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Insect–plant interactions among gall size determinants of adelgids
Author(s) -
Ozaki Kenichi
Publication year - 2000
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1046/j.1365-2311.2000.00281.x
Subject(s) - gall , shoot , biology , botany , volume (thermodynamics) , whorl (mollusc) , horticulture , genus , physics , quantum mechanics
Summary 1. The adelgid Adelges japonicus induces shoot galls in ezo‐spruce Picea jezoensis . The relative importance of shoot characteristics and the number of adelgids that induce a gall in determining resource availability on a shoot was examined. Gall volume, which is highly correlated with the number of larvae that mature in a gall, was used as a measure of resources available for adelgids on a shoot. Gall volume was partitioned into two components: the number of chambers and the chamber volume. 2. Path analysis revealed that the number of chambers in a gall was not affected by the number of leaves (which is an indirect measure of shoot length), the whorl where the gall was attached, or the number of surrounding shoots arising from the 1‐year‐old parent shoot. Each of these shoot characteristics, however, affected chamber volume: chamber volume increased with increasing numbers of leaves and surrounding shoots and with increasing heights of the whorls. 3. Two generations of adelgids contributed to gall enlargement in different ways: the number of gall founders affected the number of chambers, and the number of gall inhabitants affected chamber volume. 4. In a path diagram that incorporated the effects of both shoot characteristics and the numbers of adelgids, the numbers of adelgids in the two generations together accounted for 30% of the variance in gall volume, whereas the three shoot characteristics explained only 3.7% of the variance. This suggests that the amount of resources available in a gall is affected mainly by the numbers of adelgids but only slightly by shoot characteristics.