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由松褐天牛(Monochamus alternatus)传播的松材线虫病(Bursaphelenchus xylophilus)是我国最为严重的病虫害,目前已经传播到我国南方除海南省以外的其它13个省及北方的河南、陕西、山东省和辽宁省,每年致死大量的松树,造成了严重的经济和生态损失[1]。利用天敌昆虫生物防治其传播媒介松褐天牛是持续防控松材线虫病的有效措施之一[1-3]。目前,广泛使用的松褐天牛的天敌主要是肿腿蜂和花绒寄甲(Dastarcus helophoroides Fairmaire) [1-8],其中, 肿腿蜂有管氏肿腿蜂(Sclerodermus guani Xiao et Wu)[5, 9]、川硬皮肿腿蜂(S. sichuanensis Xiao) [7]和松褐天牛肿腿蜂(S. alternatusi Yang)[8]3个种应用到林间防治松褐天牛。在林间,肿腿蜂主要寄生松褐天牛的13龄初低龄幼虫[8],而花绒寄甲主要寄生中老龄幼虫、蛹及少数初羽化尚未出孔的成虫[1, 3]。2013年在贵州遵义,笔者发现了寄生松褐天牛中老龄幼虫的另一种重要天敌——松褐天牛深沟茧蜂(Iphiaulax monochamusi Yang) [10],其在有的林分自然寄生率达30%。该寄生蜂在遵义地区一年2代,世代重叠,是一种良好的可利用于生物防治松褐天牛的寄生蜂新种。1头松褐天牛幼虫上可寄生111头松褐天牛深沟茧蜂,但不管寄生1头深沟茧蜂还是多头,最终均能将松褐天牛幼虫杀死。为了明确这种优良寄生蜂的寄生率与寄主树木、寄主和环境因子的关系,2014年,笔者在贵州省遵义市马尾松林分中,先后解剖了有松褐天牛的马尾松死树46株,调查研究了寄主树木—害虫—天敌三者之间的关系,以期明确这种寄生蜂与寄主松褐天牛之间的关系,为生物防治利用该深沟茧蜂打下基础。
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松褐天牛深沟茧蜂的寄生率与松褐天牛幼虫的数量没有明显的关系(图 2a),而与松褐天牛幼虫的龄期呈线性关系(y=5.271x-8.698; F=51.091, df=1, 46, P=0.000 1, R=0.729 2) (图 2b)。表明松褐天牛深沟茧蜂偏好寄生35龄的松褐天牛中老龄幼虫。
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松褐天牛深沟茧蜂对不同高度分布的松褐天牛的寄生率差异显著(F=4.544, df=4, 124, P=0.000 1)(图 3),其中,松褐天牛深沟茧蜂对位于树干上部的松褐天牛寄生率最高,达27.38%;对位于树干中上部的寄生率次之,为18.23%;对位于树干中部的寄生率为10.50%;对位于树干中下部和下部的天牛寄生率较低,仅为6.13%和1.73%。上部和中上部被寄生的天牛多数在木质部,而中下部和下部被寄生的天牛多数在韧皮部。
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松褐天牛深沟茧蜂对位于马尾松树干韧皮部和木质部的松褐天牛幼虫寄生率差异显著(F=19.601, df=1, 63, P=0.000 1)(图 4)。对位于韧皮部寄主的寄生率最高达57.14%,平均为20.18%;而对位于木质部中的松褐天牛幼虫的寄生率最高为18.68%,平均仅为5.46%。
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对环境因子与松褐天牛深沟茧蜂寄生率的关系进行了逐步回归分析,结果(表 1)表明:影响松褐天牛深沟茧蜂的关键因子是坡位(X2)和其它天敌寄生率(X10),其中,坡位与松褐天牛深沟茧蜂的寄生率呈正相关,而其它天敌寄生率与松褐天牛深沟茧蜂的寄生率呈负相关。
表 1 各自变量的偏相关系数及t检验结果
Table 1. The partial correlation coefficient of each variable and t-test
变量
Variable林型
Crop type X1坡位
Slope position X2坡向
Exposure X3坡度
Slope X4郁闭度
Canopy density X5植被盖度
Percentage of vegetation X6植被高度
Height of vegetation X7枯枝层厚度
Thickness of branch litter X8马尾松密度
Density of Pinus massoniana X9其它天敌寄生率
Parasitism rate of other natural enemies X10偏相关系数Partial correlation coefficient 0.176 7 0.617 4 0.077 0 -0.133 9 -0.126 5 0.306 0 -0.306 0 0.229 8 -0.160 4 -0.467 7 t检验值 1.062 0 4.642 6 0.456 8 0.799 5 0.754 4 1.901 6 1.901 6 1.397 2 0.961 5 3.130 0 P 0.295 3 0.000 1 0.650 5 0.429 2 0.455 5 0.065 2 0.065 2 0.170 9 0.342 7 0.003 5 -
马尾松主干上其它天敌的寄生率与松褐天牛深沟茧蜂的寄生率呈显著的负相关(y=-0.697x+20.088; F=63.672, df=1, 45, P=0.000 1, R=0.769 1) (图 5),即其它天敌寄生率越高,松褐天牛深沟茧蜂的寄生率越低。
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调查发现:寄主树木马尾松林地坡位与松褐天牛深沟茧蜂寄生率呈显著的正相关(y=4.045x-3.915; F=110.622, df=1, 45, P=0.000 1, R=0.845 8) (图 6), 即松褐天牛深沟茧蜂偏向寄生处于山脊和上坡位的马尾松上的松褐天牛。
寄主树木、寄主和环境因子对松褐天牛深沟茧蜂寄生率的影响研究
A Study on Host Tree, Host and Environmental Factors Affecting the Parasitism of Iphiaulax monochamusi Yang (Hymenoptera: Braconidae), a Larval Parasitoid of Monochamus alternatus (Coleoptera: Cerambycidae)
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摘要:
