Olfactory Basis of Moth-Hostplant Interactions

4 NSF IBN-9983302 2000年2月8日 这项研究的重点是确定雌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的和广泛研究的模式昆虫，烟草天蛾。 由于对雌蛾寻找寄主知之甚少，特别是植物释放的哪些化合物促进了蛾与其特定寄主之间的相互作用，本研究包括两个主要任务：（a）挥发性化合物的化学分离（“植物挥发物”）从活植物周围的空气中收集，和（B）在受控的实验室条件下雌蛾对这些寄主植物挥发物的反应的行为测试。 在这项研究的下一年，我们将集中精力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M的行为反应。sexta蛾分离的馏分。 目前，我们正在建造一个特殊的馏分收集器，这将使我们能够捕捉挥发性化合物分离的GC，因为他们出现在GC柱。当从GC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级分对雌蛾飞行行为的影响，并且如果该级分激发适当的行为，则将通过GC与质谱联用（GC-MS）来鉴定构成该级分的化合物。 我们将专注于使用一个寄主植物物种，命名为魔鬼的爪子（长鼻目louisianica变种。fragrans）和一种非寄主植物物种，马铃薯植物（Solanum tuberosum）的叶子。 马铃薯叶的顶空挥发物在飞行隧道和台式生物测定中都会引发飞蛾强烈的行为反应，该生物测定测试了飞蛾卷曲反应（产卵前的一种简单行为）。 马铃薯植株与M. sexta和对雌蛾有吸引力，但这些植物本身不是好的寄主，因为雌蛾接触植物的叶子后，它们就被拒绝产卵。从我们以前在这个项目中的工作，我们知道，雌蛾的温室种植的马铃薯植物释放的挥发物的行为反应比几个记录的寄主植物的行为反应更强。 魔鬼爪植物与先前已知的M. sexta，但我们最近发现这种植物是一个令人惊讶的好寄主植物。 我们预计，这两种植物物种的挥发物会引起雌蛾强烈的行为反应，它们会释放出相同或非常相似的行为活性挥发性化合物。 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，我们还期望能够发现哪些挥发性化合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验证的结果，所以我们的目标将集中在引起两种关键行为反应之一的挥发物上，这两种反应是由寄主植物和从寄主植物中收集的挥发物引起的--气味调节的逆风飞行或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.