Rhynchophorus palmarum

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

Anonymous — Mon, 20 Jan 2020 02:08:26 +0000

Palmageddon: Are California’s Palms about to Face the Perfect Storm? Anonymous (not verified) Sun, 01/19/2020 - 18:08 More Blog Posts 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.

Damaged Palm in background compared to healthy palm in foreground. A collapsed palm crown is indicative of weevil feeding damage.

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.

Adult Rhynchophorus palmarum found next to its palm host

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.

The Making of a South American Palm Weevil Mini-Documentary for “Deep Look” with KQED

Anonymous — Wed, 18 Dec 2019 09:15:23 +0000

The Making of a South American Palm Weevil Mini-Documentary for “Deep Look” with KQED Anonymous (not verified) Wed, 12/18/2019 - 01:15 More Blog Posts CISR Team April 05, 2017

The weevil killed palm in San Diego that was taken down for the KQED “Deep Look” science show.

The South American palm weevil, Rhynchophorus palmarum (Coleoptera: Curculionidae), is well established in parts of San Diego County in California and is responsible for killing numerous Canary Islands date palms. The spectacular damage this invasive pest causes and the large showy adult weevils and alien-looking larvae and pupae, captured the imagination of Elliott Kennerson and Joshua Cassidy, digital media producers for the science show Deep Look with KQED Public Television and Radio in San Francisco. After a few phone calls and ensuing discussions, Elliott made the pitch to KQED to develop a story on the palm weevil and the project was given approval for development.

A plan was made to drop a weevil infested Canary Island date palm tree in a residential area in San Diego County and from this palm weevil life stages would be collected and filmed. The first challenge was finding an infested palm, which we did, and the bigger challenge was to bring the palm down and then cut it up so we could examine the crown of the dying palm for weevils.

Paul Webb with RPW Services, Inc. put us in contact with Michael Palat from West Coast Arborists, Inc. who generously offered to taken the palm down and then dispose of it free of charge.

Paul Webb (RPW Services, Inc.) (left) and Michael Palat, West Coast Aborists, Inc. (right)

The take down of the palm was done on 27 March 2017 and filmed by Josh and Elliott. This involved a lot of camera work, including Go Pro’s strapped to the helmet of the arborist who was responsible for chain sawing the palm from the bucket lift! Adult weevils, pupae, and one larva were recovered from the palm. The weevil life stages were photographed and filmed, and flight mill activity was all digitally recorded on 28 March 2017. Hours of digital footage was recorded and this will be condensed down to about 3 minutes when the final version is produced and released for public viewing in early July 2017.

Rhynchophorus palmarum

The South American Palm Weevil Invasion in San Diego County, California

Anonymous — Wed, 18 Dec 2019 08:01:59 +0000

The South American Palm Weevil Invasion in San Diego County, California Anonymous (not verified) Wed, 12/18/2019 - 00:01 More Blog Posts Mark Hoddle October 18, 2018

The South American Palm Weevil Invasion in San Diego County, California

The Situation: The South American palm weevil (SAPW), Rhynchophorus palmarum, is a non-native pest of palms that has established populations in San Diego County in California. In December 2010, this weevil was discovered infesting ornamental Canary Islands date palms (CIDP) (Phoenix canariensis) in Tijuana, Baja California, Mexico.California Department of Food and Agriculture trapping programs detected SAPW in San Ysidro (~5 miles north of Tijuana) in San Diego County in 2011. Around 2014 reports of CIDP dying from SAPW attack were confirmed in San Ysidro. It is likely that SAPW established populations in San Diego County around 2014, or perhaps earlier than this date. Weevils have also been detected in Alamo Texas in 2012 and Yuma Arizona in 2015. SAPW has not established in Texas or Arizona.

Ornamental Canary Islands date palms are ubiquitous in California and they are a defining feature of southern California’s urban landscape

What Does the Weevil Look Like? Adult weevils are large, black in color, and about 1.5 inches in length. The adult weevils have wings and are strong fliers. Weevil larvae are whitish in color and can grow up to five inches in length. Weevil larvae pupate inside fibrous cocoons that may be found in the infested crown region or in tunnels weevil larvae drill into the base of palm fronds. Adult weevils emerge from cocoons when pupation is complete.

(A) and (B) adult SAPW. (C) Mature SAPW larva. (D) SAPW cocoon. Photo credits: (A) Mike Lewis, Center for Invasive Species Research, UC Riverside, (B), (C), and (D), Ricardo Aguilar, Aguilar Plant Care.

Where is the Weevil?Tijuana (Mexico), San Ysidro, Imperial Beach, National City, Bonita, Chula Vista, El Cajon, and San Diego City (all in San Diego County) are infested to varying degrees with SAPW. The exact area of infestation in San Diego County is not known. We are relying on community scientists and concerned citizens to report palms that are suspected of having been killed by SAPW. To report an infested palm or one killed by SAPW an online form can be completed and submitted. Click here to report an infested palm.

