PRF/J: Regulation of Phytophagus Insect Populations: Density Perturbation Experiments on Microrhopala vittata, an Herbivore of Solidago

长期以来，人们一直在争论植食性昆虫的种群是否受到密度依赖过程的调节，以使其密度恢复到平衡水平，或者它们是否具有非平衡过程的特征，如局部灭绝和重新定殖。这个问题将通过对microhopala vittata进行密度扰动实验来解决，microhopala vittata是一种采叶甲虫，以黄花（一枝黄花属）为食。工作将开始于评估这种甲虫在几个小的（1000茎）黄花林中的密度、死亡率和繁殖力。然后通过实验补充种群的密度（使其比观测到的最低水平低10-20%），并对这些操作对捕食、寄生、繁殖力和传播的影响进行量化。所有死亡率和繁殖力的样本都将以非破坏性的方式进行（不会杀死微霍帕拉或敌人），以便这些过程的量化不会影响种群密度。微霍帕拉密度在扰动后回归到更适度的水平将支持平衡观点。或者，补充的种群可能会破裂，减少的种群可能会在局部灭绝；这将构成非均衡观点的证据。在加拿大蒙特利尔的魁北克大学进行为期两年的博士后研究。

It has long been debated whether populations of phytophagous insects are regulated by density-dependent processes acting to return their densities to equilibrium levels, or whether they are characterized instead by non-equilibrium processes such as local extinction and recolonization. This question will be addressed by performing density-perturbation experiments on Microrhopala vittata, a leaf-mining beetle that feeds on goldenrod (Solidago spp.). Work will commence with assessments of density, mortality and fecundity of this beetle in several small (1000 stems) stands of goldenrod. Populations will then have their density experimentally supplemented (to levels 10-20% below the minimum observed), and the effect of these manipulations on predation, parasitism, fecundity and dispersal will be quantified. All samples for mortality and fecundity will be done non-destructively (no Microrhopala or enemies will be killed) so that quantification of these processes will not affect population density. A return of Microrhopala density to more moderate levels following perturbations will support the equilibrium viewpoint. Alternatively, supplemented populations may irrupt and reduced populations may become locally extinct; this would constitute evidence for the non-equilibrium viewpoint. Funding is being awarded for two years of postdoctoral fellowship research at The University of Quebec in Montreal, Canada.