シロテンハナムグリの生活史を,屋外飼育実験の結果を基に推定した。飼育実験の結果,本種の生活史型は,年1化・幼虫越冬・多回繁殖型であった。成虫の寿命は約1年で,活動期間は5月から9月であるが,夏季に羽化した新成虫は摂食活動の後に地中で越冬して,翌年も再び活動を行った。なお,新成虫の多くは初年度には繁殖活動を行わないが,一部は初年度と次年度の2回,繁殖を行った。幼虫は3齢が終齢であり,初年度の冬季は終齢幼虫の状態で休眠室を形成し,この中で越冬した。成虫の餌資源植物について調査した結果,餌資源植物は3綱18目25科42種であった。このうち訪花植物は2綱14目19科30種,樹液利用植物は2綱3目3科5種,果実利用植物は1綱4目5科8種であった。本研究の結果から,季節を通じ成虫が花粉・花蜜食と樹液食や果実食への切替えを行っていることが,餌資源の枯渇時期を回避することに繋がり,このことが同じハナムグリ亜科の他種に比べて成虫の活動期間と寿命が長い一因であると考えられた。

The life history of Protaetia orientalis (Coleoptera : Scarabaeidae) was studied by an outdoor breeding experiment. The result of the breeding experiment showed that the chafer has [one-year life history]-[larva hibernation]-[numerous time breeding period]-life history type. The adult lifetime was about 1 year. An adult of the chafer, which underwent an adult eclosion in the summer, stayed over winter in the ground after feeding. It emerged the following year in the early summer and became active again. Incidentally, many adults did not reproduce in the first year ; however, a small number of adults had two breeding seasons, one in the first year and one in the following year. The larvae pass through a total of three instars, and in the winter of the first year, it formed a diapause chamber by the last instar larva and stayed over winter among these. After investigating the food resource plants that adult chafers visited for feeding, 42 species in 25 families of 18 orders of 3 classes were confirmed. Of these, as for visiting-plants, 30 species in 19 families of 14 orders of 2 class, and as for sap use plants, 5 species in 3 families of 3 orders of 2 classes, and as for fruit use plants, 8 species in 5 families of 4 orders of 1 class were confirmed. These results proved that the chafer changed its food source from pollen and nectar to sap and fruit, with the change of the season. In addition, by this action, it was able to avoid any lack of food resources. This factor is thought to give the chafer a long active period and lifetime as compared with other species of Cetoniinae.

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