UC Garden Blogs
Hide the cactus! There's a Mexican cactus fly in our midst.
A large black fly hovers over a Mexican sunflower (Tithonia) in our bee garden and then drops down to sip some nectar. At first glance it looks like a carpenter bee but this one hovers like a syrphid fly, aka flower fly or hover fly.
"Hover fly," I say.
Entomologists Martin Hauser, Lynn Kimsey and Robbin Thorp quickly identified the critter.
Hauser, senior insect biosystematist with the Plant Pest Diagnostics Branch of the California Department of Food and Agriculture, says it's in the genus Copestylum (with over 350 species in the new world) and figured it to be the species, mexicanum, commonly known as the Mexican cactus fly.
Said Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis: "Nice, this is actually a kind of syrphid flower fly, better known as a cactus fly. The larvae breed in rotting cactus tissue."
Native pollinator specialist Robbin Thorp, emeritus professor of entomology, also figured it to be a Mexican cactus fly, Copestylum mexicanum. "It's commonly known as a cactus fly (Syrphidae, Tribe Volucellini). "It used to be in the genus Volucella, But now it's in the genus Copestylum."
This fly is not small. It's about 3/4 of an inch long. It lays its eggs in rotting plant material "and they really like rotting cacti," Hauser commented. "As far as I know, they only go into dying cacti and do not attack healthy cacti…. But there is actually not much known about their biology."
The resident cacti expert at our house is worried, showing his best prickly pear expression. He quickly canvasses the yard. Whew! No rotting cacti. All thriving and in good health.
So far, so good...
Black hover fly, aka Mexican cactus fly, sipping nectar from a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
Side view of the black syrphid fly, a Mexican cactus flower. (Photo by Kathy Keatley Garvey)
Mexican cactus fly ready to take off. (Photo by Kathy Keatley Garvey)
This article was originally prepared for the CWSS Research Update and News (September 2014 edition). You can see it and several other articles at the CWSS website. You can also get information on the annual California Weed Science Society Conference which will be held in Santa Barbara January 21-25, 2015.
Managing Junglerice in Tree Nut Crops – a summer weed resistant to glyphosate
Marcelo L. Moretti1, Seth Watkins1, Bill Gary2, and Brad Hanson1
1University of California – Davis, CA; 2Mid Valley Ag – Linden, CA
Junglerice, or Echinocloa colona, is a summer grass commonly found in orchards, annual crops, and roadsides of California. This weed germinates in early spring and throughout the summer and can grow and reproduce quickly. Junglerice commonly is identified by purple bands on the leaves. However, in some populations or environmental conditions these stripes are less visible; thus a lack of banding should not be used as a definitive means of identification. In recent years, the feature that makes this summer grass really stand out in California fields is the discovery of glyphosate-resistant populations.
Glyphosate-resistant junglerice was first detected in the northern Central Valley in 2010. A subsequent survey in 2011 found glyphosate-resistant populations in Butte, Madera, and Kern Counties. At that time, glyphosate resistance was not found between Butte and Madera Counties. This erratic distribution of resistance suggested that these populations may have evolved resistance independently. This hypothesis was further supported by the work of Dr. Alarcon-Reverte and collaborators from UC Davis, who documented several different mechanisms of resistance in junglerice populations from California.
These findings have important implications for weed management. First, seed production and dispersal must be stopped to avoid spread of the populations that are already resistant to glyphosate. Even more important is that weed management programs should consider the adoption of strategies to mitigate selection of new glyphosate-resistant populations. Readers interested in more general information about the biology and management of herbicide resistant weeds should refer back to the January 2013 CWSS Research and Update News vol. 9 n. 1 (http://www.cwss.org/uploaded/media_pdf/4749-2013_01_CWSSResearch.pdf). In this article, the discussion will focus on herbicidal management of glyphosate-resistant junglerice in tree and vine crops.
Rotating or combining herbicide modes of actions is one of the first recommended practices to manage herbicide resistance. However, this practice is only effective when the alternate mode of action herbicide also has efficacy on the resistant species. Experiments were conducted during summer of 2013 and 2014 in tree nut crops of the Central Valley to compare postemergence control of junglerice with registered herbicides. Locations included Kern, Contra Costa, and Merced Counties. The Kern County location was known to be infested with glyphosate-resistant junglerice, but the susceptibility of the populations at the other two locations was not known.
The results indicated that glyphosate (RoundUp Powermax) was highly effective in controlling junglerice at the Contra Costa and Merced County locations; however, no control was observed with glyphosate in Kern County (figure 2). Concurrent greenhouse experiments indicated that the Kern population was 4-fold more tolerant of glyphosate than the reference susceptible population (data not shown). The other postemergence herbicides tested, glufosinate (Rely 280), paraquat (Gramoxone SL), or sethoxydim (Poast), all provided good initial control of junglerice; this indicates that there is no cross-resistance to these modes of action. However, because these herbicides have only postemergence activity, junglerice control declined by 28 days after application due to regrowth and emergence of new seedlings (figure 3). The combination treatment of glyphosate plus rimsulfuron in these studies provided good postemergence control of glyphosate-susceptible and –resistant junglerice as well as residual control for several weeks.
