Department of Entomology, MPICE, Hans-Knoell-Str. 8, 07745, Jena, Germany.
J Chem Ecol. 2013 Mar;39(3):364-76. doi: 10.1007/s10886-013-0263-6. Epub 2013 Mar 1.
Spodoptera frugiperda consists of two genetically and behaviorally different strains, the corn- and the rice-strain, which seem to be in the process of sympatric speciation. We investigated the role of strain-specific sexual communication as a prezygotic mating barrier between both strains by analyzing strain-specific variation in female pheromone composition of laboratory and field strains, and also male attraction in wind tunnel and field experiments. Laboratory-reared and field-collected females from Florida exhibited strain-specific differences in their relative amount of (Z)-7-dodecenyl acetate (Z7-12:OAc) and (Z)-9-dodecenyl acetate (Z9-12:OAc). In wind tunnel assays, we did not find strain-specific attraction of males to females. However, in field experiments in Florida, we observed some differential attraction to synthetic pheromone blends. In a corn field, the corn-strain blend attracted more males of both strains than the rice-strain blend, but both blends were equally attractive in a grass field. Thus, habitat-specific volatiles seemed to influence male attraction to pheromones. In dose-response experiments, corn-strain males were more attracted to 2 % Z7-12:OAc than other doses tested, while rice-strain males were attracted to a broader range of Z7-12:OAc (2-10 %). The attraction of corn-strain males to the lowest dose of Z7-12:OAc corresponds to the production of this compound by females; corn-strain females produced significantly smaller amounts of Z7-12:OAc than rice-strain females. Although corn-strain individuals are more restricted in their production of and response to pheromones than rice-strain individuals, it seems that differences in sexual communication between corn- and rice-strain individuals are not strong enough to cause assortative mating.
草地贪夜蛾由两个在遗传和行为上存在明显差异的种群组成，即玉米型和水稻型，它们似乎正处于同域物种形成的过程中。我们通过分析实验室和野外种群雌虫性信息素组成的种间差异，以及风洞和野外实验中雄虫对性信息素的吸引力，研究了种间特有的性通讯在这两个种群间的生殖隔离中的作用。来自佛罗里达州的实验室饲养和野外采集的雌虫在（Z）-7-十二碳烯基乙酸酯（Z7-12：OAc）和（Z）-9-十二碳烯基乙酸酯（Z9-12：OAc）的相对含量上存在种间差异。在风洞实验中，我们没有发现雄虫对雌虫的种间特有的吸引力。然而，在佛罗里达州的野外实验中，我们观察到了一些对合成性信息素混合物的差异吸引。在玉米田中，玉米型混合信息素比水稻型混合信息素吸引了更多的两种雄虫，但在草地中，这两种混合物的吸引力是相等的。因此，栖息地特有的挥发物似乎影响了雄虫对性信息素的吸引力。在剂量反应实验中，玉米型雄虫对 2%的 Z7-12：OAc 的吸引力大于其他测试剂量，而水稻型雄虫对 Z7-12：OAc 的吸引范围更广（2-10%）。玉米型雄虫对 Z7-12：OAc 的最低剂量的吸引力与雌虫产生该化合物的情况相对应；玉米型雌虫产生的 Z7-12：OAc 明显少于水稻型雌虫。尽管玉米型个体在产生和对性信息素的反应上比水稻型个体受到更多限制，但玉米型和水稻型个体之间的性通讯差异似乎还不足以导致交配偏好。
