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Zhang SS, Wang PC, Ning C, Yang K, Li GC, Cao LL, Huang LQ, Wang CZ. The larva and adult of Helicoverpa armigera use differential gustatory receptors to sense sucrose. eLife 2024; 12:RP91711. [PMID: 38814697 PMCID: PMC11139476 DOI: 10.7554/elife.91711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024] Open
Abstract
Almost all herbivorous insects feed on plants and use sucrose as a feeding stimulant, but the molecular basis of their sucrose reception remains unclear. Helicoverpa armigera as a notorious crop pest worldwide mainly feeds on reproductive organs of many plant species in the larval stage, and its adult draws nectar. In this study, we determined that the sucrose sensory neurons located in the contact chemosensilla on larval maxillary galea were 100-1000 times more sensitive to sucrose than those on adult antennae, tarsi, and proboscis. Using the Xenopus expression system, we discovered that Gr10 highly expressed in the larval sensilla was specifically tuned to sucrose, while Gr6 highly expressed in the adult sensilla responded to fucose, sucrose and fructose. Moreover, using CRISPR/Cas9, we revealed that Gr10 was mainly used by larvae to detect lower sucrose, while Gr6 was primarily used by adults to detect higher sucrose and other saccharides, which results in differences in selectivity and sensitivity between larval and adult sugar sensory neurons. Our results demonstrate the sugar receptors in this moth are evolved to adapt toward the larval and adult foods with different types and amounts of sugar, and fill in a gap in sweet taste of animals.
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Affiliation(s)
- Shuai-Shuai Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Pei-Chao Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Chao Ning
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Ke Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Guo-Cheng Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Lin-Lin Cao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
| | - Ling-Qiao Huang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
| | - Chen-Zhu Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of SciencesBeijingChina
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Hager MS, Hofland ML, Varella AC, Bothner B, Budak H, Weaver DK. Untargeted metabolomics profiling of oat ( Avena sativa L.) and wheat ( Triticum aestivum L.) infested with wheat stem sawfly ( Cephus cinctus Norton) reveals differences associated with plant defense and insect nutrition. FRONTIERS IN PLANT SCIENCE 2024; 15:1327390. [PMID: 38328705 PMCID: PMC10848266 DOI: 10.3389/fpls.2024.1327390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/03/2024] [Indexed: 02/09/2024]
Abstract
Introduction Wheat stem sawfly (WSS), Cephus cinctus Norton, is a major pest of common bread wheat (Triticum aestivum L.) and other cultivated cereals in North America. Planting of cultivars with solid stems has been the primary management strategy to prevent yield loss due to WSS infestation, however expression of this phenotype can vary depending on environmental conditions and solid stems hinder biological control of WSS via braconid parasitoids Bracon cephi (Gahan) and Bracon lissogaster Muesebeck. In the hollow stems of oat (Avena sativa L.), WSS larvae experience 100% mortality before they reach late instars, but the mechanisms for this observed resistance have not been characterized. Objective The objective of this study was to explore additional sources of resistance outside of the historic solid stem phenotype. Methods Here, we use an untargeted metabolomics approach to examine the response of the metabolome of two cultivars of oat and four cultivars of spring wheat to infestation by WSS. Using liquid chromatography-mass spectrometry (LC-MS), differentially expressed metabolites were identified between oat and wheat which were associated with the phenylpropanoid pathway, phospholipid biosynthesis and signaling, the salicylic acid signaling pathway, indole-3-acetic acid (IAA) degradation, and biosynthesis of 1,4-benzoxazin-3-ones (Bxs). Several phospho- and galacto- lipids were found in higher abundance in oat, and with the exception of early stem solidness cultivar Conan, both species experienced a decrease in abundance once infested. In all wheat cultivars except Conan, an increase in abundance was observed for Bxs HMDBOA-glc and DIBOA-β-D-glucoside after infestation, indicating that this pathway is involved in wheat response to infestation in both solid and hollow stemmed cultivars. Differences between species in compounds involved in IAA biosynthesis, degradation and inactivation suggest that wheat may respond to infestation by inactivating IAA or altering the IAA pool in stem tissue. Conclusion We propose that the species differences found here likely affect the survival of WSS larvae and may also be associated with differences in stem architecture at the molecular level. Our findings suggest pathways to focus on for future studies in elucidating plant response to WSS infestation.
