LSU AgCenter entomologists Dr. Mike Stout and Dr. Natalie Hummell pick rice water weevils for testing new compounds that could be used to treat for the pest. (Photo by Bruce Schultz)

Rice water weevils are the No. 1 insect pest faced by rice farmers. (Photo by Bruce Schultz)

LSU AgCenter entomologist Dr. Mike Stout is continuing his work to help farmers with their No. 1 insect pest, the rice water weevil.

Stout said the new chemical seed treatment, Dermacor, has been effective on drill-seeded fields, but it is not yet approved for water-seeded rice. "I think there’s a chance that will change," he said.

Stout also said he is testing three insecticides to fight weevils. One is a granular that is applied pre-flood or post-flood to kill larvae, and two are seed treatments.

"All three of them work well," Stout said. "We’re still trying to figure out how they work best."

Stout said he also is testing neonicotinoid pesticides that would be used on stinkbugs. The chemicals are good alternatives to pyrethroids and have longer residual activity, Stout said.

In addition, Stout continues to study how agricultural practices could affect insect pressure. For example, studies with early-planted rice show the practice can result in lower weevil numbers.

Stout said he is studying different varieties and lines to find out if any of them have resistance to weevil infestations. Included in the study are the varieties developed at the LSU AgCenter’s Rice Research Station since it opened almost 100 years ago.

"It looks like the older lines may be more resistant," he said.

Some newer varieties, such as CL 161, appear to be highly susceptible, Stout said.

The LSU AgCenter entomologist said it’s possible traits from varieties and experimental lines that appear to be resistant to weevils could be incorporated into newer varieties without diminishing other desired traits. –Bruce Schultz