1992 Fiscal Year Final Research Report Summary
Evolution of test formation in the Diaspididae
| Project/Area Number |
02660039
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | Hokkaido University |
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Principal Investigator |
TAKAGI Sadao Hokkaido University, Faculty of Agriculture Professor, 農学部, 教授 (70001427)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Diaspididae / Conchaspididae / Lerp-forming psyllid / test formation / Wax-secreting organs / Wax filaments / Evolution / Scanning electron microscopy |
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| Research Abstract |
Evolution of test formation in the Diaspididae was studied by the use of a scanning electron microscope. The ultrastructure of spiracular and perivulvar disc pores was observed in 19 species in order to find support for a classificatory scheme based on pygidial appendages. Four conchaspidid species and 1 lerp-forming psyllid (Celtiaspis usubai) were also studied for making a comparison with diaspidid tests. Conchaspidid tests are composed of crushed wax filaments, which are mingled with a substance excreted from the anus just like pieces of aggregate mixed with cement to make concrete. The completed lerp of C. usubai shows a similar interior structure, but it has a peculiar type of secretory organ, which produces wax filaments in a pentagonal tube. In this respect, diaspidid tests are unique by the use of long wax filaments, which are agglutinated together by a substance from the anus. This manner, when combined with the insect's movement, may produce a wide variety of tests. In an odd diaspidid (Ulucoccus), however, the test is simply a fluffy mass of wax filaments, which are cylindrical and secreted from the ducts of the geminate-pore type. In primitive forms of the Diaspididae the test is formed by flattened wax filaments, but no movement of the insect body takes place at the formation of test. Advanced forms make a movement when forming the test, and there is a graded series of movement from a slight oscillation to a complete rotation. This trend of evolution must have occurred in more than one lineage, suggesting its deep adaptive significance. In disagreement with this trend, the isolated genus Sclopetaspis produces wax tubes and, being immobile, forms an irregularly shaped mass of them. It may represent a side branch off the main stocks of the family, and may be an escape out of many experiments attempted in the course of test evolution.
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