Abiotic conditions can influence the effect that herbivores have on plant growth. Such biotic and abiotic interactions are of special interest in plant biological control programs because the goal of herbivore suppression of the target weed may not be reached in some abiotic settings. Additionally, target invasive plants typically occur across diverse landscapes raising the possibility that local adaptation to site-specific conditions leads to phenotypic variation that can affect herbivore responses. Here, we used Tamarix, an invasive plant, and its associated biological control agent, Diorhabda carinulata, to investigate how local variation in soil salinity and host plant origin influence interactions between the two taxa. To test if Tamarix was adapted to local conditions, we collected plants from sites with either low or high groundwater salinity, asexually propagated them through multiple generations, and then treated them with their home or reciprocal salinity levels. We found that plants accumulated the most biomass when grown at the salinities of their origin site. The biological control agent, D. carinulata preferred plants grown at source site salinity when given a choice against plants grown in the reciprocal salinity treatment. Although plants compensated for herbivory by regrowing foliage over three defoliation events and maintained similar leaf biomass through regrowth, they ultimately had a reduced basal area and 62% lower root biomass compared to the controls. Thus, herbivory caused a shift in plant allocation of resources from overall growth to compensation, reducing root and stem investment. Overall, D. carinulata caused a significantly greater reduction in total biomass in the high salinity plants than the low salinity ones when grown at their source salinity (averages of 63% and 32% respectively). Thus, the Tamarix biological control program may experience its greatest efficacy in high salinity areas where the impact of the agent is the greatest, likely due to increased water stress and reduced resources to enable regrowth.

非生物条件会影响草食动物对植物生长的影响。这种生物和非生物相互作用在植物生物控制程序中特别受关注，因为在某些非生物环境中可能无法达到草食动物抑制目标杂草的目的。此外，目标入侵植物通常会出现在不同的景观中，从而增加了对特定地点条件的局部适应导致表型变异的可能性，这种变异会影响草食动物的反应。在这里，我们使用了入侵植物Tamarix及其相关的生物防治剂Diorhabda carinulata，以研究土壤盐分和寄主植物起源的局部变化如何影响这两个类群之间的相互作用。测试Tamarix是否为了适应当地条件，我们从地下水盐度低或高的地点收集了植物，无性繁殖了多代，然后对其原始或倒数盐度进行了处理。我们发现，在原产地的盐度下生长时，植物积累的生物量最多。生物防治剂，D。carinulata当给予在往复盐度处理中生长的植物时，在源部位盐度生长的优选植物。尽管植物通过在三个脱叶过程中生长叶子来补偿草食动物，并通过再生长来维持相似的叶片生物量，但与对照相比，它们最终具有减少的基础面积和62％的根生物量。因此，食草引起植物资源分配从总体增长转向补偿，从而减少了根和茎的投资。总体而言，当按源盐度生长时，D。carinulata导致高盐度植物中总生物量的减少比低盐度植物大得多（平均分别为63％和32％）。因此，the柳 生物防治计划可能在高盐度地区发挥最大功效，在高盐度地区，药剂的影响最大，这可能是由于增加的水分胁迫和减少了可再生长的资源所致。