When 1 + 1 Equals 100
Garden-variety pesticides add up to more than the sum of their parts when it comes to attacking the nervous systems of salmon, a newly published study finds.
Scientists at WSU and the National Oceanic and Atmospheric Administration Fisheries Service analyzed combinations of various pesticides to learn how they would affect juvenile salmon. Previous studies tested pesticides individually to establish levels lethal to fish.
“We need to design new research that takes into effect the real-world situation where pesticides almost always coincide with other pesticides,” co-author Nathaniel Scholz, a research zoologist at the NOAA Fisheries Service Northwest Fisheries Science Center, told the Associated Press.
WSU entomologist and ecotoxicologist John Stark co-authored the study, and the research was done in his lab at the WSU Puyallup Research and Extension Center. Stark is now the center’s director. Vince Herbert with the WSU Tri-Cities Food and Environmental Quality Laboratory is also a co-author of the study.
The results of the research were published Monday in the March issue of Environmental Health Perspectives. The study examined five common pesticides: diazinon, malathion, chlorpyrifos, carbaryl and carbofuran, all of which suppress an enzyme necessary for proper nerve function.
“Fish and other organisms are exposed to many chemicals at low concentrations – and the key question is, ‘Can that cause a problem?’ With this study, we now know that the answer is, ‘Yes,’” Stark said. “The way that we normally look at these compounds is through an additive model. The compounds, in combination, are much more toxic than we would ever imagine,” he added.
HIPPOs in the House
HIPPOs, a novel strategy for improving the control of mites and insects in hops and grapes, is being developed by WSU associate professor of entomology David James. James and his research team are working on multiple field experiments with the potential to improve pest management, not only in hops and grapes, but also in a variety of crops worldwide.
Previous studies have shown that plants, when attacked by insects and mites, respond by emitting distress signals. These signals take the form of a bouquet of volatile chemicals, the signaling language plants use to warn neighboring plants that they also may be attacked and should defend themselves.
“What’s interesting is that predatory and parasitic insects and mites also are fluent in plant language, and the plants know this,” James explained. “The predators actually understand what the plants are saying and know there will be food and hosts available. The chemical dialogue plants produce when attacked benefits not only the plants, but the ‘bodyguards’ they recruit for protection.”
Although scientists have been studying plant-to-plant and plant-to-insect conversations for over 20 years, there are many questions that James’ team is hoping to answer. For instance, can the conversations plants have with each other and with beneficial insects be faster and louder? Can these improved conversations improve pest management efforts?
“There is no universal plant language. Different plant species seem to have their own unique languages. Grape talk is different from, say, bean talk,” James said. “However, there are some ‘words’ that appear to be fairly common amongst plant languages, so they are understood whether emitted by grapes or beans.”
James has coined the acronym HIPPO (Herbivore-Induced Plant Protection Odors) to indicate his research focus. More research is required in regard to deployment rates and methods before HIPPOs can be used optimally in practical crop pest management. However, dispensers containing HIPPOs are now available commercially, and some growers are using them with good results.