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Affiliation(s)
- Megan S. Hager
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, United States
- Wheat Stem Sawfly Laboratory, Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
| | - Megan L. Hofland
- Wheat Stem Sawfly Laboratory, Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
| | - Andrea C. Varella
- Corteva Agriscience™, Woodstock Research and Development Centre, Tavistock, ON, Canada
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Hikmet Budak
- Department of Agriculture, Arizona Western College, Yuma, AZ, United States
| | - David K. Weaver
- Wheat Stem Sawfly Laboratory, Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
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Solari P, Sollai G, Pasquini V, Giglioli A, Crnjar R, Addis P. Blue-Green Algae as Stimulating and Attractive Feeding Substrates for a Mediterranean Commercial Sea Urchin Species, Paracentrotus lividus. Life (Basel) 2023; 13:1510. [PMID: 37511884 PMCID: PMC10381433 DOI: 10.3390/life13071510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/23/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Sea urchins rely on chemical senses to localize suitable food resources, therefore representing model species for chemosensory studies. In the present study, we investigated the chemical sensitivity of the Mediterranean sea urchin Paracentrotus lividus to the blue-green alga Aphanizomenon flos-aquae, namely "Klamath", and to a few amino acids chosen from the biochemical composition of the same algae. To this end, we used the "urchinogram" method, which estimates the movement rate of the sea urchins in response to chemicals. Our results showed that Klamath represents a strong chemical stimulus for P. lividus as it elicits an overall movement of spines, pedicellariae, and tube feet coupled, in some cases, to a coordinated locomotion of the animals. Sea urchins also displayed a sensitivity, even if to a lesser extent, to leucine, threonine, arginine, and proline, thus implying that the amino acids contained in Klamath may account, at least in part, for the stimulating effects exerted by the whole algae. Additionally, our results show that Klamath, as well as spirulina, another blue-green alga with high nutritional value, is very attractive for this sea urchin species. These findings gain further importance considering the potential profit of echinoderms for commercial consumers and their growing role in aquaculture. Klamath and spirulina combine high nutritional profiles with attractive and stimulating abilities and may be considered potential valuable feed supplements in sea urchin aquaculture.
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Affiliation(s)
- Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, Italy
| | - Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, Italy
| | - Viviana Pasquini
- Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
| | - Angelica Giglioli
- Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, Italy
| | - Piero Addis
- Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
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Shii F, Mang D, Kasubuchi M, Tsuneto K, Toyama T, Endo H, Sasaki K, Sato R. Ultrasensitive detection by maxillary palp neurons allows non-host recognition without consumption of harmful allelochemicals. JOURNAL OF INSECT PHYSIOLOGY 2021; 132:104263. [PMID: 34052304 DOI: 10.1016/j.jinsphys.2021.104263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Most lepidopteran insect larvae exhibit stepwise feeding behaviors, such as palpation using the maxillary palps (MPs) followed by test biting and persistent biting. However, the purpose of palpation has been unclear. In particular, nothing is known about the neurons in the MP and their mode of recognition of undesired plants, although such neurons have been suggested to exist. In this study, we used larvae of the stenophagous insect Bombyx mori and compared the roles of palpation and test biting in the selection of feeding behavior. When the larvae were given non-host plant leaves, they did not initiate test biting, indicating that non-host plant leaves were recognized via palpation without biting, and that this behavior resulted in a lack of persistent biting, as the leaves were judged non-suitable for consumption. Surface extracts of inedible leaves significantly suppressed test biting of mulberry leaves, a host plant of B. mori, suggesting that secondary metabolites on the leaf surface of inedible leaves function as test biting suppressors, even when another conditions are suitable for test biting. The allelochemical coumarin, which is found in the inedible leaves of cherry, Cerasus speciosa, significantly suppressed test biting of mulberry leaves, suggesting that coumarin is a possible deterrent to the eating of cherry leaves. Using the electrophysiological method of tip recording and a leaf-surface extract as the test material, leaf-surface compound-responsive neurons were identified in the MP. In addition, several neurons that respond to coumarin in the attomolar range were identified, suggesting that the larvae use ultrasensitive neurons in the MP to recognize inedible leaves. In the HEK293T cell heterologous expression system, the B. mori gustatory receptors BmGr53 and BmGr19, which were previously found to be expressed in the MP and to respond to coumarin in the attomolar range, responded to a leaf-surface extract of C. speciosa, suggesting that these receptors may be present on the inedible-leaf-recognizing neurons of the MP. These findings suggest that ultrasensitive plant secondary metabolite-recognizing neurons in the MP allow for the recognition of non-host plants via palpation without risking damage caused by ingesting harmful allelochemicals.
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Affiliation(s)
- Fumika Shii
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Dingze Mang
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Mayu Kasubuchi
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Kana Tsuneto
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Tomoko Toyama
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Haruka Endo
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Ken Sasaki
- Graduate School of Agriculture, Tamagawa University, Tamagawagakuen 6-1-1, Machida, Tokyo 194-8610, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan.
