Offensive leaf and apical bud clipping by Temnaspis japonica suppresses the ash tree damage response and protects oviposited immatures

Temnaspis japonica (Coloeoptera, Megalopodidae) female cuts off almost all the leaves and the apical bud of the stem into which she oviposites. Larva hatches inside the stem without leaves and apical bud, and infests the pith of stem as stem borer. In order to reveal the adaptive significance of the leaf clipping behavior by female, we conducted field experiment with four treatments including artificial egg insertion into stem and leaf clipping: Treatment 1, artificial egg insertion into stem and artificial leaf and apical bud clipping; 2, artificial egg insertion into stem without leaf and apical bud clipping; 3, artificial egg insertion into stem with leaf and apical bud clipping by T. japonica; 4 (insect oviposition), oviposition into stem and leaf and apical bud clipping by T. japonica. Survival rates of immatures were compared 6 weeks after treatment. Also, stem thickening caused by egg-insertion was checked to examine the relationship among thickening degree, immature survival, and treatment. Thickening degree was divided into four categories: 0, no thickening; 1, a little thickening; 2, moderate thickening; and 3, heavy thickening.日本坦伪叶甲（Temnaspis japonica，鞘翅目（Coleoptera），大甲科（Megalopodidae））的雌虫会将自身用于产卵的茎干上的几乎全部叶片与顶端芽体切除。幼虫在失去叶片及顶端芽体的茎干内部孵化，并以蛀茎害虫的方式取食茎髓组织。为揭示雌虫切叶行为的适应性意义，本研究设置四组处理开展野外实验，实验操作涵盖人工接卵入茎与切叶两类核心环节，具体如下：处理1：人工将卵接入茎干，并人工切除叶片与顶端芽体；处理2：人工将卵接入茎干，不进行叶片与顶端芽体切除操作；处理3：人工将卵接入茎干，由日本坦伪叶甲完成叶片与顶端芽体切除；处理4（自然产卵组）：由日本坦伪叶甲在茎干内产卵，并完成叶片与顶端芽体切除。于实验处理6周后，比较各组幼期虫态的存活率。同时，统计由人工接卵引发的茎干膨大情况，以分析茎干膨大程度、幼期存活率与实验处理三者间的关联。茎干膨大程度被划分为四个等级：0级，无膨大；1级，轻度膨大；2级，中度膨大；3级，重度膨大。