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Huanglongbing Detected in Hacienda Heights, Los Angeles County

By Mark Hoddle | April 13, 2012

The Situation: On Thursday April 5 2012, after about a week of testing, the California Department of Food and Agriculture (CDFA) removed a pumelo tree with a lemon graft from Hacienda Heights in Los Angeles County after the tree and an Asian citrus psyllid found on the tree both tested positive for a lethal citrus disease, Huanglongbing (pronounced Wong-Long-Bing [HLB]). HLB is caused by a bacterium, and HLB-causing bacteria kill citrus by affecting the food transportation systems of infected trees. There is no known cure for the disease, and the HLB-bacterium does not pose a threat to humans, pets, or other plants.

The Problem: Huanglongbing, also known as yellow shoot disease, yellow dragon disease (these are English translations from the Chinese Huanglongbing indicating that the leaves of infected citrus appear an irregular mottled yellow color) or citrus greening (because fruit don’t ripen properly and remain green in areas) is spread from tree-to-tree by the Asian citrus psyllid (ACP), This small insect acts as a flying syringe carrying bacteria in its needle-like mouthparts and when infected psyllids feed on citrus they inject bacteria into trees. The disease can also spread by grafting infected branches onto healthy trees. The possibility that an infected branch was brought into California and used for a graft is being investigated.

Infected trees typically die within 5-8 years after being infected, but disease symptoms may take as long as 2 years to become obvious. This long latency period provides ample time and opportunities for ACP to visit infected plants, feed on them, acquire the bacteria and fly onto healthy trees to feed which puts these trees at risk of becoming infected with bacteria.

HLB has been a particularly devastating disease problem in Florida. In 2005, HLB was first detected and it was estimated that 10% or 60,000 acres of citrus was destroyed by HLB by 2009, just four years after the first find. This reduction of citrus acreage in Florida corresponded with an estimated loss of 6,600 jobs, $1.3 billion in lost revenues to growers, and $3.6 billion in lost economic activity associated with the citrus industry in Florida.

The commercial citrus industry is worth about $1.2 billion in California and about 300,000 acres are farmed.

Where are ACP and HLB in the USA? ACP and HLB are present in Florida, Texas, Louisiana, Georgia, and South Carolina. ACP is present in Arizona, Mississippi, and Alabama, but HLB has not yet been found. In California, ACP was first found in San Diego and Imperial Counties in 2008. Since this initial detection ACP has been found in Ventura, Orange, Santa Barbara, Los Angeles, Riverside, and San Bernardino Counties. ACP populations at this time are heaviest in Los Angeles County.

The Response: On April 5 2012, the CDFA held an open house meeting at Industry Hills Expo Center in the City of Industry. The purpose of the meeting was to provide the public with information on HLB and ACP and to respond to requests to examine citrus with disease symptoms that look suspiciously like HLB. Additionally, all citrus within an 800 meter (about 2,400 feet) radius of the infected tree have been treated with insecticides by the CDFA to kill any Asian citrus psyllids that may be carrying bacteria that cause HLB. A 93 square mile quarantine has been established in Hacienda Heights in Los Angeles County and part of northern Orange County. This quarantine prohibits the movement of all citrus nursery stock out of this area in case they are infected with HLB and these plants, if infected, could start new disease infestations in different areas of California. Any fruit from residential properties must not be moved to other areas in case ACP or HLB accidentally hitch-hike into new areas on this fruit.

A description of the Quarantine has been prepared by CDFA and maps of the Quarantine Zone are available.

What is the Future for Citrus in California? Following the find of HLB in Hacienda Heights there has been concern that a massive citrus die off in gardens is now imminent. This is unlikely because surveys have failed so far to find more than one tree infected with HLB. Further, it is unlikely that trees dying from HLB be initially widespread, it is probable that if there are other HLB infected trees in California, they are uncommon and widespread. The difficult problem facing the CDFA and USDA is finding these infected trees (should they exist) and eradicating them before ACP finds them, feeds, acquires HLB bacteria, and spreads them to healthy citrus. Because the disease is slow in killing trees, the loss of trees will be slow, and probably patchily distributed in the early stages of the spread.

What Can you Do to Help? The CDFA has set up a Pest Hotline 1-800-491-1899 and a Report-a-Pest website http://www.cdfa.ca.gov/plant/reportapest/ to help in the fight against invasive species coming into California.

Recent News Articles
Los Angeles Times: Gardeners’ Common Bond May Have Introduced Deadly Disease. 
Los Angeles Times: San Gabriel Valley Homeowners Swarm to Meeting about Citrus Disease

Topics: Asian Citrus Psyllid, Huanglongbing, Invasive Species, Mark Hoddle, News, UC Riverside | No Comments »

Entomophagy: Collecting and Eating Red Palm Weevil Larvae from Nipa Palms in Sumatra, Indonesia

By Mark Hoddle | March 9, 2012

The red stripe form of red palm weevil (referred to here as Rhynchophorus vulneratus) is harvested for food from nipa palm trunks in parts of Sumatra by rural and semi-rural agrarians. Nipa palms (Nypah fruticans; known as buah atap in Indonesia) typically grow in swampy muddy areas (in either fresh or brackish water conditions) and the fronds are used as thatch roofing, or basket making. Most of the trunk of the nipa palm grows underground and the leaves and flower stalks grow above ground. The sap and flowers are sweet, rich in sugars, and can be fermented. The trunk is high in starch and can be harvested, pounded, and dried to form a type of sweet “sago” flour.

