Symbiosis Marks Innovative Front in Battle to Control New World Screwworm

Above: LSU AgCenter entomologists Honglin Feng and Kristen Healy recently received a $691,000 U.S. Department of Agriculture Animal and Plant Health Inspection Service grant to conduct research on symbionts in an effort to combat the New World screwworm, seen here, which has recently reemerged in the United States. Stock photo

Two LSU AgCenter scientists are studying how to use symbiosis to potentially control a dangerous pest that is anything but harmless — the New World screwworm.

AgCenter entomologists Honglin Feng and Kristen Healy recently were awarded a U.S. Department of Agriculture Animal and Plant Health Inspection Service grant totaling $691,000 to conduct research focusing on engineered microbial symbionts that express lethal double-stranded RNA to control the New World screwworm (Cochliomyia hominivorax). The hope is to strengthen protection of livestock and wildlife and enhance U.S. preparedness against the pest’s recent reemergence.

The idea is to piggyback on the sterile insect technique, which entails releasing genetically modified sterile male insects into targeted areas to mate with females. Because females typically mate only once per life cycle, the technique results in a mass die-off. This was the method first used to eradicate the New World screwworm in the U.S. in the 1960s, then again in the 1980s.

The Feng/Healy research focuses on culturing, engineering and testing defined, tractable symbionts — organisms that rely on hosts to live — using a secondary screwworm, thus establishing a symbiont-based RNA interference (RNAi) control platform that complements existing sterile insect technique programs. The secondary screwworm (Cochliomyia macellaria) larvae feed on dead or decaying flesh, so are not a danger to livestock.

In layman’s terms, Feng explained that the technology he is developing can be applied on top of the sterile insect technique by engineering symbionts that will attach to sterile male secondary screwworm hosts. This will eliminate the need to inoculate millions of insects repeatedly before releasing them into the wild. ■ V. Todd Miller

AgCenter Debuts Two Promising New Rice Varieties

Next year, rice farmers will be able to plant two fresh releases from the LSU AgCenter that address key disease and grain quality issues.

The varieties — Suivant and LA22-1082 — were unveiled June 24 at the 117th annual field day at the AgCenter H. Rouse Caffey Rice Research Station near Crowley.

Suivant, a conventional long-grain variety, bears strong resemblance to a popular release called Avant, said Adam Famoso, station director and rice breeder. Both have good milling quality, reach heading and maturity early and have good ratoon, or second, crop potential.

“We see slight improvements on the first crop potential with Suivant, but one of the biggest benefits of this variety over Avant is the blast resistance,” Famoso said.

The other new release, LA22-1082, is a Clearfield long-grain variety.

“It has excellent grain appearance, very low chalk, very long grain,” Famoso said. “It’s shown excellent milling and, most importantly, exceptional yields. In four years of our testing across the state, it’s been our top-yielding line.”

The variety ratoons well and is taller, which boosts its tolerance of sheath blight disease. It also generates more biomass, a positive for rice farmers who rotate fields to crawfish production. ■ Olivia McClure