Good Fruit Grower

November 2012

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New Technology B.C.'s Sterile Insect Release program evolves S terile insect releases and pheromone mating disruption work in similar ways. In sterile insect release, male insects made sterile by expo- sure to gamma radiation are released in huge numbers to com- pete with normal wild males. When the sterile males win the mating game, females lay infertile eggs. In mating disruption, female sex hormones are released in such vol- Sterile insect release and mating disruption are being compared in British Columbia. by Richard Lehnert ume that males can't find females hidden in the overwhelming flood of perfume, so females go unmated and can't lay fertile eggs. In both cases, reproduction is disrupted as infer- tile eggs fail to produce larvae that can infest and feed on their hosts. In British Columbia's Okanagan, Similkameen, and Shuswap valleys, the two methods are in the sec- ond year of a three-year test comparing their effec- tiveness. It's a huge test covering more than 4,000 acres of apples in each method. Dr. Gary Judd, an entomologist and research sci- entist at the Pacific Agri-Food Canada Research Cen- tre in Summerland, said sterile insect release began there in 1992, and after 20 years it has been effec- tive—but somewhat expensive. "Overall, it has been highly successful," he said. "Codling moth numbers have been so reduced that on half the acreage, almost nobody sprays for codling moth." The program initially was conceived as an eradication program, and while it reduced codling moth numbers greatly, it was not able to achieve eradication. So it evolved into an annual management program. "It worked best in the area close to the U.S. border," Judd said. "At the north end of the valley, it didn't work as well. Growers there began to use mating disruption as well, but that greatly added to their expense. So the next step is to compare the two and perhaps choose one." IMPROVING SIR'S cost effectiveness north end of British Columbia's Okanagan Valley are "concerning." McCurrach is general manager of the Okanagan T Kootenay Sterile Insect Release Program, which for 20 years has been subduing codling moth in British Columbia, Canada. Since the program was not able to eradicate the codling moth, a test was established to see whether pheromone mating disruption might do better. That test started in 2011 and will end in 2013. Mating disruption is difficult because the area's orchards are made up of small acreages that are interspersed with non-orchard properties, some- thing that has also reduced the effectiveness of the sterile male release program. McCurrach hopes that when growers see the results of mating disruption, they will become more enthusiastic supporters of the sterile insect release program. She thinks it is a model that can be used against codling moth all over the world. Growers complain about its costs. 24 NOVEMBER 2012 GOOD FRUIT GROWER he data from 2012 have not yet been analyzed, but Cara McCurrach said early indications on the effectiveness of mating disruption in the Many growers drive their costs up by continuing to apply control sprays simply as a risk reduction measure, a "comfort," regardless of whether the lev- els of wild codling moth indicate a need, she said. One thing that could reduce their costs is more efficient use of the sterile moth production facility at Osoyoos. The Canadian government built that facility in 1993, at a cost of $7.4 million. "We have excess capacity at our sterile moth production facil- ity now," she said. "But we're investigating other opportunities. Perhaps other regions will buy our sterile moths." Some sterile moths from the facility are currently being sold in South Africa. Other areas are using sterile insect release as a control measure in mating disruption trials. Testing is going on at Washington State University, at the University of California, and at Michigan State Uni- versity. McCurrach is hopeful that the exposure of the SIR moths to various regions may spark interest in using SIR as a supplementary control method to current practices. Walnuts are also attacked by codling moth, so walnut growers in California may be potential buyers of sterile moths, too. The SIR Program has also collaborated with South African pome fruit growers, who have established their own programs using sterile insect releases. Canadian sterile moths were transported and released to suc- cessfully control codling moth in South Africa. "Our program has been on the leading edge for many years," McCurrach said. She's hoping the suc- cess of the 20-year-old British Columbia program— despite some problems—will spur others to implement areawide control programs using sterile insect release. She thinks that with the move toward integrated pest management regulations and more sustainable agriculture, Europe may eventually move in that direction. "We produce high quality sterile moths," she said, meaning they compete well with wild males. "We are always open to opportunities for new rev- enues supplying other programs, which will make our program less expensive for our growers." —R. Lehnert To determine sterility, squash a codling moth. The red food dye in their diets gives the guts a pinkish hue. During the test, the cost is the same for all growers. The management team, which operates the Okanagan Kootenay Sterile Insect Release Pro- gram, also provides everything needed for the mating disruption pro- gram. In a deal that goes back to the start, the costs of the SIR program are split 40-60 between growers and property-owning taxpayers, said Cara McCurrach, who heads the team. Growers pay $139 per acre of apples, pears, or quince they grow, every year. Urban and suburban property owners in the district pay a fee based on the land value of their property, which McCurrach estimates amounts to about $11 a year for an average property. The money goes to hire peo- ple to deliver the areawide program—about five full-time and 30 sea- sonal people who work in the orchards—plus nine permanent staff who operate a sterile moth production factory at Osoyoos. The Canadian gov- ernment built that facility in 1993, at a cost of $7.4 million. Lots of politics Despite the achievements of the sterile insect releases, the program is fraught with the kind of political problems McCurrach believes sur- rounds any areawide program that depends on the cooperation of lots of people. Here are some of the issues she noted: Declining fruit base—When the program began 20 years ago, it cov- ered 22,000 acres, but now covers 8,500. Why? The British Columbia fruit industry has not been doing very well, for several reasons, so growers are leaving the business. The costs of the program have remained the same over the past three years, so, with the reduction of planted acreage, the burden of paying for the program falls on fewer and fewer growers. Lofty goals—The goal in recent years has been to reduce the level of codling moth damage to less than 0.2 percent at harvest on 90 percent of the acreage, and that has been achieved. But for reasons not easily explained, growers operating about 10 percent of the acreage continue to experience "hot spots" where damage is higher.

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