Another use of the palm is for the deliberate rearing of R. vulneratus larvae for harvesting and eating. Adult weevils are attracted to exposed damaged trunks and in some instances salt may be applied to the cut area which reportedly increases the attractiveness to breeding weevils. Adult weevils attracted to the palm trunk release an aggregation pheromone which further amplifies the attractiveness of the palm for breeding and feeding. Female weevils use their long rostrum or snout to chew holes into the trunk and eggs are laid (oviposited) into these holes. After several days, the eggs hatch and the small first instar weevil larvae burrow into the trunk to feed.

Palm trunks prepared for weevil attack are opened with an axe and machete after about six weeks. If the trunk is infested with weevil larvae a distinctive fermenting odor emanates from the trunk when it is opened, the internal tissue has oxidized and taken on a brownish color with interspersed ginger-colored gelatinous globs. This fed upon and fermenting material has the consistency of sloppy oatmeal (porridge). Weevil larvae feeding inside the palm trunk are easy to find because they make large diameter tunnels, and disturbance and probing of tunnels causes the legless larvae to wriggle vigorously and once they start to move they are easy to pick out of the tunnels.

The larvae are very high in protein and are considered by FAO to be an insect food that has potential to be commercialized because it requires low inputs for the quantity and quality of nutrition provided. About 1,700 species of insects are eaten by humans, mainly in the tropics because they are available year round, diversity is high, and the harvest and sale of insects for human food is a good income supplement. Human consumption of insects is called entomophagy.

Large R. vulneratus larvae harvested from nipa logs in Sumatra can sell for as much as 1000 rupiah (~ $0.11 US) each while smaller larvae fetch around 500 rupiah. Larvae can be cooked before being eaten. To prepare larvae, the large head capsule is removed, larvae may be blanched quickly in boiling water before being battered and deep fried or prepared as a type of curry. When prepared this way weevil larvae are reminiscent of cooked shrimp or squid. Another selling point for these larvae is their apparent potency as an aphrodisiac (something I can’t confirm or deny after eating many). One of our field assistants refused to eat the larvae because he was working away from his village and wouldn’t see his wife for the next two weeks. This may be a powerful testimony to the power of this aphrodisiac.

Alternatively, larvae can be eaten raw straight from the nipa trunk. Smaller larvae are preferred because they are easier to chew and swallow. However, large larvae are no problem to eat alive. The best way to eat palm weevil larvae raw is to hold them by the head capsule between your thumb and forefinger, place the larva’s body in your mouth, and bite behind the head severing it from the body and leaving the head capsule between your fingertips. Palm weevil larvae from nipa palms are surprisingly sweet, the texture internal body contents is smooth and agreeable, and they don’t have a foul or weird taste (you’d expect them to taste like rotting wood but they don’t!) The larva cuticle or skin is very chewy and can be spat out or easily swallowed.

I was very surprised at how easy these larvae were to eat straight from the nipa palm trunk in the jungle. We washed the larvae with some drinking water to remove the fermenting palm mush prior to eating them. Our guides indicated that the most preferred weevil larvae are taken from nipa palms while those harvested from the crowns of coconuts have a less agreeable taste and texture.

For more info:
Red Palm Weevil on CISR
Edible Forest Insects – Humans Bite Back!!
Beastly Bugs or Edible Delicacies?
Time for a ‘Bug Mac’? The Dutch Aim to Make Insects More Palatable
Entomophagy: Edible forest insects

 

Topics: Invasive Species, Mark Hoddle, Red Palm Weevil | 1 Comment »

Tamarixia radiata release video

By CISR Team | January 12, 2012

Christina Hoddle explains the release of Tamarixia radiata at UC Riverside. Video recorded on December 20, 2011 at University California Riverside.

For more information about Tamarixia radiata and Asian Citrus Psyllid, visit the CISR website: http://cisr.ucr.edu/asian_citrus_psyllid.html

Topics: Asian Citrus Psyllid, Christina Hoddle, Invasive Species, News, UC Riverside | 5 Comments »

First Release of Tamarixia radiata in California for the Biological Control of Asian Citrus Psyllid

By Mark Hoddle | December 20, 2011

At 11:00 am on the 20 December 2011, approximately 30-40 people assembled at the UC Riverside Biological Control Grove to participate in the first release in California of the Asian citrus psyllid natural enemy, Tamarixia radiata. Representatives from the University of California, California Department of Food and Agriculture, Citrus Research Board, and Citrus Pest and Disease Prevention Committee were in attendance. The event was covered by local media including Riverside’s Press Enterprise. After a brief introduction and description of the problem California faces with Asian citrus psyllid, and a quick review of the approximately two year process to reach this point, Mark Hoddle invited Provost and Executive Vice Chancellor Dallas Rabenstein to make the first release of Tamarixia in Southern California.

