A ruinous insect is on its way to kill L.A.’s already diminishing palm trees — if entomologist Mark Hoddle doesn’t get ‘em first.
From the trunk of a rental car in a dusty parking lot at the Sweetwater Reserve in Chula Vista, Calif., Dr. Mark Hoddle carefully arranges the ingredients for a 5,000-year-old Egyptian recipe. Plump golden dates and baker’s yeast fill rows of glass canning jars as water is methodically poured to the brim of each container. Over the next month, this ancient concoction will ferment to create what Hoddle calls his “pharaoh’s brew.” It’s not the hefeweizen he generally enjoys, but it’s an enticing — and ultimately deadly — beverage to the South American palm weevil.
Hoddle is an entomologist and runs the Center for Invasive Species Research at UC Riverside. He’s employing his brewmaster skills in an effort to trap and study the invasive pest which has the potential to create what scientists call a ‘palmageddon’ throughout the Southland. The insect, identifiable by its glossy black body and long snout, enjoys burrowing and laying eggs in the crown of targeted trees. Their arrival in California puts the state’s distinctive palm tree population in danger.
“The South American palm weevil poses an unprecedented threat not only to the palm trees that inhabit the urban areas of California and give it its iconic look, but it’s also a serious threat to date growers in Coachella Valley,” Hoddle says. “It can fly strongly [up to 28 miles in a day] … humans can [also] accidentally move them from infested palms to clean areas.”
Mark Hoddle, director of the Center for Invasive Species Research at UC Riverside, sets bucket traps to capture South American palm weevils at the Sweetwater Summit Regional Park in Chula Vista, Calif. The traps feature Hoddle’s “pharaoh’s brew” used to attract the invasive insect. Photos by Alexis Garcia.
Hoddle’s research specializes in biological control, which focuses on managing invasive species by identifying their natural enemies. A native of New Zealand, Hoddle turned his boyhood passion for bugs into an academic career. Since 1997, he has directed UC Riverside’s invasive species research unit along with his wife Christina, who is also an entomologist working at the university. The pair’s research has led them to the far reaches of the globe — including Pakistan, Guatemala, Saudi Arabia and the Caribbean — to study and find natural solutions to Southern California’s pest problems, earning Hoddle the moniker “Indiana Jones of insects” from his peers.
“It’s kind of a cool nickname,” Hoddle says as he makes his way through the tall mustard weeds along the trails of the reserve. “I just hope it doesn’t make Harrison Ford mad.”
Since its arrival from Mexico in 2010, the South American palm weevil has been attacking and killing palm trees in San Diego County at an alarming rate. Hoddle estimates that of the 600 palms his team has mapped in the Sweetwater Reserve, nearly 30 percent of them have been destroyed by the weevil in the last three years alone. What makes them so deadly is the fact that their larvae hatch from inside the tree, making infected palms difficult to detect until it’s too late. An infected tree can host thousands of the two-inch-long insects before its fronds begin to brown and the crown collapses in on itself. The weevil can also transmit red ring nematode, a parasite that can be deadly to multiple species of palms in the region.
“The weevil is not going to stay in San Diego County. It is now as far north as La Jolla, and there’s no reason to think it will stop there,” Hoddle says. “This will work its way into Los Angeles County.”
With the future arrival of the ruinous weevil all but guaranteed in Los Angeles, — which is already experiencing heavy losses of its palm tree population estimated to take 30 to 50 years to replace — Hoddle has focused on the Sweetwater Reserve as an important battleground in the fight against the destructive pest. Every month for the last three years, he has ventured to the reserve to set and monitor bucket traps containing his pharaoh’s brew potion along with a small plastic container of pheromones to attract the insects. Once inside the bucket, the beetles fall into a bright pink bath of antifreeze, where they drown and are preserved until Hoddle can collect them to bring back to his lab.
“The South American palm weevil poses an unprecedented threat not only to the palm trees that inhabit the urban areas of California and give it its iconic look, but it’s also a serious threat to date growers in Coachella Valley.”
Mark Hoddle, director of Center for Invasive Species Research
On this particular visit, Hoddle records 129 beetles in his research ledger. He says the warmer weather attracts more of them — his traps hauled in more than 300 of the weevils last June. By experimenting with various trap shapes and bait, Hoddle can gauge what methods work best to attract and capture the pest. He then relays this information to local growers and city officials to implement on the field.
The weevil invasion is not the first major threat to California’s palms. Hoddle estimates the state sees about nine new invasive species cross its borders every year. Of those, only a few will develop into serious threats to local plant life. The impact of invasive species not only translates to environmental damage but can also lead to huge economic losses to the state’s agricultural sector. The ornamental palm industry alone is worth an estimated $70 million per year and Coachella’s date industry employs more than 6,000 workers and generates $68 million in annual revenue.
Entomologist Mark Hoddle tallies the number of South American palm weevils captured in a trap before preparing them to be examined at his UC Riverside laboratory. Photos by Alexis Garcia.
So far, Hoddle says the best way to protect endangered palms is by spraying them with insecticide, but the ultimate goal would be finding a permanent and natural solution.
A key weapon to defeating the South American palm weevil could rest in Brazil, where Hoddle has identified a parasitic fly as a natural enemy. Current observations show that the fly can kill up to 50 percent of the weevil population over the course of a year. Hoddle is eager to travel south and bring the fly back to his lab for observation and study before releasing it into the wild. He says the biggest challenge facing his team is securing and maintaining enough funding for research. His weevil research is currently funded by a California Department of Food and Agriculture specialty crops grant that runs out in 2020.
“We have very clean results from field trials now, but the issue is it’s going to cost money to do this,” Hoddle says. “One thing we are interested in pursuing is determining whether or not a biological control agent can be used to suppress the population growth of the weevil, that would give a lot of pest control that is not only effective but safe. That would be awesome.”