Projects / Programmes
The vibration sensory system of the cave cricket Troglophilus neglectus (Rhaphidophoridae): from signals to neuronal networks
| Code |
Science |
Field |
Subfield |
| 1.03.00 |
Natural sciences and mathematics |
Biology |
|
| Code |
Science |
Field |
| B361 |
Biomedical sciences |
Physiology of invertebrates |
Cave cricket species Troglophilus neglectus, Karst, behaviour, sound and vibration, vibrational receptors, neuronal networks
Researchers (4)
Organisations (1)
| no. |
Code |
Research organisation |
City |
Registration number |
No. of publicationsNo. of publications |
| 1. |
0105 |
National Institute of Biology |
Ljubljana |
5055784 |
13,265 |
Abstract
The nervous system of orthopteran insects represents one of the established invertebrate model systems for the study of processes of reception and integration of sensory information. One of the main subjects of these studies is the auditory system of crickets and bushcrickets (Orthoptera, Ensifera). There is much less comparative knowledge available from the sensory system that evolutionary preceded audition in Ensifera – the system for the detection of substrate vibrations. Sensitivity to vibrations is common to all insects and crucial for their communication in several contexts. The least investigated is the central processing of vibratory signals in the nervous system, especially at the level of both morphologically and functionally identified neurons. The only data available on this subject come from the research of the already evolutionary modified, combined auditory-vibratory system of hearing taxa. The main goal of the proposed study is to describe neural elements involved in vibration detection from the receptor organs to brain in a member of primitively non-hearing Ensifera. We selected for this the cave cricket Troglophilus neglectus (Rhaphidophoridae), one of the most abundant arthropods in the undergrounds of Slovenian karst. The species possesses in the legs a vibration-sensitive organ regarded as primitive in respect to the ensiferan ear. To better understand functional characteristics of the vibration detecting system in the cave cricket, we aim to investigate first its pre-mating behaviour with the emphasis on the analysis of vibratory signals. There is a general lack of knowledge regarding communication processes of Rhaphidophoridae, but there are indications they use vibratory signals for communication. At the receptor level we intend to identify and functionally characterise a class of highly-sensitive low-frequency vibration receptor neurons, which have not been a subject of intracellular studies so far. Several physiological and behavioural data, however, suggest their existence in orthopteran insects. At the central neural level we aim to identify homologous elements to the specialised auditory interneurons of crickets and bushcrickets and thus provide the first direct evidence on the generally presumed homology of auditory and vibratory central neural networks in Ensifera. The data on the functional organisation of the studied neurons will substantially increase the current knowledge regarding processing mechanisms in the vibratory system of insects in general. Our work will at the same time importantly contribute to the knowledge of biology in one of the worlds most extreme habitats.
Significance for science
Sound communication and hearing in Ensifera (crickets, cave crickets and bushcrickets) represent one of the main model systems for studies of neuronal basis of behavior and in invertebrates. Communication with substrate-borne sound signals is less investigated especially at the signal recognition neuronal level. Sound communication system of Ensifera evolutionary probably originates from substrate-borne sound communication one and from the sensory system for detection of substrate vibration as being described at the level of receptor organs in the non-hearing cave cricket T. neglectus. Due to controversial hypotheses on Ensifera species relationship it is not clear whether hearing developed once and reduced in some groups later in evolution or it developed in more lines independently from homologous structures. According to one hypothesis cave crickets represent the most primitive family in this insect group and with our behavioral and neurobiological experiments we have confirmed it. We have thus confirmed also the hypothesis about independent development of hearing. We first described signaling by vibratory and chemical signals in cave cricket species confirming their primitive position. Morphology of the vibratory interneurons which give origin to hearing elements in crickets and bushcrickets confirms their original and not regression shape. These data open important new views for further comparative studies of neuronal basis of behavior in other non-hearing Ensifera. At the basis of the high number of morphologically identified central nervous elements we were first to describe principals of functional organization of the vibratory neuronal system in any Orthoptera or even insect species representing thus a good basis for comparison among species.
Significance for the country
Cave crickets spent most of their life in karrst underground which represents a special ecosystem worldwide. At the same time they are one of the most abundant species in this surroundings and due to periodic migrations to the surface represent an important link in food import underground balancing the sensitive underground ecosystem. The study of different aspects of the species biology is important for Slovenia both in promotion of underground karst environment and in getting information on potential factors which help to its preservation. The research is part of the longterm research programme of the Department of Entomology of the national Institute of Biology. The department is the only one in Slovenia which conducts complex studies of insect biology with special attention to their communication, environmental impact on signal transmission and recognition at the level of their sensory systems discussed both from the functional and evolutional point of view. The group with extensive and intensive international cooperation represents the respected focus for investigations of neurobiology and neuroethology of communication processes in insects especially in the frame of vibrational communication. The results of the project will promote science in Slovenia by representations at international and national conferences, by formal and unformal scientific contacts, development and upgrading of research techniques and publications in scientific journals. Slovenia is promoted by the group also by membership in national and international editorial boards, societies, by invited lectures etc. In the frame of the project were trained one student from Slovenia and one from abroad. New knowlledge will be distributed also by education and popular articles.
Most important scientific results
Annual report
2008,
2009,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2008,
2009,
final report,
complete report on dLib.si