The Issue: In 2008, Asian citrus psyllid (ACP) was first found in California. This insect feeds on citrus and close relatives of citrus. The major problem with ACP is that is spreads a bacterium that causes a lethal disease in citrus known as Huanglongbing (HLB) . There is no cure for this disease. HLB is NOT in California.
ACP is widely established in LA County and pest populations are increasing and spreading in Riverside and San Bernardino Counties. This pest is almost exclusively restricted to backyard citrus. Spray programs to control ACP are difficult and expensive, and not every infested tree can be found and treated. Additional tools are needed for controlling ACP in California and biocontrol is one of these additional control options for ACP.

The Biocontrol Program: ACP is native to Asia and the Punjab of Pakistan and India and this area is thought to be part of the native range where this insect evolved. People have accidently moved this pest and HLB around the world through the accidental movement of infested citrus plants.
Over the last two years Mark and Christina Hoddle (Department of Entomology, University of California, Riverside) have worked in Faisalabad Pakistan looking for natural enemies of ACP. Faisalabad Pakistan was chosen for this research effort because this part of Pakistan has a very good climate match (~70-75%) with the major citrus producing areas of California which will mean the natural enemies released in California will be pre-adapted to very hot dry summers and cold foggy winters.

An ACP Natural Enemy from Pakistan: One parasitoid found attacking ACP in the Punjab of Paksitan is Tamarixia radiata. This is a very small insect that kills ACP nymphs either by parasitizing them (i.e., females eggs laid underneath ACP nymphs and the parasitoid larvae burrow into the nymph to feed which kills the pest) or by host feeding (i.e., female parasitoids stab the nymph with their ovipositor, a tube that they use to lay eggs, and they feed on the body juices that leak from these wounds. This kills the nymph too.)

Quarantine Studies: Safety tests conducted by Dr. Raju Pandey in Quarantine at UC Riverside clearly demonstrated that this parasitoid posed no undue risk to California’s environment, other species of insects, or humans. A 60 page Environment Assessment Report on Tamarixia that summarized the results of these studies was prepared by Mark Hoddle and Raju Pandey for review by USDA-APHIS. On 7 December 2012, APHIS issued a permit (P526P-11-04159) authorizing the release of Tamarixia from Quarantine for establishment in California for the biological control of ACP.

The Release Event: On 20 December 2011 at 11:00am, 12 glass vials containing 186 female Tamarixia and 95 male Tamarixia (total 281 parasitoids) were opened to release the parasitoids in the Biocontrol Grove at UC Riverside. The eight colonies in Quarantine from which these parasitoids were sourced for release were tested using DNA analyses to ensure that they were free of the bacterium that causes HLB. All tests were negative for HLB indicating that the parasitoids were free of this bacterium.
The Biocontrol Grove is a repository for natural enemies that have been imported for the biological control of citrus pests (e.g., scales, mealybugs, whiteflies, etc) in California over the last 50+ years. With the releases of Tamarixia in the Biocontrol Grove, one more natural enemy is being established here to combat an invasive pest that threatens California’s agricultural prosperity.

Expected Outcomes: This release of 281 Tamarixia is the first salvo against ACP in California. Over the next year or so it is anticipated that thousands of these parasitoids from Pakistan will be mass reared and released throughout LA, Riverside, and San Bernardino Counties and other areas as the pest continues to spread. Once Tamarixia establishes it will move by itself to find new populations of ACP to attack and kill. The parasitoids will have the ability to enter areas to kill ACP that may be difficult or impossible to reach for pesticide applications.

Tamarixia will *NOT* eradicate ACP from California but this natural enemy should reduce the populations of ACP in California. Every ACP killed by Tamarixia will be one less pest for homeowners and commercial citrus growers to worry about.

For More Information: These websites have more information on ACP and the work in Pakistan looking for natural enemies of ACP.
http://cisr.ucr.edu/asian_citrus_psyllid.html
http://cisr.ucr.edu/citrus_greening.html
http://cisr.ucr.edu/blog/psyllids/hunting-for-natural-enemies-of-asian-citrus-psyllid-in-pakistan/

Topics: Asian Citrus Psyllid, Christina Hoddle, Mark Hoddle, News | 5 Comments »

Looking for the Asian Tiger Mosquito in Southern California

By CISR Team | December 9, 2011

In September 2011, Asian Tiger Mosquito (Aedes albopictus) was found in the Southern California. Small pockets of communities were reporting extremely aggressive, daytime biting mosquitoes – a telltale sign of the Asian Tiger Mosquito. The Asian Tiger Mosquito was first found in isolated pockets of California in the early 1070’s. It was eradicated, but showed up again in the late 80’s and again in the early 2000’s. This time, the potential vector-carrying mosquito was reported in the city of El Monte, about 10 miles East of Los Angeles.

In response, two LA based agencies worked together to inform the public about its new mosquito resident and to determine the extent of its establishment in the area. The Greater Los Angeles County Vector Control District (GLACVCD) and the San Gabriel Valley Mosquito & Vector Control District (SGVMVCD) cooperatively began surveying a 20 square mile grid of homes in the El Monte. Officials knocked on doors to inform residents of the new pest, and asked for permission to check each property for potential breeding grounds around their homes.

Truc Dever, Director of Community Affairs and Steven Vetrone, Assistant Vector Ecologist are two officials from GLACVD who participated in the sweep in El Monte.

