- Author: Kathy Keatley Garvey
Or more precisely, dead fruit flies or carrion on a tarweed plant can benefit the plant in more ways that most people would ever think about, say researchers in the UC Davis Department of Entomology.
Just as human tourists can be good for the economy, ‘insect tourists” can be good for a plant.
When the hairs of a “sticky plant” trap small insects or “insect tourists,” the “tourist trap” provides food for other predators, thus becoming a defensive mechanism that spares the plant from increased herbivore damage. Other beneficial results include greater plant fitness and increased fruit production.
“We conducted a large, simple field experiment to test the hypothesis that plant-trapped insects could enhance indirect defense by increasing predator densities,” said ecologist Billy Krimmel, a graduate student in the Jay Rosenheim lab, who worked with fellow ecologist Ian Pearse of the Richard Karban lab. Pearse is now a postdoctoral fellow in Walter Koenig’s laboratory at Cornell University, Ithaca, N.Y.
“Sticky plants-- those producing resinous, oily or hooked trichomes (hairs)--often entrap small insects that land on them as they pass by,” Krimmel said. “This insect carrion functions as a type of plant-provided food for defense.”
“This is the first example of such a plant-provided food being captured from the external environment,” Krimmel said. “We coined the term 'tourist trap', referring to the sticky hairs that catch insect passers-by.”
In their research, “Sticky Plant Traps Insects to Enhance Indirect Defence,” published in the journal Ecology Letters, the ecologists revealed that the trapped insect tourists “increased the abundance of a suite of predators, decreased herbivory and increased plant fitness.”
Later the journal Nature focused on the Krimmel-Pearse research in its ecology section: "When Plants Run the Food Chain."
"We have known for a long time that carnivorous plants entrap insects for their own benefit,” Pearse said. “In our current study, we found that the entrapment of insects by plants might be even more important and general than previously thought."
Krimmel and Pearse conducted their research in the Stebbens Cold Canyon Reserve, a UC Davis Nature Reserve located in Solano County, near the outlet of Lake Berryessa. Their sticky plant was tarweed (Madia elegans), an annual flowering California native plant in the family Asteraceae. It generally flowers in mid to late summer, from approximately June through September.
At our study site, tarweed's major herbivore is the specialist caterpillar Heliothodes diminutiva, which feeds largely on plant reproductive organs and can completely sterilise its host plants,” they wrote. The adult owlet moth, Heliothodes diminutive, lays its eggs on the developing buds. The emerging caterpillars can quickly devour all the flowers and buds.
“The suite of predators commonly found on tarweed,” they wrote, “includes the assassin bug Pselliopus spinicollis, two stilt bugs Hoplinus echinatus and Jalysus wickhami, the green lynx spider Peucetia sp. and the crab spider Mecaphesa schlingeri. All can navigate tarweed's sticky surface.”
Krimmel and Pearse chose 82 tarweed plants for their experiment. They placed dead Drosophila fruit flies to half of them, five flies per week through the growing season, and then monitored all the plants throughout the growing season.
“Because tarweed is a small, annual plant, we were able to do full counts of arthropods on all plants each week, and measure lifetime fruit production by the plants, allowing us to relate our experimental treatment to plant lifetime fitness,” the authors wrote.
“The addition of 5 dead fruit flies (carrion) to plants each week over the growing season increased the abundance of all surveyed predatory arthropods associated with M. elegans plants by 76 percent to 450 percent,. For P. spinoicollis, the most abundant predator, this effect was strongest during the early growth season in June and July.”
Specifically, “the addition of carrion (fruit flies) to M. elegans plants produced a 60 percent decrease in bud damage caused by H. diminutiva, the dominant lepidopteran herbivore in this system and increased lifetime fruit production by 10 percent,” the researchers said.
Jay Rosenheim's USDA research grant helped fund the project. Krimmel received two other grants: a National Science Foundation/Graduate Research Fellowship and a Jastro-Shields Research Scholarship.
- Author: Kathy Keatley Garvey
And compelling.
In an article published this week in the Proceedings of the National Academy of Sciences (PNAS), the UC Davis medical entomologists and their colleagues found that human movement—people going from house-to-house to visit their friends and relatives—is a key component to driving the virus transmission. (Read PNAS paper)
The research site is Iquitos, nestled in the heart of the Amazon rain forest of northeastern Peru. It's considered one of the world’s primary “open laboratories” to study the transmission of the virus.
The Aedes aegypti mosquito is a day-biting mosquito and we humans are its favorite host/target.
The ground-breaking research shows why it's crucial to focus on people movement, not just on the traditional mosquito control-and-prevention methods, such as applying insecticides and eliminating water-filled containers that can provide a larval habitat.
