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Impacts of Tomicus minor on distribution and reproduction of Tomicus piniperda (Col., Scolytidae) on the trunk of the living Pinus yunnanensis trees
Author(s) -
Hui Y.,
XueSong D.
Publication year - 1999
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1046/j.1439-0418.1999.00353.x
Subject(s) - pinus yunnanensis , biology , interspecific competition , botany , ecology
This study investigated the impacts of Tomicus minor on Tomicus piniperda when the two Tomicus species coexist in the trunks of living Yunnan pine ( Pinus yunnanensis L.) trees growing in the Kunming region, in south‐western China. Tomicus piniperda mostly locates in the mid‐ and upper trunks of Yunnan pine tree; whereas T. minor mainly attacks the mid‐ and lower trunks. In the mid‐trunk area from 1.0 to 5.0 m above ground, there are overlapping attack zones for the two Tomicus species, which accounts for an average of 80% of the entire zone occupied by T. piniperda and an average of 70% of the zone occupied by T. minor. In correspondence with their attack distributions, the average attack densities of the two species varied with height along the trunk, with 165.3 egg galleries per m 2 at a height of 6 m for T. piniperda , and 138.2 egg galleries per m 2 at the 1 m height for T. minor . It is suggested that T. minor adjusts its attack pattern with respect to T. piniperda , and thereby minimizes interspecific competition. No remarkable difference of average T. piniperda egg gallery length was found between the zone in which only T. piniperda occurred and the zone in which T. piniperda and T. minor coexisted; this is suggested to be due to low host quality in the upper trunk region where only T. piniperda was present. The number of T. piniperda larval galleries was highest when only T. piniperda was present, and decreased as T. piniperda and T. minor coexisted, particularly in the case when the density of T. piniperda was less than that of T. minor . Average larval density was 1649 larval galleries per m 2 where only T. piniperda occurred. However, when T. piniperda coexisted with T. minor, T. piniperda larval density averaged 1010 per m 2 when T. piniperda density was higher than T. minor, and averaged 442 per m 2 when T. piniperda density was less than T. minor , which led to the conclusion that T. minor makes a negative impact on T. piniperda reproduction when the two Tomicus species jointly colonize the same trunk of Yunnan pine tree.