Schultz Bruce, Blanchard, Tobie M., Gould, Frances I.
LSU AgCenter entomologist Jeff Davis, right, shows field day attendees insect damage on a soybean plant at the Dean Lee Research and Extension Center in Alexandria. Photo by Olivia McClure
Photo by Dr. Matthew Baur, formerly of the LSU AgCenter, Entomology Deptartment
LSU AgCenter entomologist Jeff Davis is working on methods of controlling redbanded stink bugs without increasing soybean looper populations.
Pyrethroid insecticides are one of the best ways to control redbanded stink bugs, but loopers are resistant to the chemical, which kills beneficial insects that prey on loopers. Acephate also is effective against stink bugs, but it also has the downside of increasing loopers.
“When you remove all beneficial predators, the looper population grows exponentially,” Davis said.
Loopers don’t overwinter in the U.S. The moths migrate on winds sweeping out of the Caribbean islands and Mexico where high doses of pyrethroids have resulted in resistant populations.
“There are some populations resistant to all products available for control,” Davis said.
Insecticides for stink bugs and loopers — such as pyrethroid for stinkbugs and a diamide for loopers — can be tank-mixed and sprayed simultaneously, Davis said. But the loopers tend to feed deep within the soybean canopy and may be missed by sprayed applications. Some equipment modifications are possible for spray rigs to ensure loopers are controlled with these applications.
Insecticide residue on plants is likely to be removed by frequent rains this year, Davis said.
Tests of different insecticide combinations are being conducted this year at the Ben Hur Research Station near Baton Rouge, the H. Rouse Caffey Rice Research Station near Crowley, the Dean Lee Research Station near Alexandria and the Sweet Potato Research Station in Chase.
On-farm testing also will be conducted throughout the state at locations that typically have high stink bug and looper infestations.
Loopers tend to start showing up in southern parishes first, Davis said, and the highest numbers usually occur in August.
Loopers’ natural enemies include a parasitoid wasp and spiders, but both are killed by pyrethroids. Davis is also conducting research on how effective these predators are against loopers.
The LSU AgCenter and the LSU College of Agriculture