“If the Asian tiger mosquito becomes established here in LA County, it would be a game changer for all of us. Residents would need to be concerned about disease-transmitting mosquitoes biting them during the day,” Dever said.
Dever and Vetrone participated in a 20 square mile grid by knocking on doors in a South El Monte neighborhood. They had two primary goals: help increase the public’s awareness of the Asian Tiger Mosquito and check for areas that could provide a breeding ground. They walked around with the home owners to point out potential problems. Each pool of standing water was carefully examined for larva and eggs, and a few samples were taken back to the lab for further examinations.

The Asian Tiger Mosquito differs from other mosquito’s in that it is an aggressive day time biter. It can also carry a number of vectors like dengue, yellow fever and west nile virus. Breeding grounds can include anything that holds standing water. Trash can lids turned upside down proved popular culprit, as well as water trays under garden pots. Even some unsuspecting plants that hold water on their leaves were potential candidates for mosquito eggs.

“We need the public’s help in order to control and eradicate this dangerous pest. We are asking everyone to call us if they are getting bitten by mosquitoes during the day.” Dever said.

For more information on the Asian Tiger Mosquito, visit the CISR page

Los Angeles officials are asking residents to call and report if they see any black and white mosquitoes that bit during the day. Please contact the Greater Los Angeles County Vector Control District at (562) 944-9656 (www.glacvcd.org) or the San Gabriel Valley Mosquito & Vector Control District at (626) 814-9466 (www.SGVmosquito.org)

Topics: Asian Tiger Mosquito, Invasive Species, News | 1 Comment »

Hunting for Natural Enemies of Asian Citrus Psyllid in Pakistan

By CISR Team | November 8, 2011

Asian citrus psyllid (ACP) was found in California in late 2008 in San Diego and Imperial Counties. This invasive pest sucks sap from citrus and is a major concern for California because when feeds ACP inject into trees bacteria that cause a lethal disease of citrus known as huanglongbing (HLB). This plant disease is incurable, is restricted to citrus, and poses zero (i.e., no) risk to humans. HLB is also known as yellow shoot disease or citrus greening.

This ACP-HLB combination has been particularly devastating following its arrival in major citrus producing areas. In Florida for example, 60,000 acres of citrus, about 10% of commercial production, was taken out by HLB within 4-5 years of the first detection of the disease. At the time this blog was written (November 2011), HLB had not been detected in California. However, many suspect that the disease is present in California, and could be residing undetected in backyard citrus, possibly in plants that were smuggled into the state from areas where HLB is present (e.g., Asia, Mexico, or Florida).

Since 2008, large ACP populations have developed in Los Angeles (LA), Riverside, and San Bernardino, Counties. The vast majority of infestations found by the California Department of Food and Agriculture’s (CDFA) monitoring program have been detected in urban areas. Citrus is a very popular backyard fruit tree and homeowners grow a large variety of different citrus including oranges, mandarins, lemons, limes, kumquats, and grapefruit. It has been estimated that there is more citrus growing in people’s gardens than there is in all of California’s commercial citrus production areas combined. Surveys by UC Riverside scientists working on ACP in LA have found that ACP is encountered most often on lemons and limes, and populations can reach very high levels on Mexican limes, which appear to be a highly favored host.

Containing ACP in urban areas is a major challenge that the CDFA and Citrus Research Board (CRB) have jointly undertaken. The management plan involves treatments of residential trees that have ACP and neighboring trees within a prescribed distance of the infested tree that triggered treatments. Pesticide applications may include foliar sprays to kill ACP eggs, nymphs, and adults, and soil drenches with approved systemic insecticides that move inside the plant killing ACP when they suck sap. Finding and treating ACP infested citrus is a difficult and expensive task, and some homeowners don’t like the idea of pesticides being applied to citrus in their gardens.

UC Riverside with support from CDFA, CRB, and the Citrus Health Response Program (CHRP) has initiated a classical biological control program for ACP. This approach to ACP control involves finding natural enemies of the pest in its native range. Most scientists who work on psyllids, the group to which ACP belongs, agree that this insect is probably native to parts of central and southern Asia and has been moved unintentionally on citrus into areas where it is not native. Once in these new areas, with lots of citrus to feed on, favorable year round climates, and a lack of specialist natural enemies, ACP populations increase and spread rapidly.

Part of the native range of ACP is the Indian subcontinent, and the very first study on ACP was published by two scientists Mohammad Hussain and Dina Nath in 1927 . They conducted their research on this citrus pest in the Punjab region of modern day Pakistan and India where is it was associated with declines in lemons and oranges. Hussain and Nath (1927) also reported that there were nine species of parasitoid attacking the nymphs of ACP and that parasitism of this pest could sometimes exceed 90-95% at certain times of the year. One species of parasitoid, Tamarixia radiata, an eulophid that preferentially attacks the fourth and fifth instars of ACP was reared described from specimens that emerged from ACP infesting lemon leaves in Lyallpur in 1922!! This parasitoid has been used in Florida, Texas, Mexico, the Caribbean, Central and South America for biological control of ACP.

The Punjab has a very good climatic match (about 70% similar) with the major citrus producing areas in the Central Valley of California. Biological control theory suggests that climates that are similar in the pest’s region of origin and the intended receiving range for natural enemies is important because it increases the likelihood that biological control agents will be well adapted to the climatic conditions in the area into which they could be introduced. There are basically three seasons in the Punjab; cool and foggy (October – February), hot (March-June), baking hot and humid (monsoon season July – September).