A concern is that SAPW may invade the Coachella Valley and once established it could become a significant management issue for growers of edible dates, an industry with an annual value of around $68 million (US).

An aerial view of an edible date garden in Coachella Valley

What Species of Palms Does the Weevil Attack? In San Diego County, the weevil has shown a very strong preference for attacking CIDP to the almost complete exclusion of other palm species at this time. Attacks on other species of palms may occur when CIDP become less common. SAPW has been documented infesting and killing açaí palm (Euterpe oleracea), African oil palm (Elaeis guineensis), Canary Islands date palm (Phoenix canariensis), coco de palmito (Euterpe edulis), coconut (Cocos nucifera), edible date palm (Phoenix dactylifera), and sago palm (Metroxylon sagu).

How Does the Weevil Kill Palms? Infestations of weevil larvae in the crown of the palm can result in death if the infestation is not treated with insecticides. The apical meristem or “palm heart” produces new fronds and extensive feeding damage to this area can kill the palm as it is unable to continue growing. Once the palm heart is heavily damaged, the crown may tilt, appears collapsed, and in some instances the crown may become detached from the trunk and drop to the ground. Advanced stages of damage results in the palm trunk being ringed by a halo of fronds.

(A) CIDP crown showing damage from SAPW feeding. (B) Palms in varying stages of SAPW infestation. (C) Palm with a “halo” of fronds that has resulted from SAPW feeding in the apical meristem. (D) Palm crown that has dropped from a SAPW infested palm and rolled down the street

Infested palms present a significant dropping hazard to people, cars, and property. In addition to the risk of crown drop, dead fronds readily fall from SAPW infested palms. Wind and rain events can increase the probability of frond dropping. Palm fronds are heavy and in the case of CIDP fronds, the base has large strong spines that can cause injuries.

Identification of Potentially Infested Palms: Palms in the very early stages of weevil attack are hard to diagnose as infested because weevils are hidden in the crown and can be very hard to find. As the infestation progresses visible symptoms may become apparent. Evidence of SAPW attack can be found in the crown and some of the easiest and earliest symptoms to observe are damage to fronds that are emerging from the center of the crown. Weevil feeding damage to immature fronds becomes apparent as the fronds grow up out of the center of the palm and the leaflets as they expand appear to be “clipped,” “notched,” or “windowed.”

(A) Dead fronds that have dropped from a CIDP killed by SAPW and (B) fallen against a fence and blocking the drive way

Protecting Palms from Weevil Infestations: The best control option for protecting palms from SAPW are systemic insecticides that are either applied to the soil, trunk, or crown. These products move into the palm and accumulate in the apical meristem, the palm heart, where weevil feeding is concentrated. These products then poison weevil larvae and adults. Palms can be “cured” of moderate to heavy weevil infestations with applications of systemic insecticides. But applications need to be made before irreversible damage to the crown has occurred. In some instances all of the fronds will need to be removed, the crown thoroughly drenched, and then gradually over time, the damaged meristematic tissue will recover and new palm fronds will begin to develop. Once these pesticide programs begin they will need to continue indefinitely to protect palms from weevil attack.

Palm fronds showing damage from weevil feeding

What is Being Done in San Diego County?: The response to the establishment and spread of SAPW in San Diego County is following several different avenues. First, weevil population cycles over the course of a year are being monitored. Results so far suggest that weevils are flying all year round and don’t seem to stop over the winter. Second, more than 470 CIDP in urban areas are being monitored every six months for SAPW caused mortality. Over a two year period about 25% of palms monitored in urban areas have been killed by SAPW. Trials testing two different types of traps (bucket vs. Picusan) and types of fermenting bait with weevil aggregation pheromone are being evaluated. Insecticide trials evaluating different types of systemic pesticides for protecting palms from weevil attack have been set up with cooperators in several areas in San Diego County where weevil activity is high. These trials will likely run for two or more years until results become available. Finally, drones are being used to monitor palm mortality in riparian areas where foot access is difficult. Results of aerial monitoring of more than 760 palms indicate that over a 2 year period 28% have been killed by SAPW.

CIDP’s heavily pruned in Tunisia to facilitate crown drenches of systemic insecticides to “cure” palms of red palm weevil, Rhynchophorus ferrugineus, infestations

(A) Bucket and (B) Picusan traps are being evaluated for their ability to capture weevils. Traps are very useful for monitoring programs to determine whether adult weevils are active in an area of concern

Drone surveillance of Canary Islands date palms killed by SAPW in the Sweetwater Reserve, Bonita California

Rhynchophorus palmarum