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

23.09.2003


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:
http://www.news.cornell.edu/releases/Sept03/applemaggots.pnas.lm.html
http://www.nysaes.cornell.edu/pubs/press/current

More articles from Life Sciences:

nachricht Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State 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: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>