Liu Chang, Gibson Amanda Kyle, Timper Patricia, Morran Levi T, Tubbs R Scott
Department of Plant Pathology University of Georgia Tifton Georgia.
Department of Biology Emory University Atlanta Georgia.
Evol Appl. 2018 Dec 31;12(4):744-756. doi: 10.1111/eva.12750. eCollection 2019 Apr.
In biological control, populations of both the biological control agent and the pest have the potential to evolve and even to coevolve. This feature marks the most powerful and unpredictable aspect of biological control strategies. In particular, evolutionary change in host specificity of the biological control agent could increase or decrease its efficacy. Here, we tested for change in host specificity in a field population of the biological control organism . is an obligate parasite of the plant parasitic nematodes spp., which are major agricultural pests. From 2013 through 2016, we collected yearly samples of from eight plots in a field infested with . Plots were planted either with peanut () or with a rotation of peanut and soybean (). To detect temporal change in host specificity, we tested samples annually for their ability to attach to (and thereby infect) four clonal lines of . After controlling for temporal variation in parasite abundance, we found that from each of the eight plots showed temporal variation in their attachment specificity to the clonal host lines. The trajectories of change in host specificity were largely unique to each plot. This result suggests that local forces, at the level of individual plots, drive change in specificity. We hypothesize that coevolution with local hosts may be one such force. Lastly, we observed an overall reduction in attachment rate with samples from rotation plots relative to samples from peanut plots. This result may reflect lower abundance of under crop rotation, potentially due to suppressed density of host nematodes. As a whole, the results show local change in specificity on a yearly basis, consistent with evolution of a biological control organism in its ability to infect and suppress its target pest.
在生物防治中，生物防治剂和害虫的种群都有进化甚至共同进化的潜力。这一特性标志着生物防治策略最强大且最不可预测的方面。特别是，生物防治剂宿主特异性的进化变化可能会提高或降低其功效。在此，我们测试了一种生物防治生物田间种群中宿主特异性的变化。[生物防治生物名称]是植物寄生线虫[线虫名称]属的专性寄生虫，而[线虫名称]属是主要的农业害虫。从2013年到2016年，我们每年从一块受[线虫名称]侵染的田地里的八个地块采集[生物防治生物名称]的样本。地块要么种植花生（[花生品种名称]），要么种植花生和大豆轮作（[轮作模式名称]）。为了检测宿主特异性的时间变化，我们每年测试[生物防治生物名称]样本附着于（并由此感染）[线虫名称]四个克隆系的能力。在控制了寄生虫丰度的时间变化后，我们发现来自八个地块中的每一个地块的[生物防治生物名称]在其对克隆宿主系的附着特异性上都表现出时间变化。宿主特异性变化的轨迹在很大程度上因地块而异。这一结果表明，在单个地块层面的局部因素驱动了特异性的变化。我们推测与当地[线虫名称]宿主的共同进化可能是这样一种因素。最后，我们观察到相对于花生地块的样本，轮作地块的样本附着率总体下降。这一结果可能反映了作物轮作下[生物防治生物名称]丰度较低，这可能是由于宿主线虫密度受到抑制所致。总体而言，结果显示特异性每年都有局部变化，这与一种生物防治生物在感染和抑制其目标害虫能力方面的进化相一致。
