Sampling procedure for density estimation of bamboo galls induced by <Emphasis Type="Italic">Aiolomorphus rhopaloides</Emphasis> (Hymenoptera: Eurytomidae) in a bamboo stand |
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Authors: | E Shibata |
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Institution: | (1) Laboratory of Forest Protection, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan Tel. +81-52-789-4180; Fax +81-52-789-4180 e-mail: shibatae@agr.nagoya-u.ac.jp, JP |
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Abstract: | To establish a sampling procedure for estimating the density of bamboo galls induced by Aiolomorphus rhopaloides Walker (Hymenoptera: Eurytomidae) in a stand of bamboo Phyllostachys heterocycla (Carr. Mitf.) (Monocotyledoneae: Gramineae), 5–12 bamboo culms were cut at random in late March of each year during 1998–2001
just before gall-maker emergence. The number of galls on the branches of each bamboo culm was counted. The spatial patterns
of the galls on the culms in the stand and on the branches within each culm were measured by Iwao's patchiness regression.
Galls were distributed contagiously both on culms and on branches. Current bamboo culms that emerged the previous summer did
not require sampling because no galls were observed on them. Except for this, there was no difference in gall density on young
and old culms, suggesting that it is not necessary to distinguish them. There were few (<4%) galls above 6 m height during
the 4 years. There was no significant difference in gall density up to 4 m and above 4 m, suggesting that branches up to 4 m
can be sampled with confidence. Kuno's two-stage sampling method at different precision levels showed that the number of culms
to be sampled varied with gall density. For example, at mean density m = 1.0 per branch when the number of sampled branches per culm is 10, a total of 24 culms is required to estimate gall number
at a precision level of D = 0.2, where D is the ratio of standard error to mean.
Received: July 10, 2002 / Accepted: November 25, 2002
Acknowledgments I thank Dr. K. Kamijo for insect identification. Thanks are also due to the members of the Laboratory of Forest Protection
for their kind help with the fieldwork. This study was supported in part by a Grant-in-Aid for Scientific Research (No. 11460068)
from the Ministry of Education, Culture, Sports, Science and Technology, Japan. |
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Keywords: | Aiolomorphus rhopaloides Bamboo gall maker Density estimation Phyllostachys heterocycla Sampling procedure |
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