Effects of four field treatments on the survivorship of Monochamus alternatus Hope (Coleoptera: Cerambycidae) in pine logs

• Main Authors: Chen Shang Yuan, 陳尚遠
• Other Authors: Ching-Hsia Chen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/04434065208196002579

碩士 === 輔仁大學 === 生物學系 === 89 === Twenty 1-m pine logs were sawed and collected from Ryuryu pine (Pinus luchunesis Mayr) forest at Pei-Tou, Taipei County, Taiwan in June 2000. A week later, 5-2nd larvae of pine sawyer Monodhamus alternatus Hope were in planted in each log. An additional 10 l-m logs were set with experiment group to measure the water content of logs under different treatments. The 20 logs then were separated into 5 groups (4 logs in each group). Four of them were placed in Erh-Tzu Ping of Yangmingshen National Park, and treated as follows: covered with plastic canvas, covered with grass (in secondary forest), exposure to sunlight and uncovered (field control group). The 5th group (indoor control group) was set in the growth chamber, where constant temperature and humidity were maintained. All logs were collected in February 2001. Mortality, development and morphological character values of pine sawyers implanted were measured. Insect community in logs were recorded and collected. The result showed there are significant different between 5 group (F = 3.199，P = 0.044), the mortality of the field control group was the highest (50%) and exposure to sunlight is the second (30%). The environment of two forests was similar, and the water content in four groups in the field was also similar. Although there was a significant difference among 5 groups (F = 6.184，P = 0.001), it was mainly because the indoor control group was significantly different from the other 4 groups. Therefore the temperature, the humidity and the water content cannot have effect on the mortality of pine sawyers in the logs. The prothorax and the tergum of pine sawyer between 4 groups in the field were significant difference. (F = 22.855，P < 0.001) The prothorax and the tergum of pupa between 4 groups in the field were not significant difference. (F = 1.785，P = 0.177). The epicranium width of larva (besides covered with grass in the field) were significant different between 4 groups. (F = 3.342，P = 0.042). The dry wet of excrement of the pine sawyer were not significant different between 4 groups. (ANOVA，F = 1.180，P = 0.359). The increasing numbers of the pine sawyer of exposure to sunlight group was significant different from other field 4 groups(F = 10.477，F < 0.001). But the increasing numbers of pine sawyers in the logs with the mortality of implanted pine sawyers was not significant relationship. (r = 0.154，N = 20，P = 0.516). 134 pupa chambers are discovered in this research. The U-shape pupa chamber is the most dominant; occupying 90.71% (127/140). The shapes of other pupae chambers are occupying 5.71% (8/140). And there are 4 pupae which do not have chambers. The numbers of pupa chambers in each log and pupa chambers with irregular shape of pine sawyer are not significant relation. (r = 0.273，N = 20，P = 0.245). The mortality of U-shape pupa chambers of pine sawyer between irregular shape were not significant relation (c2 = 0.487，P = 0.619). Twenty percent (4/20) logs was peel by rodent. Percentage of peeled bark between 4 groups are significant difference (F = 2.787，P = 0.086). It was mainly because the exposure to sunlight between the uncovered (field control group) (P = 0.028) and covered with plastic (P = 0.028). The mortality of pine sawyer with pupa chamber of area that bark is bitten off (28.6%) is higher than area that is not (21.1%). But it was not significant difference between groups (c2 = 0.412，P = 0.521). The final numbers of pine sawyer were significant correlation with the mortality of that have the other form pupa chambers (r = 0.473，N = 20，P = 0.035). In addition to pine sawyers, there are 6 more species of insects were found in pine logs, Cryptorrhynchus insidiosus Roelofs, Sipalus formasanus, two unidentified species of Scolytidae, one unidentified long-horned beetle, one unidentified species of Corrodentia, and one unidentified species of Click beetle. No correlation was found between the mortality of pine sawyers and the number of each of the 6 species (Cryptorrhynchus insidiosus Roelofs：r = 0.205，N = 20，P = 0.385；Sipalus formasanus：r = -0.226，N = 20，P = 0.339；unidentified two sepses of Scolytidae：r = -0.159，N = 20，P = 0.503； Mimorsidis taiwanensis Hayashi：r = -0.326，N = 20，P = 0.106； Corrodentia：r = -0.180，N = 20，P = 0.448). The growth condition between groups, the uncovered (field control group) was the best, and the exposure to sunlight is the worst. But there is no significant difference between 2 groups. The mortality of uncovered is the highest, but the growth condition is the best. The mortality of exposure to sunlight is the lowest, but the growth condition is the worst. But it does not have significant difference between uncovered and exposure to sunlight. Based on the mortality and development of pine sawyers under different treatments in this study, leaving the cut pine logs in uncovered or exposure the pine logs to sunlight are better alternatives treatments to maintain the pine sawyers populations in the pine logs at lower level.