1992 Fiscal Year Final Research Report Summary
Detection of Beneficial Nematodes in Japan and Systematized Nematode Application
| Project/Area Number |
02506001
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物保護
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| Research Institution | Saga University |
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Principal Investigator |
ISHIBASHI Nobuyoshi Saga University, Faculty of Agriculture, Professor, 農学部, 教授 (30039333)
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| Co-Investigator(Kenkyū-buntansha) |
HATSUKADE Masayoshi Shizuoka University, Faculty of Agric., Professor, 農学部, 教授 (40091152)
IWAHANA Hidenori Tokyo University of Agric. & Technology, Professor, 農学部, 教授 (90038240)
SHONO Toshio Tsukuba Univ., Inst. of Agric. & Forestry. Professor, 農学部, 教授 (80011922)
TOJO Sumio Saga University, Faculty of Agriculture, Professor, 農学部, 教授 (50011911)
KONDO Eizo Saga University, Faculty of Agric., Associate Prof., 農学部, 助教授 (60039336)
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| Project Period (FY) |
1990 – 1992
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| Keywords | beneficial nematodes / biological control / entomopathogenic nematodes / fungivorous nematodes / mass-production / mixed application / nictating behavior / symbiotic bacteria |
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| Research Abstract |
Entomopathogenic nematodes :
1) Steinernematid nematodes distribute throughout Japan, while heterorhabditids localize in subtropical (Okinawa) and warm temperate area along the Pacific coast. These beneficial nematodes were found in woodlands and grasslands rather than from tilled fields.
2) Life cycle of a tylenchid nematode parasitizing reproductive organs of the adult Japanese pine sawyer was clarified. The nematode induces mock oviposition to adult females of the insect, eventually bringing the decline of the population density of insects. Fungivorous stages of this nematode can be mass-produced with a fungus growing on artificial medium. The inseminated adult females penetrate the larvae of the beetle, maturating synchronizingly with the gonadal development of the rost insect, and lay eggs in the host ovaries.
3) Host-finding behavior of S. carpocapsae was investigated. A simple and reprodicible bioassay was established by using exshathed infective juveniles and insect plasma. This b
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ioassay reflects the host preference or infectivity of nematodes. The attractive agent in host insect plasma was determined to be a peptide.
4) Factors affecting the growth of steinernematid nematodes were investigated. The nematodes can continue the development of the 1st the generation-type adults as long as they ate transferred individually onto fresh medium.
5) Both infective juveniles and their symbiotic bacteria destroy the defense mechanism of host insects ; both of the two agents suppress prophenol oxidase cascade activation and cellular defense in the larval haemolymph of insects.
6) Nictating juveniles killed host insects faster than did non-nictating ones. Insecticticides that enhance nictating behavior at certain concentrations can be used for mixed application with nematodes for the integrated control of insect pests. Some insecticides are non-toxic to nematodes at 100 ppm some enhance the nictating behavior, suggesting the compatibility with nematodes.
7) Antibacterial and protease activity of symbiont bacteria are responsible for the pathogenicity of entomopathogenic nematodes. The symbiont bacteria with high metabolic activity can be isolated, leading to the mass-production of nematodes with high killing-activity against insects.
Fungivorous nematode, Aphelenchus avenae: For the mass production of nematodes, the mixture (1:1) of dregs from orange juice production and wastepotatoes from potato chips production was the best substrate for nematodes and fungi as food. This mixture (8g dw) with 60% water content produced 5x10^5-1x10^6 nematodes 30 days after inoculation with100 nematodes. Maintenance of nematodes as seed should be conducted by changing the fungus species as the subculture host. B.cinerea (non-vilulent isolate) is recommended as the food of nematodes at the final production for use. In soil application of A. avenae (5x10^4/185 ml soil/pot) for controlling pre-emergence damping-off of cucumber seedlings caused by R. solani AG-4, F. oxsporum f. sp. lagenariae, Pythium sp., Phytophthora nicotiana var. parasitica, there were no significant differences in the controlling efficacy of nematodes. giving 81-85% germination, while each fungus species alone without nematodes gave no germination. Less
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