Research: Nematodes secrete proteins to kill insects, use smell to select host


July 25, 2017

A new study published in PLOS Pathogens found that nematodes (Steinernema carpocapsae) secrete deadly proteins to kill insects that damage crops. S. carpocapsae kills more than 250 insect pests that attack plants, according to UCR Today.

Prior to the study it was believed that bacteria — working in tandem with nematodes — killed the insects.

“It’s all really science fiction-like,” said co-author Adler Dillman, an assistant professor at the University of California, Riverside. “These microscopic nematodes crawl into the host, poop out toxic bacteria and then spit out the venom and turn the host into an insect milkshake.”

Researchers of the study “Activated entomopathogenic nematode infective juveniles release lethal venom proteins” collected the venomous proteins from the nematodes after exposure to insect tissue. They found the protein mixture was highly toxic to multiple species of insects, including adult fruit flies (Drosophila melanogaster).

In other nematode findings, the article “Host seeking parasitic nematodes use specific odors to assess host resources” published in Scientific Reports shows how nematodes use smell to seek out uninfected insects: Any insect already infected emits an odor, prenol, that is “repulsive” to nematodes looking for a new host, the study says.

“The nematodes are using odors like prenol to identify insects that are already infested and therefore not worth infecting because they have depleted resources,” said Tiffany Baiocchi, a graduate student in the university’s department of nematology and author of the paper in Scientific Reports. “Instead, the parasites are more likely to choose insects that are not emitting prenol, since those represent untapped resources,” she told UCR Today.

The university says researchers are hopeful they will find new insecticidal compounds to control insect pests.


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