Biopesticides Leading the Way

Protecting crops from pests and insects is necessary for growers to produce profitable crops. Although not a new field – biological pesticides first gained EPA approval for field tests in 1990 – the development of biological pesticides continues to expand. According to the University of California, Davis, more than 200 biopesticides are sold in more than 800 products, many of which, include multiple modes of action.

AF36 is prepared for application in a pistachio orchard.

Products are being created by the pesticide manufacturing giants and by small, grower-owned and start-up companies. These products are created from naturally occurring processes in response to an increasing need to meet export standards, as well as to avoid resistance development issues and harm to beneficial pests. Biological pesticides are developed through expanded technology and field-tested by unbiased scientists for their effectiveness and residual activity.

Effectively managing pesticide residue is essential for U. S. growers to market their products globally. Each country sets its own pesticide standards, and European and Asian countries have stricter standards on minimum residue levels (MRL) than the U.S. With growers struggling to keep their heads above water with increasing production costs, access to the export markets is essential.

The same global trade that inc- reases markets through exports for U. S. growers increases threats from pests and insects that come into the U.S. with imported products. “We’ve seen a lot of new pests during the past 10 years,” said Dr. Doug Walsh, an entomologist with Washington State University.

Walsh noted several advantages in new products:

  • more selective in targeting pests;
  • active in the environment only for specific times needed; and
  • avoid the release of volatiles or vapors into the air

Factors spurring changes

Several factors are at work spurring the development and use of biopesticides. While resistance development to standard pesticides has increased, and a number of products have been removed from the market, an overriding issue is the ability of growers to market U.S. products to European and Asian markets. As restrictions have increased, researchers, manufacturers and growers are responding to the need for these biological pesticides to facilitate more access to overseas markets.

While food remains a major world concern, research funding continues to be more available for major crops such as corn, soybeans and cotton. In many instances, products developed for these major crops eventually make their way to registration for specialty crops such as fruits and vegetables.

That’s where a project initiated in the 1960s sometimes comes into play. The IR-4 Project, housed at Rutgers University and funded primarily through the USDA, is made up of several programs. Dr. Michael Braverman is manager of the IR-4 Biopesticide and Organic Support Program. The stated objective is to further the development and registration of biopesticides for use in pest management systems for specialty crops or for minor uses on major crops.

Braverman said, “The IR-4 Project funds research field trials to assess effectiveness and to detect residues in products, and it assists university and U.S. Department of Agriculture (USDA) researchers and small companies in the EPA registration process.” In other instances, private companies manage their own registration process, moving products of major crop to minor crop registration.

Delegate is sprayed on apple trees to help control codling moth and other pests.

AF36 – from cotton to pistachios

An exciting first in the pesticide registration process will occur when AF36 is successfully registered for use on pistachios. Successful registration of AF36 will represent the first tree nut registration of a product previously registered for cottonseed and corn. AF36 evolved from a need of the cotton industry to protect against Aspergillus flavus. Some strains of the fungi produce aflatoxin, a liver carcinogen. Research found that some strains including AF36, do not produce aflatoxin. AF36 is produced and distributed by the grower group Arizona Cotton Research and Protection Council, Phoenix.

Dr. Themis Michailides, University of California Kearney Agricultural Center, has conducted tests on AF36 over a three-year period. Following success in the product displacing the toxigenic strains of Aspergillus flavus in an experimental orchard, an experimental use permit allowed 3,000 acres of pistachios to be treated. AF36 is introduced into wheat seed, and when applied to the soil beneath the tree canopy, water from irrigation rehydrates the wheat and AF36 produces masses of spores that displace the toxigenic strain of Aspergillus flavus.

Michailides said, “We were able to reduce the incidence of aflatoxin-contaminated nuts by about 20 percent in the first year of the trial, and by the third year the reduction increased to almost 50 percent. It is expected that once registration is obtained the contamination reduction will be even greater.” Michailides noted that comments thus far are favorable. The IR-4 Project is assisting with the process, and registration is expected in early 2012, allowing AF36 to be used in the 2012 growing season.

Untreated tomato vines on left exhibit the effects of canker, while AgriPhage-treated vines on right are canker free.

