匂い源探索における状態依存的な複数感覚統合に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 神崎 亮平, 東京大学教授 下山 勲, 東京大学教授 竹内 昌治, 東京大学特任講師 安藤 規泰, 総合研究大学院大学講師 木下 充代University of Tokyo(東京大学

Radar, Insect Population Ecology, and Pest Management

Discussions included: (1) the potential role of radar in insect ecology studies and pest management; (2) the potential role of radar in correlating atmospheric phenomena with insect movement; (3) the present and future radar systems; (4) program objectives required to adapt radar to insect ecology studies and pest management; and (5) the specific action items to achieve the objectives

The chemosensory ecology of a foraging hawkmoth

While foraging, all animals need to balance their energetic cost and gains. The sensory systems provide the information, which form the bases for these energy-economic decisions and thus, link the sensory input directly to the fitness of the animal. Night-active hawkmoth species particularly rely on their olfactory system which detects the volatiles emitted by those plants visited by the moth. This dissertation examined the olfactory system and the foraging decisions of the hawkmoth Manduca sexta to gain further insights into the ecological pressures which might have directed the evolution of the olfactory system in hawkmoths and their coevolution with the flowers they visit. In order to address these questions we first studied the odour guided flight of M. sexta to flowers of different Nicotiana species, which matched the length of the moth proboscis to different degrees. It was found that the moth already selected the best matching flower at the first encounter with the odour plume emitted by this flower and that foraging on these matching flowers did result in the highest energy gain for the moth. We could further show that M. sexta recognise a plant headspace based on the composition of this blend rather than on its concentration. However, flower odours are readily intermixed with other volatiles and their detection is hence most reliable close to the flower. Here, we show that the moth uses specific olfactory neurons on the tip of its proboscis to evaluate flowers, and that this close range detection is crucial both for foraging as well as pollination. Finally, the effect of flower orientation on the foraging of M. sexta was analysed, finding that the synchronisation of floral volatiles and orientation is crucial for this moth-plant interaction. Taken together our studies on the foraging of hawkmoth might not only help to gain new insights into the evolution of sensory systems, but also on how these systems shapes the interaction between different species

The Role of Drosophila Odorant Receptors in Odor Coding

Drosophila melanogaster is a powerful genetic model organism, and a promising model system in olfaction. At the onset of my thesis research, the expression patterns of fly’s 62 odorant receptors (ORs) were largely unknown. I set out to understand the rules of connectivity of olfactory sensory neurons and the resulting properties of olfactory circuit. Consequently, we assembled maps of the olfactory neuron projections in the fly brain and characterized the contribution of several ORs to olfactory-guided behavior. We compiled near-complete maps of OR-specific neuronal projections to the antennal lobe glomeruli of adult and larval fly brains. We analyzed expression profiles of 42 ORs, 31 of which are expressed in the adult and 21 in the larva, with an overlap of 10 ORs between the two developmental stages. Our results show surprising complexity in organization of the fly’s olfactory circuit. Four adult olfactory neuron populations co-express two ORs each and another olfactory neuron population expresses one odorant and one gustatory receptor. One glomerulus receives co-convergent input from two separate populations of olfactory neurons. Three ORs label sexually dimorphic glomeruli implicated in sexual courtship, and are thus candidate Drosophila pheromone receptors. The organization of larval antennal lobe is remarkably similar to that of adult flies and mammals; each glomerulus occupies a unique stereotyped position in the antennal lobe. Unlike in adults, each OR is expressed in only one neuron, forming glomeruli with single afferents. The olfactory sensory maps provide experimental framework for relating ORs to olfactory neuroanatomy, and ultimately, to output of the olfactory system. The Drosophila larval olfactory system shows great promise as a behavioral model. Larvae exhibit robust chemotaxis to odors and have a simple olfactory system. We utilized larvae to study response properties of three olfactory neurons to a large panel of odors. Behavioral assays of larvae with single olfactory neurons ablated, showed minimal effects on chemotaxis response, and thus great redundancy in function of olfactory neuron populations. Larvae with only Or42a olfactory neurons functional are able to chemotax robustly, demonstrating that chemotaxis is possible in the absence of the remaining elements of the olfactory circuit

Elucidating the olfactory pathways within and beyond the antennal lobe in Drosophila melanogaster

The vinegar fly Drosophila melanogaster is confronted with various odors while exploring the environment. Some odors elicit innately the approach or avoidance of the odor source, e.g. pheromones cause the approach and contaminated food causes the avoidance. How does the fly evaluate the perceived odors and how is the innate preference accomplished? The information of perceived odors is processed in a complex neural circuitry consisting of sever-al neuron populations distributed throughout distinct brain areas. This thesis aimed at elucidat-ing the neuronal interplay within and beyond the primary olfactory processing center, the an-tennal lobe (AL), on a morphological and a functional level. To characterize morphologically the AL subunits, the so-called glomeruli, we generated a transgenic fly with an endogenous labeling of neuropil structures that enabled to establish an in vivo 3D-atlas of the AL. Furthermore, we correlated the glomerular volume with the num-bers of different neuron types innervating distinct glomeruli. This revealed a dependence of the glomerular volume to the number of sensory and projection neurons. In addition, consider-ing the functional properties of all odor processing channels emphasizes a dependence of the glomerular wiring to the odor tuning profile. To investigate how odor information is transferred from the primary to the higher processing centers the morphological and functional properties of inhibitory and excitatory projection neu-rons were analyzed. This revealed that the morphological topography of the AL is retained in the lateral horn (LH), a higher brain center which is assumed to mediate innate odor-guided behavior. Furthermore, in the LH odors are represented due to their hedonic valence and in-tensity in separate, global odor response domains. Characterizing the odor processing channels in the AL and the odor coding strategies in the LH is a step further to understand the neural circuitry of innate odor-guided behavior

Area-wide Integrated Pest Management

Extensive reliance on insecticides reduces biodiversity, contributes to pollinator decline, destroys habitat and threatens endangered species. This book offers a more effective application of the Integrated Pest Management (IPM) approach, on an area-wide (AW) or population-wide (AW-IPM) basis. It addresses the importance of problem-solving research, planning and baseline data collection, integrating tools for appropriate control strategies, and pilot trials. The 48 chapters authored by 184 experts cover advances in genetics, molecular biology, biological control, resistance management, modelling, automated surveillance and unmanned aerial release systems

Bibliography of Lewis Research Center technical publications announced in 1989

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1989. All the publications were announced in the 1989 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses