|1.Research Institution||Kobe University|
|2.Research Area||Life Sciences|
|3.Research Field||Mechanisms of the Advanced Function in Insects and Proposal of New Insectech|
|4.Term of Project||FY 1999 - FY 2003|
|6.Title of Project||Mechanisms and Regulation of Bioresponses of Insects to Environment|
|Name||Institution,Department||Title of Position|
|Shigeyuki ,Mayama||Kobe University, Faculty of Agriculture||Professor|
|Names||Institution,Department||Title of Position|
|Makio ,Takeda||Kobe University, Graduate School of Science and Technology||Professor|
9.Summary of Research Results
Photoperiodic mechanism was invesitigated in three model systems: cockroach (crickets), silk worm, and giant silkmoth at a molecular level. We have cloned and obtained potentially important genes that regulate circadian oscillation in Drosophila melanogaster. The proteins expressed as fusion proteins or peptides deduced from the gene structures were used for immunization and the antibodies were obtained.
Using these antibodies, we made an extensive immunocytochemical localization of these antigens and dynamics of transcripts were followed by Realtime PCR. The noted features include great species variability in circadian structure, the importance of indoleamine pathway to regulate both circadian and photoperiodism, and polymorphism of NAT in different tissues and functions. NAT thus could be a future target of pesticides.
Mechanisms of the host specificity of a specialist herbivor, Epilachna vigintioctopunctata, was examined. The determination of the host range of the ladybird beetle involved three steps, i.e., the recognition of host plants, overcoming constitutive resistance, and overcoming induced resistance. Plant had the three inhibitory steps in various degrees and combination against the feeding. Only when the beetle passed through all of the three steps of a plant, the plant became a host. These results suggested that induced resistance may be the final barrier to block the adaptation of the specialist. Against the ladybird beetle a biocontrol system was developed using phylloplane bacteria with chitinase activity or pathogenicity to insects. When tomato was sprayed with these bacteria or alginate gel beads containing them, the damage by the ladybird beetle was decreased prominently.