Complete control of junglerice with postemergence herbicide programs can be a challenge in orchards. Summer grasses like junglerice can germinate throughout the growing season as long as soil moisture and temperature conditions are favorable; thus repeated applications of postemergence treatments will likely be needed. Additionally, junglerice plants grow rapidly and can become too big for effective control with some herbicides. Survivors and new plants can produce seed before tree nut harvest operations and further increase the infestation in the orchard. Therefore, postemergence-only herbicide programs are not likely to provide consistent and economical control of junglerice in orchard but should instead be used as part of a management program that includes preemergence herbicides applied during the winter season.
Preemergence herbicides are an important tool to be included in the weed control of junglerice and other weeds in tree and vine crops. From a resistance management standpoint, most of the preemergence herbicides have different modes of action than the available postemergence herbicides. In addition to aiding rotation of herbicide modes-of-action, the preemergence herbicides provide extended control of multiple flushes of germinating junglerice during spring and part of the summer. For example, excellent control of junglerice was observed for more than 125 days with several preemergence herbicide treatments (figure 4).A list of preemergence herbicides registered in tree & vine crops of California is available at the Weed Research and Information Center (WRIC) website (http://wric.ucdavis.edu).
Several preemergence and postemergence herbicides provided effective control of glyphosate-resistant junglerice in tree nut crops. This suggests that there is no cross-resistance to these important management tools. Growers can use these herbicides with different modes of action in an integrated approach to reduce the selection pressure for glyphosate-resistant junglerice.
In addition to the herbicide research described here, UC Davis, UCCE, CSU Fresno researchers as well as members of the private sector are also addressing aspects of biology, ecology, and genetics of glyphosate resistance. These collaborative efforts should lead to integrated weed management strategies for junglerice and other problematic weeds in tree and vine crops.
That's the theme of San Francisco's Exploratorium Pier 15 event on Thursday night, Oct. 2.
Graduate student Ralph Washington of the UC Davis Department of Entomology and Nematology, will be staffing the Bohart Museum of Entomology table at the event, open only to adults 18 and over.
Washington, who studies with major professor Steve Nadler and volunteers at the Bohart Museum, will showcase the “oh my” drawers, so named because onlookers exclaim “oh my” when they see them; and live animals from the petting zoo, which include Madagascar hissing cockroaches, walking sticks and millipedes. He also will show a PowerPoint presentation about camouflage and deception in the insect world.
The event will take place from 6 to 10 p.m., at Pier 15, located at Embarcadero at Green Street, San Francisco. General admission is $15; for members, it is $10.
“After Dark” is a mixture of theater, cabaret and a gallery, according to its website.
Tabatha Yang, education and outreach coordinator at the Bohart Museum, said "After Dark" is aimed at young adults.
From the website:
“Delve into the science behind deception at After Dark. Find out how expert wine detective Maureen Downey exposes costly counterfeits—without uncorking a bottle. Glimpse the blurred margins between science and art in Victorian spirit photography with Fine Arts Museums of San Francisco curator Melissa Buron, and walk through a virtual mirror staged by Exploratorium physicist Paul Doherty. Play with exhibits exploring the nature of perception, including a room-sized “Vanishing Act.” Encounter the uncanny in the mischievous mentalism of Brad Barton, Reality Thief, and let magician and Exploratorium scientist Luigi Anzivino show you how the odds can be stacked against you in a seemingly innocent game of chance. Learn the tricks carnivorous plants use to lure their treats, meet servals and ocelots from Bonnie Cromwell's Classroom Safari, and become a connoisseur of camouflage—animal and otherwise.”
Information on tickets and parking and other data on the Exploratorium Pier 15 website.
A walking stick is expected to be one of the Bohart Museum of Entomology attractions at Exploratorium Pier 15 on Oct. 2. (Photo by Kathy Keatley Garvey)
UC Davis entomology graduate student Ralph Washington (right) chats with UC Davis assistant professor/bee biologist Brian Johnson at the Bohart Museum open house on Sept. 27. (Photo by Kathy Keatley Garvey)
[From the December 2012 issue of the UC IPM Retail Nursery & Garden Center News] After decades of relative obscurity, bed bugs (Figure 1) are exhibiting a global resurgence. In the United States, the Northeast and Midwest regions have been...
Okra. You either love it or hate.
If you hate it, it's probably because of its characteristic "slime" that it produces. It's a mucilaginous plant. If you love it-- absolutely love it--you may be from the Deep South, where okra is king. They bread the slender green pods and deep-fry them. And they pickle them. It's also a key ingredient in gumbo.
Indeed, it's a vegetable rich in Vitamin C, fiber and potassium.
But if you're a garden spider living in the Good Life Garden at the University of California, Davis, you depend on the tall okra plants to weave your web and trap insects. Then you can spin them around, wrap them tighter than a ball of string, and feast on them later.
The Good Life Garden is located behind the Robert Mondavi Institute for Wine and Food Science on Old Davis Road. It's a well-cared for garden chock full of fruits, vegetables, herbs and ornamentals.
And predators and prey.
Its aim, according to its website, is "to educate the public on how to buy and plant seasonal vegetables for the best taste and highest nutritional content. Each season the garden's planting list will be available online along with information on how to grow, harvest, buy, and cook the various plants, herbs, and fruits found in the garden."
The garden is aptly named. The Good Life.
Good for people, predators and prey.
A garden spider wraps its prey, a honey bee, in The Good Life Garden. (Photo by Kathy Keatley Garvey)
Garden spider struggles with its prey, a honey bee. (Photo by Kathy Keatley Garvey)