Entomologist studying whether stinkbug spraying threshold needs to change

Frances Gould  |  10/24/2013 7:26:14 PM

LSU AgCenter entomologist Dr. Mike Stout, at right, and research associate Marty Frey, left, collect stinkbugs for a study to determine if the threshold for spraying rice for the insect should be changed.

LSU AgCenter entomologist Dr. Mike Stout is studying whether the long-standing threshold for spraying rice for stinkbugs should be changed.

Stout said 2010 was the first year for the three-year project, so he doesn’t have enough information to make any recommendations to farmers yet.

New varieties and new agricultural practices have been developed since the threshold was de veloped more than 25 years ago, Stout pointed out, and recent data from research in Texas indicates the number was too low.

The LSU AgCenter entomologist and his research associates placed cages in test plots on the Rice Research Station to get a better idea of how much damage can be caused by specific numbers of stinkbugs. Stinkbugs were released inside the cages, and grain harvested from inside the structures will be examined for damage.

These experiments are the first step in developing a new threshold.

The currently recommended level is more than three bugs in 10 sweeps during the first two weeks of heading and then 10 bugs in 10 sweeps for the second two weeks of heading.

Stout said it is likely the old standby, methyl parathion, will be taken off the market by federal regulators, leaving the pyrethroids, such as Karate, Mustang Max, Prolex and Declare. But he said there are indications stinkbugs are becoming resistant to pyrethroids.

Because of that issue, alternative insecticides for rice stink bug control are being evaluated, and new products could be available as early as 2011, Stout said.

"We also are looking to see if some varieties are more susceptible to stinkbug damage," he said.

Stout said a study is being done to determine if rice releases a chemical that stinkbugs interpret as a feeding invitation. He said it’s possible a monitoring system could be used to detect when such a chemical is released and then alert farmers they should be on the lookout for stinkbugs.

The use of sweep nets also is being studied, according to Stout, who said research so far has shown only 15 to 20 percent of stinkbugs in a field are recovered by sweep nets.

Stout said work on chemicals to control rice water weevils in water-seeded rice also is continuing. He said several new products could be released to the market during the next few years to help farmers fight weevil problems.

Checkoff funds for this
project in 2010: $85,000

(This article was published in the 2011 Louisiana Rice Research Board Annual Report.)

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