嗅觉学习对橘小实蝇寄主气味选择行为的影响

Influence of olfactory learning on host selection behavior in Bactrocera dorsalis(Diptera:Tephritidae)

基于嗅觉学习的行为可塑性可以提高昆虫搜寻寄主的效率。橘小实蝇已被证实有较强的嗅觉学习能力,为进一步探究嗅觉学习对橘小实蝇(Bactrocera dorsalis Hendel)成虫寄主选择行为的影响,本研究运用经典性嗅觉条件训练法在室内对橘小实蝇雄成虫进行气味与食物的联合学习训练,即10%蔗糖溶液和甜橙精油联合的奖赏性训练,以伸喙反射行为作为学习与否的判定标准,并测定学习后橘小实蝇的选择行为和趋向行为。结果发现:橘小实蝇可联系性学习甜橙精油,表现为橘小实蝇成虫对甜橙精油的伸喙反射率可从5次训练前的8.1%增加至训练后的75.7%,训练形成的记忆可保持至少6 h;Y型管选择性试验发现学习可提高其对甜橙精油的选择率,可由5次训练前的35.3%增加至训练后的63.7%;在趋性试验测定中也发现学习可显著提高橘小实蝇对甜橙精油的趋性,可由训练前的8.3%增加至52.5%。研究结果表明:橘小实蝇对甜橙精油有较强的联系性嗅觉学习能力,且学习后更趋向于选择经训练的甜橙气味,这可能与寄主搜寻行为有关。本结果可为今后橘小实蝇的行为调控研究提供重要参考。

Insects can search for host more efficiently by olfactory learning. Bactrocera dorsalis has been proved that it has strong olfactory learning capability. To explore the influence of olfactory learning on its host selection behavior, we trained B. dorsalis to associate an odor, sweet orange essential oil, with a food, 10% sucrose solution, under laboratory conditions using a classical olfactory conditioning procedure, and the proboscis extension reflex was used as the criterion for conditioning. Its preference for orange odor and orientation behavior elicited by orange odor before and after training also were tested. The selection behavior and trend behavior of B. dorsalis after learning were determined. The results showed that B. dorsalis can associate the orange odor with the sucrose solution, and the proportion of proboscis extension reflex of B. dorsalis increased from 8.1% to 75.7% after five conditioning trials, and the memory formed with conditioning could last at least 6 h. In the Y-tube choice test, B. dorsalis chose the arm containing trained orange odor more often after five conditioning trials compared with before training (increased from 35.3% to 63.7%). In the wind tunnel test, the percentage of B. dorsalis located orange odor after conditioning increased from 8.3% to 52.5% compared with before conditioning. The results indicated that B. dorsalis has a strong capability to learn orange odor, and they tended to choose the trained orange odor after learning, which might be related with host searching behavior. Our studies also can provide an important reference on behavior regulation of B. dorsalis.