The Central Valley is characterized by very hot dry summers and cold foggy winters (Tule fog). It is anticipated that parasitoids of ACP sourced from the Punjab of Pakistan will be well adapted to California’s citrus growing areas.

Foreign exploration for natural enemies of ACP in the Punjab of Pakistan was initiated with a trip over the period 28 August 2010 to 5 September 2011 to assess the potential for collaboration with scientists in the Department of Agri-Entomology at the University of Agriculture Faisalabad (UAF) (Faisalabad was formerly known as Lyallpur). It was quickly determined that UAF would be an excellent base for this project because it had research plots of citrus infested with ACP that were not treated with insecticides, UAF is closely positioned to Sargodha and Toba Tek Singh important commercial citrus production areas in the Punjab, and the Vice Chancellor of UAF, Dr. Iqrar Khan, a MS and Ph.D. graduate from UC Riverside (supervised by Dr. Mikeal Roose) and world leader in HLB research was extremely enthusiastic about developing a joint project between UAF and UC Riverside.

A four week trip to Pakistan over the period 11 March 2011 to 10 April 2011, resulted in the setting up of two research plots in Square 9 and PARS, both of which are UAF citrus research areas. In these two plots ACP and natural enemy population dynamics and flush growth patterns are being studied weekly on two different types of citrus, kinnow and sweet orange. Kinnow, a type of mandarin bred at UC Riverside by H.B. Frost in 1935 and introduced to UAF in 1940 and the first tree was planted in Square 9 one of our current study sites! Kinnow accounts for about 85% of citrus produced in the Punjab and it is an export crop for Pakistan. A Masters Student in Agri-Entomology, Mr. Shouket Zaman Khan was trained to do this work, and he is supervised by Dr. Mohammed Jalal Arif. At the end of this period, 80 Tamarixia radiata (24 males and 56 females) and 70 Diaphorencyrtus aligharhensis (25 males and 45 females) were returned to Quarantine at UC Riverside and used to establish colonies. All living material for this project is moved under USDA-APHIS permit and is cleared at LAX by Homeland Security Personnel before being moved to the Quarantine Facility at UCR.

The third trip to Pakistan to look for ACP natural enemies was conducted over the period 6 June 2011 to 13 June 2011. This trip was very successful and 406 T. radiata (151 males and 255 females) and 25 D. aligarhensis (21 males and 4 females) were returned to UCR’s Quarantine facility.

The fourth collecting trip to Pakistan was completed over 28 October to 4 November 2011. From this collecting trip about 800 T. radiata and approximately 30 D. aligarhensis were brought back to UC Riverside. From all of these collections, just two parasitoids of ACP have been collected, T. radiata and D. aligarhensis. Consequently, we are questioning the validity of Husain and Nath’s (1927) claim that ACP nymphs were attacked by nine different species of parasitoid. Based on our experiences with collecting and rearing large numbers of specimens from Pakistan and from three different time periods it seems unlikely that the parasitoid fauna associated with this pest is diverse.

Shipments of natural enemies carried from Pakistan to UCR are processed in a receiving room in Quarantine. During this initial inspection phase, shipments are checked for accidental contaminants which are eliminated and destroyed immediately. Colonies of these natural enemies are set up in Quarantine at UC Riverside and are maintained as isocage lines to preserve genetic diversity. Maintaining colonies of ACP and its natural enemies in Quarantine is very difficult, time consuming, and requires meticulous attention to detail. Colonies of ACP and natural enemies are double caged, kept in secure rooms that are within secure rooms, and workers must wear coveralls which are removed in a designated changing room once work in the colonies is finished for the day.

T. radiata and D. aligarhensis are undergoing safety testing to ensure that they will pose no undue risk to the environment in California. Release of T. radiata for biological control of ACP in California is anticipated for Spring 2012 once the Environment Assessment Report has been reviewed and approved by USDA-APHIS.

Topics: Asian Citrus Psyllid, Christina Hoddle, Mark Hoddle, Psyllids | 6 Comments »

Testing Red Palm Weevil Pheromone Traps in the Philippines

By CISR Team | November 7, 2011

In August 2010, red palm weevil (RPW), was officially detected in Laguna Beach, Orange County California. This insect was recovered from a dying Canary Islands palm in a residential property and has been declared by FAO to be the world’s most destructive palm pest. At least 2-3 additional palms are thought to have been killed by this insect in Laguna Beach, and two Canary Islands palm trees showing RPW damage have been treated with insecticides. Intensive trapping efforts by CDFA for more than one year using the commercially-available RPW aggregation pheromone, ethyl acetate (weevil magnet), and fruit additives placed together in bucket traps have failed to capture RPW in the immediate vicinity of previous detection sites.

This pheromone-based trapping program has been used successfully for monitoring in other countries where the orange and black form of R. ferrugineus has invaded, and it is an important management component of IPM programs in Middle Eastern commercial date plantations for this pest.

A major point of interest regarding the trapping program in California using the commercially available RPW pheromone is whether or not it is attractive to the red palm weevil morph found in Laguna Beach. The RPW color morph found in Laguna Beach is black with a prominent dorsal red stripe that runs from the rear margin of the head across the thorax to the anterior margin of the abdomen. Until its detection in southern California this red stripe form of RPW was only known from southeast Asia (e.g., south Thailand, Malaysia, Indonesia, and the Philippines.)

