), 948; https://doi.org/10.3390/insects14120948 - 14 Dec 2023

Viewed by 1351

Abstract

In insects, the chemical senses influence most vital behaviors, including mate seeking and egg laying; these sensory modalities are predominantly governed by odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs). The codling moth, Cydia pomonella, is a global pest of [...] Read more.

In insects, the chemical senses influence most vital behaviors, including mate seeking and egg laying; these sensory modalities are predominantly governed by odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs). The codling moth, Cydia pomonella, is a global pest of apple, pear, and walnut, and semiochemically based management strategies limit the economic impacts of this species. The previous report of expression of a candidate pheromone-responsive OR in female codling moth ovipositor and pheromone glands raises further questions about the chemosensory capacity of these organs. With an RNA-sequencing approach, we examined chemoreceptors’ expression in the female codling moth abdomen tip, sampling tissues from mated and unmated females and pupae. We report 37 ORs, 22 GRs, and 18 IRs expressed in our transcriptome showing overlap with receptors expressed in adult antennae as well as non-antennal candidate receptors. A quantitative PCR approach was also taken to assess the effect of mating on OR expression in adult female moths, revealing a few genes to be upregulated or downregulating after mating. These results provide a better understanding of the chemosensory role of codling moth female abdomen tip organs in female-specific behaviors. Future research will determine the function of specific receptors to augment current semiochemical-based strategies for codling moth management. Full article

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14 pages, 1829 KiB

Open AccessArticle

Age and Task Modulate Olfactory Sensitivity in the Florida Carpenter Ant Camponotus floridanus

by Stephen T. Ferguson, Isaac Bakis, Nicholas D. Edwards and Laurence J. Zwiebel

Insects 2023, 14(9), 724; https://doi.org/10.3390/insects14090724 - 23 Aug 2023

Cited by 1 | Viewed by 849

Abstract

Age-related changes in behavior and sensory perception have been observed in a wide variety of animal species. In ants and other eusocial insects, workers often progress through an ordered sequence of olfactory-driven behavioral tasks. Notably, these behaviors are plastic, and workers adapt and [...] Read more.

Age-related changes in behavior and sensory perception have been observed in a wide variety of animal species. In ants and other eusocial insects, workers often progress through an ordered sequence of olfactory-driven behavioral tasks. Notably, these behaviors are plastic, and workers adapt and rapidly switch tasks in response to changing environmental conditions. In the Florida carpenter ant, smaller minors typically perform most of the work needed to maintain the colony, while the larger majors are specialized for nest defense and rarely engage in these routine tasks. Here, we investigate the effects of age and task group on olfactory responses to a series of odorant blends in minor and major worker castes. Consistent with their respective roles within the colony, we observed significant age-associated shifts in the olfactory responses of minors as they transitioned between behavioral states, whereas the responses of majors remained consistently low regardless of age. Furthermore, we have identified a unitary compound, 3-methylindole, which elicited significantly higher responses and behavioral aversion in minor nurses than in similarly aged foragers suggesting that this compound may play an important role in brood care. Taken together, our results suggest that age- and task-associated shifts in olfactory physiology may play a critical role in the social organization of ant colonies. Full article

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11 pages, 2109 KiB

Open AccessArticle

Novel Methodology for Localizing and Studying Insect Dorsal Rim Area Morphology in 2D and 3D

by Vun Wen Jie, Arttu Miettinen and Emily Baird

Insects 2023, 14(8), 670; https://doi.org/10.3390/insects14080670 - 28 Jul 2023

Viewed by 847

Abstract

Polarized light-based navigation in insects is facilitated by a polarization-sensitive part of the eye, the dorsal rim area (DRA). Existing methods to study the anatomy of the DRA are destructive and time-consuming. We presented a novel method for DRA localization, dissection, and measurement [...] Read more.

Polarized light-based navigation in insects is facilitated by a polarization-sensitive part of the eye, the dorsal rim area (DRA). Existing methods to study the anatomy of the DRA are destructive and time-consuming. We presented a novel method for DRA localization, dissection, and measurement using 3D volumetric images from X-ray micro-computed tomography in combination with 2D photographs. Applying the method on size-polymorphic buff-tailed bumblebees, Bombus terrestris, we found that the DRA was easily obtainable from photographs of the dorsal eye region. Allometric analysis of the DRA in relation to body size in B. terrestris showed that it increased with the body size but not at the same rate. By localizing the DRA of individual bumblebees, we could also perform individual-level descriptions and inter-individual comparisons between the ommatidial structures (lens, crystalline cones, rhabdoms) of three different eye regions (DRA, non-DRA, proximate to DRA). One feature distinct to the bumblebee DRA was the smaller dimension of the crystalline cones in comparison to other regions of the eye. Using our novel methodology, we provide the first individual-level description of DRA ommatidial features and a comparison of how the DRA varies with body size in bumblebees. Full article

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18 pages, 1692 KiB

Open AccessArticle

Pheromone and Host Plant Odor Detection in Eastern Spruce Budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae)

by Thanusha Suresh, Lucas E. Roscoe and N. Kirk Hillier

Insects 2023, 14(7), 653; https://doi.org/10.3390/insects14070653 - 21 Jul 2023

Viewed by 888

Abstract

Spruce budworm, Choristoneura fumiferana Clemens, is an ecologically significant defoliator of spruce and balsam fir in North America. Optimization of semiochemical-mediated control is needed to improve the existing integrated pest management systems such as mating disruption and population estimation. This study used single [...] Read more.