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Xu W. How do moth and butterfly taste?-Molecular basis of gustatory receptors in Lepidoptera. INSECT SCIENCE 2020; 27:1148-1157. [PMID: 31433559 PMCID: PMC7687262 DOI: 10.1111/1744-7917.12718] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/21/2019] [Accepted: 08/10/2019] [Indexed: 05/04/2023]
Abstract
Insect gustatory system plays a central role in guiding insect feeding behaviors, insect-plant interactions and coevolutions. Gustatory receptors (GRs) form the interface between the insect taste system and their environment. Previously, most studies on insect GRs are focused on Drosophila; much less attention has been paid to Lepidoptera species, which consist of a large number of serious agricultural crop pests. With the exceptional advances in the next generation sequencing (NGS), cellular biology, RNA interference (RNAi), and clustered regularly interspaced short palindromic repeats (CRISPR) technologies in recent years, extraordinary progresses have been achieved elucidating the molecular mechanisms of Lepidopteran GRs. In this review, we highlighted these advances, discussed what these advances have revealed and provide our new insights into this field.
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Affiliation(s)
- Wei Xu
- Agricultural SciencesCollege of Science, Health, Engineering and Education, Murdoch UniversityWAAustralia
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Corda G, Solari P, Dettori MA, Fabbri D, Delogu G, Crnjar R, Sollai G. Association between olfactory sensitivity and behavioral responses of Drosophila suzukii to naturally occurring volatile compounds. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 104:e21669. [PMID: 32190926 DOI: 10.1002/arch.21669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/04/2020] [Accepted: 03/07/2020] [Indexed: 06/10/2023]
Abstract
Drosophila suzukii Matsumura (Diptera: Drosophilidae) is an invasive, destructive crop pest that originated in South East Asia. D. suzukii recently invaded Western countries and is threatening both European and American fruit industries. It is extremely attracted to otherwise undamaged, ripening fruits, unlike most other Drosophila species that attack only decaying or rotten fruits. Recent studies on different insect species showed that several naturally occurring compounds of easy market availability showing deterrent action may be used to supplement mass catches with food traps. Based on these considerations, the aim of the present work was to test the effects of some natural compounds (alone or in the mixture) on the olfactory system of the D. suzukii and the behavioral responses evoked. We measured by electroantennogram (EAG) recordings, the olfactory sensitivity of antennae to increasing concentrations of eugenol, vanillin, menthol, cis-jasmone; eugenol + vanillin, +menthol, +cis-jasmone; vanillin + menthol, +cis-jasmone. In addition, the behavioral responses to the same compounds and mixtures were evaluated. Our electrophysiological results show a dose-response relationship between the EAG amplitudes and the increasing concentrations of the olfactory compound. The behavioral results show that the number of laid eggs is significantly different between the standard diet and the standard diet + natural compound. These results underline a specificity in the olfactory sensitivity and in the ovipositing behavior of D. suzukii females; also, they could be valuable for the identification of key chemicals aimed at the future development of strategies in the management and control of this harmful insect for crops.
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Affiliation(s)
- Giulia Corda
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | - Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | | | - Davide Fabbri
- National Research Council (CNR) Institute of Biomolecular Chemistry, Sassari, Italy
| | - Giovanna Delogu
- National Research Council (CNR) Institute of Biomolecular Chemistry, Sassari, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | - Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
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Sollai G, Crnjar R. The contribution of gustatory input to larval acceptance and female oviposition choice of potential host plants in Papilio hospiton (Géné). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 100:e21521. [PMID: 30418667 DOI: 10.1002/arch.21521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Lepidopteran Papilio hospiton uses only plants belonging to the Apiaceae and the Rutaceae families as hosts. Both adult females and larvae are equipped with gustatory receptor neurons (GRNs) capable of detecting sugars, bitters and salts, thus providing information for evaluating the chemical composition of the plant. Since the activation of these neurons may affect insect behavior, the aim of this study were: (a) to study the gustatory sensitivity of both females and larvae to the sap of two Apiaceae, Foeniculum vulgare (fennel) and Daucus carota (carrot), that are not used as host plants; (b) to cross-compare the spike activity evoked from these two plants with that evoked by Ferula communis (ferula), the host plant preferred by ovipositing females of P. hospiton and where the larvae perform best; (c) finally, to confirm that the gustatory system can provide the central nervous system with the necessary information to evaluate differences between plant saps. The results show that: (a) fennel and carrot both evoke a higher neural activity from the bitter-sensitive neurons and lower from the sugar-sensitive neurons with respect to ferula, in both adult females and larvae; (b) on the basis of the different patterns of neural activity generated in tarsal, lateral and medial sensilla by fennel and carrot versus ferula, both adult and larvae possess enough information to discriminate among these plants; (c) adult females of P. hospiton lay eggs where the larvae have the greatest growth success and this confirms the importance of taste sensitivity in host plants selection.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Monserrato, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Monserrato, Italy
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Solari P, Sollai G, Masala C, Maccioni R, Crnjar R, Liscia A. Octopamine modulates the activity of motoneurons related to calling behavior in the gypsy moth Lymantria dispar. INSECT SCIENCE 2018; 25:797-808. [PMID: 29473996 DOI: 10.1111/1744-7917.12580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/31/2018] [Accepted: 02/17/2018] [Indexed: 06/08/2023]
