Volatile Pheromones

Pope M. M., Gaston L. K. and Baker T. C. (1984) Composition, quantification, and periodicity of sex pheromone volatiles from individual Heliothis zea females. Journal of Insect Physiology 30, 943-945. 

Chanical signaling often involves the use of pheromones, volatile chemicals released into the environment, usually as sex attractants. They are extremely specific and affect only others of the same species. The concentrations of pheromones that elicit a response are extremely small. Glypure, the gypsy moth sex attractant pheromone, has a male threshold value of about 1.25 x lO kg/m in the air (Johnson, 1999). Female gypsy moths release the glypure into the air and males follow the scent to the female. Artificially synthesized insect pheromones are used in two ways (1) to trap insect pests, and (2) to overwhelm and confuse insects to disrupt mating. 

Baker, T.C., L.K. Gaston, M.M. Pope, L.P.S. Kuenen, and R.S. Vetter A High-Efficient Collection Device for Quantifying Sex Pheromone Volatilized from Female Glands and Synthetic Sources. J. Chem. Ecol. 7, 961-968 (1981). 

The Afncan dwarf crocodile secretes a volatile substance believed to be a sex pheromone It IS a mixture of two stereoisomers one of which is shown... 

Gas chromatography (GC) has also been used for preparative purposes, but is restricted to relatively volatile racemates such as anesthetics, pheromones or monoterpenes and, therefore, very few applications are reported. Nevertheless, in the cases to which GC may be applied, it could be considered as an economical alternative to HPLC. Most of the resolutions of enantiomers were performed on cyclodex-trin-derived CSPs [109, 144-153], and only on very few occasions were other chiral selectors used [153]. 

The dioxolanones 33 <95JAP07291959> and 34 <95JAP07285960> are both reported to be useful as solvents, while 35 has been used as an X-ray contrast medium <96MIP19487>. Carboxydioxolanes such as 36 are useful for controlled release of volatile aldehyde pheromones <96JCR(S)274> and pharmaceutically active amines R2NH can be administered in... 

Novotny M., Ma W., Wiesler D. and Zidek L. (1999). Positive identification of the puberty-accelerating pheromone of the house mouse the volatile ligands associating with the major urinary protein. Proc Roy Soc Lond (B) 266, 2017-2022. 

O Connell R.J., Singer A.G., Pfaffmann C. and Agosta W. (1979). Pheromones of hamster vaginal discharge attraction to femtogram amounts of dimethyl disulfide and to mixtures of volatile components. J Chem Ecol 5, 575-585. 

Rasmussen L.E.L., Lee T.D., Daves G. and Schmidt M.J. (1993). Female-to-male sex-pheromones of low volatility in the Asian Elephant, Elephas maximus. J Chem Ecol 19, 2115-2128. 

Unlike parasitoids of other insect orders that have host-seeking larvae, most parasitic hymenoptera lay their eggs on, in, or very close to a host individual [11]. This requires the adult female to find a suitable host, often with the aid of chemical cues from host frass, pheromones, plant volatiles emitted upon host feeding or egg-deposition, silk, honeydew and other secretions. She may then chemically mark the host following oviposition to reduce superparasitism by herself or intra- and inter-specific insects [11]. 

Tetratrophic interactions between a host plant, a phytophagous pest (primary host), a hymenopteran parasitoid or symbiont (secondary host) and a hymenopteran hyperparasitoid (which parasitizes the secondary host) are of considerable importance, because hyperparasitism can significantly reduce populations of economically beneficial parasitoids [11]. Hyperparasitoids use host-marking (=spacing) pheromones, sex pheromones [12], and host-detection cues [42], but they also show additional chemically mediated interactions with the other partners. These include detection of the primary host s secretions by the hyperparasitoid [43], detection of plant volatiles by the hyperparasitoid [44], and detection of the hyperparasitoid s secretions by the primary host [45] or by the secondary host. The latter causes the secondary host to avoid locations where the hyperparasitoid is foraging [46]. 

Parasitic hymenoptera often eavesdrop on the pheromone communication of their host species. The type of host pheromone recognized depends on the host stage parasitized. Phoretic egg parasitoids are often attracted by the host sex pheromone, while species that parasitize later stages (larval, pupal) often do not respond to host sex pheromone components [ 11,42]. Larval parasitoids often recognize volatiles from the damaged host plant and/or host larval frass volatiles. Parasitoids of forest beetles respond to the beetle aggregation pheromones [42]. 

An example of a larval parasitoid that responds to the host sex pheromone is seen with Cotesiaplutellae (Braconidae), also a parasitoid of the diamondback moth. These insects were attracted equally to the pheromone blend (31,32,33, see above), the acetate 32, or aldehyde 31 components [80]. This larval parasitoid, however, was also strongly attracted to host frass volatiles, in particular, dipropyl disulfide 34, dimethyl disulfide 35, allyl isothiocyanate 36, and dimethyl trisulfide 37. In contrast, the egg parasitoid Trichogramma chilonis was only weakly attracted to 36. In both, T. chilonis and C. plutellae, plant volatiles, in particular (3Z)-hex-3-en-l-yl acetate 38, significantly enhanced attraction by the pheromone [80]. 

Plant volatiles [enhancement of pheromone attraction] (3Z)-Hex-3-en-l-yl acetate 38 [80]... 

Flowers of some orchids mimic both the appearance and sex pheromone of virgin females of certain species of bees or wasps. This sexual deception results in pollination by male hymenoptera that would not normally visit flowers. Japanese honey bee drones (Apis cerana japonica) cluster on the oriental orchid (Cymbidiumpumilum) while on their mating flights [ 134]. By comparing volatile profiles of orchids and the female hymenoptera they mimic, or by GC-EAD and GC-MS analysis of orchid volatiles, several compounds have been identified that may mediate this attraction for the solitary bee Andrena nigroaenea [135, 136] and the scoliid wasp Campsoscolia ciliata [135]. 

While the earlier studies in chemical ecology of mammals were preoccupied with relatively gross measurements (e.g., presence or absence of a chemi-cal/pheromone in an olfactory stimulus), the new quantitative capabilities make it now imperative to evaluate more accurately the volatile compound ratios or patterns under different biological circumstances. 

---