Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Looking for love in all the right places: Fruit odors lure some flies to evolve into new species, Cornell researchers discover


For apple maggots, the dating scene is simple -- flies only mate on a specific host fruit. Using new technology developed at the New York State Agricultural Experiment Station, Cornell University researchers have demonstrated that this fact of fly life has resulted in the emergence of two distinct races of the pest in just 150 years.

In research published in the Online Early Edition of the Proceedings of the National Academy of Sciences Web site Sept. 22, the scientists show that one mechanism by which these flies find their host plant is a preference for specific blends of fruit odors. The preference is both strong enough and sensitive enough that the two races of maggot no longer interbreed, the first step in the evolution of a new species. The discovery, the researchers say, opens up a possible new area of organic pest control.

The researchers at the Geneva Experiment Station, part of the College of Agriculture and Life Sciences at Cornell, Ithaca, N.Y., are Charles Linn, Satoshi Nojima and Wendell Roelofs. Their collaborators are Jeffrey Feder from the University of Notre Dame and Stewart Berlocher from the University of Illinois.

Evolutionary biologists theorize that two populations of a species must be isolated from each other if they are to develop into two distinct species, and Darwin provided the example of one species of bird diverging and becoming reproductively isolated on separate islands in the Galapagos. Recently it has been proposed that the separation need not be geographic or even physical. A shift in the use of a new host plant for mating and the laying of eggs could be enough to keep insects that occupy the same area at the same time from mating. This process is termed "sympatric speciation," and that is what the researchers believe has happened with hawthorn maggots.

The apple and hawthorn maggots are common names for the same species, Rhagoletis pomonella . The pest and the hawthorn plant are native to North America, but the apples they now infest were introduced from Europe around 250 years ago. During the 1860s, in New York’s Champlain Valley, some hawthorn flies shifted to apple plants as their host, while others did not."There are no morphological differences between the two, so they are still the same species, but two races can be distinguished by looking at the diversity of protein structures of whole populations and by the specificity of individual flies to different host plants," explained Roelofs, who is the Liberty Hyde Bailey Professor of Insect Biochemistry at Cornell.

R. pomonella has been studied for many years, but it was only with the development by postdoctoral researcher Nojima of sophisticated laboratory techniques to select the key components of fruit odors that the behavior of the insects could be rigorously tested.

Using a process called solid phase microextraction, volatiles were absorbed from the fruit and identified in a gas chromatograph using a live insect’s own antennae as part of the detection process to determine which volatiles the flies use for host-plant identification. Once key compounds were identified, Linn ran behavioral tests in a flight tunnel. Blends of the apple and hawthorn volatiles identified in the lab were synthesized and then tested for insect behavior. If the insect recognized the test odor, it oriented itself toward the source and flew upwind to reach it. The scientists found that almost exclusively apple maggots only responded to apple odors, and hawthorn maggots only responded to hawthorn odors.

Behavioral tests also were conducted in the field. Traps were baited with one of the two blends and placed in hawthorn stands and apple orchards. Just as in the lab, the flies of one race largely ignored, or even avoided, the chemical scent of the other race’s fruit.

"The results in the field are really very strong," said Linn. "It adds a level of validation that we also saw the same pattern in field trials in Michigan and Indiana."

In addition to the impact on ecology and evolutionary biology, the research has several applications. Other scientists at Cornell already are using the blends developed in this research to monitor populations of hawthorn and apple maggots in orchards and fields across New York state.

The team also identified several components of hawthorn and flowering dogwood -- a third member of the R. pomonella species complex. These blends are not simply ignored; some actually deter apple maggots. Roelofs’ lab has begun field trials to see if introducing the dogwood and hawthorn odor, or components of it, into apple orchards or around the fruit itself could provide a means of organic pest control against the apple maggot.

The research was funded by a $1.6 million grant from the National Science Foundation.

Linda McCandless | Cornell News
Further information:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>