- Author: Kathy Keatley Garvey
Plants communicate. They do.
Ecologist Richard Karban, a professor in the UC Davis Department of Entomology, points out that one of the simplest forms of communication involves shade.
When a plant is shaded, it grows away from the plant or other object that's shading it.
Today he published research in the Proceedings of the Royal Society B: Biological Sciences that is truly amazing readers. It involves kinship, communication and defenses.
Basically, if you’re a sagebrush and your nearby kin is being eaten by a grasshopper, deer, jackrabbit, caterpillar or other predator, it’s good to be closely related. Through volatile (chemical) cues, your kin will inform you of the danger so you can adjust your defenses.
If you’re not closely related, communication won’t be as effective.
Kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors," Karban says. For example, fire ants can recognize kin. “Ants will destroy queens that are not relatives but protect those who are."
That ability is less well studied for plants--until now.
“When sagebrush plants are damaged by their herbivores, they emit volatiles that cause their neighbors to adjust their defenses,” Karban said. “These adjustments reduce rates of damage and increase growth and survival of the neighbors.”
“When sagebrush plants are damaged by their herbivores, they emit volatiles that cause their neighbors to adjust their defenses,” Karban said. “These adjustments reduce rates of damage and increase growth and survival of the neighbors.”
“Why would plants emit these volatiles which become public information?” he asked. “Our results indicate that the volatile cues are not completely public, that related individuals responded more effectively to the volatiles than did strangers. This bias makes it less likely that emitters will aid strangers and more likely that receivers will respond to relatives.”
The research, “Kin Recognition Affects Plant Communication and Defense,” is co-authored by two scientists from Japan and two from UC Davis: Kaori Shiojiri of the Hakubi Center for Advanced Research, Kyoto University, and Satomi Ishizaki of the Graduate School of Science and Technology, Niigata University; and William Wetzel of the UC Davis Center for Population Biology, and Richard Evans of the UC Davis Department of Plant Science.
To simulate predator damage, the researchers “wounded” the plants by clipping them and then studied the responses to the volatile cues. They found that the plants that received cues from experimentally clipped close relatives experienced less leaf damage over the growing season that those that received cues from clipped neighbors that were more distantly related.
“More effective defense adds to a growing list of favorable consequences of kin recognition for plants,” they wrote.
The researchers performed their field work on sagebrush (Artemisia tridentata) at Taylor Meadow, UC Sagehen Creek Field Station, near Truckee. They conducted four field experiments over three years “that compared the proportion of leaves that were damaged by herbivores over the growing season when plants were provided with volatile cues clipped from a close relative versus cues from a distant relative,” the scientists wrote.
For closely related kin, they snipped stem cuttings (clones), potted them, and then returned the pots to the field. They determined relatedness “by using microsatellites that varied among individual sagebrush clones.”
The result: “Plants responded more effectively to volatile cues from close relatives than from distant relatives in all four experiments and communication reduced levels of leaf damage experienced over the three growing seasons,” they wrote. “This result was unlikely to be caused by volatiles repelling or poisoning insect herbivores.”
Karban, who has studied plant communication among the sagebrush at the site since 1999, likened the plant communication to neighbors “eavesdropping.” They “hear” the volatile cues of their neighbors as predators damage them.
Eavesdropping. Kinship. Plant communication. Plant defenses.
Fascinating stuff.
Who knew?
- Author: Kathy Keatley Garvey
They're under attack by entomologist Diane Ullman of UC Davis and her team of eight other investigators.
Ullman just received a five-year, $3.75 million grant from the Agriculture and Food Research Initiative, United States Department of Agriculture's National Institute of Food and Agriculture, to develop and implement a national scientific and educational network to limit thrips-caused crop losses.
Yes, you've seen thrips or the damage they've caused. Probably on your tomato or red pepper plants, for example. They pierce a wide variety of agricultural crops, ranging from tomatoes and grapes to strawberries and soybeans. They're direct pests. And they transmit plant viruses in the genus Tospovirus, such as Tomato spotted wilt virus.
She's been researching thrips and tospoviruses since 1987.
Ullman and co-principal investigator John Sherwood, head of the Department of Plant Pathology at the University of Georgia, Athens, Ga., will alternate years as program directors. Sherwood, a past president of the American Phytopathological Society (APS), is a former program leader of the Plant Biosecurity Program of the U.S. Department of Agriculture’s Cooperative State Research, Education and Extension Services (CSREES) and the USDA program leader for the joint Microbial Observatories Program with the National Science Foundation.
Read more about the grant on the UC Davis Department of Entomology website and who's involved.
This is massive nationwide effort against pests that cause billions of dollars in damage to U.S. agricultural crops. Let the grant begin!
- Author: Kathy Keatley Garvey
But how many people know about its migration?