Abstract
A morphofunctional investigation of the different neuronal subpopulations projecting through each of the nerves IV-VI emerging bilaterally from the terminal abdominal ganglion (TAG) was correlated with the octopaminergic activity in the ganglion that controls the ovipositor movements associated with calling behavior in the female gypsy moth Lymantria dispar. Tetramethylrodamine-dextran backfills from nerve stumps resulted in a relatively low number of TAG projections, ranging from 12 to 13 for nerve pair IV, 12 to 14 for nerve pair V, and 8 to 9 for nerve pair VI. Furthermore, as assessed by electrophysiological recordings, a number of fibers within each of these nerves displays spontaneous tonic activity, also when the ganglion is fully disconnected from the ventral nerve cord (VNC). Octopamine (OA) applications to the TAG strongly enhanced the activity of these nerves, either by increasing the firing rate of a number of spontaneously firing units or by recruiting new ones. This octopaminergic activity affected calling behavior, and specifically the muscle activity leading to cycling extensions of the intersegmental membrane (IM) between segments VIII and IX (ovipositor). Our results indicate that in the female gypsy moth the octopaminergic neural activity of the TAG is coupled with extensions and retractions of IM for the purpose of releasing pheromone, where motor units innervated by nerve pair IV appear antagonistic with respect to those innervated by nerve pair V.
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Affiliation(s)
- Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
| | - Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
| | - Carla Masala
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
| | - Riccardo Maccioni
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
| | - Anna Liscia
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, University Campus, Monserrato, CA, Italy
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Sollai G, Biolchini M, Crnjar R. Taste sensitivity and divergence in host plant acceptance between adult females and larvae of Papilio hospiton. INSECT SCIENCE 2018; 25:809-822. [PMID: 29484829 DOI: 10.1111/1744-7917.12581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/30/2018] [Accepted: 02/10/2018] [Indexed: 06/08/2023]
Abstract
On the island of Sardinia the lepidopteran Papilio hospiton uses Ferula communis as exclusive host plant. However, on the small island of Tavolara, adult females lay eggs on Seseli tortuosum, a plant confined to the island. When raised in captivity on Seseli only few larvae grew beyond the first-second instar. Host specificity of lepidopterans is determined by female oviposition preferences, but also by larval food acceptance, and adult and larval taste sensitivity may be related to host selection in both cases. Aim of this work was: (i) to study the taste sensitivity of larvae and ovipositing females to saps of Ferula and Seseli; (ii) to cross-compare the spike activity of gustatory receptor neurons (GRNs) to both taste stimuli; (iii) to evaluate the discriminating capability between the two saps and determine which neural code/s is/are used. The results show that: (i) the spike responses of the tarsal GRNs of adult females to both plant saps are not different and therefore they cannot discriminate the two plants; (ii) larval L-lat GRN shows a higher activity in response to Seseli than Ferula, while the opposite occurs for the phagostimulant neurons, and larvae may discriminate between the two saps by means of multiple neural codes; (iii) the number of eggs laid on the two plants is the same, but the larval growth performance is better on Ferula than Seseli. Taste sensitivity differences may explain the absence of a positive relationship between oviposition preferences by adult females and plant acceptance and growth performance by larvae.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042, Monserrato (CA), Italy
| | - Maurizio Biolchini
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042, Monserrato (CA), Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042, Monserrato (CA), Italy
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Sollai G, Solari P, Crnjar R. Olfactory sensitivity to major, intermediate and trace components of sex pheromone in Ceratitis capitata is related to mating and circadian rhythm. JOURNAL OF INSECT PHYSIOLOGY 2018; 110:23-33. [PMID: 30142313 DOI: 10.1016/j.jinsphys.2018.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/18/2018] [Accepted: 08/20/2018] [Indexed: 06/08/2023]
Abstract
The Mediterranean fruit fly, Ceratitis capitata Wied., is a worldwide pest of several fruits given its extremely wide host range which includes more than 250 different species of fruits and vegetables. Its high biological potential is mainly due both to its ability to readily adapt to new environments and its high reproductive capacity as it completes multiple generations each year. Since sexually mature males emit a sex pheromone to call both other males for "lekking" and receptive females for mating, many studies have been directed to characterize the chemical composition of the sex pheromone. Besides, the release of sex pheromone appears to be modulated both by mating and time of day. Based on these considerations, we measured the olfactory sensitivity of antennae and palps of C. capitata to six volatiles of the male sex-pheromone: α-farnesene and geranyl acetate (major components), linalool and β-myrcene (intermediate components), β-farnesene and 2,3-butanediol (minor/trace components). The electroantennogram (EAG) and electropalpogram (EPG) responses were evaluated in both sexes, at different physiological states (virgin and mated), and at different times of the day (morning and afternoon). The results show that the EAG amplitude values in response to all stimuli are higher in the morning than in the afternoon for both sexes and in both virgin and mated insects. Furthermore, in both sexes, the olfactory sensitivity of virgin insects is higher than in mated ones. The EPG amplitude in response to all stimuli is higher in the morning in mated females than in virgin females and higher in the morning than in the afternoon in both mated sexes. By gaining knowledge on the effects of sex, physiological state and time of day on the olfactory sensitivity of C. capitata, one could better understand the medfly reproductive behavior.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy.
| | - Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy
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Kasubuchi M, Shii F, Tsuneto K, Yamagishi T, Adegawa S, Endo H, Sato R. Insect taste receptors relevant to host identification by recognition of secondary metabolite patterns of non-host plants. Biochem Biophys Res Commun 2018; 499:901-906. [DOI: 10.1016/j.bbrc.2018.04.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 11/16/2022]
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Xu W, Liu N, Liao Y, Anderson A. Molecular characterization of sugar taste receptors in the cotton bollworm Helicoverpa armigera. Genome 2017; 60:1037-1044. [DOI: 10.1139/gen-2017-0086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Insects utilize sugars as their essential energy and nutrient sources; therefore, the sense of sugar detection plays a critical role in insect behaviours. Previously, using genomic and transcriptomic approaches, we identified eight putative sugar gustatory receptor (GR) genes from the cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Here, we further validated these annotated sugar receptor genes (HarmGr4–HarmGr8 and HarmGr10–HarmGr12) and found HarmGr10 may be a pseudogene carrying a stop codon in the open reading frame. Sequence alignment revealed H. armigera sugar GR sequences are conserved at C-terminus and phylogenetic analysis showed that insect sugar GRs have evolved in a family-specific manner. Interestingly, all eight H. armigera sugar GRs are localized in a tandem array on the same scaffold of the genome. In silico gene expression and reverse transcription (RT)-PCR analysis showed that HarmGr10 is specifically expressed in male adult testes while HarmGr11 is specifically expressed in female adult ovaries, suggesting H. armigera sugar GRs may be involved in reproduction-related functions. This study improves our knowledge on insect sugar receptors and gustatory systems.
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Affiliation(s)
- Wei Xu
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Naiyong Liu
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Yalin Liao
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Alisha Anderson
- CSIRO Ecosystem Sciences, Black Mountain, ACT 2601, Australia
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13
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Pentzold S, Burse A, Boland W. Contact chemosensation of phytochemicals by insect herbivores. Nat Prod Rep 2017; 34:478-483. [PMID: 28485430 PMCID: PMC5436039 DOI: 10.1039/c7np00002b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Contact chemosensation, or tasting, is a complex process governed by nonvolatile phytochemicals that tell host-seeking insects whether they should accept or reject a plant. During this process, insect gustatory receptors (GRs) contribute to deciphering a host plant's metabolic code. GRs recognise many different classes of nonvolatile compounds; some GRs are likely to be narrowly tuned and others, broadly tuned. Although primary and/or secondary plant metabolites influence the insect's feeding choice, their decoding by GRs is challenging, because metabolites in planta occur in complex mixtures that have additive or inhibitory effects; in diverse forms composed of structurally unrelated molecules; and at different concentrations depending on the plant species, its tissue and developmental stage. Future studies of the mechanism of insect herbivore GRs will benefit from functional characterisation taking into account the spatio-temporal dynamics and diversity of the plant's metabolome. Metabolic information, in turn, will help to elucidate the impact of single ligands and complex natural mixtures on the insect's feeding choice.
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Affiliation(s)
- Stefan Pentzold
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745 Jena, Germany.