Spruce budworm, Choristoneura fumiferana Clemens, is an ecologically significant defoliator of spruce and balsam fir in North America. Optimization of semiochemical-mediated control is needed to improve the existing integrated pest management systems such as mating disruption and population estimation. This study used single sensillum recordings (SSR) to identify the responses of olfactory receptor neurons (ORNs) in the antennal sensilla of adult male and female C. fumiferana to host plant volatiles, and female sex pheromones. There have been few SSR studies done on spruce budworm, and to our knowledge, the present study represents the first attempt to examine the responses of ORNs from antennal sensilla in response to a range of host and conspecific stimuli. A total of 86 sensilla were characterized and sorted into 15 possible sensillum categories based on odor responses. We observed that specialist sensilla responding to few ligands were more abundant in both male and female than sensilla exhibiting more generalized odorant responses. (E/Z)-11-tetradecenal elicited responses from ORNs from any sensilla which were sensitive to pheromones in both males and females. Female C. fumiferana ORNs were able to detect and physiologically respond to female-produced sex pheromones with the same degree of sensitivity as their male counterparts. Together, these data improve our knowledge of mechanisms by which adult budworms respond to pheromone and host plant volatiles and provide insights that may be complementary to existing integrated pest management (IPM) strategies based on the chemical ecology of spruce budworm. Full article

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18 pages, 4553 KiB

Open AccessArticle

The Leg Sensilla of Insects from Different Habitats—Comparison of Strictly Aquatic and Riparian Bugs (Corixidae, Ochteridae, Gelastocoridae: Nepomorpha: Insecta: Heteroptera)

by Agnieszka Nowińska, Barbara Franielczyk-Pietyra and Dan A. Polhemus

Insects 2023, 14(5), 441; https://doi.org/10.3390/insects14050441 - 07 May 2023

Cited by 1 | Viewed by 1717

Abstract

The aim of this study was to analyze morphological types and arrangement of the leg sensilla of Corixidae, Ochteridae and Gelastocoridae, in relation to their various habitats. The leg sensilla of four species of Corixidae, six of Gelastocoridae and two of Ochteridae were [...] Read more.

The aim of this study was to analyze morphological types and arrangement of the leg sensilla of Corixidae, Ochteridae and Gelastocoridae, in relation to their various habitats. The leg sensilla of four species of Corixidae, six of Gelastocoridae and two of Ochteridae were studied. Eight main types of sensilla with six subtypes of sensilla trichodea and four subtypes of sensilla chaetica were found and described. The greatest variability was observed among mechanoreceptive sensilla. The study showed differences in the shape of the legs between strictly aquatic and terrestrial taxa. It is the first attempt to describe leg sensilla among nepomorphan taxa. Full article

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2022

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16 pages, 5641 KiB

Open AccessArticle

Two Antenna-Enriched Odorant Binding Proteins in Dioryctria abietella Tuned to General Odorants and Insecticides

by Chun Wu, Ningna Yin, Yuruo Guo, Zhengquan Wang and Naiyong Liu

Insects 2022, 13(12), 1145; https://doi.org/10.3390/insects13121145 - 12 Dec 2022

Cited by 6 | Viewed by 1284

Abstract

The management of forest pests has become a significant challenge, particularly for wood borers, because they spend most of the time in the trunks or cones. The coneworm, Dioryctria abietella, is a representative of cone borers as its larvae feed on the cones [...] Read more.

The management of forest pests has become a significant challenge, particularly for wood borers, because they spend most of the time in the trunks or cones. The coneworm, Dioryctria abietella, is a representative of cone borers as its larvae feed on the cones of Pinaceae plants. The molecular mechanisms underlying the interactions between this species and host plants or habitats can assist in developing strategies for pest control. In this study, we extended the expression profiles of 32 odorant binding proteins (OBPs) in the reproductive tissues of D. abietella, revealing the detectable transcription of 29 genes. Using two DabiOBPs highly expressed in antennae (DabiOBP5 and DabiOBP14) as targets, six compounds with high affinities (dissociation constants < 13 μM) were identified through a reverse chemical ecology strategy, including insecticides widely used for the control of lepidopteran pests. Of these compounds, a floral volatile β-ionone and a pear-produced ester ethyl-(2E,4Z)-decadienoate may serve as behaviorally active compounds in D. abietella. The strong binding of DabiOBPs to insecticides suggested their involvement in insecticide resistance, reflecting sophisticated detoxification mechanisms of this moth. In the molecular simulations, DabiOBP14 possessed stronger interactions with the six ligands compared to DabiOBP5, in which a few key residues within the binding pockets were involved in the formation of hydrogen bonds. This study provides some valuable reference active compounds for the development of lures or repellents in D. abietella and unravels the putative roles of two antenna-dominant DabiOBPs in the perception of plant-derived odorants and insecticides. Full article

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13 pages, 2718 KiB

Open AccessArticle

Electrophysiological and Morphological Characterization of Contact Chemosensilla in Adults and Larvae of the Butterfly, Atrophaneura alcinous

by Kazuko Tsuchihara, Takuma Takanashi and Kiyoshi Asaoka

Insects 2022, 13(9), 802; https://doi.org/10.3390/insects13090802 - 02 Sep 2022

Cited by 1 | Viewed by 1837

Abstract

Distribution and electrophysiological responses of contact chemosensilla were examined in the Aristolochiaceae-feeding butterfly Atrophaneuraalcinous. In adult butterflies, tarsal contact chemosensilla of the foreleg were classified into two groups based on length: long- and short-type sensilla. Long-type sensilla were distributed much more [...] Read more.

