- Author: Kathy Keatley Garvey
Molecular neurobiologist Anupama Dahanukar, assistant professor at UC Riverside, will speak on "Taste Receptors and Feeding Preferences in Insects" at the UC Davis Department of Entomology seminar from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
UC Davis assistant professor Joanna Chiu, who studies the molecular genetics of animal behavior, will host the seminar, which is scheduled to be recorded for later viewing on UCTV.
The seminar will focus on the common fruit fly, Drosophila melanogaster, exciting research under way in the Dahanukar lab.
"We are interested in the molecular neurobiology of feeding behavior," Dahanukar says. "Insects use highly diverse groups of gustatory receptors (Grs) to taste the chemical world and determine the palatability of potential food sources. In Drosophila melanogaster, the 68 receptors of this family are expressed in complex combinatorial patterns in taste neurons. In previous studies we and others identified a highly conserved clade of eight Gr genes that encode sugar receptors. Although some of these have been linked to detection of sweet compounds by genetic analysis, their precise functions are still poorly understood. Little is also known about how stimuli that are typically not rich in sugars trigger highly attractive gustatory responses in Drosophila."
"Using genetic and evolutionary analysis, we recently found that Gr64e, a receptor in this clade, plays an essential role in feeding preference for beer and other yeast fermentation products. We identified that Gr64e is necessary for neuronal and behavioral responses to an abundant component of yeast and fermentation products, glycerol. Moreover, Drosophila species that carry a polymorphism disrupting Gr64e function have reduced behavioral preference for beer, suggesting that Gr64e may contribute to specific evolutionary variations in appetitive selectivity. Ectopic expression of the Gr64e receptor in an olfactory neuron is sufficient to confer glycerol sensitivity. We have extended this ectopic expression system to identify that each sweet Gr protein serves as a determinant for recognition of unique but overlapping subsets of sweet tastants."
"We have also obtained functional expression of a taste receptor from the mosquito Anopheles gambiae in Drosophila. We are now poised to further investigate taste detection and Gr function in Drosophila and other insects."
A noted scientist, Dahanukar received a National Science Foundation Career Award in 2012; the Whitehall Foundation Award in 2011; and the 2000 Ruth L. Kirschstein National Research Service Award. She was awarded a Government of India National Merit Scholarship in 1990.
Dahanukar holds a bachelor of science degree in life sciences from Bombay University, India; a master's degree in environmental management from Duke University, Durham, N.C.; and a doctorate in genetics in 1999 from Duke University, where she studied patterning along the anterior-posterior axis in Drosophila embryos. In 1999, she joined the laboratory of John Carlson at Yale University to pursue post-doctoral training in the molecular neurobiology of insect chemosensory systems. Dahanukar joined the faculty of the UC Riverside Department of Entomology in 2009.
- Author: Kathy Keatley Garvey
'Tis the season for the return of the insects.
Many a honey bee foraged in the flowering quince (Chaenomeles speciosa) last weekend. But wait, what's that? A spotted cucumber beetle (Diabrotica undecimpunctata) tucked inside a blossom.
Spotted cucumber beetles, which overwinter as adults, are major agricultural pests. The beetle is so named because of its preference for cucumbers (cucurbits), but just about anything will do before, during and after the cucumber crop. True, it gravitates toward other members of the cucurbits family, including squashes, gourds, pumpkins and melons, but it also goes after beans, peas, corn, potatoes, beets, tomatoes, eggplants, cabbage, and assorted ornamentals, such as roses and dahlias.
The yellowish-green beetle with black spots may look pretty tucked inside a flowering quince, but looks are deceiving.
Very deceiving.
- Author: Kathy Keatley Garvey
It's good to see that the Xerces Society for Invertebrate Conservation and noted bumble bee expert Robbin Thorp of UC Davis have filed a petition with the U.S. Fish and Wildlife Service for Endangered Species Act protection for the beleagured rusty-patched bumble bee.
They previously filed a petition to save Franklin's bumble bee, a bumble bee known to inhabit a small area of southern Oregon and northern California. Thorp has been monitoring Franklin's bumble bee (Bombus franklini) since 1998 but hasn't seen it since August 2006 when he detected one at Mt. Ashland.
In a recent press release, the Xerces Society related that the rusty-patched bumble bee, (Bombus affinis), "has disappeared from 87 percent of its historic range (which once included 25 states). Where it is still found, this bee is much less abundant than it was in the past."
