| Co-Investigator(Kenkyū-buntansha) |
ITO Yosiaki Nagoya University, Professor Emeritus, 名誉教授 (50115531)
KOJIMA Jun'ichi Ibaraki University, college of Science, Professor, 理学部, 教授 (00192576)
SHIYOMI Masae Ibaraki University, college of Science, Professor, 理学部, 教授 (80250976)
MIYANO Shin'ya Natural History Museum and Institute, Department of Animal Sciences, Curator and head, 動物研究科・科長(研究職) (20250152)
TSUCHIDA Koji Gifu University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (00252122)
BRANDAO C.roberto f. Universidad de Sao Paulo, Zoological Museum, Professor and the Director of the Museum
ZUCCHI Ronaldo Universidad de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Professor
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| Budget Amount *help |
¥10,400,000 (Direct Cost: ¥10,400,000)
Fiscal Year 2002: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2000: ¥3,700,000 (Direct Cost: ¥3,700,000)
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| Research Abstract |
This research project was carried out in succession of a previous project done in 1998/1999, and aimed to advance further the study of evolution of swarm-founding and permanent polygyny (multi-queen social system) in wasps of tribe Epiponini in South America. To know the social structure from genetic point of view, which is substantial to understand the evolution of multi-queen social systems, the project put emphasis on the estimation of genetic relatedness among adult and immature individuals in given colonies of an epiponine wasp, Polybia paulista (1). To compare with the above highly advanced social system, some sociological and ecological observations were made on pre-emergence colonies of Mischocyttarus spp. , which are independent-founders of another tribe Mischocyttarini (2). Further, to know the significance of nests as a basis for wasps' social life, chemical components, e. g. , amino acids, contained in the oral secretion secreted by adult wasps were analyzed for Polybia pau
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lista, 3 Mischocyttarusu species, and some other polistine species (3). The oral secretion is used to bind nest materials foraged by wasps from the outside of nest. Another aspect of nests, the thermal characteristics, was examined in two nests of Polybia paulista and P. occidentalis (4). On the basis of these studies, two reviews "Multi-queen social systems in eusocial insects, particularly among the Polistinae" (Y. Ito, 2002), and "Recent advances in a study of Polistinae" (S. Miyano, 2003) were published.
(1) Allozyme and DNA analyzes of 15 Polybia paulista colonies taken on the campus of Sao Paulo University in Ribeirao Preto, Sao Paulo State revealed that in every colony the genetic relatedness was very low, 0-0.2. Thus, adult individuals of the whole colony and also immatures from separately removed combs were virtually non-related. This means that many queens were laying eggs even in the later phase of colony cycle. This result is not consistent with a hypothesis of "cyclical oligogyny" proposed by West-Eberhard (1978), and another hypothesis has to be developed.
(2) Founding females of more than 30 pre-emergence colonies of two Miscocyttarus species were censused to know the relation between the number of founding females and the body size (weight) of adult females emerged from the first batch of brood reared by the foundresses. The distribution pattern of the number of females were also analyzed with a "Zero-truncated model".
(3) Amino acid composition of the oral secretion used for binding extraneous nest materials by wasps was analyzed with a HPLC for three Mischocyttarus species and some other polistine species, Polybia paulista, Protopolybia exigua, etc. , and the results were compared with those so far studied until now. The amino acid composition was constant within the same species, and closely similar among species of the same genus, but fairly different among genera. This suggests that the kinds and relative amounts of amino acids produced reflect the phylogenetic relations.
(4) Two diel measurements of nest temperature were carried out for a nest of Polybia paulista, one was done in an active state with more than 500 adult wasps and the other done after all the adults were removed. One diel measurement was done for an active nest of P. occidentalis with more than 2500 adults. Nest temperatures, though different at positions at which thermocouples were set were relatively independent from the ambient temperature. This is possibly due to high heat insulation ability of an enveloped and multi-layered-comb structure. The result also showed virtual absence of active thermoregulation by adult wasps. Less
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