In a ground-breaking discovery encompassing six years of research, an international team of scientists led by UC Davis chemical ecologist Walter Leal announced they've identified the sex pheromone of the pest, which feeds on citrus and transmits the bacteria that causes the deadly citrus greening disease known as Huanglongbing (HLB).
Leal, a native of Brazil and a fellow of both the Entomological Society of America and the Entomological Society of Brazil, revealed the discovery during his presentation Dec. 5 at the 10th Annual Brazilian Meeting of Chemical Ecology in Sao Paulo. His team included scientists from UC Davis, University of Sao Paulo, and the Fund for Citrus Protection (FUNDECITRUS) from the state of Sao Paulo.
“Dr. Leal's discovery of the Asian citrus psyllid pheromone is a significant breakthrough in preventing the spread of this serious citrus insect, and may offer a less toxic method for its control,” said integrated pest management specialist Frank Zalom, distinguished professor with the UC Davis Department of Entomology and Nematology and a past president of the Entomological Society of America. He was not involved in the study.
“Having a lure to dramatically improve captures of this psyllid with the conventional sticky traps is a major progress toward integrated pest management,” said Professor Jose Robert Parra of the University of Sao Paulo.
Identifying the sex pheromone proved “complicated and quite a challenge” because of the insect's complex behavior and biology, said Leal, a UC Davis distinguished professor who has discovered the sex pheromones of moths, beetles, bugs, cockroaches, mites and other arthropods. A patent was filed Friday, Dec. 1, and journal publication is pending.
Citrus trees infected with HLB usually die within five years, according to the UC Statewide Integrated Pest Management Program. There is no known cure. “The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees,” UC IPM says on its website.
Native to Asia, the Asian citrus psyllid, Diaphorina ciri, was first detected in the United States in June 1998 in Palm Beach County, Florida, and in California in August 2008 in San Diego County. Scientists discovered HLB in Florida in August 2005, and in Los Angeles in March 2012. The mottled brown insect, about 3 to 4 millimeters long, or about the size of an aphid, is now widespread throughout Southern California and is now found in 26 of the state's 58 counties.
The Asian citrus psyllid, or ACP, feeds on new leaf growth of oranges, lemons, mandarins, grapefruit and other citrus, as well as some related plants. Infected psyllids can transmit the bacterium Candidatus Liberibacter asiaticus, which causes the fatal citrus disease. An early symptom of HLB in citrus is the yellowing of leaves on an individual limb or in a sector of a tree's canopy.
Currently growers are using yellow sticky traps to detect the insect and to monitor the population. “Efficient lures,” Leal said, “are sorely needed for sticky traps, particularly for early ACP detection. Otherwise, growers have to resort to regular sprays to avoid infection given that infected insects from gardens and noncommercial areas migrate to citrus farms.”
Pheromones and other semiochemicals are widely used in agriculture and medical entomology. “Growers use them as lures in trapping systems for monitoring and surveillance, as well as for strategies for controlling populations, such as mating disruption and attraction-and-kill systems,” Leal noted.
Although ACP is present in Arizona and California, the disease itself has not been established, Leal said. “The emphasis is on detection, eradication and limiting the spread of the disease. In Florida, where HLB is widespread, monitoring ACP populations is essential to avoid reinfection after eradication of infected plants.”
The detection of the pest has led to widespread eradication of citrus trees in China, Brazil and the United States. “In Brazil as many as 46.2 million citrus trees, representing 26 percent of the currently planted trees, have been eradicated since the detection of HLB in 2004,” Leal said. “In Florida, HLB has caused severe losses to the citrus industry. This year's production loss is estimated to be about 28 million fewer boxes of oranges than in 2014-2015.”
The announcement of the discovery coincides with the 40th anniversary celebration of FUNDECITRUS in Araraquara, Sao Paolo. “I am delighted that Walter Leal accepted our challenge to work on this project as the lead investigator,” said Juliano Ayres, FUNDECITRUS director. “The combination of his work ethics and qualifications are unparalleled. And, he loves challenges.”
In response to the ACP invasion in California, the California Department of Food and Agriculture (CDFA) has launched an extensive monitoring program to track the distribution of the insect and disease. They check yellow sticky traps in both residential areas and commercial citrus groves, and also test psyllids and leaf samples for the presence of the pathogen.
Survey methods for ACP include visual inspections, sweep netting, and placement of yellow sticky traps in trees in citrus nurseries, commercial citrus-producing areas and residential properties throughout the state, according to the CDFA. They also place sticky traps in California fruit packing houses, specialty markets, retail stores and airports that receive such produce from areas known to be infested with ACP.
Since August 2008, ACP has now been detected in 26 of California's 58 counties: Alameda, Contra Costa, Fresno, Imperial, Kern, Kings, Los Angeles, Madera, Merced, Monterey, Orange, Placer, Riverside, San Benito, San Bernardino, San Diego, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Solano, Stanislaus, Tulare, Ventura, and Yolo. “The ACP has the potential to establish itself throughout California wherever citrus is grown,” the CDFA says on its website.