目的 松材线虫病是我国对森林危害和威胁最严重的病害,控制其传播媒介昆虫松褐天牛是防治松材线虫病的主要手段。作者发现的松褐天牛深沟茧蜂(Iphiaulax monochamusi Yang)是寄生松褐天牛中老龄幼虫的重要天敌。为明确松褐天牛深沟茧蜂的寄生率与寄主树木、寄主和环境因子的关系,开展了本研究。 方法 通过解剖46株松褐天牛危害致死的马尾松,调查了松褐天牛深沟茧蜂寄生率与马尾松、松褐天牛和环境因子之间的关系。 结果 调查研究表明:寄主树木的高度、胸径和树龄对松褐天牛深沟茧蜂寄生率没有显著影响,松褐天牛的数量对松褐天牛深沟茧蜂寄生率亦没有显著影响,而松褐天牛幼虫龄期和松褐天牛幼虫在树干上的位置显著影响松褐天牛深沟茧蜂寄生率。松褐天牛深沟茧蜂寄生率与松褐天牛龄期呈显著正相关,其偏好寄生3~5龄幼虫;就天牛在其危害寄主树木上的位置而言,松褐天牛深沟茧蜂偏好寄生马尾松主干上部和在韧皮部危害的松褐天牛幼虫,其对位于马尾松树干上部的寄主幼虫寄生率最高,达27.38%,对在韧皮部生活、危害的寄主幼虫寄生率为20.18%,显著高于位于木质部生活的寄主幼虫寄生率(5.46%)。逐步回归分析表明:影响松褐天牛深沟茧蜂寄生率的关键环境因子是寄主树木的坡位和其它天敌寄生率,其中,坡位与松褐天牛深沟茧蜂呈显著正相关,其它天敌寄生率与松褐天牛深沟茧蜂寄生率呈显著负相关。 结论 以上研究初步明确了松褐天牛深沟茧蜂的寄生率与寄主树木、寄主害虫和天敌之间的关系,为今后利用该重要天敌控制松褐天牛打下了基础。 Abstract:Objective Iphiaulax monochamusi Yang is an important parasitoid on larvae of Monochamus alternatus Hope in Zunyi County, Guizhou Province. For determining the main factors affecting the parasitism of the parasitoid, the relationships among host tree, host and environmental factors were investigated. Method 46 Pinus massoniana trees died from M. alternatus attacking were investigated in the forests at Zunyi County to explore the effects of host tree, host and environmental factors nor the natural control of the parasitoid. Result It was found that the effect of neither height, DBH and age of host tree or the number of M. alternatus host on the parasitism were little. However, the M. alternatus' instar and location on host tree had a great influence on parasitism. There was a significant positive correlation between larval instars of the M. alternatus host and the parasitism of the parasitoid. The parasitoid's preference was 3-5 instars of host larvae. The parasitoid had partiality for the host larvae tunneled at the phloem and upper trunk of host pine tree. Therefore the parasitism on those parts of host pine trees was the highest with an average parasitism of 27.38%, and the parasitism in the phloem of host trees was 20.18% which was significantly higher than that in the xylem (5.46%). The slope position of the host trees had a significantly positive correlation with the parasitism of I. monochamusi, and the parasitism of I. monochamusi had a significantly negative correlation with the parasitism of other natural enemies. Conclusion The present study provided a basic information of the relations between parasitism and host tree, host and environmental factors and it would provide references for the biological control of wood borer pests by applying the parasitoid. -
Key words:
- Monochamus alternatus
- / Pinus massoniana
- / Iphiaulax monochamusi Yang
- / parasitism
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表 1 各自变量的偏相关系数及t检验结果
Table 1. The partial correlation coefficient of each variable and t-test
变量
Variable林型
Crop type X1坡位
Slope position X2坡向
Exposure X3坡度
Slope X4郁闭度
Canopy density X5植被盖度
Percentage of vegetation X6植被高度
Height of vegetation X7枯枝层厚度
Thickness of branch litter X8马尾松密度
Density of Pinus massoniana X9其它天敌寄生率
Parasitism rate of other natural enemies X10偏相关系数Partial correlation coefficient 0.176 7 0.617 4 0.077 0 -0.133 9 -0.126 5 0.306 0 -0.306 0 0.229 8 -0.160 4 -0.467 7 t检验值 1.062 0 4.642 6 0.456 8 0.799 5 0.754 4 1.901 6 1.901 6 1.397 2 0.961 5 3.130 0 P 0.295 3 0.000 1 0.650 5 0.429 2 0.455 5 0.065 2 0.065 2 0.170 9 0.342 7 0.003 5 -
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