Distribution and electrophysiological responses of contact chemosensilla were examined in the Aristolochiaceae-feeding butterfly Atrophaneuraalcinous. In adult butterflies, tarsal contact chemosensilla of the foreleg were classified into two groups based on length: long- and short-type sensilla. Long-type sensilla were distributed much more widely in females than in males, whereas short-type sensilla were found at the edge of the tarsi in a similar manner in both sexes. Taste responses of the long- and short-type sensilla to methanol extracts of Aristolochia debilis and Citrus spp. were recorded. Aristolochia debilis extracts evoked spikes with different amplitudes, whereas Citrus spp. extracts evoked spikes with a single amplitude in the long-type sensilla. Short-type sensilla did not respond to either extract. Moreover, we recorded responses to different concentrations of sucrose and NaCl. Results suggest that adult butterflies can discriminate the taste of host plant components from other chemicals using long-type sensilla during oviposition and may recognize diets containing sugar and salts during feeding using short-type sensilla. In the larval mouthparts, there were lateral and medial styloconic sensilla on the maxillary galea and epipharyngeal sensillum on the epipharynx. Electrophysiological responses of these sensilla suggest that larvae can discriminate between host plant compounds. Full article

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17 pages, 9452 KiB

Open AccessArticle

Ultrastructure Characteristics and Sexual Dimorphism of Antennal Sensilla in Tirathaba rufivena (Lepidoptera: Pyralidae)

by Jixing Guo, Zimeng Du, Guangchao Cui, Zheng Wang, Junfang Wang and Xiang Zhou

Insects 2022, 13(9), 797; https://doi.org/10.3390/insects13090797 - 01 Sep 2022

Cited by 3 | Viewed by 2110

Abstract

Tirathaba rufivena Walker, a major insect pest of Areca catechu L., has severely threatened areca nut cultivation in Hainan, China. To improve our understanding of the communication mechanism in host plant seeking and mate-finding for T. rufivena, we described and further characterized [...] Read more.

Tirathaba rufivena Walker, a major insect pest of Areca catechu L., has severely threatened areca nut cultivation in Hainan, China. To improve our understanding of the communication mechanism in host plant seeking and mate-finding for T. rufivena, we described and further characterized the external morphology and internal sensilla structures using scanning electron microscopy and transmission electron microscopy in this study. The antennal morphology was similar between males and females, and there was no significant difference in length between the two sexes. In total, nine sensilla types were identified: sensilla trichodea (Str), sensilla chaetica (Sch), sensilla basiconica (Sba), sensilla auricillica (Sau), sensilla coeloconica (Sco), sensilla styloconica (Sst), Böhm sensilla (Bs), uniporous peg sensilla (Ups) and sensilla squamiformia (Ssq). Sexual dimorphism mainly occurs in variation in the length of Sba, Sch, Sco1 and Bs, and the abundance of Sba, Sau1 and Sau2. The Sba had larger size and numbers on female antennae than that on males, suggesting that these sensilla might have important roles in locating host plants. Both Sau1 and Sau2 were significantly more abundant in females and were probably associated with the detection of mates and host plant for oviposition. These data were important for ongoing studies on host plant seeking and mate-finding behavior in T. rufivena and provided a theoretical foundation to further studies of semiochemical control for this pest. Full article

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12 pages, 1887 KiB

Open AccessArticle

Validation of an Optogenetic Approach to the Study of Olfactory Behavior in the T-Maze of Drosophila melanogaster Adults

by Ruth Coya, Fernando Martin, Laura Calvin-Cejudo, Carolina Gomez-Diaz and Esther Alcorta

Insects 2022, 13(8), 662; https://doi.org/10.3390/insects13080662 - 22 Jul 2022

Cited by 1 | Viewed by 1891

Abstract

Optogenetics enables the alteration of neural activity using genetically targeted expression of light activated proteins for studying behavioral circuits in several species including Drosophila. The main idea behind this approach is to replace the native behavioral stimulus by the light-induced electrical activation [...] Read more.

Optogenetics enables the alteration of neural activity using genetically targeted expression of light activated proteins for studying behavioral circuits in several species including Drosophila. The main idea behind this approach is to replace the native behavioral stimulus by the light-induced electrical activation of different points of the circuit. Therefore, its effects on subsequent steps of the circuit or on the final behavior can be analyzed. However, the use of optogenetics to dissect the receptor elements of the adult olfactory behavior presents a challenge due to one additional factor: Most odorants elicit attraction or avoidance depending on their concentration; this complicates the representative replacement of odor activation of olfactory sensory neurons (OSNs) by light. Here, we explore a dual excitation model where the subject is responding to odors while the OSNs are optogenetically activated. Thereby, we can assess if and how the olfactory behavior is modified. We measure the effects of light excitation on the response to several odorant concentrations. The dose-response curve of these flies still depends on odor concentration but with reduced sensitivity compared to olfactory stimulation alone. These results are consistent with behavioral tests performed with a background odor and suggest an additive effect of light and odor excitation on OSNs. Full article

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12 pages, 3719 KiB

Open AccessArticle

Brain Investigation on Sexual Dimorphism in a Gynandromorph Moth

by Elena Ian, Xi Chu and Bente Gunnveig Berg

Insects 2022, 13(3), 284; https://doi.org/10.3390/insects13030284 - 14 Mar 2022

Cited by 1 | Viewed by 2376

Abstract

The present study was dedicated to investigating the anatomical organization of distinct neuropils within the two brain hemispheres of a gynandromorphic moth of the species Helicoverpa armigera. High quality confocal imaging of a synapsin immuno-stained preparation combined with three-dimensional reconstructions made it possible [...] Read more.