CDFA has set up a hotline at 1-800-491-1899 for residents to report suspicious insects or disease symptoms in their citrus trees.
California Department of Food and Agriculture (CDFA)
Save Our Citrus: Hotline Information
UC Agriculture and Natural Resources (UC ANR)
It's not a question of whether katydid did or didn't.
In answer to what-are-we-going-to-see-next-in-insect-sightings-today-in-our-weird-climate-changing patterns, a katydid appeared on our yellow rose bush on Nov. 21 in Vacaville, Calif.
And stayed for several days.
Usually, they are difficult to see in green vegetation, what with their green bodies and detailed venation. It's not good camouflage to hang out on a yellow rose.
"Katydids resemble grasshoppers but have long antennae," according to the UC Statewide Integrated Pest Management Program (UC IPM) in its pest management website on Scudderia furcata. "Female katydids lay their gray, oval 1/8- to 1/4-inch long eggs in two overlapping rows on twigs and leaves or into the edges of their chewing damage. Nymphs appear in April and May and require 2 to 3 months to mature. Katydids produce one generation a year."
They do like fruit, including peach, nectarine, apricot, and pear. "Katydids may feed on leaves or fruit. Katydids do not eat the whole fruit. They often take a bite and move on, allowing the feeding site to become covered with grayish scar tissue and the expanding fruit to become misshapen. Most damage is done by nymphs."
Last summer we saw them feeding on our nectarines, and later we noticed them hanging out on our Mexican sunflower (Tithonia). Usually they're gone by October.
Not this katydid.
Fly away home.
Your house is on fire
And your children are gone.
How many times have you heard that nursery rhyme?
Better yet, how many times have you seen a lady beetle (because they're beetles, not bugs) take off?
Look closely for lady beetles in aphid-infested milkweed plants and you might see this phenomenon. The lady beetle opens its elytra (a modified hardened protective wing case) and out pop the wings.
This lady beetle (below) was munching and crunching aphids on a tropical milkweed this afternoon in Vacaville, Calif., and then opted to take flight. Just another beneficial insect eating soft-bodied pests and then heading off to another "restaurant" that features its prey.
Goes to prove that lady beetles are garden heroes. And when they take flight, they look like super heroes: the superman/superwoman of the garden.
You can learn more about lady beetles from the Natural Enemies Gallery, part of the UC Statewide Integrated Pest Management (UC IPM) website. "Although they are extremely important natural enemies of aphids, their propensity to disperse makes it difficult for them to be used in inoculative or inundative biological control programs," UC IPM points out.
Tell that to the children chanting the nursery rhyme and they'll probably grow up wanting to learn more about these amazing insects and it's not about their house being on fire: "Their propensity to disperse makes it difficult for them to be used in inoculative or inundative biological control programs."
This is an insect that looks as if it were assembled by a dysfunctional committee: long angular legs, long antennae, and beady eyes on a thin green body.
All hail the katydid.
It's usually camouflaged, disguised as a leaf in the vegetation--Nature's gift.
But in our pollinator garden, we see them. Two of them. One is tucked beneath red rose petals, and another is nestled inside a white cosmos.
Katydids feed on leaves, flowers, fruit and plant seeds, and often will take just a bite of fruit, such as apricot, pear, peach, plum, blueberry and citrus, but enough to cause considerable damage. If they're agricultural pests, check out the UC Statewide Integrated Pest Management Program (UC IPM) website and learn how to manage them.
These katydids proved to be photogenic.
Can the larvae of lady beetles (aka ladybugs) eat aphids?
Yes, they can. And yes, they do.
We spotted some lady beetle larvae on our yellow roses today and guess what they were doing? Right, eating aphids. Eating lots of aphids.
The larvae look a little like miniature alligators, which is probably why they're often mistaken for pests.
Oooh, what's that weird-looking thing on the roses? It can't be good. Kill it!
Sadly, that's what many people do.
Lady beetles (family Coccinellidae) are beneficial insects that gobble up aphids, mites, scales and other soft-bodied insects. Check out the Quick Tips on the UC Statewide Integrated Pest Management Program (UC IPM) website for more information and photos.
And, be sure to attend the 103rd annual UC Davis Picnic Day on Saturday, April 22. It's "open house" throughout the campus. At Briggs Hall, the UC Davis Department of Entomology and Nematology and UC IPM will answer your questions about insects (as will scientists at the Bohart Museum of Entomology in Room 1124 of the Academic Surge Building). (See news story.)
Bugs. Briggs. Bohart. What could be better? Well, youngsters visiting the UC IPM booth at Briggs Hall are in for a special treat: they will be gifted with lady beetles to take home. Watch out, aphids!