Using different scents to attract or repel insects

March 31, 2014
Turnip rape with pollinating bumblebee and caterpillar. Credit: UZH

Flowering plants attract pollinating insects with scent from their flowers and bright colours. If they have become infested with herbivores like caterpillars, they attract beneficial insects like parasitic wasps with the help of scent signals from their leaves. The wasps then lay their eggs in the caterpillars and kill the parasites. Floral and foliar scents can, however, mutually reduce their attractiveness. That's why flowering plants face a dilemma: should they use their resources to attract pollinating insects and, by extension, for reproduction or should they invest in defence against herbivores? A Swiss-Italian research team headed by Florian Schiestl from the University of Zurich has now demonstrated that plants are able to adjust their scent bouquet to their needs at any given time and, in this way, to attract partner or useful insects in a more targeted manner.

The scientists examined the reactions of turnip rape – an edible flowering plant closely related to rape – after its infestation with herbivores. The researchers demonstrate that the infested plants markedly reduce their floral scent so as to attract parasitic wasps with scent signals from their leaves. "Decreasing the floral scent makes the plant less attractive to the insects which pollinate it. At the same time, it is then more attractive for the parasitic wasps", is how Florian Schiestl explains this mechanism. After infestation with and attracting wasps, the plants produce more flowers to compensate for their reduced attractiveness and to attract . "Floral scents are thus part of a complex trade-off with other scents that likewise attract ", says Schiestl.

The results illustrate important ecological interactions when a plant attracts partner insects. Schiestl is of the opinion that the new findings may be relevant for the organic cultivation of useful plants. "One could try to optimise the attraction of with less fragrant varieties and the attraction of pollinators with more fragrant ones."

Explore further: Insects use plant like a telephone

Related Stories

Insects use plant like a telephone

April 23, 2008

Dutch ecologist Roxina Soler and her colleagues have discovered that subterranean and aboveground herbivorous insects can communicate with each other by using plants as telephones. Subterranean insects issue chemical warning ...

Plants mimic scent of pollinating beetles

April 3, 2012

The color and scent of flowers and their perception by pollinator insects are believed to have evolved in the course of mutual adaptation. However, an evolutionary biologist from the University of Zurich has now proved that ...

Plants cry for help when an attack can be expected

September 7, 2012

Eggs of insect pests deposited on plants trigger the production of scents by plants that affect different plant community members probably helping the plant to get rid of the pest before it becomes harmful.

Caterpillars attracted to plant SOS

July 1, 2013

Plants that emit an airborne distress signal in response to herbivory may actually attract more enemies, according to a new study published in the open-access journal Frontiers in Plant Science .

More to biological diversity than meets the eye

March 13, 2014

Most of us already imagine the tropics as a place of diversity—a lush region of the globe teeming with a wide variety of exotic plants and animals. But for researchers Andrew Forbes and Marty Condon, there's even more diversity ...

Nectar: A sweet reward from plants to attract pollinators

March 16, 2014

Evolution is based on diversity, and sexual reproduction is key to creating a diverse population that secures competitiveness in nature. Plants had to solve a problem: they needed to find ways to spread their genetic material. ...

Recommended for you

Male seahorse and human pregnancies remarkably alike

September 1, 2015

Their pregnancies are carried by the males but, when it comes to breeding, seahorses have more in common with humans than previously thought, new research from the University of Sydney reveals.

Parasitized bees are self-medicating in the wild, study finds

September 1, 2015

Bumblebees infected with a common intestinal parasite are drawn to flowers whose nectar and pollen have a medicinal effect, a Dartmouth-led study shows. The findings suggest that plant chemistry could help combat the decline ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.