By Surendra K. Dara
If California and Florida compete (or collaborate, to be politically correct) for anything of agricultural importance other than strawberries and oranges, it would be the influx of invasive pests. Being major ports of entries for international trade and travel on the Pacific and Atlantic coasts, and having ideal environmental conditions — not just for people — both states are frequently bombarded by invasive pests that thrive on a variety of potential hosts under warm weather.
Ficus leaf-rolling psyllid (FLRP), Trioza brevigenae, is the newest invasive insect in southern California, which, as the name suggests, attacks ficus trees and causes galls in the form of leaf rolls. Chinese banyan or Indian laurel fig (Ficus microcarpa) is a popular landscape tree and commonly seen in California. FLRP infestations were found on several trees in six southern California counties.
Linda Ohara, a lab technician at the El Camino College in Torrence, a suburb of Los Angeles, found leaf rolls on her backyard ficus tree in February, 2016 and contacted Donald Hodel, landscape horticulture advisor with University of California Cooperative Extension. They collected the samples and took them to the county entomologist, Gevork Arakelian. Arakelian found psyllids in the tight leaf rolls and immediately noticed that it is an unusual species. He sent the specimens to CDFA and, with the help of a psyllid specialist in Switzerland, the specimens were eventually identified as T. brevigenae. Based on the symptoms of damage and the host plant, this psyllid that hitherto had no common name has been christened to be the ficus leaf-rolling psyllid.
FLRP adults are 2.6-2.8 mm long with reddish eyes, and greenish or brownish bodies, and transparent wings. Its biology is not known, but multiple nymphal instars with distinctive white, waxy filaments are seen in the leaf rolls. FLRP is reported only from India, and is not known to occur anywhere else in the world.
Ficus trees already have a variety of pests, including invasive species such as the weeping fig thrips (Gynaikothrips uzeli) and the ficus eye-spot midge (Horidiplosis ficifolii), which were found in California in 2014, and FLRP appears to be a new threat to the popular ornamental and landscape tree.
“It is very discouraging that we are seeing more and more of these invasive pests because of the global warming, international travel, and commerce,” said Hodel.
“It is particularly bad for Ficus microcarpa because it appears to be a magnet for FLRP,” he added. “Ficus microcarpa is already a host of Indian laurel thrips, weeping fig thrips, leaf gall wasp, ficus eye-spot midge, curtain fig psyllid, ficus whitefly and the ficus branch dieback disease.”
“It is very fascinating to see how this bug forms the leaf rolls and lives inside,” said Ohara, who is new to entomology and is very enthusiastic about knowing more about FLRP. “We have been monitoring the infested leaves every week and seeing different stages of development of these psyllids.”
“All the listed recent pests of ficus, except for psyllids, had invaded Hawaii or Florida before arriving in California,” Arakelian said, expressing concerns about the movement of the invasive species within the US. “The curtain fig psyllid and the ficus leaf-rolling psyllid are unique by arriving in California first, most likely from Southeast Asia.”
Invasive pests have a significant impact on agricultural economy and environmental balance. It is important for the general public to understand the risk and take appropriate measures to prevent the accidental introduction of invasive species.
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Dr. Surendra Dara is a strawberry and vegetable crops advisor and an affiliated IPM advisor with University of California Cooperative Extension. He specializes in entomopathology and IPM, but is also actively involved in research and extension related to all aspects of crop production and protection. He lends his IPM expertise to farmers in several developing countries, and he publishes two popular eNewsletters – Strawberries and Vegetables and Pest News. Surendra is an obligate entomologist, a facultative standup comedian, and a motivational speaker. Follow him on Twitter at @calstrawberries and @calveggies.