Evolution of critical day length for diapause induction enables range expansion of Diorhabda carinulata, a biological control agent against tamarisk (Tamarix spp.)

In classical weed biological control, small collections of arthropods are made from one or a few sites in the native range of the target plant and are introduced to suppress the plant where it has become invasive, often across a wide geographic range. Ecological mismatches in the new range are likely, and success using the biocontrol agent may depend on post release evolution of beneficial life history traits. In this study we measure evolution of critical day length for diapause induction, (day length at which 50% of the population enters dormancy), in a beetle (Diorhabda carinulata) introduced into North America from China to control an exotic shrub, Tamarix spp. Beetle populations were sampled from four sites in North America seven years after introduction and critical day length was shown to have declined, forming a cline over a latitudinal gradient At one field site decreased critical day length was correlated with 16 additional days of reproductive activity, resulting in a closer ...经典杂草生物防治（classical weed biological control）中，研究者会从目标植物（target plant）原生分布区（native range）的一处或少数几处位点采集少量节肢动物（arthropods）样本，将其引入该植物已发生入侵的区域以抑制其扩散，此类入侵区域往往覆盖广阔的地理范围。在新入侵区域中，生态失配（ecological mismatches）现象大概率存在，而该生物防治剂（biocontrol agent）的防控效果可能取决于其有益生活史性状在释放后的演化。本研究针对一种从中国引入北美、用于防控外来灌木（exotic shrub）柽柳属（Tamarix spp.）的甲虫（Diorhabda carinulata），测定了其滞育诱导临界光周期（critical day length for diapause induction，即种群中50%个体进入滞育（diapause）的光周期）的演化情况。研究人员于该甲虫引入七年后，从北美的四个位点采集了甲虫种群，结果显示其滞育诱导临界光周期已出现下降，并沿纬度梯度（latitudinal gradient）形成了渐变群（cline）。在其中一处野外位点，滞育诱导临界光周期的下降与生殖活动（reproductive activity）时长增加16天相关，最终使得……