The present study was dedicated to investigating the anatomical organization of distinct neuropils within the two brain hemispheres of a gynandromorphic moth of the species Helicoverpa armigera. High quality confocal imaging of a synapsin immuno-stained preparation combined with three-dimensional reconstructions made it possible to identify several brain structures involved in processing odor input and to measure their volumes in the male and female hemispheres. Thus, in addition to reconstructing the antennal lobes, we also made digital models of the mushroom body calyces, the pedunculus, and the vertical and medial lobes. As previously reported, prominent sexual dimorphism was demonstrated in the antennal lobes via the identification of a male-specific macroglomerular complex (MGC) and a female-specific complex (Fc) in each of the two brain hemispheres of the gynandromorph. Additionally, sex-specific differences were found in volume differences for three other neuropil structures—the calyces, pedunculus, and vertical lobe. The putative purpose of larger volumes of three mushroom body neuropils in females as compared to males is discussed. Full article

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13 pages, 2149 KiB

Open AccessArticle

Scanning Electron Microscopic Analysis of Antennal Sensilla and Tissue-Expression Profiles of Chemosensory Protein Genes in Ophraella communa (Coleoptera: Chrysomelidae)

by Chao Ma, Yang Yue, Yan Zhang, Zhen-Ya Tian, Hong-Song Chen, Jian-Ying Guo and Zhong-Shi Zhou

Insects 2022, 13(2), 183; https://doi.org/10.3390/insects13020183 - 09 Feb 2022

Cited by 3 | Viewed by 1957

Abstract

Ophraella communa is an efficient biocontrol agent used against the invasive weed Ambrosia artemisiifolia. It is an herbivorous insect that feeds on specific plants; the olfactory functions of this insects plays an important role in their search for host plants. There are [...] Read more.

Ophraella communa is an efficient biocontrol agent used against the invasive weed Ambrosia artemisiifolia. It is an herbivorous insect that feeds on specific plants; the olfactory functions of this insects plays an important role in their search for host plants. There are no reports on O. communa sensilla types, morphology, or chemosensory protein (CSP) genes. In this study, we observed the external structure and distribution of antennal sensilla in adult O. communa antennae by scanning electron microscopy; moreover, we cloned 11 CSPs (CSP1–CSP11) and elucidated their tissue-expression profiles using quantitative real-time polymerase chain reaction. Six types of sensilla were identified: sensilla trichodea (including two subtypes), sensilla chaetica, sensilla basiconica (including two subtypes), sensilla styloconica, sensilla coeloconica, and Böhm bristles. Both male and female antennae had all six types of sensilla, and no sexual dimorphism was noted in sensillar types or distribution. We also found that the expression levels of CSP2, CSP3, CSP4, CSP6, and CSP7 in male and female antennae were higher than those in other tissues, which suggests that these five CSPs may be related to olfactory function in O. communa. Ultimately, our results lay the foundation for interpreting the olfactory functions of adult O. communa. Full article

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18 pages, 2606 KiB

Open AccessArticle

Species-Specificity in Thermopreference and CO₂-Gated Heat-Seeking in Culex Mosquitoes

by Joanna M. Reinhold, Karthikeyan Chandrasegaran, Helen Oker, José E. Crespo, Clément Vinauger and Chloé Lahondère

Insects 2022, 13(1), 92; https://doi.org/10.3390/insects13010092 - 14 Jan 2022

Cited by 14 | Viewed by 3083

Abstract

Combining thermopreference (T_p) and CO₂-gated heat-seeking assays, we studied the thermal preferendum and response to thermal cues in three Culex mosquito species exhibiting differences in native habitat and host preference (e.g., biting cold and/or warm-blooded animals). Results show that [...] Read more.

Combining thermopreference (T_p) and CO₂-gated heat-seeking assays, we studied the thermal preferendum and response to thermal cues in three Culex mosquito species exhibiting differences in native habitat and host preference (e.g., biting cold and/or warm-blooded animals). Results show that these species differ in both T_p and heat-seeking behavior. In particular, we found that Culex territans, which feed primarily on cold-blood hosts, did not respond to heat during heat-seeking assays, regardless of the CO₂ concentration, but exhibited an intermediate T_p during resting. In contrast, Cx. quinquefasciatus, which feeds on warm blooded hosts, sought the coolest locations on a thermal gradient and responded only moderately to thermal stimuli when paired with CO₂ at higher concentrations. The third species, Cx. tarsalis, which has been shown to feed on a wide range of hosts, responded to heat when paired with high CO₂ levels and exhibited a high T_p. This study provides the first insights into the role of heat and CO₂ in the host seeking behavior of three disease vectors in the Culex genus and highlights differences in preferred resting temperatures. Full article

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2021

Jump to: 2024, 2023, 2022, 2020

13 pages, 1655 KiB

Open AccessArticle

Habituation to a Deterrent Plant Alkaloid Develops Faster in the Specialist Herbivore Helicoverpa assulta Than in Its Generalist Congener Helicoverpa armigera and Coincides with Taste Neuron Desensitisation

by Dong-Sheng Zhou, Chen-Zhu Wang and Joop J. A. van Loon

Insects 2022, 13(1), 21; https://doi.org/10.3390/insects13010021 - 23 Dec 2021

Viewed by 2342

Abstract

The two closely related moth species, Helicoverpa armigera and H. assulta differ strongly in their degree of host-plant specialism. In dual-choice leaf disk assays, caterpillars of the two species that had been reared on standard artificial diet were strongly deterred by the plant-derived [...] Read more.

