The fruit fly Drosophila melanogaster is pickier than previously thought when it comes to when it comes to choosing the best site for egg-laying. Using behavioral assays, researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, and their colleagues in Nigeria discovered that the insects prefer the smell of citrus.
An orange is an ideal oviposition substrate for fruit flies because the parasitoid wasp Leptopilina boulardii, which lays its eggs inside Drosophila larvae, is repelled by the odor of citrus.
M. C. Stensmyr / Lund University
This preference is controlled by one single odorant receptor. In nature, laying eggs on oranges is advantageous, because parasitoid wasps feeding on the larvae of Drosophila avoid citrus fruits. The same smell that is attractive to the flies also repels the wasps.
The scientists used imaging techniques to visualize the activity in certain areas of the flies’ brains while these were stimulated with different odors, and they were able to localize and identify the receptor for citrus. Flies in which this receptor was silenced were no longer able to distinguish oranges from other fruits. (Current Biology, December 5, 2013, DOI 10.1016/j.cub.2013.10.047)
For egg-laying insects, selecting the best site to lay eggs is crucial for the survival of the eggs and larvae. Once the eggs have been deposited, the maternal care of the female flies ends: eggs and larvae are henceforth at the mercy of their environment; their range is usually limited. Suitable and sufficient food sources for the hungry larvae and protection against predators and parasites are important selection criteria for the best oviposition substrates.
Multiple choice experiment shows fruit flies like citrus
First, Marcus Stensmyr, Bill Hansson and their colleagues in the Department of Evolutionary Neuroethology tested the preferred egg-laying substrates of fruit flies by letting insects select among different ripe fruits. They excluded damaged fruits to make sure that the smell of yeast would not influence the flies’ choices (yeast is the flies’ main food source). An analysis of the behavioral assays showed that female flies preferred to lay their eggs on oranges. Further selection experiments helped to identify the odor that was the crucial factor for the flies’ choice: the terpene limonene. Flies were not attracted to limonene-deficient oranges. On the other hand, they were immediately drawn to fruits that had been spiked with synthetic limonene. Although citrus is not an attractant for the flies, it elicits egg laying. Interestingly, evolution has split the perception of odors into two channels: those that guide flies to their food source and those that elicit the oviposition behavior.
A single odorant receptor controls preference for oranges
By performing electrophysiological measurements, the scientists were able to quantify the flies‘ responses to limonene and to localize and identify the olfactory sensory neurons responsible for detecting citrus. Subsequently, they tested the flies’ responses to 450 different odors. Apart from limonene, valencene, another component of citrus fruit, also triggered a strong response. Valencene distinguishes the scent of oranges from that of lemons; lemons are less favored by flies because of their acidity. Compounds that activated these particular sensory neurons induced oviposition. In vivo calcium imaging of the flies’ brains stimulated with citrus enabled the researchers to identify the corresponding odorant receptor.
"It is fascinating that a complex behavior, such as choosing an egg-laying site, can be broken down into multiple sub-routines that have such a simple genetic basis," says Marcus Stensmyr. "We were quite surprised that by silencing just this single odorant receptor, flies could no longer localize their preferred egg-laying substrate."
Citrus protects Drosophila larvae against parasites
In nature, a considerable proportion of Drosophila larvae are killed by enemies, mainly parasitoid wasps that lay their eggs inside the larvae. It is astonishing that these wasps are repelled by citrus odors, although citrus should guide them to their food source: Drosophila larvae. The parasitoid wasp Leptopilina boulardii, which specializes in Drosophila melanogaster, is repelled by valencene. In a further choice experiment, the wasps had to choose larvae from two substrates − one with valencene and one without − and they clearly preferred the larvae on the valencene-free substrate. It is still unknown why the wasps avoid citrus. However, it is certain that female fruit flies have learned to let their offspring grow on citrus fruits, because there the larvae are better protected against parasites.
These research results provide important information about the criteria that insects use to select an oviposition site that guarantees the improved development of their offspring. Marcus Stensmyr is convinced that “there are similar processes in other insects and ways to manipulate them.” These insights may lead to new ways to control insects, especially those that destroy crops or transfer diseases. [AO]Original Publication:
Dr. Marcus C. Stensmyr, Lund University, email@example.comContact and picture requests:
Download of high resolution pictures on http://www.ice.mpg.de/ext/735.html
Angela Overmeyer | Max-Planck-Institut
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
26.10.2016 | Power and Electrical Engineering
26.10.2016 | Awards Funding
26.10.2016 | Power and Electrical Engineering