“Our cooperator in this project, Dr. Peter Cotty, USDA-ARS and the University of Arizona at Tucson, pioneered research on cotton and corn and was able to get AF36 registered on cotton some years ago and corn in 2010. When AF36 is registered for pistachios, it will be the first such registration on a tree crop.”

PFR-97 insecticidal fungus helps control insects

Produced by Certis USA, PFR-97 is a microbial insecticide with multiple modes of action developed from the Apopka 97 strain of the fungus Isaria fumosorosea discovered by University of Florida researchers. It was licensed to WR Grace Biopesticides, a predecessor to Certis USA. Recently registered in the U.S., it has previously been used in Europe to control whiteflies and thrips. The insecticide is registered for the control of thrips, whiteflies, psyllids, mealybugs and spider mites on fruits and vegetables. The product has been used by growers in Europe and is a popular control measure for whiteflies and thrips.

David Silva, Certis USA product manager, said, “PFR-97 can control thrips in all life stages, eggs, immatures and adults.” Silva cited the multiple action modes of PFR-97 as an important aspect. It can penetrate through direct contact with germinating spores when applied to the crop or the soil, and it can grow on plant surfaces and enter the hosts that come in contact with it.

Silva said, “It works on a wide crop range. It works for berries, grapes, potatoes and fruiting vegetables. It’s safe on beneficial insects.”

Insecticide resistance has eroded the effectiveness of insecticides, and PFR-97 provides a new microbial mode of action to forestall resistance development.

From bacteria to bait

Seduce and Bug-N-Sluggo are two bait-type biological pesticides produced by Certis USA. The active ingredient in Seduce is spinosad, which is derived from a soil-dwelling microorganism called Saccharopolyspora spinosa. The bacteria produce compounds in fermentation that have been formulated into insecticides. Seduce is registered for almost all crop groups for use against earwigs and cutworms. Silva said, “We are currently conducting research to apply for registration of Seduce to control cabbage maggots and ants.”

Bug-N-Sluggo is a combination of spinosad and iron phosphate, and is registered to control earwigs and cutworms, as well as snails and slugs.

AgriPhage – soft attack on tomato canker

AgriPhage, produced by OmniLytics, Sandy, Utah, represents an earlier biological pesticide gaining registration about five years ago. Naturally occurring bacteriophages are beneficial viruses that can destroy specific bacteria on contact. With the increased interest on the part of consumers in greenhouse-produced tomatoes, that avenue of tomato production has increased. Bacterial canker has recently become the most serious problem in greenhouse tomato production. AgriPhage can be used on both greenhouse and field-produced tomatoes as a spray on growing plants.

“We’re seeing an increased use of biological pesticides,” said Dr. David Ingram, plant pathologist, Mississippi State University. Ingram conducted field studies on AgriPhage funded by the IR-4 Project to assess its effectiveness and residue when used on tomato vines. Results indicated that canker was reduced more than 50 percent in treated plants. Ingram said, “In my three years of studies of AgriPhage, I found that the disease is slowed to allow more fruit to be harvested.”

Ingram noted that an increasing number of small growers are focused on producing and promoting healthy food for local markets. At the same time, large commercial growers must look to meeting standards for exporting their produce to markets in Europe and Asia. When combined, these factors contribute to the increased interest in biological pesticides.

Delegate and Radiant target pests while maintaining beneficial insects

Delegate WG, developed for fruit applications, and Radiant SC, aimed at vegetables, are biological insecticides produced by Dow AgroSciences. Both products are derived from naturally occurring soil bacteria and were accepted for registration under the U.S. EPA Reduced-Risk Initiative. Development of the active ingredient was spearheaded by Dr. Thomas Sparks, a scientist with Dow AgroSciences. Sparks was recently named winner of the 2012 International Award for Research in Agrochemicals by the American Chemical Society.

Delegate provides control for the codling moth, the bane of fruit growers as well as oriental fruit moth and leaf rollers. Radiant targets thrips, worms and leaf miners.

With both resistance avoidance and maintenance of beneficial populations a major concern, both products contribute to these goals. Brian Timmerman, Dow portfolio market leader for insecticides, said, “Both Delegate and Radiant maintain most beneficial populations. The unique chemistry found in these insecticides gives producers an effective mode of action that can easily be rotated with other products to stave off resistance.”

Nancy Riggs is a freelance writer. She resides in Mount Zion, Ill.