Development and survivorship of the Japanese giant weevil, Sipalinus gigas (Fabricius) (Coleoptera: Rhynchophoridae), in cut pine [Pinus densiflora] bolts
2002
Nakamura, K. (Forestry and Forest Products Research Inst., Kumamoto (Japan). Kyushu Research Center) | Lang, X.
Cut pine bolts were exposed to allow a held population or sipalnus gigas to oviposit and the colonized insects in the bolts were examined periodically up to 29 mo after oviposition. The estimated survival rate of the immatures in the bolts decreased throughout the first and second season, and reached almost zero before the second overwintering. Predation was thought to be one of the major mortality factors of immature S. gigas. The increase of larval size and formation of a pupal chamber indicated that larval growth of S. gigas was completed within 4-5 mo after oviposition. The occurrence of pupae, callow adults and emerged adults suggested that S. gigas have bimodal adult emergence, namely they emerge in autumn of the year when they were laid as eggs as well as in the autumn of the following year. Although a small number of live larvae were found just before the second overwintering, they were less likely to grow into adults in the third season because of the high mortality of immatures in the second and third seasons.
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