Olfactory Basis of Moth-Hostplant Interactions

摘要本研究的重点是确定雌性飞蛾如何利用嗅觉找到合适的植物产卵。我们研究了一种实验上有利且被广泛研究的模式昆虫——烟草角蛾。由于对雌性飞蛾寻找寄主植物知之甚少，特别是植物释放的哪些化合物有助于飞蛾与其特定寄主植物之间的相互作用，因此本研究包括两个主要任务：(a)从活植物周围的空气中收集挥发性化合物（“植物挥发物”）的化学分离，以及(b)在受控的实验室条件下对雌性飞蛾对这些寄主植物挥发物的反应进行行为测试。在这项研究的下一年中，我们将重点利用一种称为制备气相色谱（GC）的化学分离技术来分离从活植物中获得的顶空挥发性混合物，并测试成年雌性雄性飞蛾对分离组分的行为反应。目前，我们正在构建一个特殊的馏分收集器，它将使我们能够捕获GC分离的挥发性化合物，当它们从GC柱中出现时。当从气相色谱柱出来的馏分进入馏分收集器中的冷却收集管时，馏分中的挥发性化合物将被捕获。然后可以在实验室中测试分离的部分对雌性飞蛾飞行行为的影响，如果部分引起适当的行为，组成该部分的化合物将通过气相色谱结合质谱（GC- ms）进行鉴定。我们将重点使用一种寄主植物，命名为魔鬼之爪（路易斯安那长鼻鲸变种香），和一种非寄主植物，马铃薯植物的叶子（龙葵）。马铃薯叶片的顶空挥发物在飞蛾的飞行隧道和测试卷腹反应（一种产卵前的简单行为）的台式生物测定中都引发了强烈的行为反应。马铃薯植株与性蛾寄主亲缘关系密切，对雌蛾有吸引力，但这些植株本身并不是很好的寄主，因为当雌蛾接触到马铃薯植株的叶片后，它们会被拒绝产卵。从我们之前在这个项目中的工作中，我们知道雌性飞蛾对温室种植的马铃薯植物释放的挥发物的行为反应比对几种有记录的寄主植物的行为反应更强烈。魔爪草与以前已知的寄主植物无亲缘关系，但我们最近发现这种植物仍然是一种令人惊讶的好寄主植物。我们期望这两种植物，其挥发物引起雌性飞蛾强烈的行为反应，将释放相同或非常相似的行为活性挥发物化合物。通过研究和比较它们的挥发物和这些化合物引起的行为效应，我们进一步期望能够发现哪些挥发物对寄主植物的吸引力负责。因为我们的研究计划是在一年内获得可发表的结果，我们的目标将集中在引发寄主植物和从寄主植物收集的挥发物引起的两种关键行为反应之一的挥发物上——要么是气味调节的逆风飞行，要么是产卵前的腹部卷曲行为。

4NSF IBN-9983302 8 February 2000Lay Abstract This research focuses on determining how female moths use their sense of smell to find appropriate plants on which to lay their eggs. We study an experimentally favorable and extensively investigated model insect, the tobacco hornworm moth Manduca sexta. Because little is known about hostplant finding by female moths, and in particular which compounds released by plants facilitate this interaction between moths and their specific hostplants, this research comprises two main tasks: (a) chemical separation of volatile compounds ("plant volatiles") collected from the air surrounding living plants, and (b) behavioral testing of the responses of female moths to these hostplant volatiles under controlled laboratory conditions. In the next year of this research, we will focus on utilizing a chemical separation technique called preparative gas-chromatography (GC) to fractionate headspace-volatile mixtures obtained from living plants and on testing the behavioral responses of adult female M. sexta moths to the isolated fractions. Currently we are constructing a special fraction collector that will allow us to trap volatile compounds separated by GC as they emerge from the GC column. As a fraction emerging from the GC column pass into a cooled collection tube in the fraction collector, the volatile compounds in the fraction will be trapped. The isolated fraction then can be tested for its effects on the flight behavior of female moths, in the laboratory, and if the fraction elicits appropriate behaviors, compounds making up that fraction will be identified by means of GC coupled with mass spectroscopy (GC-MS). We will focus on using one hostplant species, named devil's claw (Proboscidea louisianica var. fragrans), and one non-hostplant species, foliage of potato plants (Solanum tuberosum). Headspace-volatiles from potato foliage trigger strong behavioral responses in the moths both in the flight tunnel and in a bench-top bioassay that tests abdomen-curling responses (a simple behavior that immediately precedes egg-laying). Potato plants are closely related to hostplants of M. sexta and are attractive to female moths, but these plants are not good hostplants themselves because they are rejected for oviposition after a female moth has contacted the leaves of the plant. From our previous work in this project, we know that the behavioral responses of female moths to the volatiles released by greenhouse-grown potato plants are stronger than behavioral responses to several documented hostplants. Devil's claw plants are not related to the previously known hostplants of M. sexta, but we recently found that this plant is a surprisingly good hostplant nevertheless. We expect that both of these plant species, whose volatiles elicit strong behavioral responses from the female moths, will emit the same or very similar behaviorally active volatile compounds. By studying and comparing their volatiles and the behavioral effects those compounds elicit, we furthermore expect to be able to discover what volatile compounds are responsible for the attractiveness of hostplants. Because our research plan is directed toward obtaining publishable results within one year, our goal will be to focus on volatiles that elicit one of the two key behavioral responses that are elicited by hostplants and volatiles collected from them -- either odor-modulated upwind flight or the abdomen- curling behavior that precedes egg-laying.