Kher S V, Dosdall L M, Cárcamo H A
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada.
Environ Entomol. 2014 Oct;43(5):1295-308. doi: 10.1603/EN14066.
The cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), is a new invasive insect pest of oat, wheat, and barley in western Canada. Biological control with its principal larval parasitoid, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is the primary management strategy. However, to implement control successfully, a thorough understanding of the spatio-temporal dynamics of the interactions between these two species is important. We examined the nature of spatial associations and distribution dynamics of O. melanopus and T. julis with reference to host plant nutrients and plant vigor traits using Spatial Analysis by Distance Indices. A grid design was used to understand spatial associations between O. melanopus and T. julis. Distributions of O. melanopus and T. julis indicated the presence of significant patches and gaps. Plant nutrient availability and plant vigor varied across the grid in all study years. On a spatial scale, O. melanopus and T. julis represented a tightly coupled system demonstrating the strong density-dependent nature of parasitoid dispersal. Among the factors examined, plant vigor traits significantly influenced field distributions of both O. melanopus and T. julis. Areas across grids with high plant density, greater plant height, and high availability of plant leaves indicated higher establishment of O. melanopus larvae, consequently exhibiting bottom-up effects on T. julis distributions. Maintenance of uniform plant vigor can be a critical aspect in mitigating yield losses from O. melanopus infestation.
谷物叶甲（Oulema melanopus (L.)，鞘翅目：叶甲科）是加拿大西部燕麦、小麦和大麦的一种新入侵害虫。利用其主要幼虫寄生蜂朱利斯四棒小蜂（Tetrastichus julis Walker，膜翅目：优茧蜂科）进行生物防治是主要的管理策略。然而，要成功实施防治，深入了解这两个物种之间相互作用的时空动态非常重要。我们使用距离指数空间分析，参照寄主植物养分和植物活力特征，研究了谷物叶甲和朱利斯四棒小蜂的空间关联性质及分布动态。采用网格设计来了解谷物叶甲和朱利斯四棒小蜂之间的空间关联。谷物叶甲和朱利斯四棒小蜂的分布表明存在显著的斑块和间隙。在所有研究年份中，网格内植物养分有效性和植物活力各不相同。在空间尺度上，谷物叶甲和朱利斯四棒小蜂代表了一个紧密耦合的系统，表明寄生蜂扩散具有很强的密度依赖性。在所研究的因素中，植物活力特征显著影响谷物叶甲和朱利斯四棒小蜂的田间分布。网格中植物密度高、植株高度大且叶片可用性高的区域，谷物叶甲幼虫的定殖率更高，因此对朱利斯四棒小蜂的分布产生自下而上的影响。保持均匀的植物活力可能是减轻谷物叶甲侵害造成产量损失的关键因素。
