"The virus improves the cues that insects use to identify food by elevating some aspect of a trait that is already in the plant," said Mark C. Mescher, assistant professor of entomology. "In this case they appear to elevate the odor cue, without changing it."
This type of host alteration has implications beyond agriculture. If pathogens can alter hosts to make transmission more efficient, they may be doing it in such insect-transmitted human diseases as malaria or dengue fever.
Some plant viruses entice insects to visit infected plants and stay awhile, incorporating the virus into the insect's system. Then, when they fly to another plant, they transfer the virus. This is a persistent mode of transmission because the plants will infect all the subsequent plants the insects dine on. However, the insects needed to spend a sizable amount of time on the original infected plant.
Aphids transmit cucumber mosaic virus, which will infect the entire squash family of plants. The researchers investigated two species of aphids that can transmit the virus, one that prefers squash but will eat other things, and one that prefers turnips but will also eat squash. They used a special insect arena developed for testing aphid responses to plant odors. The aphids could not see or alight on the plants so they did not have color or taste cues. The insects could only access the chemicals the plants released into the surrounding air.
"We wanted to see where they aggregated most often," said Mauck. "They tended toward the plants that were infected rather than the healthy leaves."
Mauck, Mescher and Consuelo De Moraes, associate professor of entomology, next tested the aphids to see which plant allowed them to reproduce the best. They found that the aphids reproduced less well on the infected plants than they did on the healthy plants.
Next the researchers tested the aphids to see how long they stayed on infected or healthy plants. While the sick plants initially attracted the aphids, probably because of the increased odor cues, the insects remained on the healthy plants much longer.
"We demonstrated that there were attraction cues combined with a repellant response when the plant was eaten," said Mauck. "We used two species of aphid to ensure that it was not a fluke that one aphid behaved this way."
The researchers have not done a time study to see how many aphids actually visit sick and healthy plants over time. All the studies so far have been only a snapshot in time. They have tested the sick plants and determined that these plants produce much more volatile chemicals than healthy plants, but that the chemicals are the same as those produced by healthy plants.
"If the viruses caused the sick plants to produce altered volatile cues, then the insects could learn how the sick plants smelled and avoid them," said Mescher. "Because the virus only increases the amount of chemicals, there may be no way for the insects to distinguish between sick and healthy plants until they feed on them."
Mescher notes that the team is working on similar questions in human disease systems.
"We know that malaria-infected people are more attractive to malaria-transmitting mosquitoes," said Mescher. "We do not know if the same principles as in cucumber mosaic virus apply to malaria, but we are working on it."
The U.S. Department of Agriculture supported this work.
A'ndrea Elyse Messer | EurekAlert!
Fine organic particles in the atmosphere are more often solid glass beads than liquid oil droplets
21.04.2017 | Max-Planck-Institut für Chemie
Study overturns seminal research about the developing nervous system
21.04.2017 | University of California - Los Angeles Health Sciences
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy