After years of investigation into the make-up of the cockroach sex pheromone, finally it seems, scientists have made a breakthroug...
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Wanted: Mature males looking for a good time. Must have all six legs, strong antennae and love city life. Proclivity to procreate a must. Apply at crack in the bathroom wall, apartment 8B.
Believe it or not, female German cockroaches looking to attract male German cockroaches have much better ways of sending "come hither" signals than want ads. Simply by raising her wings, lowering her abdomen, and stilting her legs the female German cockroach sends out sex pheromones, advertising her availability to adult males.
Prior to a recent discovery by American entomologists, scientists were unable to figure out the exact chemical composition of these pheromones. However, now more than a decade of uncertainty about the actual chemical composition of the pheromone has ended with scientists now able not only to define the chemicals signals, but also to replicate them.
In a study published in the journal Science, the scientists characterised the pheromone – gentisyl quinone isovalerate, which they call blattellaquinone – for the first time, creating a synthetic version of the pheromone and then utilising behavioural studies to show the synthetic version is just as effective as the natural version in getting adult male German cockroaches to "come hither".
The study could have important pest control implications, and advances the knowledge of fundamental biological and chemical properties of arguably the most important cockroach in the world.
The researchers combined two study methods – gas chromatography, in which chemical compounds are studied in a controllable oven, and electroantennographic detection, which records the electrical responses of the antenna, the cockroach's nose, to odours – to purify and identify the sex pheromone in female German cockroaches.
The researchers placed samples of complex extracts from the bodies of female cockroaches into the gas chromatograph, where the extracts were separated and then analysed on a mass spectrometer, which tells the identity of each chemical compound. At the same time, the compounds were tested on the electroantennograph, a device that contained the extremely sensitive antennae of an adult male cockroach.
To make sure it was female sex pheromone and not another attractant or possibly even a repellent, the researchers isolated the pure compound, identified and synthesized it, and did behavioural tests with male cockroaches to see if they'd approach the synthetic compound or stay away from it.
The research showed that the males were indeed attracted to blattellaquinone, with higher doses of the pheromone attracting more males. Also, when the sex pheromone was placed in traps, higher amounts trapped more males; females and sexually immature males were not caught in the traps.
The German cockroach is an important – arguably the most important – pest that is associated with allergic disease and asthma in children and the elderly, especially in the inner city. The pheromone could offer novel approaches to controlling cockroaches by increasing the efficiency of traps in places like schools, hospitals and nursing homes, for instance, and of sprays and baits in homes and farm buildings.
Article provided by SDA Pest Control