The two closely related moth species, Helicoverpa armigera and H. assulta differ strongly in their degree of host-plant specialism. In dual-choice leaf disk assays, caterpillars of the two species that had been reared on standard artificial diet were strongly deterred by the plant-derived alkaloid strychnine. However, caterpillars of both species reared on artificial diet containing strychnine from neonate to the 5th instar were insensitive to this compound. Fifth instar caterpillars of H. assulta and 4th or 5th instars of H. armigera not exposed to strychnine before were subjected to strychnine-containing diet for 24 h, 36 h, 48 h, or 72 h. Whereas H. assulta displayed habituation to strychnine after 48 h, it took until 72 h for H. armigera to become habituated. Electrophysiological tests revealed that a deterrent-sensitive neuron in the medial sensillum styloconicum of both species displayed significantly reduced sensitivity to strychnine that correlated with the onset of habituation. We conclude that the specialist H. assulta habituated faster to strychnine than the generalist H. armigera and hypothesis that desensitization of deterrent-sensitive neurons contributed to habituation. Full article

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33 pages, 47874 KiB

Open AccessArticle

Morphology of the Antennal Sensilla of Notonectoidea and Comparison of Evolutionary Changes in Sensilla Types and Distribution in Infraorder Nepomorpha (Insecta: Heteroptera)

by Agnieszka Nowińska and Jolanta Brożek

Insects 2021, 12(12), 1121; https://doi.org/10.3390/insects12121121 - 14 Dec 2021

Cited by 3 | Viewed by 2404

Abstract

This article introduces the results of a study of three families of Nepomorpha and is the last part of a series of studies that sums up our work on the morphologies of the antennal sensory structures in this taxon. The morphologies and distribution [...] Read more.

This article introduces the results of a study of three families of Nepomorpha and is the last part of a series of studies that sums up our work on the morphologies of the antennal sensory structures in this taxon. The morphologies and distribution of the sensilla in the families Notonectidae, Pleidae and Helotrephidae were studied under a scanning electron microscope. Six main types (sensilla trichodea, chaetica, campaniformia, basiconica, ampullacea and coeloconica) and ten subtypes (five subtypes of sensilla trichodea and five subtypes of sensilla basiconica) were described. The results were compared with other studies on the antennal sensilla of Nepomorpha in order to assess evolutionary changes within the infraorder. With the use of cladistics analysis, the monophyly of the families Nepidae, Micronectidae, Corixidae and Gelastocoridae was supported. On the other hand, the occurrence of some clades forming superfamilies was weakly supported by bootstrap analysis. These results, supported by presence of the numerous autapomorphies, suggest that antennal sensilla evolved within inner groups. Full article

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13 pages, 1249 KiB

Open AccessReview

Evolution of the Sex Pheromone Communication System in Ostrinia Moths

by Dan-Dan Zhang

Insects 2021, 12(12), 1067; https://doi.org/10.3390/insects12121067 - 28 Nov 2021

Cited by 2 | Viewed by 2459

Abstract

It remains a conundrum in the evolution of sexual communication how the signals and responses can co-ordinate the changes during speciation. The genus Ostrinia contains several closely related species as well as distinctive strains with pheromone polymorphism and represents an example of ongoing [...] Read more.

It remains a conundrum in the evolution of sexual communication how the signals and responses can co-ordinate the changes during speciation. The genus Ostrinia contains several closely related species as well as distinctive strains with pheromone polymorphism and represents an example of ongoing speciation. Extensive studies in the genus, especially in the species the European corn borer O. nubilalis (ECB), the Asian corn borer O. furnacalis (ACB) and the adzuki bean borer O. scapulalis (ABB), have provided valuable insights into the evolution of sex pheromone communication. This review presents a comprehensive overview of the research on pheromone communication in different Ostrinia species over the past four decades, including pheromone identification and biosynthesis, the ligand profiles of pheromone receptor (PR) genes, the physiology of peripheral olfactory sensory neurons (OSNs) and the projection pattern to the antennal lobe. By integrating and comparing the closely related Ostrinia species and strains, it provides an evolutionary perspective on the sex pheromone communication in moths in general and also outlines the outstanding questions that await to be elucidated by future studies. Full article

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12 pages, 1644 KiB

Open AccessArticle

Sensory Organ Investment Varies with Body Size and Sex in the Butterfly Pieris napi

by Zahra Moradinour, Christer Wiklund, Vun Wen Jie, Carlos E. Restrepo, Karl Gotthard, Arttu Miettinen, Craig D. Perl and Emily Baird

Insects 2021, 12(12), 1064; https://doi.org/10.3390/insects12121064 - 27 Nov 2021

Cited by 2 | Viewed by 3151

Abstract

In solitary insect pollinators such as butterflies, sensory systems must be adapted for multiple tasks, including nectar foraging, mate-finding, and locating host-plants. As a result, the energetic investments between sensory organs can vary at the intraspecific level and even among sexes. To date, [...] Read more.

In solitary insect pollinators such as butterflies, sensory systems must be adapted for multiple tasks, including nectar foraging, mate-finding, and locating host-plants. As a result, the energetic investments between sensory organs can vary at the intraspecific level and even among sexes. To date, little is known about how these investments are distributed between sensory systems and how it varies among individuals of different sex. We performed a comprehensive allometric study on males and females of the butterfly Pieris napi where we measured the sizes and other parameters of sensory traits including eyes, antennae, proboscis, and wings. Our findings show that among all the sensory traits measured, only antenna and wing size have an allometric relationship with body size and that the energetic investment in different sensory systems varies between males and females. Moreover, males had absolutely larger antennae and eyes, indicating that they invest more energy in these organs than females of the same body size. Overall, the findings of this study reveal that the size of sensory traits in P. napi are not necessarily related to body size and raises questions about other factors that drive sensory trait investment in this species and in other insect pollinators in general. Full article

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23 pages, 3130 KiB

Open AccessReview

Stink Bug Communication and Signal Detection in a Plant Environment

by Andrej Čokl, Alenka Žunič-Kosi, Nataša Stritih-Peljhan, Maria Carolina Blassioli-Moraes, Raúl Alberto Laumann and Miguel Borges

Insects 2021, 12(12), 1058; https://doi.org/10.3390/insects12121058 - 25 Nov 2021

Cited by 4 | Viewed by 3415

Abstract

Plants influenced the evolution of plant-dwelling stink bugs’ systems underlying communication with chemical and substrate-borne vibratory signals. Plant volatiles provides cues that increase attractiveness or interfere with the probability of finding a mate in the field. Mechanical properties of herbaceous hosts and associated [...] Read more.

