LSU AgCenter entomologist Blake Wilson looks at masses of apple snail eggs growing on rice plants in a crawfish pond. Photo by Craig Gautreaux

In the battle against insects that prey on rice, insecticides play a critical role in helping farmers keep damage to their crop to a minimum.

LSU AgCenter scientists stay on top of new insecticide options and insect threats, conducting studies to identify the best chemical control strategies. They’re also exploring other methods of managing insect populations, such as cultural practices and developing rice varieties that are resistant to pests.

“Alternative tactics are needed to improve sustainability through reduced costs and environmental impacts,” said entomologist Blake Wilson.

He is working on several projects with fellow entomologist Mike Stout and rice breeder Adam Famoso.

The researchers have worked over the past year to analyze rice water weevil and stem borer susceptibility levels in advanced experimental lines as well as current commercial varieties. They’ve categorized the resistance levels and will use that information to make better recommendations to growers this fall.

They also are examining novel sources of resistant germplasm that could offer weevil and borer resistance. And they want to learn more about how silicon and volatile compounds influence rice plants’ resistance to insects. Plants that are deficient in their uptake of silicon from the soil display extreme susceptibility to brown spot disease, and it is possible the deficiency also affects insect susceptibility.

Apple snail eggs. Photo by Craig Gautreaux

Other ongoing projects focus on the following:

• Apple snails. The entomologists have found that copper sulfate can provide about 80% control of apple snails, which continue to increase in number and in range, without harming crawfish. In the next year, the scientists want to pinpoint the conditions that are most conducive to apple snail infestations in rice and crawfish ponds.
• Row rice. As this furrow-irrigated growing system becomes more popular, entomologists have found billbugs to be a problem in row rice fields. Seed treatments have proven ineffective in controlling billbugs, so research plans include learning more about billbug biology, developing better scouting strategies and estimating potential yield losses.
• Insecticidal seed treatments. They appear to be up to 50% less effective in controlling the rice water weevil and stem borers in rice that was planted late in May. March-planted rice fared better. The researchers recommend considering foliar insecticide applications to protect yields in late-planted rice.
• Emerging pests. Entomologists are keeping an eye on Mexican rice borer populations as they spread eastward and northward in Louisiana. They also are monitoring for infestations of the South American rice miner, which is a growing threat to late-planted rice, and the rice delphacid, a pest not yet in Louisiana but that has caused severe damage to rice in neighboring Texas.