Under reduced solar UV radiation, such as in polycarbonate-covered nurseries, the two-spotted spider mite Tetranychus urticae is a major pest of all citrus cultivars, while under natural solar radiation, only sensitive cultivars are infested. We hypothesized that citrus resistance to T. urticae is induced by UV. We infested seedlings of Citrus volkameriana rootstock with T. urticae under natural and under UV-screened solar radiation, along with non-infested control seedlings. We then monitored the establishment of the spider mites and analyzed the volatile leaf profile using GC-MS. The density of spider mites was reduced dramatically on seedlings exposed to solar UV. Overall, ninety volatile compounds (47 monoterpenes, 35 sesquiterpenes, and 8 aldehydes) were detected in the leaves, many of them known to be herbivore-induced and/or UV enhanced. Their levels were affected not only by solar UV radiation or by mite infestation independently. Synergistic interaction of these two factors resulted in 90% of the volatiles suppressed by T. urticae infestation in the absence of UV radiation. This suggests that plant induced resistance is dependent on exposure to UV radiation.

在减少的紫外线照射下，例如在覆盖聚碳酸酯的苗圃中，二斑叶螨Tetranychus urticae是所有柑桔品种的主要害虫，而在自然阳光照射下，只有敏感品种受到感染。我们假设柑橘对荨麻疹的抗性是由紫外线诱导的。我们用T. urticae侵害了Volkameriana柑橘砧木的幼苗在自然和紫外线屏蔽的太阳辐射下，以及未感染的对照幼苗。然后，我们监测了叶螨的建立，并使用GC-MS分析了挥发性叶的轮廓。在暴露于太阳紫外线下的幼苗上，红蜘蛛的密度显着降低。总体上，在叶片中检测到90种挥发性化合物（47个单萜，35个倍半萜和8个醛），其中许多已知是草食动物诱导和/或紫外线增强的。它们的水平不仅受到太阳紫外线辐射或螨虫侵害的影响。这两个因素的协同相互作用导致90％的挥发物在无UV辐射的情况下被荨麻疹侵染所抑制。这表明植物诱导的抗性取决于暴露于紫外线辐射。