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Insect invaders

May/June 2015 California Bountiful magazine

Protecting California from bad bugs



More online:Bugging out


Setting traps for the invasive Asian citrus psyllid is one way county pest inspectors such as Kevin Martyn protect neighborhood landscaping, citrus farms and the state's environment.

Stroll through a neighborhood or park in California and look up. As you scan tree branches and tall shrubs, don't be surprised to find a yellow card, green tube or tent-shaped container hanging like an odd ornament, well beyond the reach of children and pets.

Casual observers may shrug and walk on, not realizing the strategically placed "decorations" are insect traps—frontline protection for gardening, urban landscapes, food crops and the environment. What isn't seen is the complex environmental defense system behind the trap.

A network of experts stretches from neighborhoods to county offices to state and federal agencies, all prepared to respond when a pest emergency erupts. Without this sophisticated protection, invaders would happily eat gardens and crops, as well as damage native habitat.

"We've done a fair amount of work lately setting traps to detect Asian citrus psyllid, which can spread a deadly citrus disease," explained Kevin Martyn, a Yolo County agricultural inspector. "The pest was found in February in Santa Clara County, which set off alarms and triggered a quarantine. We haven't found it in our county—yet."

The tiny aphid-like insect doesn't look scary, he said, but it can take a heavy toll on citrus trees if allowed to move around the state unchecked, potentially spreading a bacterium that causes huanglongbing, or citrus greening, which kills citrus trees in commercial groves, as well as backyards.

The threat is real: Plant disease experts say the combination of citrus greening and another plant disease, citrus canker, has cut Florida's citrus production in half. In the past five years, crop value declines and job losses there have totaled about $8 billion.

In California, farmers, homeowners and government officials and scientists are working to prevent the same thing from happening here. And the psyllid is just one threat.


State entomoligists often use the California State Collection of Arthropods as reference in identifying insects found in the field.

Stowaways

California pest detection experts say a non-native, invasive species shows up in the state about every two months. They arrive through airports with luggage, in overseas shipping containers and on trains, trucks and cars. There are safeguards at U.S. and California borders, but invasive species can find their way in and quickly spread; sometimes, infected plants are moved by unsuspecting gardeners.

Reducing the threat and catching the culprits starts with setting and checking insect traps, which is all in a day's work for Martyn, a botanist who calls driving around and seeing the beauty of healthy gardens and crops the "best part of my job." Referring to an occupational hazard, he said he carries dog biscuits and stays out of backyards while setting traps in residential neighborhoods.

"I like interacting with people in the community, and it's not unusual for them to bring up concerns about pests and plant diseases when I'm working," Martyn said. "They usually understand we're in the field trying to find specific pests before they can do any harm and they're cooperative when we ask if traps can be placed on their property."

Homeowners can play a big role in protecting their own gardens, as well as commercial crops, he said: One of the biggest helps is public awareness of the risks from sharing, transporting and planting non-certified plants. Certified nursery plants have been grown under controlled conditions and have been inspected to ensure they don't have pests or plant diseases before shipment to retail outlets.

"It's the cuttings from the gardens of family and friends that pose a serious risk," Martyn said.


State entomologist Stephen Gaimari works behind the scenes to identify potential insect invaders.

Identifying the invaders

All of California's 58 counties have pest detection and identification programs, said Jim Allen, Solano County agricultural commissioner and president of the California Agricultural Commissioners and Sealers Association.

Allen said the insect traps placed by county pest inspectors don't pose a threat to people, plants or animals. Some have sticky coatings; others have natural bait-like materials that attract only certain pests. Traps are placed strategically—grid patterns, distances apart, plant types—and then are checked at set frequencies.

If a suspect species shows up, he said it's reviewed by trained entomologists at the county level and then rushed to the state Entomology Laboratory in Sacramento. Once there, insect experts including Stephen Gaimari swing into action with sophisticated technology to make positive identifications of any invading pests and plant pathogens.

