Infected Insects Cause a Stink

UCR Today


UCR research showing how nematodes use smell to select new insect hosts could improve biological control of crop pests
By Sarah Nightingale on July 24, 2017
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RIVERSIDE, Calif. (www.ucr.edu) — Tiny eel-like creatures called nematodes are surrounding us. While they can be free-living (a cup of soil or seawater contains thousands), the most well-known nematodes are the parasitic kind that wreak havoc in people, animals and plants.
Despite their reputation, scientists at the University of California, Riverside are studying nematodes as a force for good: to kill insects that infect crops and trees.
In a paper published today in Scientific Reports, a team led by Adler Dillman, assistant professor of parasitology in UCR’s College of Natural and Agricultural Sciences, has shown how nematodes use smell to seek out uninfected insects, which they then enter and kill. The findings support the group’s long-term goal of improving how gardeners and the agricultural industry use nematodes in biological pest management.
Nematodes, which are transparent or milky white unsegmented worms between 0.1 and 2.5 millimeters long, represent a whopping 80 percent of all animal life on earth. The varieties that infect insects, such as the Steinernema carpocapsae species studied at UCR, enter their hosts through natural body openings, replicate, and secrete a deadly cocktail of proteins. These nematodes show promise as biological insecticides for more than 250 pests that attack plants such as corn, oranges, tomatoes, peaches, and pine trees.
Insects (like the larva shown in this figure) that have been infested with nematodes emit an odor called prenol that repels other nematodes seeking a host.
While previous research has shown that nematodes can differentiate between insects that have already been infected and those that have not, the mechanism by which this occurs has remained a mystery. In the current study, the researchers discovered that infected insects emit an odor called prenol ...

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