1999 Fiscal Year Final Research Report Summary
Conservation biology of a solitary wasp on the coastal sand dune
| Project/Area Number |
10680556
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
環境保全
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| Research Institution | Kobe College |
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Principal Investigator |
ENDO Tomoji School of Human Sciences, Kobe College Associate Professor, 人間科学部, 助教授 (60289030)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Coastal sand dune / Pompilidae / Argiopidae / Central place foraging / Conservation biology / Spatial distribution / Food resources / Trait-mediated indirect effects |
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| Research Abstract |
A solitary wasp Batozonellus annulatus and its main prey species Argiope bruennichii provide a model system for studying conservation biology of central place forager on the coastal sand dune ecosystem. The wasps build a nest in the patch of bare sandy ground surrounded by vegetated area and carry an argiopid spider as prey from the vegetated area. Two-year census data showed declines of available spider densities near nesting area during the nesting seasons of both years. Lower survival of released spiders at places nearby the nesting area and the estimated numbers of victims indicated that wasp hunting possibly induced these spider declines. High spider densities were maintained at distant area. To sustain the wasp population for longer term, therefore, it is a requisite that prey resources near nesting area are constantly recruited from distant source area. Generally, in the conservation policy of central place foragers it needs to protect not only physical structures suitable for nest-site and foraging spaces, but also further outside source populations for rapid resource renewal, as they are likely to deplete available food resources. Indirect effects of spider declines on plant and behavior of flying insects were also investigated. As a result, any consistent differences in the Vitex leaf damage by herbivores were not detected between near and distant places. However, spiders and webs removal experiments showed a remarkable decrease in flying frequencies of both Lepidoptera and Hymenoptera insects. Such trait-mediated indirect effects may play an important ecological role in the coastal sand dune ecosystems.
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