). Jpn. J. Appl. Entomol. Zool. 41: 7-15 (1997) A total of 184 Illicium anisatum L. plantations were surveyed in Shikoku Island, Southwest Japan, to analyze damage caused by the Camphor Tree Weevil, Dyscerus hylobioides (DESBROCHERS) larvae. In Kochi, Ehime, Tokushima and Kagawa, 81%, 77%, 58% and 14% of plantations were invaded by this weevil, respectively. Damaged plantations were distributed widely in the west and south parts of the island (Kochi, Ehime and southern Tokushima), but there were few in northeast parts (Kagawa and northern Tokushima).Multiple regression analyses show that the percentage of trees injured by D. hylobioides larvae is higher with increasing plantation age and is high in plantations near forests. Damage is high in weedy plantations, but lower with increased frequency of spraying agricultural chemicals. To reduce damage to plantations, we recommend controlling weeds and spraying insecticides, especially in west and south parts of Shikoku.
We investigated the life cycle of the Camphor Tree Weevil, Dyscerus hylobioides (DESBROCHERS) on the Japanese anise-tree, Illicium anisatum L. in Tosayama, Kochi Prefecture, southwestern Japan. Overwintered adults appeared on host trees from April. They mated on the trees and deposited eggs in the bark near the trunk base. Eggs were observed from late spring to autumn with a peak in early summer. Hatched larvae bored into wood and spent five instar stages from summer to the next early summer in the wood. The overwintering larvae were the 2nd to 5th instars. Larvae moved to the lower parts of trees as they aged, and the pupae and adults were mainly found in underground parts of trees. Pupation and adult emergence occurred mainly in the second mid-summer. Newly-emerged adults ate host shoots, and remained on trees until autumn. Therefore, D. hylobioides probably requires 2 years for one generation in the mountain region of Kochi Prefecture.
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