Plants influenced the evolution of plant-dwelling stink bugs’ systems underlying communication with chemical and substrate-borne vibratory signals. Plant volatiles provides cues that increase attractiveness or interfere with the probability of finding a mate in the field. Mechanical properties of herbaceous hosts and associated plants alter the frequency, amplitude, and temporal characteristics of stink bug species and sex-specific vibratory signals. The specificity of pheromone odor tuning has evolved through highly specific odorant receptors located within the receptor membrane. The narrow-band low-frequency characteristics of the signals produced by abdomen vibration and the frequency tuning of the highly sensitive subgenual organ vibration receptors match with filtering properties of the plants enabling optimized communication. A range of less sensitive mechanoreceptors, tuned to lower vibration frequencies, detect signals produced by other mechanisms used at less species-specific levels of communication in a plant environment. Whereas the encoding of frequency-intensity and temporal parameters of stink bug vibratory signals is relatively well investigated at low levels of processing in the ventral nerve cord, processing of this information and its integration with other modalities at higher neuronal levels still needs research attention. Full article

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15 pages, 4083 KiB

Open AccessArticle

Olfactory Sensilla and Olfactory Genes in the Parasitoid Wasp Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

by Basman H. Al-Jalely and Wei Xu

Insects 2021, 12(11), 998; https://doi.org/10.3390/insects12110998 - 05 Nov 2021

Cited by 11 | Viewed by 2614

Abstract

Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is a tiny natural egg parasitoid of several agricultural pest insects, which has been widely used in the biological control for Plutella xylostella, Helicoverpa armigera, Spodoptera frugiperda and Ectomyelois ceratoniae. However, limited studies have been [...] Read more.

Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is a tiny natural egg parasitoid of several agricultural pest insects, which has been widely used in the biological control for Plutella xylostella, Helicoverpa armigera, Spodoptera frugiperda and Ectomyelois ceratoniae. However, limited studies have been conducted on T. pretiosum olfactory system, which is critical in regulating insect behaviours. In this study, T. pretiosum adult antennae were investigated under ascanning electron microscopy (SEM). Four types of olfactory sensilla were observed, including chaetica sensilla (CS), trichoid sensilla (TS), faleate sensilla (FS) and placoid sensilla (PS). Using T. pretiosum genome, 22 putative odorant binding proteins (OBPs) and 105 odorant receptors (ORs) were identified, which were further compared with olfactory genes of Apis mellifera, Nasonia vitripennis and Diachasma alloeum. The expression patterns of OBPs between T. pretiosum male and female adults were examined by quantitative real time PCR (qRT-PCR) approaches. Three female-specific OBPs (TpreOBP19, TpreOBP15 and TpreOBP3) were identified, which may play crucial roles in T. pretiosum host-seeking and oviposition behaviours. This study enriches our knowledge of T. pretiosum olfactory genes and improves our understanding of its olfactory system. Full article

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26 pages, 12375 KiB

Open AccessArticle

Hermetia illucens (L.) (Diptera: Stratiomyidae) Odorant Binding Proteins and Their Interactions with Selected Volatile Organic Compounds: An In Silico Approach

by Carmen Scieuzo, Marisa Nardiello, Donatella Farina, Andrea Scala, Jonathan A. Cammack, Jeffery K. Tomberlin, Heiko Vogel, Rosanna Salvia, Krishna Persaud and Patrizia Falabella

Insects 2021, 12(9), 814; https://doi.org/10.3390/insects12090814 - 11 Sep 2021

Cited by 27 | Viewed by 4198

Abstract

The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has considerable global interest due to its outstanding capacity in bioconverting organic waste to insect biomass, which can be used for livestock, poultry, and aquaculture feed. Mass production of this insect in colonies requires [...] Read more.

The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has considerable global interest due to its outstanding capacity in bioconverting organic waste to insect biomass, which can be used for livestock, poultry, and aquaculture feed. Mass production of this insect in colonies requires the development of methods concentrating oviposition in specific collection devices, while the mass production of larvae and disposing of waste may require substrates that are more palatable and more attractive to the insects. In insects, chemoreception plays an essential role throughout their life cycle, responding to an array of chemical, biological and environmental signals to locate and select food, mates, oviposition sites and avoid predators. To interpret these signals, insects use an arsenal of molecular components, including small proteins called odorant binding proteins (OBPs). Next generation sequencing was used to identify genes involved in chemoreception during the larval and adult stage of BSF, with particular attention to OBPs. The analysis of the de novo adult and larval transcriptome led to the identification of 27 and 31 OBPs for adults and larvae, respectively. Among these OBPs, 15 were common in larval and adult transcriptomes and the tertiary structures of 8 selected OBPs were modelled. In silico docking of ligands confirms the potential interaction with VOCs of interest. Starting from the information about the growth performance of H. illucens on different organic substrates from the agri-food sector, the present work demonstrates a possible correlation between a pool of selected VOCs, emitted by those substrates that are attractive for H. illucens females when searching for oviposition sites, as well as phagostimulants for larvae. The binding affinities between OBPs and selected ligands calculated by in silico modelling may indicate a correlation among OBPs, VOCs and behavioural preferences that will be the basis for further analysis. Full article

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18 pages, 2488 KiB

Open AccessArticle

Olfactory Learning Supports an Adaptive Sugar-Aversion Gustatory Phenotype in the German Cockroach

by Ayako Wada-Katsumata and Coby Schal

Insects 2021, 12(8), 724; https://doi.org/10.3390/insects12080724 - 13 Aug 2021

Cited by 2 | Viewed by 2790

Abstract

An association of food sources with odors prominently guides foraging behavior in animals. To understand the interaction of olfactory memory and food preferences, we used glucose-averse (GA) German cockroaches. Multiple populations of cockroaches evolved a gustatory polymorphism where glucose is perceived as a [...] Read more.

