摘要 : The effects of O. humeralis on the number and size structure of its host plants were studied from August 2000 to March 2003 in Serra do Japi, Sao Paulo, Brazil. Several native Miconia (M. sellowiana, M. jucunda and M. latecrenata)... 展开 The effects of O. humeralis on the number and size structure of its host plants were studied from August 2000 to March 2003 in Serra do Japi, Sao Paulo, Brazil. Several native Miconia (M. sellowiana, M. jucunda and M. latecrenata) and Leandra (L. scabra and Leandra sp.) species were abundant in the study area. Of the 296 M. sellowiana individuals sampled during 1999-2000, 67 (23%) had the trunk girdled by O. humeralis and had lost their crown. Of the 126 individuals sampled in 2002-03, 11 (9%) had their canopy cut down by the beetle. Only 3 individuals died for a reason other than beetle attack. Of the 35 individuals cut by O. humeralis that were monitored in 2001, 15 (43%) died and the remaining individuals produced 2-5 new shoots near the point of the cut in the following year. The host species M. sellowiana and L. scabra decreased by approximately 60 and 40%, respectively, during the study, whereas M. jucunda and M. latecrenata did not significantly change in abundance. M. sellowiana was the most abundant plant species in the first period of the study, but became less dominant after 2 years of infestation. Larger individuals of M. sellowiana decreased in proportion from 1999-2000 to 2002-03. Despite the decrease in the number of smaller individuals and increase in larger individuals of L. scabra, there was no significant difference in size structure of the populations between sampling. Because of the change in size structure, O. humeralis gradually attacked smaller plants of M. sellowiana in successive years.. 收起