烟粉虱B生物型的若虫、皮蜕及其成虫的提取物作为一种利它素信息源,在室内对其在双斑蚜小蜂寻找寄主取食、寄生行为的影响进行了生物测定.烟粉虱的若虫、皮蜕及其成虫分别用正己烷、乙醇和无菌水进行粗提.研究结果发现,双斑蚜小蜂在处理区寻找寄主停留的时间高于对照区.在处理区,双斑蚜小蜂行动活泼,对利它素源表现出高的正趋向性和选择性.对于同一利它素源、同一提取介质的两种不同浓度,双斑蚜小蜂在若虫-水提取物的高浓度区停留的时间(111.23s)最长,与在低浓度区的停留时间差异显著;而在烟粉虱皮蜕及其成虫的水、正己烷和乙醇提取物处理区,不同浓度的提取物对蚜小蜂停留的时间影响差异不显著.本研究的结果表明,利它素可以增加蚜小蜂寻找寄主的效率,有利于蚜小蜂寻找到适宜的寄主.%The response of female Encarsia bimaculata Heraty et Polaszek to its host, Bemisia tabaci (Gennadius) nymph, exuviae or adult extractions was bioassayed in a petri dish arena. The tested materials were extracted by hexane, ethanol and water.The data show that females spent much longer times searching in treated patches than controls. The parasitoids intensified their search in the treated patches and exhibited both orthokinetic and klinotaxic responses. The highest mean of the retention time in the treated patches was in those treated with material extracted from nymphs with water ( 111.23 seconds), otherwise parasitoids spent equal time in treated patches irrespective of the concentrations of the tested materials. Such kairomones might enhance female searching efficiency and guide them to hosts.
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