As lead author/medical entomologist Steve Stoddard said: "This finding has important implications for dengue prevention, challenging the appropriateness of current approaches to vector control."
“Interestingly, it didn’t matter how far away the visited houses were," Stoddard said. "The mosquito that transmits dengue virus prefers to stay in small areas, say in less than a 100-meter radius, but the distance between houses was often much greater than this. So it only makes sense that humans are frequently spreading the virus around as they commute between their homes and the homes of their friends and family. Altogether the data demonstrate what we expected, that human movements are really key to the transmission of this mosquito-borne virus.”
Said Scott, professor of entomology at UC Davis and director of the Mosquito Research Laboratory: “Dengue takes an enormous toll on human health worldwide, with as many as 4 billion people at risk—half of the world’s population--and 400 million new infections each year. The results from our study are focusing attention to the role human social networks in virus invasion and epidemic spread.
"At our Peru study area, we found that infection risk is based on the places a person visits and transmission dynamics are driven by overlapping movements of people who recently visited the same places, like the homes of their family and friends.”
Bottom line: The scientists found that people movement not only defined individual infection risk and local patterns of incidence, but resulted in the rapid spread of the virus and marked heterogeneity in transmission rates.
Next phase of the research? It's aimed at "understanding how variation in human behavior influences transmission and applying that knowledge in enhanced disease prevention strategies,” said Scott, the principal investigator of a National Institutes of Health (NIH)-funded grant.
With some 4 billion people worldwide at risk, and with 400,000 million new infections each year, dengue is indeed taking its toll. Every year some 500,000 people with severe dengue are hospitalized, and 2.5 percent die.
- Author: Kathy Keatley Garvey
It's a brief appearance but the message is important.
Pollination ecologist Neal Williams, assistant professor of entomology at UC Davis, appears briefly in a segment on native pollinators produced by America's Heartland. The show is now airing throughout the country. (Watch video)
Reporter Sarah Gardner of America’s Heartland touches on the declining population of honey bees--which European colonists brought here in 1622--and native pollinators, which are also declining.
“Farmers, scientists and others in U.S. agriculture are mounting an effort to develop a unique pollinator partnership promoting the growth of native plants on farms, orchards and ranches all across America,” Gardner said.
Williams is quoted as saying: “In the East, native bees can potentially provide all the pollination that’s necessary in the vast majority of those farms.”
It's great to see the focus on pollinators!
Gardner interviewed Mace Vaughn of the Xerces Society for Invertebrate Conservation; Ernie Shea of the Native Pollinators in Agriculture Project; and A. G. Kawamura, former California Secretary of Agriculture, among others.
Vaughn said that “unless we encourage native pollinators, consumers are going to see fewer food choices and higher prices. The conservationist is urging farmers and growers to add native plants to their growing areas in an effort to attract different bee species, butterflies, hummingbirds and other animals that can help in cross pollinating crops.”
Williams, who joined the UC Davis Department of Entomology in 2009, was a featured speaker at the International Symposium on Pollinator Conservation, held last January in Fukuoka, Japan. He explored agricultural landscape change and the role of bee life history in predicting and understanding responses of bee communities.
(Editor's Note: America's Heartland is airing the program beginning this week (Jan. 1-6) and it can also be seen on America's Heartland website. To learn when the program airs in your zip code, access this site.)
- Author: Kathy Keatley Garvey
What an unexpected find!
It was the first day of 2013 and what did we see: a queen bumble bee, Bombus melanopygus, aka black-tailed bumble bee.
Like scores of others, we decided to take a walk on Jan. 1 in the Benicia State Recreation Area. Located in Solano County, just outside the city of Benicia, the 447-acre park on State Park Road offers a view of the Carquinez Strait amid lush grasslands, rocky beaches and a marsh filled with cattails about to lose their charm as they go to seed.
It's a good place to walk, run, cycle, and engage in picnicking, fishing, and bird watching.
And bee watching.
When the temperature hits 55 degrees, it's common to see honey bees foraging among eucalyptus, manzanita and wild mustard this time of year.
In mid-morning, Jan. 1, the temperature registered 50 degrees. No honey bees did we see. But as we stopped to admire the manzanita in the native plant garden, we spotted her: a black-tailed queen bumble bee, as later identified by native pollinator specialist Robbin Thorp, emeritus professor, UC Davis Department of Department.
"Yes, a queen of Bombus melanopygus, earliest of our bumble bees to emerge from hibernation and start nests each year," Thorp said. "I had heard that some were flying in December in the Bay Area. Keep an eye out for the first workers or first queens with pollen loads. Those will be the signs that nests have been established. Otherwise, seeing queens out on a nice sunny warm day, even sipping nectar, may mean that they are just stretching their wings and checking things out between naps, before getting down to the serious business of starting a new nest."
