Could palm weevil treatment harm Point Loma-OB’s parrots and other wildlife?
Concern about insecticides’ potential effects sparks discussion, though the city of San Diego maintains that the insecticides used are safe and adhere to regulations.
As the city of San Diego grapples with infestations of South American weevils on local date palms, questions have been raised about the safety of the insecticides used to protect the trees and their potential effects on local ecosystems, including the parrots of Point Loma and Ocean Beach.
While the city maintains that the insecticides used pass safety standards set by the California Department of Pesticide Regulation, Clayton Tschudy, executive director of environmental organization San Diego Canyonlands, worries that insecticides — particularly systemic insecticides, which are sprayed at the roots and absorbed into the tree system — could be harmful to wildlife that nests in or feeds off the trees.
The majestic palm tree is part of San Diego’s iconography — symbolizing Southern California and the beach, the feel of a tropical paradise.
Tschudy, a Point Loma resident who is an environmental biologist and sustainable horticulturalist, said that because systemic insecticides travel through the tree’s entire system, it’s harder to control their effects on wildlife.
“Systemic pesticide is kind of a broad application that’s meant to kill any threat, and it’s not targeted to the beetle,” he said.
The South American palm weevil is a type of beetle that first made its presence known in Southern California in 2011. When palm weevils infest a tree, it shows signs of disease, such as brown, drooping fronds. Once larvae hatch and begin feeding on the palm heart, the tree dies.
Because the Canary Island palm trees in question are non-native, they aren’t used by as much wildlife. If systemic insecticides were being applied to native trees, Tschudy said, the impact on wildlife would be much higher because “natives have a very high habitat value, being used by all kinds of insects, by squirrels, by birds.”
However, even non-native trees have an effect on the surrounding wildlife. In Point Loma and Ocean Beach, multiple species of parrots live in and feed off the palm trees.
Sarah Mansfield, operations manager for SoCal Parrot, a nonprofit urban parrot rescue group, said a parrot’s system is delicate and can absorb toxins quickly.
“With parrots, their system — like their heart, their respiratory system — moves anywhere from five to 10 times faster than ours does, so even just a little bit of something in their little bodies that are pumping super fast is going to have a huge, almost always deadly, impact on them,” Mansfield said.
“Specifically with regard to Ocean Beach, Point Loma and all the palm trees there, that’s where the majority of San Diego County parrots go to find nesting cavities and have babies,” she added. “And they’re also eating the palm fruit. So any time that any sort of tree or plant is treated with chemicals, it’s going to have some sort of impact on whatever wildlife is consuming it or living inside of it.”
Whether birds have been harmed by such tree treatment is unclear. Mansfield said SoCal Parrots had seen birds showing signs of toxicity, likely from ingesting poison, but the exact cause could not be pinned down.
San Diego is home to five species of wild parrots: red-crowned amazons, lilac-crowned amazons, red-masked conures, mitred conures and blue-crowned conures. While all five can be found in Point Loma and Ocean Beach, that area is particularly important for the blue-crowned conure.
“Specifically in Point Loma and OB, there’s a flock of about 25 to 30 blue-crowned conures, and that’s the only place you’ll find them in Southern California. So we really like them,” Mansfield said.
City arborist Brian Widener said he could not specifically identify which insecticides are used to control the palm weevil. But he said the city’s tree services contractor, West Coast Arborists, is licensed and follows guidelines set by the California Department of Pesticide Regulation.
Donna Durckel, a group communications officer for the San Diego County Department of Agriculture, Weights and Measures, said her
department’s Pesticide Regulation Program “promotes the safe and legal use of pesticides by regulating pesticide use regionwide in partnership with the California Department of Pesticide Regulation. This is done through evaluations of restricted material permits, outreach, inspections, complaint and illness investigations and enforcement.”
For a pesticide to be used in California, it must be reviewed and registered by the Department of Pesticide Regulation, Durckel said.
“For a pesticide to be applied by a company for hire, the pest control business must be licensed by the DPR and be registered with our office,” she added. “The company must follow all applicable pesticide laws, regulations and the pesticide label.”
Widener said the city replaces trees as part of its process.
“If we’re making the determination that the tree has to go, we leave an actual letter with the property owner letting them know that we’re taking away the tree, but they can also go to [city web page] Free Tree SD to request a new tree,” he said.
For Tschudy, the solution would be to discontinue treating trees for the weevil to avoid putting other ecosystems in jeopardy. He feels the city should remove and replace the affected trees with trees that aren’t affected by the palm weevil.
“If the pesticides can move up the food chain and kill a suite of different animals, or even if they just kill the parrots, it seems completely unnecessary to me,” Tschudy said. “The real issue here is not the trees vs. the parrots, because you can always find alternative ornamental trees to replace these with.”
Other types of palms that could work in Point Loma-Ocean Beach include the California fan palm, Mexican fan palm and a king palm that looks similar to the dying queen palms.
“There are lots and lots of options,” Tschudy said.