Steve Reppert, chair and professor of the Department of Neurobiology at the University of Massachusetts Medical School, will speak on "Monarch Butterfly Migration: Behavior to Genes" at the Department of Entomology seminar on Wednesday, Feb. 13 from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
"Studies of the iconic migration of the eastern North American monarch butterfly have revealed mechanisms behind its navigation using a time-compensated sun compass," Reppert says. "Skylight cues, such as the sun itself and polarized light, are processed through both eyes and integrated in the brain’s central complex, the presumed site of the sun compass. Circadian clocks that have a distinct molecular mechanism and that reside in the antennae provide time compensation. The draft sequence of the monarch genome has been presented, and gene-targeting approaches have been developed to manipulate putative migration genes. The monarch butterfly is an outstanding system to study the neural and molecular basis of long-distance migration." (See lab research.)
Hosts are Joanna Chiu, assistant professor of entomology, and Hugh Dingle, emeritus professor of entomology, will host the talk. Dingle, an authority on animal migration, was featured in a National Geographic cover story, "Mysteries of Great Migrations" in November 2010.
Reppert received his bachelor's degree from the University of Nebraska, Omaha, in pre-medicine, and his medical degree from the University of Nebraska College of Medicine. He completed a post-doctoral fellowship in neurobiology at the National Institutes of Child Health (NICHD), NIH, in 1979. He is a professor of pediatrics (neuroscience) at Harvard Medical School (2001 to the present) and since 2000, a pediatrician at the Massachusetts General Hospital.
Reppert became the chair of the Department of Neurobiology, UMass Medical School in 2001, the same year he became the Higgins Family Professor of Neuroscience at UCMass Medical School. He is a fellow of the American Association for the Advancement of Science.
Among his publications on monarchs:
Reppert SM, Gegear RJ, Merlin C (2010). Navigational mechanisms of migrating monarch butterflies. Trends in Neurosciences (TINS) 33:399-406.
Heinze S, Reppert SM (2011). Sun compass integration of skylight cues in migratory monarch butterflies. Neuron 69:345-358.
Zhan S, Merlin C, Boore JL, Reppert SM. The monarch genome yields insights into long-distance migration. Cell 2011; 147:1171-1185.
Reppert's talk will be video-recorded and posted on UCTV at a later date.
- Author: Kathy Keatley Garvey
Honey bee guru Eric Mussen, Extension apiculturist with the UC Davis Department of Entomology, said today that almond growers may not have enough bees to pollinate this year's crop of 800,000 acres.
“We need 1.6 million colonies, or two colonies per acre, and California has only about 500,000 colonies that can be used for that purpose,” he said. “We need to bring in a million more colonies, but due to the winter losses, we may not have enough bees.”
Those winter losses--still being tabulated--and the resulting fewer bees per hive could spell trouble for almond growers, he said.
The fact is 2012 was a bad year for bee nutrition. Honey production appears to be way down, maybe the worst ever in our nation's history. Nectar and pollen foraging are closely linked, Mussen says, and malnutrition is one of the stressors of colony collapse disorder (CCD), which since 2006 has decimated about a third of our nation's bees.
Bee scientists believe that CCD--characterized by adult bees abandoning the hive, leaving behind the queen, brood and food stores--is caused by multiple factors, including pests, parasites, pesticides, diseases, viruses, stress, and yes, malnutrition.
“Many, many colonies are not going to make it through the winter,” said Mussen, an apiculturist in the UC Davis Department of Entomology since 1976 (and who plans to retire in June of 2014). “We won’t have as large a bee population as in the past.”
Already brokers are getting calls from beekeepers saying “I can’t fulfill the contract. I’m going to be short.” Beekeepers charge the almond growers an average of $150 per hive.
The average almond orchard in California is in full bloom around Feb. 14, but some orchards bloom earlier or later, depending on the cultivar and the weather.
It remains to be seen what will happen in the almond orchards this year. Mussen says it may all work out well in the end as “bees pollinate almonds on a community basis. The strong colonies will make up for the weak colonies. The strong colonies will clean the orchard of pollen by early afternoon and then go down the street and grab food from nearby orchards.”
Almonds are California's biggest export. This year the National Agricultural Statistics Service is forecasting a record-breaking 2.10 billion meat pounds, valued at approximately $3 billion. California grows 80 percent of the global supply of almonds, and about 70 percent of California’s crop is marketed overseas.
No bees? No almonds.
- Author: Kathy Keatley Garvey
Ah, what an intoxicating scent!
If you've ever been around the winter daphne, Daphne odora, cultivar "Aureomarginata," you know that its aroma precedes it.
You'll ask "What's that fragrance?" before you even see the showy pink-and-white blossoms and its green leaves edged in gold.
The winter daphne, an evergreen, is now blooming in the Ruth Risdon Storer Garden on Garrod Drive, UC Davis Arboretum.
The Storer Garden is aptly named. Ruth Storer, Yolo County’s first pediatrician, loved gardening.
We think she would have liked the honey bee hovering today in the dappled shadows of the daphne. "Table for one, please!"
