Lygus No. 1 insect enemy in many Far West areas

There will be no monuments built to or songs written about the western tarnished plant bug. However, the tiny insect pest known simply as the "lygus bug" is gaining the same dubious distinction as the insect immortalized in stone and tune, the boll weevil.

The tiny insect is much more voracious cotton-loving weevil because it can damage many crops, feeding on the tender shoots and buds of dozens of row, vegetable and permanent crops in the West, reducing yields and crop quality. It has become such a problem that is has been elevated to pest enemy No. 1 in many areas. It has evolved to warranting its own entomological summit, organized by University of California regional IPM advisor Pete Goodell. More than 170 researchers, pest control advisors and producers from not only California, but Arizona and the Pacific Northwest were in Visalia, Calif., recently for the first ever Lygus Summit to try to throw a blanket of commonality over an insect pest that has almost 400 hosts in 55 families. The goal of the summit was to hopefully create strategies to bring lygus under control.

Of course, lygus is not a new pest and certainly not exotic. It has been around for a half-century with nine damaging species identified worldwide. Westerners have had to live with lygus for years, but it seems to be getting worse, both literally in the West and cognizably elsewhere.

Of the 54 crops covered by the UC IPM Pest management guidelines, 10 lists the lygus bug as damaging. Many of the more than 250 crops grown in California and the West are lygus hosts, but not all are damaged by the pest. However, many of those crops act as reservoirs for migrating lygus populations. Entomologist says damaging populations almost always migrate to the crop where the damage is done.

Lygus in many areas of Sun Belt has been elevated up the damaging pest scale with the control of boll weevil via eradication and Heliothine complex using transgenic cottons.

No. 1 in Arizona "Lygus has become the No. 1 item in Arizona farmers' pest control budget," said Peter Ellsworth, University of Arizona IPM Specialist. A decade ago growers spent a little more than $17 per acres to for two lygus control treatments. Two years ago that was up to $55 per acre for almost three applications.

"Losses to lygus can be staggering," said Ellsworth. That is what Arizona farmers used to say about boll weevil, pink bollworm and silverleaf whitefly. However, those pests are under control or gone with new chemistry, transgenic cottons or eradication.

In the South where boll weevils have all but been eliminated through mandatory eradication, Goodell said the same mandatory approach is being considered to destroy host plants to bring lygus under control.

That would not work for California and the West because of the wide diversity of cultivated and wild host plants.

However, Goodell and Ellsworth believe voluntary, informal community-based programs could reduce lygus damage. "Lygus are not a threat to everyone every year," Goodell explained and that precludes use of a mandatory program.

However, by using a wide array of approaches from wild vegetation management to trap crops to managing host crops to prevent lygus migration, Goodell and Ellsworth believe lygus damage can be reduced. However, it will not be easy. "There is no silver bullet solution," said Goodell - no single insecticide, cultural technique, or biological approach.

However, Goodell believes there are incentives to develop voluntary, multi-tactic programs because:

- Farmers are searching for ways to reduce costs, and one of the biggest can be pesticides.

- Everyone can easily implement cultural control techniques.

- Multiple tactics can reduce the general population density, but no tactic will reduce the entire problem.

- An entire area may not have to be committed because suppression and management are the goals. Eradication would be unfeasible.

"A successful management program will result in the overall reduction in lygus," said Goodell. "This in return should result in reduced movement into susceptible crops, fewer broad-spectrum insecticides required for lygus management; less secondary disruptions and improved stability in field and fruit crops."

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