This species of bumble bee is native to western North America and is found from California to British Columbia and as far east as Idaho. "In the southern part of its range, the third and fourth segments of the abdomen are black instead of the red color seen in the northern populations, and this black color form was formerly known by the name Bombus edwardsii," according to Wikipedia.
Now it's Bombus melanopygus.
Soon we saw that we were not alone. Several other queen bumble bees quietly appeared, all to sip the sweet nectar of manzanita on the first day of 2013.
Soon we expect to see them with a load of pollen.
- Author: Kathy Keatley Garvey
Art Shapiro knows where to find the cabbage white butterflies (Pieris rapae).
No sooner had he announced his annual "Beer-for-a-Butterfly" Contest, then he found one. Actually, two.
Shapiro, distinguished professor of evolution and ecology at UC Davis, has sponsored the annual contest since 1972 to draw attention to the butterfly and its first flight. He's been monitoring butterflies for more than three decades.
He awards a pitcher of beer (or its cash equivalent) to the first person who collects the first cabbage white of the year in a three-county area: Yolo, Solano and Sacramento.
Tuesday, Jan. 1 2013 dawned rather cold. Not to worry. That afternoon, at precisely 1:18 p.m., Eureka! Shapiro collected a cabbage white near a railroad embankment in the Yolo County city of West Sacramento and spotted another at the same site.
“At 1:29 p.m., I saw a second rapae there but did not pursue it,” Shapiro said. “I figured that by the time I got near it, it would be somewhere else, so I let it be. The one that I took is unambiguously of the fall brood, based on phenotype--though it appears to have emerged today. Rapae was still flying here Dec. 17 and Dec. 24, so I was not entirely surprised to find it today.”
Of the contest, Shapiro said: “I do not close my beer contest if the fall brood slops over. So the contest is still open and will be until someone gets an actual example of the 2013 brood! Which, I suspect, will not be for 10-14 days...but I'll be looking, especially since the computer models are forecasting the next two weeks ‘dry.’
Shapiro related the details of his find. “Our family traditionally attends a New Year's Day party in Sacramento, regardless of the weather,” Shapiro said. “If the weather is good, I go in the field first--usually to North Sacramento, which is close to the party venue in Boulevard Park. But this year I went to West Sac instead, advisedly, because I was intensely curious whether rapae would indeed be out.”
“The wind was biting and made it feel colder than it was, but West Sac is wind-sheltered (the railroad embankment) and the south-facing slope was 50 degrees when I arrived at 11:45 a.m. It eventually topped out around 55-56 and actually felt warmer."
The cabbage white butterfly inhabits vacant lots, fields and gardens where its host plants, weedy mustards, grow. Shapiro saw some wild radish (Raphanus) in bloom, but no wild mustard (Brassica) in bloom. The first butterfly he saw was a Red Admiral (Vanessa atalanta) flying “from south to north, lickety-split.”
At 1:18 p.m. he spotted a rapae flying rather unsteadily parallel to the service road. “I lost it momentarily, then spotted it body-basking on a wild mustard leaf and caught it easily. It was a male of a typical late-autumn phenotype, heavy black pattern above, underside of hindwing bright yellow with a sprinkling of gray scales.”
“And it was incredibly fresh--the wings seemed soft, and one forewing got outside its corresponding hindwing in the net. This is something that happens occasionally with newly hatched bugs that are not fully ‘hardened’--I was afraid it might break off! I think it must have emerged today, and I got it on its maiden flight."
Shapiro, who usually wins his own contest, snagged the first cabbage white butterfly of 2012 at 11:50 a.m. on Sunday, Jan. 8 in West Sacramento. He caught the first cabbage white butterfly of 2011 at 1:21 p.m., Monday, Jan. 31 in Suisun City, Solano County.
Meanwhile, the contest is still under way, pending the declaration of a winner.
The rules state that butterfly must be collected outdoors in one of the three counties and delivered live to the office of the Department of Evolution and Ecology, 2320 Storer Hall, during work hours, 8 a.m. to 5 p.m., Monday through Friday. All entries must list the exact time, date and location of the capture and the collector’s name, address, phone number and/or email.
“The receptionist will certify that it is alive and refrigerate it,” Shapiro said. “If you collect it on a weekend or holiday, hold it your refrigerator but do not freeze it. A few days in the fridge will not harm it.”
Shapiro, who is in the field more than 200 days a year, has been defeated only three times since 1972. And all were his graduate students, whom he calls “my fiercest competitors.” Adam Porter defeated him in 1983; and Sherri Graves and Rick VanBuskirk each won in the late 1990s.
For more information on the beer-for-a-butterfly contest, contact Art Shapiro at amshapiro@ucdavis.edu, (530) 752-2176