To assess the attractiveness of the commercial RPW pheromone used by CDFA in Laguna Beach to the “vulneratus” morph, a small trial was run in a 60 ha commercial coconut plantation in Quezon on Luzon Island in the Philippines from 20 October 2011 to 26 October 2011. This area has been reported previously to have both RPW color morphs in sympatry. Three treatments were set up and checked twice per day at 6:00am and 4:00pm for captures of RPW:

Treatment one:This treatment consisted of traps with RPW aggregation pheromone + ethyl acetate (weevil magnet) + fermented dates. The aggregation pheromone and weevil magnet were supplied by CDFA and are the same products being used to monitor for RPW in Laguna Beach. Previous studies have demonstrated that fermented dates are an extremely potent “additive” to this set-up for attracting the orange and black morph of RPW. Dates were used for 3 days and then replaced with cut pieces of palm hearts. Traps were hung either in immature coconuts (a highly preferred host stage for RPW to attack) (see photo below) or on dead coconut trunks ~ 2.0 m above the ground (a height similar to that of CDFA deployed traps in Laguna Beach). This treatment was replicated three times in the plantation. 

Treatment 2: Freshly felled coconut palms that were bucked, stacked, and had palm hearts arranged on the wood pile were inspected for RPW attracted to this resource. This treatment was replicated three times. The plantation owner was asked to fell five palms that were suspected to be infested with RPW. All five palms exhibited extensive internal damage, but no RPW life  stages were found and it is was difficult to determine if feeding damage had been caused by RPW or another serious coconut pest, Oryctes rhinoceros beetles. 

Treatment 3: This treatment consisted of Treatment one (bottle trap with RPW pheromone + ethyl acetate + fermented dates or palm hearts) and Treatment two combined and was replicated three times at different sites in the plantation. 

Results: The results of these trials were clear cut and consistent. Treatments one and two did not result in the capture of any RPW over the 6 day monitoring period. Treatment three, pheromone bottle traps placed on freshly cut stumps of coconut palms with cut sections of palm trunk and palm hearts resulted in the capture of 23 RPW over the course of the trial. All three replicates of Treatment three resulted in the capture of RPW and the first captures were made ~ 24 hr after the palms were felled, sectioned, and stacked with the pheromone bottle trap. Captures ranged from 1 – 5 RPW at a site. RPW were found either inside the bottle traps, or more often underneath the wood stacked on top of the palm stump, or in chainsaw blade width slices made into bucked pieces of palm trunk. Adults are exceptionally thigmotactic and can push themselves deeply into very tight crevices, hence the notches on the cut pieces of palm trunk.

The color morphs of RPW that were captured in Treatment three included R. ferrugineus, “R. vulneratus”, and a color and pattern spectrum between these two distinct forms.

 

The sex ratio of captured RPW was highly female biased (n = 18 females [78%]; n = 5 males [22%]). Unidentified phoretic mites were found on 60% and 67% of males and females, respectively. Phoretic mites have been recorded previously on RPW adults but their potential role as control agents of RPW is uncertain.

The majority, 78% (n = 18) of RPW were captured when treatments were examined at 6:00am, the remaining 22% (n = 5) were captured at 5:00pm. This result suggests the RPW flight activity in the Philippines may be crepuscular or nocturnal.

Conclusions: The RPW traps baited with pheromone and weevil magnet (ethyl acetate) used by CDFA in Laguna Beach failed to capture any weevils in a commercial coconut plantation in the Philippines unless they were deployed in conjunction with freshly felled coconut palms. The pheromone + weevil magnet + fruit additives alone did not catch any weevils, nor did the fresh-cut palm logs attract any weevils.  The reasons for this are not clear. This small study had low treatment replication and treatments were not blocked to account for site effects – although they were dispersed widely through the plantation. The bottle traps may not have been adequate for retaining RPW attracted to Treatment 1. This trial was run at the end of the monsoon season, a time of year reported to have low RPW activity. This situation may have been worsened by a wetter than normal “dry” season (the owner of the coconut plantation indicated that the dry season had been unusually wet this year) that preceded the monsoon season and RPW densities may have been lower than normal for this time period.

Thus, our results suggest that the bait combinations being used in Laguna Beach may not attractive to the RPW morph that is present.  Our results suggest that at a minimum, pheromone and weevil magnet baits should be deployed in combination with fresh-cut palm material, especially newly cut palm trunks and if possible this treatment should be set up and trialed in Laguna Beach to see if it can attract and retain RPW.

Topics: Christina Hoddle, Mark Hoddle, Red Palm Weevil | 1 Comment »

Invasive species rise after 9-11

By CISR Team | October 21, 2011

Recently CISR Director, Mark Hoddle, was interviewed on the Voice of Russia Radio about new research on invasive species after 9-11. The Associated Press reported hundreds of agricultural scientist who normally conducted inspections for invasive species were redirected to Homeland Security, causing a huge spike of invasive species coming into the US. AP reports its cost the US billions of dollars in cleanup. Follow the link for the interview on this problem.

