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.

日本扁甲（Temnaspis japonica）为鞘翅目（Coleoptera，原文笔误为Coloeoptera）大甲科（Megalopodidae）昆虫，其雌成虫会将自身产卵所用茎干的几乎全部叶片与顶端芽体切下。幼虫于无叶片及顶端芽体的茎干内部孵化，以蛀茎害虫的身份蛀食茎髓组织。为揭示该雌成虫切叶行为的适应意义，我们设置4组处理开展野外实验，处理方案涵盖人工接卵与切叶操作，具体如下：处理1：人工将卵接入茎干，并人工切去叶片与顶端芽体；处理2：人工将卵接入茎干，但不切去叶片与顶端芽体；处理3：人工将卵接入茎干，且由日本扁甲完成叶片与顶端芽体的切取；处理4（自然产卵组）：由日本扁甲在茎干上产卵，并切去叶片与顶端芽体。处理后6周，对各组未成熟虫体的存活率进行比较分析。此外，我们还检测了接卵所引发的茎干膨大情况，以探究茎干膨大程度、未成熟虫体存活率与实验处理三者间的关联。茎干膨大程度划分为4个等级：0级，无膨大；1级，轻微膨大；2级，中度膨大；3级，重度膨大。