The behavioral functions of larval firefly lights have been studied, and several theories have been proposed. 1 Male flash patterns are thought to be affected by sexual selection and females have been shown to prefer certain light signal characteristics. 2 In addition to these behaviors, it is generally assumed that most non-luminous fireflies locate mates through the use of pheromones. The courtship patterns of Japanese fireflies seem to indicate numerous types of communication, which include pheromones as well as light signals. 3 Our analytical study of fireflies was based on the hypothesis that a certain chemical signal mediates a particular interaction between male and female fireflies. This hypothesis can be tested by collecting, analyzing and identifying these compounds. Using our previously reported method, pheromones were adsorbed by direct contact with glass surfaces. 4 We call this method direct contact extraction. Because this technique is nondestructive, it is possible to subject extracted hydrocarbons to gas chromatography-mass spectrometry (GC-MS) directly using a solvent. Here, we report on the GC-MS profiles of extracts from three Japanese firefly species (Luciola lateralis, Luciola cruciata, and Lucidina biplagiata) and three North American firefly species (Lucidota atra, Photuris lucicrescens, and Photuris cinctipennis). Several research aspects concerning present analytical methods are discussed: (1) distinguish firefly species using the GC-MS profile as finger prints, (2) the intraspecific differences of fireflies, which could be interpreted as a geographic variation, and (3) chemical-ecological strategy of luminous and non-luminous fireflies. ExperimentalLuciola lateralis were collected in Yokohama, Kanagawa prefecture and Chino, Nagano prefecture. Luciola cruciata were collected in Yokohama, Kanagawa prefecture. Lucidina biplagiata were collected in Hayama, Kanagawa prefecture. Lucidota atra, Photuris lucicrescens, and Photuris cinctipennis were collected in Meramec state park Missouri, USA.Glass vials (50 ml) were washed in hexane and dried at 200˚C in an electric oven. Three fireflies were collected; if this was not possible, one or two fireflies were collected and placed into one clean glass vial at the field site. Fireflies were free to crawl inside the glass vials for 2 -3 h during the mating period. After the fireflies were released, 1 ml of dichloromethane was added to the glass vials, which were then shaken several times to collect any remaining compounds from the firefly without further condensation.Extracts (1 µl) were analyzed using a mass spectrometer (MS) (JMS-SX102A; JEOL, Tokyo, Japan) equipped with a gas chromatograph (GC) (HP 5890A; Hewlett Packard, Palt Alto, USA). An HP-5 capillary column (30 m length, 0.32 mm i.d., 0.25 mm film thickness; Hewlett Packard, Palt Alto, USA) was used to separate the products into the volatile components. The initial temperature was 50˚C, the final temperature was 280˚C and a linear temperature program of 20˚C/min was applied. The injector te...
The difficulties to analyze an insect pheromone have been well known, and various analytical methods have been reported. 1,2 One can point out some difficulties concerning the analysis of insect pheromones. The amounts of the compounds are very small, and many homogenized species are required to collect the pheromones. Also, many preparation procedures are needed to reduce the lipid components. For rare insect species, abundant measurements would be required. Here, we propose an alternative method to collect the sex-attractant pheromone from just one firefly, without causing any physical damage to it.Ohba has already successfully obtained the sex-attractant pheromones of the firefly Genus Pyrocoelia Gorham, using organic solvent extraction, and has confirmed their biological activities. 3,4 The purpose of the present study is to detect sexattractant pheromones by gas chromatography mass spectrometry (GC/MS), and to characterize their chemical properties. We report on the first detection of sex-attractant pheromones of firefly Pyrocoelia oshimana NAKANE, by gas chromatography mass spectrometry. ExperimentalFireflies Pyrocoelia oshimana NAKANE were collected from a field site on Hakedake, Tokunoshima Island, Kagoshima prefecture. We put one female firefly in a clean glass bial, which had been washed using hexane, and dried at 200˚C in an electric oven. We did not observe any chemical background Ogawacho, Kodaira, Japan *2 Kanagawa Prefectural Daishi Highschool, Yotsuyashimocyo, Kawasaki, Japan *3 Materials Characterization Central Laboratory, Waseda University, Okubo, Shinjuku, Japan *4 Yokosuka City Museum, 95, Fukatadai, Yokosuka, Japan
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