“American anti-terror measures prompt insect invasions” 

Topics: Invasive Species, Mark Hoddle, News | No Comments »

Palmaggedon: Are California’s Palms about to Face the Perfect Storm?

By Mark Hoddle | July 24, 2011

Two species of giant palm weevils, Rhynchophorus ferrugineus (commonly known as the red palm weevil) and Rhynchophorus palmarum (South American palm weevil) have both been detected in Southern California. The red palm weevil (RPW) was officially discovered in Laguna Beach in Orange County (California USA) in September 2010. The beetle has been declared by FAO as a category-1 pest of date palms in the Middle-East. RPW, native to south east Asia, has been particularly devastating following its successful invasion into Mediterranean countries in Europe and Africa (e.g., Egypt). For about one year now, the California Department of Food and Agriculture (CDFA) has been intensively monitoring for RPW in Laguna Beach with approximately 250 RPW traps baited with aggregation pheromone and fruit. These traps have failed to capture adult RPW. Visual ground inspections of palms in Laguna Beach have identified trees potentially infested with RPW. One palm was inspected on 25 May 2011 and physical inspection confirmed feeding damage from RPW, but NO live RPW were found. This palm was treated with insecticides. On 2 June 2011, a second palm displaying symptoms of RPW damage was inspected physically. Again, feeding damage was confirmed but NO live RPW were detected. This palm was also treated with insecticides.

In December 2010 reports were received from palm enthusiasts in Tijuana Mexico of dying Canary Islands palms and these moribund palms were displaying symptoms similar to that expected from a RPW infestation. Physical inspection confirmed the presence of live palm weevils in at least one palm, and this weevil was officially identified at Rhynchophorus palmarum, the South American palm weevil (SAPW). This weevil is native to Mexico, Central and South America and is a well known palm pest, especially of coconuts. This weevil has been recorded feeding on 35 plant species in 12 different families, but is found predominantly on palms. SAPW has been problematic in Puerto Vallarta where in 2008 it was apparently linked to the mortality of more than 500 coconut palms in this popular tourist area.

In addition to the damage that SAPW larvae inflict while feeding inside the palm crown and trunk, this weevil also vectors a nematode, Rhadinaphelenchus cocophilus, which causes red-ring disease of coconut. The contamination of healthy plants with red-ring disease occurs only if SAPW are present. The nematode cannot survive outside of it’s palm hosts and it is moved from palm to palm by adult weevils. The nematode may also cause disease in oil palms, Elaeis guineensis.

Following the discovery of SAPW in Tijuana, the CDFA commenced a monitoring program in San Ysidro in San Diego County (California USA) in March 2011. The area under surveillance with traps baited with SAPW aggregation pheromone is close to the USA-Mexico border. Mexican collaborators have also deployed SAPW pheromone traps in Tijuana to monitor for this pest. Monitoring efforts have trapped adult male and female SAPW weevils in San Ysidro and Tijuana that flew into traps in response to aggregation pheromone. So far no infested palm trees have been found in the San Ysidro area. Consequently, it is difficult to determine whether or not SAPW has breeding populations in San Diego County as pheromone traps may simply be catching SAPW dispersing from Tijuana into Southern California. This situation is being monitored very closely by the CDFA and the USDA.

Potentially, for the first time, an extraordinary invasion scenario may be unfolding in Southern California with respect to exotic palms and invasive palm weevils. Should RPW and SAPW establish in Southern California this will be the first time these two weevils have ever been together in the same place at the same time and potentially attacking the same palms simultaneously!

So what could this mean for the palms of Southern California? This is obviously difficult to answer, but one potential concern could be the ability of RPW to acquire from SAPW the red-ring disease nematode and spread it as well. If this happens, it may increase the vector capacity for this nematode as two weevil species instead of one could spread the nematode to susceptible palms. This could cause a severe disease epidemic for California’s palms. Should both palm weevils infest the same palm tree will this speed up the rate of palm mortality or will different larvae species attack each other while competing for food and slow the rate of palm mortality? Could both weevil species interbreed and produce less fit offspring (hybrid or outbreeding depression) or could hybridization create a more aggressive strain of palm weevil (hybrid vigor)? Finally, what is amazing about speculating over this situation is that it is an entirely a human-made problem! People have moved exotic palms to Southern California (e.g., Canary Islands palms from the Canary Islands and date palms from the Middle East), and people have facilitated the movement of exotic palms weevils from South East Asia (i.e., RPW) and Latin America (i.e., SAPW). People have also provided an ideal but highly artificial environment (i.e., irrigated urban and agricultural landscapes) for invasive weevils to potentially establish and proliferate on exotic palms in a part of the world where none of the players (i.e., palms and weevils) are native, but the climate is agreeable for their mutual co-existence.

Topics: Invasive Species, Mark Hoddle, News, Red Palm Weevil, Rhynchophorus palmarum | 7 Comments »

Red Palm Weevil in Laguna Beach Dealt a Second Blow

By Mark Hoddle | June 2, 2011

On June 2 2011, a second Canary Islands palm was inspected for red palm weevil in Laguna Beach, approximately one week (May 25 2011) after the first palm suspected to be infested with red palm weevil was inspected and confirmed to have red palm weevil activity, and subsequently treated with insecticides.  

