Pincebourde Sylvain, Casas Jérôme
Institut de Recherche sur la Biologie de l'Insecte (IRBI, CNRS UMR 6035), Université François Rabelais, Faculté des Sciences et Techniques, 37200 Tours, France.
J Insect Physiol. 2006 Feb;52(2):194-201. doi: 10.1016/j.jinsphys.2005.10.004. Epub 2005 Nov 15.
Very little is known about alterations in microclimate when an herbivore feeds on host plant. Modifications of leaf transmittance properties induced by feeding activity of the leaf miner Phyllonorycter blancardella F. were measured using a spectrometer. Their effects on the herbivore's body temperature and respiration rate have been determined under controlled conditions and varying radiation level employing an infrared gas analyser. By feeding within leaf tissues, a miner induces the formation of feeding windows which transmit a large portion of incoming radiations within a mine. As a result, body temperature and respiration rate increase with radiation level when positioned below feeding windows. Therefore, the miner is not always protected from radiations despite living within plant tissues. The amount of CO(2) released by larvae below feeding windows at high radiation levels is about five-fold that recorded in the dark. By contrast, body temperature and respiration rate increase only slightly with radiation level when the insect is positioned below intact tissues through which radiation is only weakly transmitted. A mine offers its inhabitant a heterogeneous light environment that allows the insect larva to thermoregulate through behavioural modification. Our results highlight the importance of physical feedbacks induced by herbivory which alter significantly an insect's metabolism independently of its nutritional state.
当食草动物取食寄主植物时，人们对小气候的变化知之甚少。利用光谱仪测量了潜叶蛾Phyllonorycter blancardella F. 的取食活动所引起的叶片透光特性的改变。在可控条件下，采用红外气体分析仪，测定了不同辐射水平下这些变化对食草动物体温和呼吸速率的影响。通过在叶片组织内取食，潜叶蛾会诱导形成取食窗口，这些窗口能使矿道内的大部分入射辐射透过。因此，当处于取食窗口下方时，体温和呼吸速率会随着辐射水平的升高而增加。所以，尽管潜叶蛾生活在植物组织内，但它并不总是能免受辐射影响。在高辐射水平下，取食窗口下方幼虫释放的二氧化碳量约为黑暗中记录量的五倍。相比之下，当昆虫处于完整组织下方，辐射只能微弱透过时，体温和呼吸速率随辐射水平的增加幅度较小。矿道为其居住者提供了一个异质的光照环境，使昆虫幼虫能够通过行为改变来调节体温。我们的研究结果突出了食草行为所引发的物理反馈的重要性，这种反馈能显著改变昆虫的新陈代谢，而与昆虫的营养状态无关。