An association of food sources with odors prominently guides foraging behavior in animals. To understand the interaction of olfactory memory and food preferences, we used glucose-averse (GA) German cockroaches. Multiple populations of cockroaches evolved a gustatory polymorphism where glucose is perceived as a deterrent and enables GA cockroaches to avoid eating glucose-containing toxic baits. Comparative behavioral analysis using an operant conditioning paradigm revealed that learning and memory guide foraging decisions. Cockroaches learned to associate specific food odors with fructose (phagostimulant, reward) within only a 1 h conditioning session, and with caffeine (deterrent, punishment) after only three 1 h conditioning sessions. Glucose acted as reward in wild type (WT) cockroaches, but GA cockroaches learned to avoid an innately attractive odor that was associated with glucose. Olfactory memory was retained for at least 3 days after three 1 h conditioning sessions. Our results reveal that specific tastants can serve as potent reward or punishment in olfactory associative learning, which reinforces gustatory food preferences. Olfactory learning, therefore, reinforces behavioral resistance of GA cockroaches to sugar-containing toxic baits. Cockroaches may also generalize their olfactory learning to baits that contain the same or similar attractive odors even if they do not contain glucose. Full article

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15 pages, 1726 KiB

Open AccessArticle

Compass Cue Integration and Its Relation to the Visual Ecology of Three Tribes of Ball-Rolling Dung Beetles

by Lana Khaldy, Claudia Tocco, Marcus Byrne and Marie Dacke

Insects 2021, 12(6), 526; https://doi.org/10.3390/insects12060526 - 06 Jun 2021

Cited by 3 | Viewed by 2349

Abstract

To guide their characteristic straight-line orientation away from the dung pile, ball-rolling dung beetles steer according to directional information provided by celestial cues, which, among the most relevant are the sun and polarised skylight. Most studies regarding the use of celestial cues and [...] Read more.

To guide their characteristic straight-line orientation away from the dung pile, ball-rolling dung beetles steer according to directional information provided by celestial cues, which, among the most relevant are the sun and polarised skylight. Most studies regarding the use of celestial cues and their influence on the orientation system of the diurnal ball-rolling beetle have been performed on beetles of the tribe Scarabaeini living in open habitats. These beetles steer primarily according to the directional information provided by the sun. In contrast, Sisyphus fasciculatus, a species from a different dung-beetle tribe (the Sisyphini) that lives in habitats with closely spaced trees and tall grass, relies predominantly on directional information from the celestial pattern of polarised light. To investigate the influence of visual ecology on the relative weight of these cues, we studied the orientation strategy of three different tribes of dung beetles (Scarabaeini, Sisyphini and Gymnopleurini) living within the same biome, but in different habitat types. We found that species within a tribe share the same orientation strategy, but that this strategy differs across the tribes; Scarabaeini, living in open habitats, attribute the greatest relative weight to the directional information from the sun; Sisyphini, living in closed habitats, mainly relies on directional information from polarised skylight; and Gymnopleurini, also living in open habitats, appear to weight both cues equally. We conclude that, despite exhibiting different body size, eye size and morphology, dung beetles nevertheless manage to solve the challenge of straight-line orientation by weighting visual cues that are particular to the habitat in which they are found. This system is however dynamic, allowing them to operate equally well even in the absence of the cue given the greatest relative weight by the particular species. Full article

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25 pages, 5261 KiB

Open AccessArticle

Effects of Multi-Component Backgrounds of Volatile Plant Compounds on Moth Pheromone Perception

by Lucie Conchou, Philippe Lucas, Nina Deisig, Elodie Demondion and Michel Renou

Insects 2021, 12(5), 409; https://doi.org/10.3390/insects12050409 - 01 May 2021

Cited by 3 | Viewed by 2203

Abstract

The volatile plant compounds (VPC) alter pheromone perception by insects but mixture effects inside insect olfactory landscapes are poorly understood. We measured the activity of receptor neurons tuned to Z7-12Ac (Z7-ORN), a pheromone component, in the antenna and central neurons in male Agrotis [...] Read more.

The volatile plant compounds (VPC) alter pheromone perception by insects but mixture effects inside insect olfactory landscapes are poorly understood. We measured the activity of receptor neurons tuned to Z7-12Ac (Z7-ORN), a pheromone component, in the antenna and central neurons in male Agrotis ipsilon while exposed to simple or composite backgrounds of a panel of VPCs representative of the odorant variety encountered by a moth. Maps of activities were built using calcium imaging to visualize which areas in antennal lobes (AL) were affected by VPCs. We compared the VPC activity and their impact as backgrounds at antenna and AL levels, individually or in blends. At periphery, VPCs showed differences in their capacity to elicit Z7-ORN firing response that cannot be explained by differences in stimulus intensities because we adjusted concentrations according to vapor pressures. The AL neuronal network, which reformats the ORN input, did not improve pheromone salience. We postulate that the AL network evolved to increase sensitivity and to encode for fast changes of pheromone at some cost for signal extraction. Comparing blends to single compounds indicated that a blend shows the activity of its most active component. VPC salience seems to be more important than background complexity. Full article

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13 pages, 3813 KiB

Open AccessArticle

Ultrastructure of the Olfactory Sensilla across the Antennae and Maxillary Palps of Bactrocera dorsalis (Diptera: Tephritidae)

by Zhao Liu, Ting Hu, Huai-Wang Guo, Xiao-Fei Liang and Yue-Qing Cheng

Insects 2021, 12(4), 289; https://doi.org/10.3390/insects12040289 - 26 Mar 2021

Cited by 12 | Viewed by 3076

Abstract

The sensilla on the antennae and maxillary palps are the most important olfactory organs, via which the insect can perceive the semiochemicals to adjust their host seeking and oviposition behaviors. The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a major agricultural [...] Read more.

