Department of Agro-environmental Sciences, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
PLoS One. 2022 Aug 4;17(8):e0272565. doi: 10.1371/journal.pone.0272565. eCollection 2022.
The western conifer seed bug (WCSB, Leptoglossus occidentalis) is a pest of many pine species and is invasive worldwide. WCSB directly and indirectly deteriorates pine nut production by sucking seeds from cones. Currently, researchers think that WCSBs search for food by a combination of cues from visible light, infrared radiation, and chemicals such as monoterpenes. Some research revealed that WCSBs prefer larger cones, and it was thought that WCSBs suck seeds from and obtain more heat on larger cones. However, in early spring, we observed that most WCSBs gathered on male cones rather than on female cones and young cones. We hypothesized that male pine cones were warmer than female cones and needles, and WCSBs sucking male cones may receive more heat. To test these hypotheses, we measured spectral reflectance with a hyperspectral sensor and temperature of pine organs with tiny thermocouples, and the data were analyzed by a heat budget model. Our results revealed that male cones were significantly warmer and more reflective than female cones and needles, which may attract WCSBs. These results supported our hypothesis that WCSBs on male cones were warmer than those on other organs. This study will help further understanding of WCSBs and the adaptive value of pine cone colors.
西方松叶蜂（Leptoglossus occidentalis）是许多松树的害虫，在全球范围内具有入侵性。西方松叶蜂通过吸食松球中的种子，直接和间接地降低了松子的产量。目前，研究人员认为西方松叶蜂通过可见光、红外线辐射和单萜等化学物质的组合线索来寻找食物。一些研究表明，西方松叶蜂更喜欢较大的松球，并且人们认为西方松叶蜂在较大的松球上吸食种子并获得更多的热量。然而，在早春，我们观察到大多数西方松叶蜂聚集在雄球果上，而不是雌球果和幼球果上。我们假设雄性松球果比雌性球果和针叶更温暖，吸食雄性松球果的西方松叶蜂可能会获得更多的热量。为了验证这些假设，我们使用高光谱传感器测量了松树器官的光谱反射率和微小热电偶的温度，并通过热预算模型对数据进行了分析。研究结果表明，雄球果的温度明显高于雌球果和针叶，反射率也更高，这可能吸引了西方松叶蜂。这些结果支持了我们的假设，即雄球果上的西方松叶蜂比其他器官上的西方松叶蜂更温暖。本研究将有助于进一步了解西方松叶蜂以及松果颜色的适应价值。
