Grasping Abilities of Japanese Oak Silkworm Larvae Grown on Artificial Dites

Research Project

Project/Area Number	11660056
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	蚕糸・昆虫利用学
Research Institution	Shinshu University
Principal Investigator	KANEKATSU Rensuke Shinshu University, Faculty of Textile Science and Technology, Associate Professor, 繊維学部, 助教授 (60092871)
Co-Investigator(Kenkyū-buntansha)	NISHIOKA Takahiko Shinshu University, Faculty of Textile Science and Technology, Associate Professor, 繊維学部, 助教授 (10164542)
Project Period (FY)	1999 – 2001
Project Status	Completed (Fiscal Year 2001)
Budget Amount *help	¥3,300,000 (Direct Cost: ¥3,300,000) Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1999: ¥1,800,000 (Direct Cost: ¥1,800,000)
Keywords	Japanese oak silkworm / Artificial diet / Grasping abilities of larvae / Tensile test / Artificial hatching / Walking behavior / Computer graphic analyses / Total rearing system / 腹脚 / 飼料組成 / 引張り試験
Research Abstract	In order to estimate the grasping abilities of Japanese oak silkworms, a tensile meter was applied for the larvae on a thic plastic net. Although various kind of patterns were obtained for time - tensile strength curves, it was known that the larval grasping abilities were expressed using the average values calculated from the observed values of 3 major tensile peaks. This method of estimation was applied in comparing the grasping abilitiess of larvae raised on fresh oak leaves and those grown on artificial diets. It was shown that a significant decrease of grasping abilities occurs in the larvae grown on artificial diets comparing to that of larvae oh fresh-leavs. Condition of artificial diets ( e. g. content of leaf powder, water content etc. ) or style of rearing ( e.g. with or without rigid structures on which larvae grasp and walk around ) showed little effect on the larval grasping abilities. Artificially hatched larvae by the imidazole compound treatment showed similar results. Enough grasping abilities were recovered when the larvae ecdysed into a new instar after they were transfered on fresh leaves, although a knowledge about a nutiritional factors affecting on the grasping abilities was left unsolved. Walking behaviors of larvae were analyzed using VTR and computer graphic analyzes. It was clearly shown that movements of larval body segments were not well synchronized to each other while walking, in the case of artificial diet grown larvae. Finally, we presented a total growing system composed of ( 1 ) raising young larvae on artificial diet, ( 2 ) growing on fresh oak leaves in a rearing room for a period of certain instar and ( 3 ) growing up on the oak trees for a sufficient production of cocoons of Japanese oak silkworms.