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14
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Sollai G, Biolchini M, Solari P, Crnjar R. Chemosensory basis of larval performance of Papilio hospiton on different host plants. JOURNAL OF INSECT PHYSIOLOGY 2017; 99:47-57. [PMID: 28242202 DOI: 10.1016/j.jinsphys.2017.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 06/06/2023]
Abstract
Papilio hospiton Géné is an oligophagous species, endemic of the islands of Corsica and Sardinia, using various Apiaceae and Rutaceae as host plants, such as Ferula communis, Ferula arrigonii, Peucedanum paniculatum, Ruta lamarmorae and Pastinaca latifolia. We previously found that the lateral maxillary styloconic sensillum in the larva has two deterrent neurons, one phagostimulant and one salt specific, while the medial sensillum has two phagostimulant neurons, one deterrent and one salt specific. In this work we studied the sensitivity of gustatory receptor neurons (GRNs) to saps of F. communis, F. arrigonii, P. paniculatum, P. latifolia and R. lamarmorae and evaluated the relationship between taste sensitivity to different host-plants and larval growth rate on each of them. The spike activity was recorded from medial and lateral taste sensilla stimulated with plant saps, and GRN response patterns were cross compared in the light of a different feeding acceptance. The phagodeterrent GRNs show a higher activity in response to F. arrigonii and R. lamarmorae than to F. communis, P. paniculatum and P. latifolia. Behavioral trials showed that the time to pupation is significantly longer when larvae are reared on F. arrigonii and R. lamarmorae than on the other host-plants. These results suggest that the different activity of the phagodeterrent GRNs may inhibit food acceptance and extend the duration of the larval stage.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato (CA), Italy
| | - Maurizio Biolchini
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato (CA), Italy
| | - Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato (CA), Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato (CA), Italy.
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15
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Trans-generational desensitization and within-generational resensitization of a sucrose-best neuron in the polyphagous herbivore Helicoverpa armigera (Lepidoptera: Noctuidae). Sci Rep 2016; 6:39358. [PMID: 27966640 PMCID: PMC5155215 DOI: 10.1038/srep39358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/22/2016] [Indexed: 11/08/2022] Open
Abstract
Dietary exposure of insects to a feeding deterrent substance for hours to days can induce habituation and concomitant desensitization of the response of peripheral gustatory neurons to such a substance. In the present study, larvae of the herbivore Helicoverpa armigera were fed on diets containing either a high, medium or low concentration of sucrose, a major feeding stimulant. The responsiveness of the sucrose-best neuron in the lateral sensilla styloconica on the galea was quantified. Results showed the response of the sucrose-best neuron exposed to high-sucrose diets decreased gradually over successive generations, resulting in complete desensitization in the 5th and subsequent generations. However, the sensitivity was completely restored in the ninth generation after neonate larvae were exposed to low-sucrose diet. These findings demonstrate phenotypic plasticity and exclude inadvertent artificial selection for low sensitivity to sucrose. No significant changes were found in the sensitivity of caterpillars which experienced low- or medium-sucrose diets over the same generations. Such desensitization versus re-sensitization did not generalise to the phagosimulant myo-inositol-sensitive neuron or the feeding deterrent-sensitive neuron. Our results demonstrate that under conditions of high sucrose availability trans-generational desensitization of a neuron sensitive to this feeding stimulant becomes more pronounced whereas re-sensitization occurs within one generation.
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16
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Agnihotri AR, Roy AA, Joshi RS. Gustatory receptors in Lepidoptera: chemosensation and beyond. INSECT MOLECULAR BIOLOGY 2016; 25:519-529. [PMID: 27228010 DOI: 10.1111/imb.12246] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Lepidoptera is one of the most widespread insect orders and includes several agriculturally important insect species. Ecological success of the lepidopteran insects partly depends on their adaptive chemoreception tactics, which play an important role in the selection of hosts, egg-laying sites and mates. Members of the G-protein coupled receptor family, gustatory receptors (GRs), are an integral part of the Lepidoptera chemosensory machinery. They are expressed in chemosensory neurones and are known to detect different environmental stimuli. Here, we discuss various aspects of the lepidopteran GRs with an emphasis on their roles in different processes such as chemosensation, host selection and adaptation. Phylogenetic analyses have shown that the large diversity of GR genes may have been generated through gene duplication and positive selection events, which also show lineage- and tissue-specific expression. Moreover, lepidopteran GR proteins are diverse and demonstrate broad ligand selectivity for several molecules including sugars, deterrents, salts and CO2 . Binding of ligands to GRs generates multiple downstream changes at the cellular level, which are followed by changes in behaviour. GRs play a critical role in chemosensation and influence the insect's behaviour. Overall, insect GRs are potential targets in the design of effective insect control strategies.
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Affiliation(s)
- A R Agnihotri
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University (formerly University of Pune), Ganeshkhind, Pune, MS, India
| | - A A Roy
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University (formerly University of Pune), Ganeshkhind, Pune, MS, India
| | - R S Joshi
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University (formerly University of Pune), Ganeshkhind, Pune, MS, India
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Kikuta S, Endo H, Tomita N, Takada T, Morita C, Asaoka K, Sato R. Characterization of a ligand-gated cation channel based on an inositol receptor in the silkworm, Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 74:12-20. [PMID: 27132146 DOI: 10.1016/j.ibmb.2016.04.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 06/05/2023]
Abstract
Insect herbivores recognize non-volatile compounds in plants to direct their feeding behavior. Gustatory receptors (Gr) appear to be required for nutrient recognition by gustatory organs in the mouthparts of insects. Gr10 is expressed in Bombyx mori (BmGr10) mouthparts such as maxillary galea, maxillary palp, and labrum. BmGr10 is predicted to function in sugar recognition; however, the precise biochemical function remains obscure. Larvae of B. mori are monophagous feeders able to find and feed on mulberry leaves. Soluble mulberry leaf extract contains sucrose, glucose, fructose, and myo-inositol. In this study, we identified BmGr10 as an inositol receptor using electrophysiological analysis with the Xenopus oocyte expression system and Ca(2+) imaging techniques using mammalian cells. These results demonstrated that Xenopus oocytes or HEK293T cells expressing BmGr10 specifically respond to myo-inositol and epi-inositol but do not respond to any mono-, di-, or tri-saccharides or to some sugar alcohols. These inositols caused Ca(2+) and Na(+) influxes into the cytoplasm independently of a G protein-mediated signaling cascade, indicating that BmGr10 is a ligand-gated cation channel. Overall, BmGr10 plays an important role in the myo-inositol recognition required for B. mori larval feeding behavior.
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Affiliation(s)
- Shingo Kikuta
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Haruka Endo
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Natsuo Tomita
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Tomoyuki Takada
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Chiharu Morita
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Kiyoshi Asaoka
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
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18
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Sollai G, Tomassini Barbarossa I, Solari P, Crnjar R. Taste discriminating capability to different bitter compounds by the larval styloconic sensilla in the insect herbivore Papilio hospiton (Géné). JOURNAL OF INSECT PHYSIOLOGY 2015; 74:45-55. [PMID: 25702827 DOI: 10.1016/j.jinsphys.2015.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 06/04/2023]
Abstract
Herbivorous animals may benefit from the capability to discriminate the taste of bitter compounds since plants produce noxious compounds, some of which toxic, while others are only unpalatable. Our goal was to investigate the contribution of the peripheral taste system in the discrimination of different bitter compounds by an herbivorous insect using the larvae of Papilio hospiton Géné as the experimental model, showing a narrow choice range of host plants. The spike activity from the lateral and medial styloconic sensilla, housing two and one bitter-sensitive gustatory receptor neurons (GRNs), respectively, was recorded following stimulation with nicotine, caffeine, salicin and quercitrin and the time course of the discharges was analyzed. Nicotine and caffeine activated all three bitter-sensitive GRNs, while salicin and quercitrin affected only two of them. In feeding behavior bioassays, intact larvae ate glass-fiber disks moistened with salicin and quercitrin, but rejected those with nicotine and caffeine, while lateral sensillum-ablated insects also ate the disks with the two latter compounds. The capability to discriminate bitter taste stimuli and the neural codes involved are discussed.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy
| | - Iole Tomassini Barbarossa
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy
| | - Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, 09042 Monserrato, CA, Italy.
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19
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Sollai G, Tomassini Barbarossa I, Masala C, Solari P, Crnjar R. Gustatory sensitivity and food acceptance in two phylogenetically closely related papilionid species: Papilio hospiton and Papilio machaon. PLoS One 2014; 9:e100675. [PMID: 24956387 PMCID: PMC4067346 DOI: 10.1371/journal.pone.0100675] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 05/30/2014] [Indexed: 11/25/2022] Open
Abstract
In herbivorous insects, food selection depends on sensitivity to specific chemical stimuli from host-plants as well as to secondary metabolites (bitter) and to sugars (phagostimulatory). Bitter compounds are noxious, unpalatable or both and evoke an aversive feeding response. Instead, sugars and sugar alcohols play a critical role in determining and enhancing the palatability of foods. We assumed that peripheral taste sensitivity may be related to the width of the host selection. Our model consists of two closely phylogenetically related Papilionid species exhibiting a difference in host plant choice: Papilio hospiton and Papilio machaon. The spike activity of the lateral and medial maxillary styloconic taste sensilla was recorded following stimulation with several carbohydrates, nicotine and NaCl, with the aim of characterizing their gustatory receptor neurons and of comparing their response patterns in the light of their different acceptability in feeding behaviour. The results show that: a) each sensillum houses phagostimulant and phagodeterrent cells; b) the spike activity of the gustatory neurons in response to different taste stimuli is higher in P. hospiton than in P. machaon; c) sugar solutions inhibit the spike activity of the deterrent and salt cells, and the suppression is higher in P. machaon than in P. hospiton. In conclusion, we propose that the different balance between the phagostimulant and phagodeterrent inputs from GRNs of maxillary sensilla may contribute in determining the difference in food choice and host range.