On many days, the lab's lobby has a collection of ice coolers, boxes and envelopes with specimens from counties—and sometimes other states and nations—waiting to be processed. Samples are reviewed under electron microscopes and scanners, and what the team finds could trigger a response from state and federal officials.

Gaimari stands in the state's insect "library," an international reference and research collection where more than 1.5 million specimens are catalogued and stored in pull-out drawers.

Worldwide network

The state lab is part of a worldwide network of pest laboratories and houses one of the most comprehensive insect reference collections in the nation.

"However they arrive, we need to know all about a pest before they ever get here so, if we find one, we can quickly recommend the most effective ways to eradicate and control it," said Gaimari, who is a world authority on fruit flies.

Explaining why the lab's work is important, Gaimari cited examples of what these bad bugs can do: In California, West Nile virus, which is spread by infected mosquitoes, sickens and kills people; ticks spread Lyme disease; red imported fire ants damage school playing fields and parks, as well as deliver stinging bites; and Mediterranean fruit flies lay eggs in and ruin fruit.

Gaimari and his colleagues prepare for the possibility of pest invasions by going on scientific expeditions to areas where pests might come from—Thailand, Vietnam, China, Madagascar, Borneo, Australia, Ghana and the West Indies, for example. The specimens they bring back are cataloged in the state insect library at the lab and used for comparison when a potential non-native pest is found.

The state's collection began in 1883 with the founding of what is now the California Department of Food and Agriculture.

Collective efforts

With more than 1.5 million specimens accumulated since its founding in 1883, the state's collection has become one of the largest of its kind in the nation, said Gaimari, who is the collection's head curator. Maintained as a research center by the California Department of Food and Agriculture's Plant Pest Diagnostic Branch, the collection is not open to the public. But Giamari, who holds a Ph.D. in entomology, said there are a number of good public collections that welcome visitors.

"Basically, when something suspicious is found in a county or state trap, they contact us," he said. "Once we provide a positive ID, the hope is that it's just a one-off bug. Unfortunately, that isn't always the case."

With good field inspectors, county entomologists, state and federal research scientists and officials all following precise protocols, Gaimari said there's a lot going on behind the traps to protect California.

The public can play a role in this critical defense system by becoming familiar with the bugs and plant diseases normally found in home gardens and knowing who to call if something seems amiss.

"We encourage people to call us if they find a new or suspicious insect on their property," Martyn said.

Kate Campbell
kcampbell@californiabountiful.com

Editor's note: The California Department of Fish and Wildlife is sponsoring a youth art contest to promote awareness of plant and animal invaders that threaten our state's native species, as part of the 2015 California Invasive Species Action Week, June 6-14. Visit the Action Week website for details and entry forms.

 

Pest patrol

Keeping pests out of farm fields and backyards keeps state and federal agricultural officials busy. Sometimes that means setting up quarantines to help prevent invasive pests from being moved around. Here are seven of the major offenders in California. The state Department of Food and Agriculture also additional information about these and other invasive species

Asian citrus psyllid

Native to southern Asia. Feeds on leaves and stems of all plants in citrus family. Extremely dangerous because it can spread citrus greening disease, which kills trees and plants.

Mediterranean fruit fly

Native to Africa, but has spread to many parts of the world. Most destructive pest in the world. Lays maggots in more than 250 cultivated and wild fruits, making the food inedible.

Gypsy moth

Native to Europe. Adult females are large and white, but flightless. Males are brownish and strong fliers. Moth has defoliated millions of forested acres in the U.S., killing trees.

European grapevine moth

Native to southern Europe. Feeds on flowers and fruit of grapevines and olive trees, as well as carnations, persimmons and rosemary.

Asian longhorned beetle

Native to northeast Asia and China. Feeds on and eventually kills hardwood trees in forests and gardens.

Light brown apple moth

Native to Australia. Feeds on many kinds of fruit and nut trees, as well as landscape plants, including roses and camellia. Also damages strawberries and blackberries.

Red imported fire ant

Native to South America. Arrived in the U.S. in the 1920s and spread to California in 1998, infesting farmland, gardens and parks. Venom from stings is dangerous to people and pets.


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