“The charismatic and once common rusty patched bumble bee has suffered severe and widespread declines throughout its range in the eastern U.S. since 1997," Thorp said. "The few scattered recent sightings thanks to intensive searches are encouraging, but the species is in critical need of federal protection.”
Why has the population of the rusty-patched bumble bee declined? Good question, and one with no fully determined answer, according to Thorp and Sarina Jepsen, the Xerces Society's endangered species program director.
"However, in related bumble bees that also are declining, researchers at the University of Illinois have recently found higher levels of a fungal pathogen and lower levels of genetic diversity," Jepson wrote in a press release. "Notably, the rusty-patched bumble bee was too scarce in the landscape to be included in these analyses."
"The leading hypothesis," Jepson says, "suggests that this fungal pathogen was introduced from Europe by the commercial bumble bee industry in the early 1990s, and then spread to wild pollinators. Although it has not been proven, the hypothesis is supported by the timing, speed and severity of the decline—a crash in laboratory populations of bumble bees occurred shortly before researchers noticed a number of species of formerly common bumble bees disappearing from the wild."
Meanwhile, we hope that Bombus affinis doesn't go the way of Bombus franklini.
As the Xerces Society's press release points out: "Pollinators are critical components of our environment and essential to our food security—providing the indispensable service of pollination to more than 85 percent of flowering plants and contributing to one in three bites of the food that we eat. Bumble bees are among the most widely recognized and well understood group of native pollinators in North America and contribute to the pollination of food crops such as squash, melon, blueberry, cranberry, clover, greenhouse tomato and greenhouse pepper, as well as numerous wildflowers."
Read more about this bumble bee from the Xerces website. And why researchers call the declining bumble bee population "alarming."
The Xerces Society, an international organization founded in 1971 and headquartered in Portland, Ore., is a nonprofit organization that "protects wildlife through the conservation of invertebrates and their habitat" and "is at the forefront of invertebrate protection worldwide, harnessing the knowledge of scientists and the enthusiasm of citizens to implement conservation programs."
- Author: Kathy Keatley Garvey
"Where'd that yellow pollen come from?"
Beekeepers who watch their bees return to their hives with pollen loads like to guess the origin of the pollen. Red, yellow, blue, white...
It's not unlike "What Color Is Your Parachute?" the job-hunting guide by Richard N. Bolles.
Sunday the bees foraging in flowering quince collected yellow pollen--heavy loads of pollen. They struggled with the weight and then headed home to help feed their colonies.
Blue skies, pink flowers, yellow pollen...life is good.
- Author: Kathy Keatley Garvey
UC Berkeley professor Nick Mills will head to UC Davis on Wednesday, Feb. 20 to speak on just that: "The Light Brown Apple Moth--Not a Typical Invader."
The seminar, hosted by the UC Davis Department of Entomology, is set from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
Mills, with the UC Berkeley Department of Environmental Science, Policy and Management, says "exotic insect pests typically become invasive by building populations and spreading through a new geographic region in the absence of constraints from co-evolved natural enemies. While it is well known that environments can differ substantially in their resistance to invasions of alien species little is known of the factors responsible for this variation."
The light brown apple moth, aka LBAM, has caused quite a stir since its detection in California in 2006. That's when emeritus professor Jerry Powell of UC Berkeley discovered the invader in his back yard in Berkeley.
As a leafrolling caterpillar, LBAM loves just about everything from A to Z: apple, apricot, beans, caneberries (blackberry, blueberry, boysenberry, raspberry), cabbage, camellia, chrysanthemum, citrus, clover, cole crops, eucalyptus, jasmine, kiwifruit, peach, pear, persimmon, plantain, pumpkin, strawberry, tomato, rose and zea mays (corn).
Mills says that since its discovery in California, LBAM "has accumulated a rich set of resident parasitoid species comparable to that seen in its native Australia. However, in contrast to the low levels of parasitism that invasive hosts typically experience from resident parasitoids, parasitism levels for light brown apple moth are very high."
He will discuss, among other things, "the importance of resident parasitoids as barriers to the invasions of light brown apple moth in California."
Plans are to record the seminar for later posting on UCTV. Hosting the seminar is entomologist Mary Louise Flint of the Department of Entomology/UC Statewide Integrated Pest Management Program.