Ginger root helps conserve stag beetles

WASHINGTON - Ecologists have indicated that ginger root could be the key to conserving the largest and most spectacular terrestrial beetle - the stag beetle.

Ecologists from Royal Holloway, University of London and the University of York have developed a series of new methods to monitor stag beetle numbers including ginger lures to trap adult beetles and tiny microphones to detect sounds made by the larvae in their underground nests.

The new research has found that a combination of ginger-baited aerial traps to catch adult stag beetles, plus tiny microphones to record the underground larvae’s sounds and samplers to detect the chemicals they emit, give an accurate picture of the species’ abundance.

“Our new methods offer genuine promise for monitoring the population of this elusive and rare insect, one that we think is declining across much of its European range. We need to know where the stag beetle lives - and in what numbers - to be able to conserve it effectively,” said Deborah Harvey, one of the study’s authors.

Harvey and her colleagues discovered ginger was irresistible to adult stag beetles only after testing the attractiveness of many other fruit and vegetables - including banana, strawberry, tomato and cherry - as well as wine and beer.

Ginger works because it contains large amounts of alpha copaene, a chemical known to attract other insects that live in dead and decaying wood.

By using ginger, and designing the trap using heavy-duty plastic, Harvey was able to produce a very cost-effective trap.

Using other methods of trapping insects, such as light traps or traps baited with food, do not work with adult stag beetles because they are not reliably attracted to light and the species does not eat during the adult phase of its life cycle.

“Sampling subterranean insects without destroying the larval habitat is notoriously difficult. These diffusive samplers are widely used to monitor environmental pollution, but this is the first time they have been used for insect detection. Because longifolene can be produced by plants, we used it together with sound recording to come up with a more accurate method of finding stag beetle larvae,” said Harvey.

The team found that stridulation patterns produced by stag beetle larvae are very different from other species likely to live nearby, such as the rose chafer (Cetonia aurata) and the lesser stag beetle (Dorcus parallelipipedus).

The study has been published in the Royal Entomological Society’s journal Insect Conservation and Diversity. (ANI)