麦长管蚜唾液中几种酶的鉴定、活力测定与功能分析

用Parafilm膜夹营养液法，以两种食料介质饲喂麦长管蚜Macrosiphum avenae 3龄若蚜并收集其唾液，对唾液中的酶类进行了鉴定、活力测定和功能分析。结果表明，在20%蔗糖介质提取液中，鉴定有果胶酶、多酚氧化酶和纤维素酶； 在水介质提取液中鉴定有纤维素酶； 两种介质提取液中都未鉴定出过氧化物酶。酶活力测定结果表明， 在20%蔗糖介质提取液中， 每30头蚜虫分泌的果胶酶、多酚氧化酶和纤维素酶的酶活力分别为2.59×10^-3 U/g、7×10^-3 U/g和7.89×10^-3 U/g； 在水介质提取液中，纤维素酶活力为3.68×10^-3 U/g。行为反应试验结果表明，果胶酶处理麦苗的挥发物组分能引起麦长管蚜寄生性天敌燕麦蚜茧蜂Aphidius avenae和捕食性天敌七星瓢虫Coccinella septempunctata 的嗅觉偏好反应，因此，果胶酶在麦长管蚜取食诱导小麦植株的间接防御反应中具有重要作用。

Identification, activity and function determination of several salivary enzymes secreted by Macrosiphum avenae

Parafilm method was adopted for feeding the third instar nymphs of Macrosiphum avenae on two liquid diets (20% sucrose and redistilled water). Their saliva after feeding for 24 h was collected and assayed identifying salivary enzymes and determining their activities. The results showed that pectinase, polyphenol oxidase and cellulase were identified in 20% sucrose diet; cellulase was identified in redistilled water diet; peroxidase was not identified in both diets. The activities of pectinase, polyphenol oxidase and cellulase secreted into 20% sucrose diet by 30 aphids were 2.59×10^-3 U/g, 7×10^-3 U/g and 7.89×10^-3 U/g, respectively; and cellulase activity secreted into redistilled water diet by 30 aphids was 3.68×10^-3 U/g. In the behavioral response test, the predator Coccinella septempunctata and parasitoid Aphidius avenae of M. avenae showed much preference for the volatiles in wheat seedlings treated by pectinase. It was so concluded that pectinase secreted by M. avenae play an important role in wheat plant indirect defense induced by aphid feeding.