Analysis of damage to Japanese anise-tree, Illicium anisatum L. plantations caused by the camphor tree weevil, Dyscerus hylobioides (Desbrochers) (Coleoptera: Curculionidae) larvae in Shikoku island, southwest Japan

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.