Graduate School of Science, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2014 Feb;200(2):161-7. doi: 10.1007/s00359-013-0872-0. Epub 2013 Dec 6.
Photoreceptors involved in photoperiodism in insects and mites can be either the retinal photoreceptors in the visual system or nonvisual extraretinal photoreceptors. Mites with no eyes have a clear photoperiodic response, suggesting the involvement of extraretinal photoreceptors in mite photoperiodism. In mites equipped with eyes, however, it is not known whether the retinal or extraretinal photoreceptors are involved in photoperiodism. The two-spotted spider mite Tetranychus urticae possesses two pairs of eyes. Adult females of this species terminate diapause in response to long days. To investigate whether the eyes function as photoperiodic photoreceptors in T. urticae, their eyes were ablated using a laser ablation system. Mites with their eyes intact terminated diapause under long days after low temperature exposure, whereas they remained in diapause under short days. Under constant darkness, they did not terminate diapause. When all eyes were removed, the mites remained in diapause even when they were maintained under long days. In contrast, the mites showed clear photoperiodic response when only the anterior or posterior eyes were removed. These results indicate that both the anterior and posterior eyes function as photoreceptors in photoperiodic termination of diapause in T. urticae.
参与昆虫和螨虫光周期的感光器可以是视觉系统中的视网膜感光器，也可以是非视觉的视网膜外感光器。没有眼睛的螨虫具有明显的光周期反应，这表明非视觉视网膜外感光器参与了螨虫的光周期。然而，在配备眼睛的螨虫中，尚不清楚是视网膜感光器还是视网膜外感光器参与了光周期。二斑叶螨 Tetranychus urticae 有两对眼睛。这种物种的成年雌性会在长日照的刺激下终止休眠。为了研究眼睛是否在 T. urticae 中起光周期感光器的作用，我们使用激光消融系统对其眼睛进行了消融。在低温暴露后，完整眼睛的螨虫在长日照下会终止休眠，而在短日照下则会继续休眠。在持续黑暗中，它们不会终止休眠。当所有的眼睛都被移除后，即使在长日照下，螨虫仍然处于休眠状态。相比之下，当仅移除前或后眼时，螨虫表现出明显的光周期反应。这些结果表明，在前、后眼中，感光器都能在 T. urticae 的休眠期结束中起作用。
