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May 29, 2015 CapitalPress.com 11 Scientists pursue gene-disrupting pesticides RNA interference touted as pest- specific weapon By MATEUSZ PERKOWSKI Capital Press Since appearing in West Coast fruit orchards several years ago, the spotted wing drosophila has forced grow- ers to increase their chemical usage. The invasive fruit fly has also seriously set back the in- tegrated pest management ap- proach to controlling insects with biological methods. A USDA researcher is hop- ing to give farmers a powerful new weapon against the in- sect: a biopesticide that dis- rupts critical genes specific to spotted wing drosophila but doesn’t harm other species. At this point, entomologist Man-Yeon Choi is still early in the process of identifying gene sequences that are es- sential to the fly’s physical processes or its ability to re- produce. Interfering with the func- tion of those genes would either kill the pest or prevent it from generating viable off- spring. Once that is accomplished, Choi will still have to find a delivery mechanism, like a bait, that will effectively be taken up by the fly. “This is a long-term proj- ect,” he said. Choi isn’t alone in his re- search. Some scientists ex- pect the mechanism known as RNA interference will be used against a variety of agri- cultural pests with much few- er environmental effects than current pesticides. “It’s not going to be broad spectrum. It’s going to be a surgical strike,” said Wayne Hunter, a USDA research en- tomologist. “You can go and remove one organism from an ecosystem.” However, the technology still faces practical hurdles. While the concept is prom- USDA RNA interference injection equipment is used to treat spotted wing drosophila fruit flies with a biopesti- cide that disrupts the expression of genes. ‘There are a lot of things we don’t know about it that are potentially pertinent to risk. Do you go forward without knowing what you’re doing, or do you step back and figure it out?’ — Doug Gurian-Sherman Senior scientist, The Center for Food Safety ising, it’s unlikely to be a sil- ver bullet for all agricultural pests, said Greg Heck, a sci- entist at Monsanto Co. who specializes in RNA interfer- ence. The feeding strategies of some insects would basically disarm an RNA interference pesticide, while others would have to consume so much of the substance as to render it unfeasible, Heck said. “If it takes tons and tons of RNA, you’re not going to be able to produce it and apply it in a cost-effective way,” he said. RNA interference is al- ready encountering opposi- tion from critics who fear the pesticide industry will rush ahead without fully under- standing the consequences of the technology. The Center for Food Safe- ty, a nonprofit that has battled genetically engineered crops for years, worries that RNA interference isn’t as specific or benign as supporters ex- pect. “There are a lot of things we don’t know about it that are potentially pertinent to risk. Do you go forward with- out knowing what you’re doing, or do you step back and figure it out?” said Doug Gurian-Sherman, senior sci- entist and director of sustain- able agriculture for the group. RNA interference works by manipulating natural pro- cesses at the cellular level. Ribonucleic acid, or RNA, is a molecule that carries out various functions directed by genes, such as making en- zymes needed for digestion. While RNA is most often in the form of a single “strand,” there is also “double-strand- ed” RNA that’s crucial to the replication of viruses. When double-stranded RNA is encountered by spe- cial proteins in a cell, they assume it’s a virus and chop it up. If corresponding ge- netic sequences are found elsewhere, the proteins also destroy them to prevent the virus from spreading. Scientists realized they could trick the cell into destroying its own genet- ic sequences by inserting double-stranded RNA that matches those sequences. A susceptible insect that in- gests such specially designed RNA would then shut off the expression of key genes, neu- tralizing itself as a pest. “Other insects can eat the compound but it won’t affect them because they don’t have USDA RNA interference injection equipment is used to treat spotted wing drosophila fruit flies with a biopesticide that disrupts the expression of genes. the same gene sequences,” said Hunter. While RNA interfer- ence affects gene function, it doesn’t change the genetic makeup of the pest, he said. “This technology is non-transgenic. It does not transform the insect,” Hunter said. Gurian-Sherman of the Center for Food Safety argues that double-stranded RNA taken up by an insect can af- fect genes beyond the targeted sequence. RNA interference could affect genetic sequences that are similar but not