The sensilla on the antennae and maxillary palps are the most important olfactory organs, via which the insect can perceive the semiochemicals to adjust their host seeking and oviposition behaviors. The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a major agricultural quarantine pest infesting more than 250 different fruits and vegetables. However, the sensilla involved in olfaction have not been well documented even though a variety of control practices based on chemical communication have already been developed. In this study, the ultrastructure of the sensilla, especially the olfactory sensilla on the antennae and maxillary palps of both males and females, were investigated with field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Three types of olfactory sensillum types including trichodea, basiconica, and coeloconica, and two non-olfactory sensilla including both chaetica and microtrichia, were observed. Each of these three types of olfactory sensilla on the antennae of B. dorsalis were further classified into two subtypes according to the morphology and number of receptor cells. For the first time, the pores on the sensilla trichodea and basiconica cuticular wall were observed in this species, suggesting they are involved in semiochemical perception. This study provides new information on B. dorsalis olfaction, which can be connected to other molecular, genetic, and behavioral research to construct an integral olfactory system model for this species. Full article

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16 pages, 5193 KiB

Open AccessArticle

Antennal Transcriptome Analysis and Identification of Candidate Chemosensory Genes of the Harlequin Ladybird Beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

by Gabriele Rondoni, Alessandro Roman, Camille Meslin, Nicolas Montagné, Eric Conti and Emmanuelle Jacquin-Joly

Insects 2021, 12(3), 209; https://doi.org/10.3390/insects12030209 - 02 Mar 2021

Cited by 11 | Viewed by 3213

Abstract

In predatory ladybirds (Coleoptera: Coccinellidae), antennae are important for chemosensory reception used during food and mate location, and for finding a suitable oviposition habitat. Based on NextSeq 550 Illumina sequencing, we assembled the antennal transcriptome of mated Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) males [...] Read more.

In predatory ladybirds (Coleoptera: Coccinellidae), antennae are important for chemosensory reception used during food and mate location, and for finding a suitable oviposition habitat. Based on NextSeq 550 Illumina sequencing, we assembled the antennal transcriptome of mated Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) males and females and described the first chemosensory gene repertoire expressed in this species. We annotated candidate chemosensory sequences encoding 26 odorant receptors (including the coreceptor, Orco), 17 gustatory receptors, 27 ionotropic receptors, 31 odorant-binding proteins, 12 chemosensory proteins, and 4 sensory neuron membrane proteins. Maximum-likelihood phylogenetic analyses allowed to assign candidate H. axyridis chemosensory genes to previously described groups in each of these families. Differential expression analysis between males and females revealed low variability between sexes, possibly reflecting the known absence of relevant sexual dimorphism in the structure of the antennae and in the distribution and abundance of the sensilla. However, we revealed significant differences in expression of three chemosensory genes, namely two male-biased odorant-binding proteins and one male-biased odorant receptor, suggesting their possible involvement in pheromone detection. Our data pave the way for improving the understanding of the molecular basis of chemosensory reception in Coccinellidae. Full article

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2020

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15 pages, 17851 KiB

Open AccessArticle

The Antennal Pathway of Dragonfly Nymphs, from Sensilla to the Brain

by Silvana Piersanti, Manuela Rebora, Gianandrea Salerno and Sylvia Anton

Insects 2020, 11(12), 886; https://doi.org/10.3390/insects11120886 - 16 Dec 2020

Cited by 5 | Viewed by 3138

Abstract

Dragonflies are hemimetabolous insects, switching from an aquatic life style as nymphs to aerial life as adults, confronted to different environmental cues. How sensory structures on the antennae and the brain regions processing the incoming information are adapted to the reception of fundamentally [...] Read more.

Dragonflies are hemimetabolous insects, switching from an aquatic life style as nymphs to aerial life as adults, confronted to different environmental cues. How sensory structures on the antennae and the brain regions processing the incoming information are adapted to the reception of fundamentally different sensory cues has not been investigated in hemimetabolous insects. Here we describe the antennal sensilla, the general brain structure, and the antennal sensory pathways in the last six nymphal instars of Libellula depressa, in comparison with earlier published data from adults, using scanning electron microscopy, and antennal receptor neuron and antennal lobe output neuron mass-tracing with tetramethylrhodamin. Brain structure was visualized with an anti-synapsin antibody. Differently from adults, the nymphal antennal flagellum harbors many mechanoreceptive sensilla, one olfactory, and two thermo-hygroreceptive sensilla at all investigated instars. The nymphal brain is very similar to the adult brain throughout development, despite the considerable differences in antennal sensilla and habitat. Like in adults, nymphal brains contain mushroom bodies lacking calyces and small aglomerular antennal lobes. Antennal fibers innervate the antennal lobe similar to adult brains and the gnathal ganglion more prominently than in adults. Similar brain structures are thus used in L. depressa nymphs and adults to process diverging sensory information. Full article

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