OREGON STATE UNIVERSITY

Biocontrol of pests a "secret" success story

02/10/1997

CORVALLIS - A survey examining the success of biological control of insects in agriculture concludes that this natural approach to pest control is far more effective than often appreciated and should be more widely used.

Several case studies explored by researchers at Oregon State University found that biological pest control can effectively solve problems on a long term basis - and may also yield a return on investment of 100 to 1,000 percent in the first year alone, after which the benefits go up in perpetuity.

"In these specific cases we were surprised at the degree of success of biocontrol, how widespread and quickly it worked, how cost-effective it was," said M.T. AliNiazee, an OSU professor of entomology. "Based on this there's no doubt in my mind that biocontrol should be more heavily exploited."

The survey examined the economic, environmental and socio-political impacts of biological control in a number of successful case studies.

In an agricultural world riddled with insect pests, biological control most often is the use of an insect parasitoid, predator or pathogen to control the damaging pest. Other tools like pheromones and trapping also are used.

The use of this approach, AliNiazee said, does not suggest that chemical pest control is entirely ruled out. Often lower amounts of chemicals, or careful timing of their use, can be combined with biological control and other agricultural tools in a concept called "integrated pest management," or IPM.

Biocontrol has found some of its greatest success, AliNiazee said, in perennial crops including fruits and nuts. But the study of its potential is just beginning, he added, and there are probably great opportunities awaiting in larger mainstream crops such as cotton, corn, soybeans and potatoes.

"There are some clear advantages that make biological control socially desirable," AliNiazee said. "It can reduce harm to the environment, improve health and safety of food products, even lower consumer costs."

In the early 1900s, before a huge agro-chemical industry developed, there was considerable interest in biological control, AliNiazee said. With increasing consumer skepticism about chemical usage and the growth of insect resistance to pesticides, attitudes may now have come full circle, he said.

"It's still hard to break the agricultural dependence on chemicals because it provides that insurance that most growers would rather have," he said. "Here in the Willamette Valley we've developed an effective monitoring program for cherry fruit flies. But relatively few growers monitor for fly emergence and may use chemicals against this pest even when evidence suggests it may not be present in their orchards."

Among the biocontrol examples studied in the OSU survey:

-A search by OSU researchers in southern Italy for a biological control of the filbert aphid discovered a parasite that was imported to Oregon, mass released, and is highly effective. A total cost of about $30,000 in research is now saving about $400,000 a year in chemical spray costs, while reducing overall crop damage, pesticide resistance and pesticide residues on the nuts.

-Biological control of spider mites and an IPM program nearly saved the Washington apple industry, reducing some chemical sprays by nearly 96 percent, saving almost $3 million a year while improving fruit value and boosting apple exports.

-Tansy ragwort has been controlled by the importation of two insect predators, dramatically reducing the threat of this poisonous weed to Pacific Northwest cattle and saving the Oregon livestock industry up to $4.8 million a year.

The OSU survey concluded that some of these more prominent success stories for biological control may be paying off at ratios of about $10,000 for every dollar invested, when considered over a 50-year period.

Yet there is room for improvement, AliNiazee said.

"There's a lot more that could be done, but we have to confront the chemical-dependent mentality," he said. "For instance, cotton farmers use extensive sprays to control pests such as the boll weevil and boll worm, but in the process create several new problems by killing beneficial insects."

Breaking that cycle with different chemical regimens, protection of useful insect predators, and other tools of IPM is radically reducing pesticide use in that crop in some regions, AliNiazee said. And similar progress might be made with other primary crops in U.S. agriculture.

"Oregon, California and Hawaii have been very progressive in encouraging biological control, even though we need more research funding all over the country," AliNiazee said. "However, there's a lot more work to do throughout this country and the world as a whole."