As HLB spreads across citrus producing regions around the world on the wings of its vector the Asian citrus psyllid, scientists are targeting hundreds of research projects at the pest. A team at the University of California-Riverside has zeroed in on the olfactory system of the psyllid, and identified a suite of odorants (odor molecules) the psyllid olfactory system detects. Some of these odorants can modify the behavior of the insect and lead to the development of tools to tackle its spread worldwide.
Building A Better Trap
One of the major gaps in psyllid control is the lack of effective surveillance traps to track the rapid spread of these highly invasive insects that are fast spreading globally. Currently, HLB is mostly managed by spraying insecticides and swiftly removing infected trees. But, if the pest develops insecticide resistance, commercially managed citrus groves could be in jeopardy. Further, abandoned citrus groves could become prolific reservoirs of HLB.
“The psyllid’s olfactory system is sensitive to a variety of odorants released by citrus plants. This presents an opportunity to develop attractants and repellents using odors,” says Anandasankar Ray, an associate professor of entomology and the director of the Center for Disease Vector Research, who led the research project.
An Attractive Blend
Ray explains the psyllid detects citrus plant odors using tiny pit-like sensors on its antenna. His lab performed a large-scale analysis of numerous citrus-emitted odors and identified those odors that strongly activate the citrus odor sensitive neurons on its antenna. Then, using a blend of activating odorants, the researchers developed an efficient attractant that could lure psyllid to yellow sticky traps.
The blend of odors Ray and his team of researchers identified consisted of myrcene, ethyl butyrate, and p-cymene — odors found in nature. To test whether this blend was effective as an attractant, Ray and his team of researchers performed field trials, spread over 10 weeks, in citrus trees located in back yards in a residential neighborhood. They found the odor-based yellow traps caught nearly 230% more psyllids than conventional yellow traps placed on the same trees.
“What’s particularly encouraging is these three chemicals are affordable, useful in small quantities, and safe for human handling,” Ray says. “They could be developed into monitoring and surveillance tools. Similar approaches can be taken to develop control strategies using odors for other insect pests of crops as well. Our study also reports identification of odors that block the psyllid’s olfactory system from detecting citrus odors and have potential for development into repellents.”
Study results on the lures appeared in the Oct. 27 issue of PLOS ONE.
Information for this story appeared in the University of California’s UCR Today.