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Affiliation(s)
- Giorgia Sollai
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | | | - Carla Masala
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | - Paolo Solari
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
| | - Roberto Crnjar
- Department of Biomedical Sciences, Section of Physiology, University of Cagliari, Cagliari, Italy
- * E-mail:
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20
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Tang QB, Huang LQ, Wang CZ, Tang QB, Zhan H, van Loon JJA. Inheritance of electrophysiological responses to leaf saps of host- and nonhost plants in two Helicoverpa species and their hybrids. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2014; 86:19-32. [PMID: 24599618 DOI: 10.1002/arch.21154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The polyphagous cotton bollworm Helicoverpa armigera (Hübner) and the oligophagous oriental tobacco budworm Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae) display contrasting heritable feeding preferences for cotton and pepper leaves. In this study, electrophysiological response patterns to cotton and pepper leaf saps in gustatory sensilla styloconica on the maxillae of these two species, their reciprocal F1 hybrids, and backcrossed lines were investigated using the tip recording technique. The identity of the neurons responding to the two leaf saps has been established using action potential waveform analysis. The two plant leaf saps elicited neural activity in at least six of the eight taste neurons innervating the lateral and medial sensilla styloconica of the parental species and crosses. Discriminant analysis of this multineural input predicted that correct classification occurred in 87 - 92% of the cases. Differences in taste neuron responses between insect lines to the two plant saps were consistent with differences in feeding preference behaviors. Comparisons of taste neuron response patterns of parental species, F1 hybrids and backcrosses indicate that autosomal loci contributed to the difference in gustatory response patterns between the two Helicoverpa species with the H. armigera derived alleles being partly dominant to those carried by H. assulta. These findings contribute to the understanding of gustatory codes for preference and provide insight into taste evolution of lepidopteran insects.
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Affiliation(s)
- Qing-Bo Tang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, The Chinese Academy of Sciences, Beijing, China
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Tang QB, Zhan H, Cao H, Berg BG, Yan FM, Zhao XC. Central projections of gustatory receptor neurons in the medial and the lateral sensilla styloconica of Helicoverpa armigera larvae. PLoS One 2014; 9:e95401. [PMID: 24740428 PMCID: PMC3989337 DOI: 10.1371/journal.pone.0095401] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/25/2014] [Indexed: 11/19/2022] Open
Abstract
Food selection behavior of lepidopteran larvae is predominantly governed by the activation of taste neurons present in two sensilla styloconica located on the galea of the maxilla. In this study, we present the ultrastructure of the sensilla styloconica and the central projection pattern of their associated receptor neurons in larvae of the heliothine moth, Helicoverpa armigera. By means of light microscopy and scanning electron microscopy, the previous findings of two morphologically fairly similar sensilla comprising a socketed conic tip inserted into a large peg were confirmed. However, the peg size of the medial sensillum was found to be significantly bigger than that of the lateral sensillum. The sensory neurons derived from each sensillum styloconicum were mapped separately using anterograde staining experiments combined with confocal laser-scanning microscopy. For determining the afferents' target regions relative to each other, we reconstructed the labeled axons and placed them into a common reference framework. The sensory axons from both sensilla projected via the ipsilateral maxillary nerve to the suboesophageal ganglion and further through the ipsilateral circumoesophageal connective to the brain. In the suboesophageal ganglion, the sensory projections targeted two areas of the ipsilateral maxillary neuropil, one located in the ventrolateral neuromere and the other adjacent to the neuromere midline. In the brain, the axon terminals targeted the dorso-anterior area of the ipsilateral tritocerebrum. As confirmed by the three-dimensional reconstructions, the target regions of the neural projections originating from each of the two sensilla styloconica were identical.
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Affiliation(s)
- Qing-Bo Tang
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan, China
| | - Huan Zhan
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan, China
| | - Huan Cao
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan, China
| | - Bente G. Berg
- Department of Psychology, Neuroscience Unit, Norwegian University of Science and Technology, Trondheim, Norway
| | - Feng-Ming Yan
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan, China
| | - Xin-Cheng Zhao
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan, China
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