identical, he said. “That type of speci- ficity doesn’t occur in reality.” As a result, beneficial pests could inadvertently be harmed by the technology, particu- larly if they’re related to the target pest, Gurian-Sherman said. The structure of some ge- netic configurations can be similar in different species, so it’s conceivable even humans could be impacted, he said. “Evolution conserves these things and reuses them as we evolve.” Hunter of USDA said these concerns are unfounded be- cause conventional pesticides have a much greater potential to injure non-target species. RNA interference pesticides will also be tested to avoid non-target effects prior to commercialization. There’s no evidence the technology would affect hu- mans, who have evolved to break down RNA, he said. “We’ve been eating dou- ble-stranded RNA since we’ve been eating vegetables.” RNA interference pesti- cides have little persistence when exposed to the elements, which is a double-edged sword — it’s good for the en- vironment, but reduces pest exposure to the substance, said Heck of Monsanto. When the technology is ready for the market, it will be most effective as one of several modes of action, he said. “It’s something we will have to integrate into control systems.” Train-the-trainer IPM workshops set By MITCH LIES For the Capital Press Agricultural research- ers at the three Northwest land grant universities are hosting a series of train-the- trainer workshops on inte- grated pest management in June. The series includes two three-day workshops: • At the Oregon State University Hermiston Agri- cultural Research and Ex- tension Center on June 8, 9 and 10. • At the Washington State University Whitman County Extension Center in Colfax on June 24, 25 and 26. Two more will be held in 2016, said Silvia Rondon, OSU Extension entomolo- gist specialist. The workshops are de- signed for extension field faculty, agency profession- als and crop consultants. They will include presen- tations on monitoring tech- niques, pest identification and pest management tech- niques. “It’s all about increasing use of IPM in the region,” Rondon said. She added that Oregon State University Oregon State University Extension entomologist Silvia Rondon leads a train-the-trainer IPM workshop at the Hermiston Agricultural Research and Extension Center in a past workshop. Rondon and other researchers will be conducting two three-day train-the-trainer workshops in June, one in Hermiston and one in Colfax, Wash. the workshops are “very re- gion specific.” The land grant univer- sities have offered short courses on IPM for control of insects in years past, Rondon said, but this is the first year the universities are adding diseases and weeds to the course agendas. As part of the courses, participants will be provid- ed materials for collecting weeds, insects and diseased Online More information is available at http: //extension.oregon- state.edu/umatilla/ipm plant tissue. Participation is limited to no more than 20 per session, and the workshops “are very hands on,” Rondon said. All sessions will also be available on line, she said. Judge dismisses pesticide challenge Legal fight over cyantraniliprole likely to continue By MATEUSZ PERKOWSKI Capital Press A federal judge has dis- missed a lawsuit against the U.S. Environmental Protection Agency’s com- mercialization of a new insecticide, but the ruling won’t likely end the legal dispute. Last year, the EPA ap- proved the registration of cyantraniliprole for a wide variety of crops, offering farmers a new mode of ac- tion against pests. However, environmen- tal groups — the Center for Biological Diversity, the Center for Food Safety and Defenders of Wildlife — filed a lawsuit against EPA claiming it violated the En- dangered Species Act by registering the chemical. The plaintiffs claimed the pesticide is highly toxic to sensitive species and sought an injunction against its commercializa- tion until EPA implement- ed steps to prevent those harms. U.S. District Judge Gladys Kessler has now dismissed that lawsuit for procedural reasons, find- ing that plaintiffs can- not directly challenge the agency under the Endan- gered Species Act, but must instead seek relief under the Federal Insec- ticide, Fungicide and Ro- denticide Act. The environmental groups plan to continue fighting EPA’s approval of cyantraniliprole, either by appealing Kessler’s ruling or pursuing the FIFRA op- tion, said Brett Hartl, en- dangered species policy co- ordinator for the Center for Biological Diversity. The new pesticide has the potential to harm 1,300 species, he said. “It’s a large realm of ecological impact across the board.” Capital Press was unable to reach a spokesperson for DuPont, the product’s man- ufacturer, for comment as of press time. 22-7/#6