The process for selecting and treating palms at Laguna Beach has followed a strict process: (1) Palms with suspected red palm weevil damage (figure “7″ notches and straight edges on the tips of fronds, or the presence of pupal cocoons lying on the ground underneath palms) were identified from visual surveys conducted on the ground. These palms were recommended for secondary inspection. (2) Detailed secondary visual inspection of suspect palms required the cutting of an observation window to access the central growing area of the palm to look for red palm weevil feeding damage. This is a highly favored feeding and breeding site. During frond removal to create the observation window, cut  palm fronds were examimed for weevil feeding damage, the presence of pupation chambers and cocoons, and live and dead life stages, especially pupae and adults. (3) Confirmation of red palm weevil infestation (e.g., the presence of pupal cocoons in the tree, feeding tunnels made by larvae, or body parts of dead adults) based on the detailed secondary inspection triggered pesticide applications to control the pest population in the palm. This three step evaluation process culminating with the ultimate decision to treat with insecticides involved representatives from the Orange County Agricultural Commissioner’s Office, CDFA, USDA and local (UC Riverside), national (University of Florida), and international University (Spain and Israel) experts.

At the Pacific Coast Highway site, approximately 10  lower-level fronds on this palm were either dead or dying, and about 5-7 additional fronds exhibited red palm weevil feeding damage (i.e., the terminal ends of fronds were straight-across  instead of pointed and figure “7” notches  were present). Because of this easily observed visual damage, this palm was thought to be infested with red palm weevil and was prioritized for seconday inspection and if weevil activity was obvious, treatments would be applied.

This inspection and treatment event was organized by Dr. John Kabashima (UCCE) and was attended by Dr. Mark Hoddle (UC Riverside), Laura Petro and Mohammed Alzubaidy (both CDFA), Nick Nisson (Orange County Entomologist), Roger Peterson (Approved Tree Care), Will Harrison (Target Specialty Products),  and Chuck Galanti (MPA Landscape Services).

Starting at 8:00am, Caltrans closed one northbound lane of the Pacific Coast Highway (PCH) to allow Approved Tree Care to set up a bucket lift to access the crown of the potentially infested palm. UC Riverside Entomologist, Mark Hoddle, with the assistance of an Approved Tree Care employee maneuvered the bucket approximately 25-30 feet above the PCH to reach the palm crown. An observation window was cut into the crown and approximately 12 palm fronds and around 5 fruit bunches were removed from the crown to create the window. None of the fronds cut from the palm showed evidence of red palm weevil tunneling, pupation chambers, or empty cocoons.

Inspection of the cut bases of fronds that had been removed previously during routine maintenance revealed the presence of old red palm weevil cocoons, and empty tunnels made by feeding larvae. The body parts of one dead adult red palm weevil were found. This dead adult weevil was red and black, the same color morph that has been found at other sites in Laguna Beach.

NO LIVE RED PALM WEEVIL LIFE STAGES WERE FOUND DURING THESE INSPECTIONS.

All material cut from the palm was chipped on site and transported to a local landfill to be buried.

The inspection window was treated with the maximum label rate of bifenthrin (donated by Target Specialty Products). Bifenthrin is a contact insecticide. It will kill red palm weevils by direct contact should wet spray hit the weevils, or if weevils move into the palm after the application they may be killed when they contact dried residues. This product provides immediate protection to cut areas of the palm that red palm weevil may find attractive and attack.

A second insecticide, 5% imidacloprid, was hand-injected with an Arbor-Systems Wedgle Direct-Inject System into the trunk about 0.5 m above the ground. Imidacloprid is a slow moving systemic insecticide and it will move from the point of injection through the trunk of the palm to the crown where red palm weevil larvae and adults may be feeding.

Injection needles were gently knocked into the trunk with a spacing of approximately six inches around the entire circumference. One hand-squeeze of the Direct-Inject System applied 1 ml of product through each needle into the trunk.  Needles were removed following injections and sanitized prior to reuse. Trunk injections were made by Will Harrison, Target Specialty Products.

A third insecticide, dinotefuran, a fast moving systemic, was hand sprayed onto the trunk of the palm from ground level to a height of approximately 2 meters by a certified arborist from Approved Tree Care. This product will move quickly across the bark to enter the nutrient transport system of the palm which will move it to the crown where red palm weevil larvae and adults may be feeding. It is anticipated that this product will reach the crown more quickly than imidacloprid, but its persistence in the crown will not be particularly long. Although it is thought that imidacloprid will take longer to reach the crown than dinotefuran, it will last for significantly longer thereby increasing the time the palm will be protected internally from red palm weevil.

The CDFA collected palm foliage prior to the application of pesticides to test for insecticide residues. These analyses will provide the base line against which the concentration of the products applied today will be compared. The CDFA intends to take monthly foliage samples to test for imidacloprid and dinotefuran to determine how quickly and in what concentrations these insecticides occur in the foliage of this treated palm post-treatment. These data (especially the concentrations of the insecticides) will tell us how effective treatments may have been for controlling red palm weevil in this palm.

A pheromone bucket trap for red palm weevil was set at this site to trap adults that may fly to this palm. Every two weeks the CDFA will look for red palm weevil activity in the palm crown through the observation window.

For more information on Red Palm Weevil, visit the CISR website

Topics: News, Red Palm Weevil | 4 Comments »

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