Study on the recognition mechanisms of sucking site by green leafhopper

绿色叶蝉黑尾叶蝉（Nephotettix cincticeps Uhler）和绿尾叶蝉（Nephotettix virescens）是亚洲大多数国家的水稻害虫。其取食行为包括两个阶段：探针插入植物后寻找并到达一个吮吸位点，称为探针插入行为;吮吸植物汁液，称为吸吮行为。据说这两个阶段由不同的因素独立控制。然而，目前尚不清楚这种昆虫为什么能到达水稻植株的吸吮部位。本研究的重点是探究行为。本研究通过生物活性测定和化学纯化，分离鉴定了对条头小蠹探测行为有强烈刺激作用的化合物为麦黄酮5-O-β-D-吡喃葡萄糖苷（tricin 5-O-β-D-glucopyranoside），并分离鉴定了包括麦黄酮5-O-β-D-glucopyranoside在内的几种黄酮类化合物为寡食性白背飞虱（Sogatella furciffera Horvath）和灰飞虱（Laodelphax striatellus Fallen）的探测刺激物。报道了8种C-糖基黄酮类化合物作为褐飞虱的探测刺激物。从这些结果和报道来看，叶蝉和稻飞虱的寄主范围与探测刺激物之间似乎存在一定的关系。也就是说，这些结果可能表明，单食性昆虫需要多种探测刺激物严格区分其寄主植物，而具有广泛寄主范围的多食性昆虫需要少量探测刺激物才能识别许多植物作为寄主植物。因此认为探针刺激物是寄主识别物质。

The green leafhopper Nephotettix cincticeps Uhler and Nephotettix virescens are known as pests of rice plants in most Asian countries. Their feeding behavior consists of two phases ; stylet insertion into plants followed searching and reaching a sucking sites, which is called as the probing behnavior, and sucking plant saps, which is called as the sucking behavior. It is said that these two phases are independently controlled by different factors. However It has not been clear why this insect can reach sucking site in the rice plant. In this study, the focus was put on the probing behavior. An attempt was made to be clear the problem.Through a preparative bioassay and chemical purify, the compound which strongly stimulates the probing behavior of N.cincticeps was isolated and identified as tricin 5-O-β-D-glucopyranoside.A few kinds of flavonoid including tricin 5-O-β-D-glucopyranoside were also isolated and identified as probing stimulants for oligophagous Sogatella furciffera Horvath and Laodelphax striatellus Fallen.On the other hand, eight kinds of C-glycosyl flavone have been reported as probing stimulants for Nilaparvata lugens which is known as monophagous insect. Judging from these results and report, there seemed to be some relationships between probing stimulants and host range of leafhoppers and planthoppers. That is, these results may show that monophagous insects require many kind of probing stimulants strictly to distinct their host plants and polyphagous insects which has a wide host range require a few probing stimulants to recognize many plants as host plants. It is hence considered that probing stimulant is host recognition substance.